NeuroSymposium 2021 Abstracts

Published online: 2 August 2021

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Neurophysiology, Synapses and Glia

Role of calcium sensor proteins in somatodendritic dopamine release

Jana Kano¹, Benoît Delignat-Lavaud¹, Nicolas Giguère¹, Samuel Burke Nanni¹, Louis-Éric Trudeau¹
¹Université de Montréal, Montreal, QC, Canada
Corresponding Author: Jana Kano, email jana_kano@hotmail.com

Abstract

Dopaminergic neurons play a key role in many functions including motor control and motivation. These neurons originate in the mesencephalon, particularly within the ventral tegmental area (VTA) and the substantia nigra pars compacta (SNc) and their axon projects to the striatum. Not only do these neurons exhibit a classic vesicular release from their axons, but they also release dopamine (DA) from their cell bodies and dendrites. Somatodendritic (STD) release requires different calcium sensors than those found in the axons. Of interest, synaptotagmin 1 (Syt1) has been shown to be implicated in fast DA release in the axons. However, recent research in our lab shows that in mice with conditional knockout (cKO) of syt1 in DA neurons, there is a decrease of STD DA release in the VTA. In addition, Syt1 cKO mice strikingly did not exhibit any major motor dysfunction even with an important decrease in axonal DA release. We are presently considering two hypotheses. The first is that Syt1 is directly involved in STD DA, in which case it should be detectable in the soma or dendrites of these neurons. The second hypothesis is that local axonal collaterals of DA neurons are found in the VTA and contribute to DA release detected in this area, in which case Syt1 positive dopaminergic axonal varicosities should be detectable. I will first use super-resolution microscopy and primary cultured DA neurons to test the first hypothesis and examine in detail the subcellular localisation of Syt1 in these neurons. In preliminary experiments, we were able to obtain high-resolution images of the STD domain of primary mouse DA neurons and we failed to detect Syt1 in the cell body and dendrites. We now plan to extend these experiments by validating these results in a more quantitative way and examine the distribution of Syt1 in comparison to VMAT2 (vesicular monoamine transporter), another protein well known to be present in the STD compartment of DA neurons. We will also test our hypothesis in a more functional way by using optogenetics with a soma-targeted channelrhodopsin (ChR2-Kv) in combination with HPLC to directly measure STD DA release in cultured neurons. Finally, we will test our second hypothesis by labelling DA neuron axons in the intact mouse brain using a conditional EYFP AAV vector and examining with confocal microscopy the presence of dopaminergic axons in the VTA. In preliminary experiments, we used a AAV vector to conditionally express this channel in primary DA neurons. We found that optical stimulation of these neurons with blue light pulses induced an increase in extracellular DA levels. We will now extend these initial experiments by comparing this DA release in Syt1 cKO cultures and WT cultures. Additionally, in initial experiments, we have been able to detect axon-like EYFP-positive structures in the VTA, but further experiments will be necessary in WT and Syt1 cKO mice to evaluate if these varicosities in WT mice contain or not Syt1. This research will contribute to a better understanding of the fundamental mechanisms of DA release in the brain. Because in animal models of Parkinson’s disease, STD DA release is more resilient compared to axonal DA release, we hypothesise this form of release is critical for functional compensations at early stages of this disease.

Implication de la co-transmission glutamatergique des neurones à sérotonine dans les dyskinésies induites par la L-Dopa.

Lydia Saïdi¹, Christophe Proulx¹, Martin Parent¹
¹Centre de Recherche CERVO, Université Laval, Québec, QC, Canada
Corresponding Author: Lydia Saïdi, email lydia.saidi.1@ulaval.ca

Abstract

La maladie de Parkinson (MP) se caractérise par une perte progressive des neurones dopaminergiques de l’axe nigrostriatal. A ce jour, le traitement pharmacologique le plus efficace est la prise quotidienne du précurseur de la dopamine, la L-3,4-dihydroxyphénylalanine (L-Dopa). Cependant, son utilisation chronique entraîne au bout de quelques années l’apparition d’effets secondaires handicapants : des mouvements involontaires anormaux connus sous le nom de dyskinésies. Des découvertes récentes suggèrent l’implication des neurones à sérotonine (5-HT) dans l’expression de ces dyskinésies induites par la L-Dopa. A travers cette étude, nous avons déterminé le rôle fonctionnel de la co-transmission glutamatergique par les neurones 5-HT du noyau raphé dorsal (NRD) dans l’expression des dyskinésies. Nous avons utilisé la méthode CRISPR/Cas9 et des injections virales dans le but de déléter ou surexprimer le transporteur vésiculaire du glutamate de type 3 (VGluT3) spécifiquement dans les neurones 5-HT du NRD de souris adultes. Après caractérisation de ces différents modèles de souris transgéniques, une injection intracérébrale de 6-hydroxydopamine entrainant une lésion spécifique des neurones dopaminergiques nigrostriataux a été réalisée sur ces souris, suivie d’une administration quotidienne de L-Dopa induisant des dyskinésies. Les tests d’hybridation in situ (RNAscope) et de triple immunomarquage ont confirmé la déplétion ou surexpression de VGluT3 dans les neurones 5-HT infectés du NRD. Les tests de comportements ont montré une augmentation significative de l’activité verticale, de l’impulsivité et un manque d’intérêt pour une récompense des souris déplétées en VGluT3, sans modification de comportements des souris surexprimant VGluT3. Après lésion dopaminergique et traitement par L-Dopa, les souris déplétées montrent une susceptibilité accrue aux dyskinésies par rapport aux souris contrôles ou surexprimant VGluT3. Grâce à ces différents modèles de souris transgéniques, nous avons pu mettre en évidence l’implication de VGluT3 dans la régulation de comportements moteurs, impulsifs et ceux impliquant le système de récompense ainsi que son implication dans la régulation des mouvements involontaires anormaux induits par L-Dopa.

Le modèle des ganglions de la base revisité par l’étude unitaire des caractéristiques neurochimiques et anatomiques des neurones striatofuges

Laetitia R. Reduron^1,2, Martin Parent^1,2
¹Département de Psychiatrie et Neurosciences, Faculté de médecine, Université Laval, Québec, QC, Canada
²Centre de Recherche CERVO, Québec, QC, Canada
Corresponding Author: Laetitia Rouleau Reduron, email laetitia.reduron.1@ulaval.ca

Abstract

Le striatum (STR) est la principale composante intégratrice des ganglions de la base (GB), avec peu de projections efférentes ciblant principalement le globus pallidus (GP), le noyau entopédonculaire (ENT) et la substance noire reticulée (SNr). Le modèle actuel des GB repose sur la ségrégation des projections striatales efférentes en une voie directe et une voie indirecte, ayant respectivement pour origine les neurones GABAergiques striataux exprimant le récepteur dopaminergique D1, la substance P (SP) et la dynorphine (DYN) et projetant à la SNr et l’ENT; et les neurones striataux exprimant D2 ainsi que l’enképhaline (ENK) et projetant au GP. Toutefois, des études de traçage axonal unitaire effectuées chez le rat et le singe ont démontré que la plupart des neurones striataux possèdent un axone s’arborisant dans toutes les cibles du STR, suggérant que les projections striatales efférentes ne soient pas aussi ségréguées qu’on ne les pensait. Nous présentons ici des données préliminaires qui supportent cette hypothèse en montrant la distribution peptidergique dans les neurones striataux D1 et D2. Nous procédons présentement à la reconstruction axonale entière et unitaire de neurones striataux D1 et D2 chez la souris, ainsi qu’à la description de la distribution peptidergique (SP, DYN, ENK) dans leurs axones. Des injections in vivo d’AAV cre-dépendant ont été réalisées dans le STR de souris transgéniques DRD1-cre et DRD2-cre. Un marquage immunohistochimique pour SP, DYN et ENK a permis de visualiser la distribution peptidergique dans les neurones infectés en utilisant la microscopie confocale. Au moment de la soumission, des expériences sont encore en cours de réalisation. Des données préliminaires ont été acquises, montrant la distribution d’ENK, SP et DYN chez les axones infectés D1 et D2, et ce, dans toutes les cibles du STR. Nos données préliminaires supportent l’hypothèse voulant que les neurones striataux D1 et D2 transportent le GABA et des neuropeptides dans leur axone qui s’arborisent dans toutes les cibles du STR, où ils libèrent ces peptides de manière différentielle. De pair avec des reconstructions axonales unitaires des neurones infectés D1 et D2, nous visons à caractériser le transport axonal complexe des neuropeptides dans l’axone collatéralisé des neurones striatofuges.

Remodelage de la connectivité corticale causé par un accident vasculaire ischémique dans le cortex visuel de la souris

Solenn Tissier¹, Catherine Albert¹, Véronique Chouinard¹, Bruno Oliveira¹, Christian Casanova¹, Jean-François Bouchard¹, Matthieu Vanni¹
¹Université de Montréal, Montréal, QC, Canada
Corresponding Author: Solenn Tissier, email solenn.tissier@umontreal.ca

Abstract

Lors d’un dommage cortical causé par exemple, par un accident vasculaire cérébral (AVC), une partie des fonctions corticales perdues peuvent être récupérées grâce à des mécanismes cellulaires et moléculaires permettant d’induire une plasticité corticale. Ces réorganisations impliquent des modifications dans la connectivité entre les régions ainsi que dans les propriétés fonctionnelles des aires corticales épargnées. Grâce au développement important de l’imagerie calcique ces dernières années, les connexions et les propriétés fonctionnelles des différentes régions du cortex peuvent être mesurées longitudinalement sur la souris avec une grande précision. Plusieurs études ont montré l’implication des récepteurs aux endocannabinoïdes sur la plasticité et la croissance neuronale. L’objectif de cette étude était de démontrer l’impact des récepteurs aux endocannabinoïdes sur la réorganisation fonctionnelle du cortex à la suite d’un AVC dans le cortex visuel (cécité corticale). Dans cette étude, n=22 souris femelles de 2 à 4 mois ont été utilisées. Les souris ont été injectées (IV) avec un virus permettant l’expression d’un indicateur calcique dans tout le cortex (AAV, PHPeB, Syn, GCaMP6s). Suite à l’implantation d’une chambre optique chronique, l’imagerie calcique du cortex dorsal a été évaluée avec et sans stimuli visuels toutes les semaines. Après trois semaines de mesures d’activité normale, un accident vasculaire cérébral a été induit dans le cortex visuel primaire par photothrombose. Du rose bengal a été injecté (IP) à la souris et un laser vert a été utilisé pour réaliser une thrombose focalisée dans le cortex visuel. Les limites des dommages corticaux ont alors été établies grâce à l’imagerie Speckle permettant de mesurer spatialement des baisses de flux sanguin. Ces limites ont ensuite été confirmées par anatomie. Après l’induction de la photothrombose, nous avons alors mesuré les changements de connectivité fonctionnelle au repos, de la rétinotopie du cortex et de sensibilité aux contrastes et aux fréquences spatiales et temporelles toutes les semaines pendant 8 semaines post AVC. Nos résultats préliminaires d’anatomie et d’imagerie Speckle nous ont montré que le modèle de photothrombose pouvait induire une lésion définie de 1 mm3 associée à des déficits à long terme. L’absence de récepteurs CB2 a perturbé la réorganisation fonctionnelle à la suite de ces lésions dans le cortex visuel. Cette approche va nous permettre d’étudier les mécanismes impliqués dans la plasticité corticale à la suite d’une lésion dans le cortex visuel. Dans le futur, l’impact de l’environnement dans lequel se développe un animal va être exploré grâce à cette approche expérimentale.

Synaptic alterations of neuronal outputs from the lateral habenula in the model of chronic social defeat

Jose Cesar Hernandez Silva¹, Nikola Pausic¹, Christophe Proulx¹
¹Département de Psychiatrie et Neurosciences Faculté de Médecine Université Laval, Québec ,QC, Canada
Corresponding Author: Jose Cesar Hernandez Silva, email jose-cesar.hernandez-silva.1@ulaval.ca

Abstract

The Lateral Habenula (LHb), the main disappointment center of the brain, is a glutamatergic nucleus located in the dorsal part of the thalamus. It is a key region connecting affective signals from various limbic nuclei to the monoaminergic centers of the midbrain. In people with depression, as well as in various models of depression, LHb is hyperactive. However, how synaptic transmission to different aminergic centers is affected in depression is not known. Here, we use optogenetics and electrophysiology measurements to examine the synaptic transmission from LHb to three of its main downstream targets: the serotonergic dorsal raphe nucleus (DRN), the rostromedial tegmental nucleus (RMTg) and the ventral tegmental area (VTA), in mice under chronic social defeat stress (CSDS). To selectively activate LHb efferent, an AAV-ChR2-mCherry was first injected into the LHb. Ten days later, the mice were subjected to 10 days of CSDS and tested in the social interaction test (SI) to determine their resilience or susceptibility to chronic defeat stress. Acute brain sections were obtained from control, sensitive and resilient mice and synaptic transmission was examined using whole-cell patch-clamp recordings. At the LHb-DRN synapses, chronic stress did not change paired-pulse ratio (PPR) but increased the evoked AMPAr/NMDAr ratio in susceptible mice. At the LHb-RMTg synapses, CSDS decreased paired-pulse ratio both in susceptible and resilient mice but no change was observed in AMPAr/NMDAr ratio. Finally, at the LHb-VTA synapses, CSDS decreased AMPAr/NMDAr ratio in resilient mice while no change was observed for PPR. These results show that synaptic transmission to neuronal LHb outputs is affected differently by CSDS and suggest that these neuronal LHb outputs contribute in different ways to the development or maintenance of depressive disorders.

Light-inducible α-synuclein aggregation in the midbrain disrupts nigrostriatal dopaminergic transmission

Raquel Rodriguez-Aller^1,2,3, Sarah Malvaut^3,4, Morgan Bérard^1,2, Razan Sheta^1,2, Armen Saghatelyan^3,4, Abid Oueslati^1,2
¹Axe Neurosciences du Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec, QC, Canada
²Department of Molecular Medicine, Faculty of medicine, Université Laval, Quebec City, QC, Canada
³CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
⁴Department of Psychiatry and Neurosciences, Faculty of medicine, Université Laval, Quebec City, QC, Canada
Corresponding Author: Raquel Rodriguez Aller, email raquel.rodriguez-aller.1@ulaval.ca

Abstract

Parkinson’s disease (PD) is characterized by intracellular inclusions of misfolded α-synuclein (α-syn), known as Lewy bodies, and by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNc) that leads to dopamine (DA) depletion at the striatum. However, it remains elusive how the aggregates of α-syn can affect the normal function of dopaminergic projections, especially due to the absence of proper models that can reproduce the features of PD. In this context, our laboratory has recently developed an in vitro and in vivo model of PD based on the optogenetics technology named LIPA (light-inducible protein aggregation) that controls the aggregation of α-syn under the control of blue light. We showed that LIPA mimics the histopathological characteristics of PD, and allow thus to study how the aggregation of α-syn in dopaminergic cells of SNc can cause a progressive disruption in the nigrostriatal pathway. To investigate the impact of LIPA-induced α-syn aggregation on the dopaminergic projections, we assessed the activity of striatal cells. Briefly, we implanted mini-endoscopes coupled with an optic fiber to induce α-syn aggregation in the SNc, and analyzed the neuronal activity using the calcium indicator GCaMP6s in the striatum of freely moving mice. Our results show a progressive decrease in the synchronized activity and frequency of striatal cells caused by the aggregation of α-syn. Altogether, our data showed that the use of this new LIPA-α-syn system offer a unique tool to elucidate the morphological, and physiological changes occurring in the dopaminergic projections in the context of PD.

Dissecting the lateral hypothalamic input to the dorsal raphe nucleus and its role in major depression

Renata Sadretdinova¹, Ekaterina Martianova¹, Christophe D.Proulx¹
¹CERVO Brain Research Center, Faculty of Medicine, Université Laval, Quebec City, QC, Canada
Corresponding Author: Renata Sadretdinova, email sadretdinova.renata.1@ulaval.ca

Abstract

Disturbance of the central serotonin system has long been thought of playing a leading role in major depressive disorder. The main serotonergic nucleus of the brain, the dorsal raphe nucleus (DRN), integrates inputs from multiple brain regions, a large fraction of which is coming from the lateral hypothalamic area (LHA). In this study, we have examined whether plasticity at the LHA-DRN pathway contributes to the development of depressive or resilient phenotypes in mice undergoing chronic social stress. To activate LHA terminals in DRN, an AAV-ChR2-YFP was injected in the LHA of 6 weeks old C57BL/6J male mice. Two weeks later, these mice were subjected to chronic social defeat stress (CSDS) protocol. 24-h after CSDS, mice were classified as either susceptible or resilient when evaluated in a social interaction test, and acute brain slices encompassing the DRN were prepared. During whole-cell patch-clamp recordings of DRN neurons, 5 ms blue light pulses were delivered to activate LHA axons terminals, and postsynaptic currents were measured to investigate pre- and postsynaptic plasticity. In resilient mice, we found a significant increase in paired-pulse ratio at GABAergic synapses, indicating the decreased GABA release probability. In susceptible mice, we measured an important trend toward a decrease in the AMPAr/NMDAr ratio, indicating synaptic depression at the LHA-DRN pathway caused by CSDS. These results suggest that synaptic dysfunction at LHA-DRN pathway may play an important role in the behavioral phenotype found in depression.

Optogenetics as a robust method to study cortical connections in mouse visual cortex

Veronique Chouinard¹, Bruno Souza^2,3, Solenn Tissier², Matthieu Vanni^1,2
¹Département de neurosciences, Université de Montréal, Montréal, QC, Canada
²École d’Optométrie, Université de Montréal, Montréal, QC, Canada
³Labeo Technologies Inc., Montréal, QC, Canada
Corresponding Author: Véronique Chouinard, email veronique.chouinard.2@umontreal.ca

Abstract

Studying visual perception require rigorous knowledge on the function and organization of visual areas. Although visual cortex is well-known in primates, its equivalent in murine models remains largely enigmatic. Given the tremendous advantages of mice models in vision neurosciences, the lack of knowledge on the subject represents a serious handicap. Multiple studies have shown that different mouse higher visual areas possess different sensibilities to spatial frequencies and temporal frequencies. Mouse higher visual areas receive inputs from both the primary visual cortex and other higher visual areas; however, it remains unknown how those pathways interact in visual discrimination and scene analysis. Thus, we sought to study how these connections contributes to define mouse visual areas properties using reversible inactivation. Mice will be injected with a vector allowing the expression of a fluorescent calcium sensor and a photoactivated opsin. An optical chamber will be implanted, and we will perform reversible optogenetic inactivation and mesoscopic calcium imaging. Repetitive full-field gratings will be presented to the mice to classify the spatial and temporal selectivity of all visual areas (PM, AM, A, RL, AL, LM et P, V1). Visual areas borders will have been previously identified using mesoscopic retinotopic mapping. Next we will project on the brain patterned-light stimulation using a transformed videoprojector to inactivate specific visual areas during the presentation of a visual stimulus. Our methods have demonstrated that all injected mice show clear visual response in the hemisphere contralateral to the stimulus with an increase up to 10% in fluorescence. Furthermore, areas like the anterolateral (AM) and posteromedial (PM) area show clear segregation of spatial and temporal frequency selectivity as it has been observed before. Next, we confirmed stimulation parameters using excitating opsins. Optogenetic activations have shown promising results; both single-point stimulation and patterned stimulation cause an increase by at least 10% of the calcium response with a precise control over the stimulated area. Early results of optogenetic inactivation experiments have reciprocated the activation experiments by showing, on a similar scale, a decrease in fluorescence. In conclusion, we have demonstrated that photoactivated opsins used in conjunction with patterned-laser stimulation is a robust method to target extrastriate areas and modulate their activity. These methods are crucial for accurate cartography of the functional mouse brain. This project could also have significative impact in fundamental vision neuroscience specifically in murine models who are largely used in neuroscience.

Calcium signaling dynamics of brain pericytes

Braxton Phillips^1,2, Éric Martineau, PhD¹, Ravi Rungta, PhD¹
¹Faculté de Médecine Dentaire, Université de Montréal, Montréal, QC, Canada
²Faculty of Science, McGill University, Montreal, QC, Canada
Corresponding Author: Ravi Rungta, email ravi.rungta@umontreal.ca

Abstract

Brain pericytes are cells embedded in the basement membrane of the central nervous system (CNS) vasculature – a position that signifies them as key mediators of CNS function in health and disease. For example, pericytes help maintain the blood-brain barrier, and exert control over blood flow. In health, brain pericytes display spontaneous calcium signaling confined to microdomains. As calcium signaling is essential for numerous cellular functions, we sought to investigate the mechanisms underlying these signals in brain pericytes. We examined brain pericyte calcium signaling dynamics within ex vivo brain slices of PDGFRB-Cre mice expressing the calcium indicator GCaMP6f. Using the calcium chelator EGTA, we tested whether these signals are mediated by extracellular calcium influx. Next, we perfused specific blockers of ion channels (such as nifedipine to block L-type voltage gated calcium channels) to test if these signals are mediated by influx through a specific calcium-permeable channel. Removal of extracellular calcium with the calcium chelator EGTA largely abolished pericyte calcium signaling, indicating that frequent extracellular calcium influx is required for their spontaneous signals. However, despite transcriptional databases showing the expression of L-type voltage-gated calcium channels (VGCCs), T-type VGCCs, and TRPC3 channels in pericytes, blocking either of these ion channels did not reduce the frequency of spontaneous calcium signals, suggesting that these signals are mediated by a yet unidentified mechanism which requires Ca2+ influx. Future experimentation is needed to uncover the plasma membrane ion channel(s) or transporters that are responsible for spontaneous calcium signaling in pericytes. Likewise, future work should aim to determine if and how these signals are modulated during disease pathology.

An optogenetic approach to modulate the thalamocorticol network

Antonio Inserra¹, Minza Haque¹, Athanasios Markopoulos¹, Gabriella Gobbi¹
¹Neurobiology Unit, Department of Psychiatry, McGill University, Montreal, QC, Canada
Corresponding Author: Minza Haque, email minza.haque@mail.mcgill.ca

Abstract

The activation of the thalamus and its projections to the cerebral cortex are believed to underlie our conscious experience. Thalamo-cortical networks are essential for cognitive and emotional processes, and their dysfunction is implicated in interfering with complex human experiences such as sociability and depression. The vast majority of neuroimaging studies show disruptions in functional and structural connectivity across multiple brain regions in Major Depressive Disorder (MDD). Recent fMRI data has shown that MDD patients have predominantly increased connectivity between the medial thalamus and temporal areas and the severity of symptoms strongly correlates with thalamo-temporal connectivity. In our study, we use optogenetic manipulation to excite or inhibit neurons in the medial prefrontal cortex (mPFC) and the medial dorsal thalamus (MDT) to identify the effects of modulating thalamo-cortical networks on social behavior and neurotransmission. For the optogenetic procedure, mice were anesthetized with isoflurane and their skulls secured on a stereotaxic frame. A single craniotomy was performed and a Hamilton syringe fitted with a 28-gauge needle was used to place a viral bolus (1 μl) at the following coordinates in millimeters within the mPFC (AP: 1.9, ML: 0.4, DV −2.5), and were infused with AAV-CamKII-Arch.3.0-EYFP, AAV-GAD65-ChRh.3.0-EYFP or a control vector expressing eYFP (AAV-CamKII-eYFP). 22 days later, mice were prepared for electrophysiological recordings and a unilateral optic fiber cannula (0.7 mm center-to-center, 200 μM, 0.22 NA, ) was lowered above the viral bolus using the following coordinates (AP:1.9, ML:1, DV: -2.47, with an angle of 20°). Photo-inhibition and excitation was performed using a laser. For in vivo electrophysiology recordings of mPFC pyramidal neurons, mice were anesthetized and placed on a stereotaxic frame. Fiberoptic patchcords (200 μM, 0.22 NA, ) and mono fiberoptic cannulae were connected to a dual laser diode (LD) fiber light source (450nm-75 mW/520nm-60 mW) and lowered into the mPFC together with a multi-barreled recording electrode as mentioned before. After isolating a neuron, mice transfected with the virus received received green or blue light for 10s. For the behavioral experiments, the optical fiber will be implanted 15 days post viral injection. Fibers will be fixed to the skull using dental cement and a pair of skull screws. The mice will be tested in the DSI, TCT, OFT, FST and SPT. Our results indicate that exciting the PFC using an optogenetic approach increases firing rate of pyramidal neurons. Exciting the PFC also increases firing in the reticular thalamus, and induces a sustained rhythmic activity. We anticipate that inhibiting the PFC will decrease firing of pyramidal neurons in the PFC, and decrease the bursting in the reticular thalamus. We anticipate that excitation, but not inhibition of the PFC and MDT will elicit a pro-social behaviour and antidepressive effect in mice. Moldulation of thalamo-cortical circuitry affects social behaviour and neurotransmission in the PFC and RT.

Neural Correlates of Appetitive Pavlovian Extinction

Ingrid Matei¹, Alexa Brown¹, Nadia Chaudhri¹
¹Concordia University, Montreal, QC, Canada
Corresponding Author: Ingrid Matei, email ingrid.matei@mail.concordia.ca

Abstract

Pavlovian extinction occurs when a conditioned stimulus (CS) is no longer followed by an unconditioned stimulus (US). Extinction is a progressive decline in conditioned responding, and is thought to produce new inhibitory learning that does not erase previously acquired associations during conditioning. Previous research investigating the neural mechanisms of appetitive extinction has predominantly focuses on operant drug-seeking procedures. Extinction of appetitive operant conditioning is thought to be mediated by infralimbic cortex (IL) projections to the nucleus accumbens sell (NAcSh). Whether the same pathway mediates the extinction of appetitive Pavlovian conditioning remains unknown. The objective of this study was to investigate c-fos immunoreactivity, an indirect marker of neuronal activity, in subregions of the medial prefrontal cortex (mPFC; IL, prelimbic cortex (PL)) and ventral striatum (nucleus accumbens core (NAcCore), medial NAcSh, and lateral NAcSh) to assess their roles in early vs. late appetitive Pavlovian extinction. After appetitive Pavlovian conditioning, rats in the Paired, Unpaired (ITI), and Unpaired (H-C) training conditions underwent either one extinction (early) or six extinction (late) sessions. We observed similar c-fos expression in the IL of Paired and Unpaired (ITI) conditions following one and six extinction sessions, whereas greater c-fos expression was found in the PL of Paired and Unpaired (ITI) rats following one extinction session compared to six extinction sessions. No statistically significant differences as a function of training condition or extinction group were detected in the NAcCore, lateral NAcSh, and the medial NAcSh. Together, these findings suggest that the IL, but not the PL, play a role in the inhibition of conditioned responding through its continual activation in appetitive Pavlovian extinction. Our results support the hypothesis of the opposing roles of the mPFC subregions in learning, with the IL being important in the inhibition of conditioned responding during extinction, and the PL being important in the expression of appetitive conditioned responding.

Role of the calcium sensor synaptotagmin-1 in dopamine release

Benoît Delignat-Lavaud^1,2,3, Jana Kano^1,2,3, Ian Massé⁴, Charles Ducrot^1,2,3, Sriparna Mukherjee^1,2,3, Nicolas Giguère^1,2,3, Catherine Lévesque⁵, Marie-Josée Bourque^1,2,3, Samuel Burke Nanni^1,2,3, Daniel Lévesque⁵, Louis De Beaumont⁴, Louis-Éric Trudeau^1,2,3
¹Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
²Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
³Groupe de recherche sur la signalisation neurale et la circuiterie, Montréal, QC, Canada
⁴Hôpital du Sacré-Coeur-de-Montréal, Université de Montréal, Montréal, QC, Canada
⁵Faculté de Pharmacie, Université de Montréal, Montréal, QC, Canada
Corresponding Author: Benoît Delignat-Lavaud, email bdelignat@gmail.com

Abstract

Dopamine (DA) neurons of the mesencephalon play a key role in motor control, motivated behaviors and cognition. DA neurons can release DA via an exocytotic mechanism from their axonal terminations or from their somatodendritic compartment (STD). In this study, we explored the role of Syt1, the main calcium sensor of the synaptotagmin family, in axonal and STD DA release. Conditional Syt1 KO mice in the DA system (Syt1 cKODA) were generated and we’ve evaluated the impact of the Syt1 gene deletion by using Fast Scan Cyclic Voltammetry, immunostainings, confocal imaging, stereological counting, autoradiography, primary culture model, biomolecular and behavioral assays. Measurement of evoked DA release by cyclic voltammetry in brain slices of conditional Syt1 KO (cKODA) mice showed a 94% decrease in the striatum and a 69% decrease in the midbrain, demonstrating a key role of Syt1 in these two forms of release. Surprisingly, despite this dramatic impairment of DA release, Syt1 cKODA mice do not exhibit any obvious motor defects in multiple taks including the pole-test, the grip strength test, the rotarod and in open field locomotion after treatment with cocaine, amphetamine or DA receptor antagonists. Important adaptations of the DA system of these mice were revealed by immunostaining, confocal microscopy and autoradiography. Strikingly, basal extracellular levels of DA in the striatum measured by microdialysis/HPLC are unchanged by the deletion of Syt1, suggesting that spontaneous DA release is unaffected and key to maintain motor behaviors. Overall, while demonstrating the involvement of Syt1 in evoked-DA release, our study also reveals the plasticity of the dopaminergic DA system in the context of a near-abolition of phasic DA release. These Syt1 cKODA mice represent an interesting new tool for studying the mechanisms and roles of spontaneous DA release. These findings may also be relevant to understand why motor functions are so resilient in Parkinson's disease, with impairements only appearing after extensive loss of DA neurons.

Cognitive impairment in mice with a gain-of-function mutation in retinoic acid receptor beta (RARB)

Devanshi Shah^1,2, Eve Racette^1,2, Jacques L. Michaud^1,2
¹Centre de Recherche du Centre Hospitalier Universitaire Sainte-Justine, Brain and Child Development, Montreal, QC, Canada
²Department of Neuroscience, Université de Montreal, Montreal, QC, Canada
Corresponding Author: Devanshi Shah, email devanshi.shah@umontreal.ca

Abstract

Retinoic acid (RA) signaling has emerged as an essential regulator for the development of the brain. In target cells, RA transduces its signal by binding to heterodimers formed by retinoic acid receptor (RAR) and retinoic X receptor (RXR), which function as transcription factors by binding to RA response elements. Our group has previously described that patients with mutations in retinoic acid receptor beta gene (RARB) show motor and cognitive impairment. We found that these mutations increase the RA-induced transcriptional activity of RARB by 2- to 3- fold in the context of an in-vitro assay, suggesting a gain-of-function (GOF) mechanism. We hypothesize that the disruption of RARB signaling impairs cognition by affecting the development and/or function of the striatum, where RARB is primarily expressed. To investigate this hypothesis, we used Crispr-Cas9 technology to generate mice carrying the variant p.Arg394Cys (p.R394C), which is homologous to the GOF variant p.Arg387Cys (p.R387C) found in almost half of the patients. RarbR394C/R394C mice die perinatally whereas RarbR394C/+ mice survive and show a motor behavior that is reminiscent of that of the patients. We have assessed the behavior of RarbR394C/+ and wild-type mice at P60 aged mice using the novel object recognition, contextual fear conditioning, and T-maze paradigms. Additionally, to determine whether these cognitive deficits are linked to some striatal dysfunction, we are comparing the transcriptome of the striatum of embryos and adult mice with various genotypes at E18.5, P0, and P40. Behavioral assessment of RarbR394C/+ mice showed a strong decrease in freezing behavior in the contextual fear conditioning paradigm as well as deficits in exploration time of the novel and familiar object in the novel object recognition paradigm. However, spatial working memory was not altered in the T-maze. Transcriptomic studies of the striatum of adult RarbR394C/+ mice showed significant changes in the expression of direct targets of RARB, including components of the dopamine signaling pathway, when compared to the striatum of wild-type mice. Rarb gain of function (GOF) causes cognitive deficits potentially associated with the disruption of dopamine signaling in the striatum. This work will shed light on a form of intellectual disability as well as common neurodegenerative disorders of the basal ganglia including Huntington’s and Parkinson’s disease, in which RA and RARB signaling appears to be compromised.

Nicotine Self-administration Behavior Under Continuous Access Versus Intermittent Access Conditions in Male and Female Rats

Hajer E. Algallal¹, Anne N. Samaha²
¹Department of Biomedical Sciences, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
²Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
Corresponding Author: Hajel Algallal, email Hajer.algallal@gmail.com

Abstract

Tobacco smoking is the main cause of preventable disease in Western Europe and North America, where it is the cause of one in five deaths (Danaei et al, 2009; Hughes, 2016). Most preclinical studies on nicotine have used self-administration procedures that provide continuous nicotine access during each self-administration session (Long-access). However, cigarette smokers consume cigarettes intermittently, rather than continuously throughout each day. We are going to compare nicotine-seeking and -taking behaviours in female and male rats given long access (LgA; continuous nicotine access, 6 h/day) versus intermittent access (IntA; 12 min ON, 60 min OFF, for 6 h/day) to nicotine (15 µg/kg/infusion) for 10 daily sessions. We will assess consumption patterns, the incentive motivation to take nicotine as measured by breakpoints under a progressive ratio schedule of reinforcement of nicotine reinforcement, as well as cue- and nicotine-induced reinstatement of nicotine-seeking behaviour (measures of relapse) after abstinence. For now, the results are not complete, I am still running the experiment, but they will be ready soon. The expected results would have important implications for modeling distinct features of tobacco addiction in preclinical studies and for the design of studies examining sex differences in the response to nicotine at different stages of the addiction process.

Neuropsychology, Cognitive, Clinical Neurosciences

Art-based Rehabilitation Training (ART) for Upper Limb Sensorimotor Recovery Post Stroke: A Pilot Study

April Christiansen, MSc¹, Marta Scythes, MSc¹, Mary-jo Demers, PT¹, Ben Ritsma, MD¹, Vince DePaul, PT, PhD¹, Stephen Scott, PhD¹
¹Queen's University, Providence Care Hospital
Corresponding Author: April Christiansen, email 15ac106@queensu.ca

Abstract

High repetitions of task-oriented practice are essential to drive motor and functional recovery of the upper limb (UL) after stroke. Unfortunately, therapy time focused on arm and hand function is limited and movement repetitions low. Art-based Rehabilitation Training (ART) is a program designed to augment UL rehabilitation by engaging stroke survivors in progressive, structured art-based activities outside of conventional therapy sessions. The objectives of this study were to assess the feasibility of delivering ART in an inpatient setting, collecting clinical and robotic-based measures of sensorimotor function, and quantifying UL use during ART sessions. A convenience sample of patients admitted to a stroke rehabilitation unit with hemiparesis (n=36) were enrolled in the ART program. The program included 9 sessions of supervised tracing and free-hand drawing tasks completed with both hands over 3 weeks. Feasibility outcomes included session completion, acceptability, and outcome assessment completion. Activity intensity was quantified as session time and UL movement time measured by forearm-mounted accelerometers. Sensorimotor function was assessed using the Kinarm robot and clinical measures recorded at baseline, immediately post-training, 2-months and 6-months post-ART. Program retention and acceptability were high, with 29 (80%) participants completing ART and reporting high levels of satisfaction. Participants completed an average of 8 (±2) sessions. ART session duration recorded from a subset 13 participants (77 sessions) yielded a median [IQR] session time of 44 [35-53.3] minutes. In-session UL movement time ranged from 15.2-47.1 minutes. Kinarm and clinical measures were feasible to collect and baseline and post-ART but challenging to collect at 2 and 6 months. The ART Program was shown to be feasible to implement, acceptable to patients, and result in augmented UL activity in patients undergoing stroke rehabilitation. Further research is warranted to explore the impact of this program on sensorimotor control, function and UL use.

Exploration of salient factors involved in mild cognitive impairment

Alexandria Samson¹, Anthony R. McIntosh¹
¹Rotman Research Institute & University of Toronto, Toronto, Canada
Corresponding Author: Alex(andria) Samson, email asamson@research.baycrest.org

Abstract

Mild cognitive impairment (MCI) is a prevalent and complex condition among older adults that often progresses into Alzheimer’s disease (AD). Although MCI affects individuals differently, there are common indicators of risk and indicators of protection against MCI that are associated with the development of the condition including: sex, educational attainment, cerebral spinal fluid (CSF) biomarker levels, and cardiovascular health. To mitigate MCI and other dementias, risk and protective factors need to be recognized and understood to develop preventative plans and treatments. Using a multivariate approach, we were able to explore relationships, trends, and specificity of seven MCI risk factor categories within a large sample of cognitively healthy older adults compared to those diagnosed with MCI (n = 531). To extract the salient dimensions that differentiated the groups, partial least squares was used. Five risk factor categories were established as significantly different across the diagnosis groups. At the group level, the cognitively healthy groups differentiated from the MCI groups. As would be expected, the neuropsychological risk factors differed the most across groups such that the cognitively healthy groups performed better on the memory and cognitive assessments while, the MCI groups had larger functional health scores, such as less independence. Participants with subjective and objective cognitive impairment demonstrated CSF biomarker concentrations similar to AD-like pathological levels. -ApoE4 carriers were more common among the healthy control group while, +ApoE carriers were more common among the more severe MCI group (late MCI). Unlike previous research, poor cardiovascular health, older age, and lower educational attainment had no relation to MCI diagnoses in our sample. Altogether, the results highlighted factors that were more pervasive in persons with MCI, due to probable AD, which establishes possible future directions to concentrate on for both MCI and AD research.

Fréquence de l’intérêt précoce pour le matériel écrit en autisme : étude sur dossiers

Marie-Pier Côté¹, Alexia Ostrolenk¹, Laurent Mottron¹
¹Université de Montréal, Montréal, QC, Canada
Corresponding Author: Marie-Pier Côté, email marie-pier.cote.6@umontreal.ca

Abstract

L’hyperlexie, une condition fréquemment associée à l’autisme, est définie par un développement atypique des capacités de lecture. En fait, 6% à 20% des enfants autistes seraient hyperlexiques. Ces enfants apprennent à lire très tôt en l’absence d’enseignement explicite. Bien que l’intérêt précoce pour le matériel écrit soit le premier signe le plus souvent observable de l’hyperlexie, aucune étude ne l’a documenté. La présente étude sur dossier s’intéresse donc à la fréquence de l’intérêt précoce pour le matériel écrit chez 56 (52,68±2,09mois;37M) enfants ayant été référés pour une évaluation d’autisme à l’Hôpital Rivière-Des-Prairies en 2019. Parmi ces enfants, 29 ont reçu un diagnostic positif d’autisme (45,90±2,16mois;14M) et 27 ont reçu un diagnostic négatif d’autisme (57,89±3,31mois;23M). À partir d’informations tirées de leur dossier médical, les participants ont été divisés selon une variable catégorielle à deux niveaux : « intérêt pour le matériel écrit » et « pas d’intérêt pour le matériel écrit ». Un Khi-carré ( "?" ^2(1) = 3.90, p = .048, "?c" =.26) a révélé une différence de fréquence de l’intérêt précoce pour le matériel écrit significative entre les autistes (51,72%) et les non autistes (25,93%). Ces résultats suggèrent que l’intérêt précoce pour le matériel écrit est plus fréquent dans l’autisme, bien qu’il existe également, de manière beaucoup moins importante, chez d’autres populations cliniques, renforçant ainsi la preuve du lien entre autisme et hyperlexie.

Concentrating to avoid falling in seniors: New data and future directions

Marie Julie Vermette^1,2, Louis Bherer^1,2,3, Benjamin Pageaux^1,2, François Prince⁴, Julie Messier^1,2
¹École de kinésiologie et des sciences de l’activité physique, Université de Montréal, Montréal, QC, Canada
²Research Center of the University Institute of Geriatrics of Montréal, Montréal, QC, Canada
³Research Center of the Montreal Heart Institute, Montréal, QC, Canada
⁴Department of Surgery, Université de Montréal, Montréal, QC, Canada
Corresponding Author: Marie Julie Vermette, email mariejulievermette@gmail.com

Abstract

Falls are a major adversary to the quality of life in seniors and carry heavy economical burdens to society. They have been attributed to both a decline in proprioceptive function as well as an inability to efficiently allocate attentional resources to balance in multi-task conditions. Growing research has suggested an interaction between proprioception and attention. However, this relationship has yet to be systematically investigated. We have explored the interaction between the proprioceptive and attentional demand of dynamic postural control in seniors using a novel dual-task. Old (n=21) and young (n=17) sedentary adults performed a postural stability limit task in five experimental conditions that varied the availability of vision and the presence of a secondary attentional task: (a) attentional task while sitting, (b) postural task with eyes open, (c) postural task with eyes closed (d) postural task with eyes open and secondary attentional task and (e) postural task with eyes closed and secondary attentional task. Ground reaction force data was collected at 200 Hz using an AMTI force platform and center of foot pressure (COP) was analysed. The functional limits of stability were quantified as the maximum center of pressure excursion during voluntary leaning in the anterior-posterior and mediolateral axes. Older adults exhibited smaller limits of postural stability in the anterior, right, and left leaning directions compared to young adults(p < 0.05). However, all groups were significantly affected by the removal of vision in all leaning directions(p < 0.05). Notably, the impact of removing visual information was more important when older adults performed the attentional task simultaneously with the postural stability limit task, as reflected by their decreased performance in the attentional task in all leaning directions(p <0.05). These findings suggest that the attentional demand of postural control is greater in older adults than in young adults, and that this trend was more prominent when the demand for proprioceptive processing was higher (i.e., when vision was removed). This result is consistent with a significant interaction between proprioception and attention in the postural control of seniors. Future studies will test a) the attentional demand of proprioceptive processing when there is no postural control requirements and b) the effect of a p and aerobic training intervention programs aimed at improving proprioception for postural control in complex everyday situations. The development of such intervention programs is essential for fall prevention in older adults and in neurological disorders producing proprioceptive processing impairments (e.g., Parkinson's disease).

Le jugement du bien et du mal à l'adolescence : Une étude sur le genre et le principe moral de non-nuisance

Justine Le Blanc-Brillon¹, Max-Antoine Allaire¹, Frédérick Morasse¹, Mélodie Roy¹, Sébastien Hétu¹
¹Université de Montréal, Montréal, QC, Canada
Corresponding Author: Justine Le Blanc-Brillon, email justine.le.blanc-brillon@umontreal.ca

Abstract

Le fonctionnement social des individus est en partie sous-tendu par un système moral qui serait à la base de toute activité morale. Ce système est représenté par cinq principes moraux, soit la non-nuisance, l’équité, la loyauté, l’autorité et la pureté, qui permettent à l’individu de différencier le bien du mal afin de réguler les conduites et attitudes sociales. Parmi ceux-ci, le principe de non-nuisance proscrit les actions qui causeraient volontairement du mal à autrui et est lié à des comportements prosociaux visant la protection des autres. Plusieurs recherches dans le domaine de la moralité et des habiletés sociocognitives suggèrent l’existence d’une relation entre le genre et les habiletés sociomorales. En particulier, à l’adolescence, les femmes auraient de meilleures capacités d’empathie, de compassion et de raisonnement moral que les hommes. Cependant, à ce jour, aucune étude n’a encore entrepris de vérifier si de telles différences pourraient aussi concerner le principe de non-nuisance. L’objectif de cette étude était de vérifier si des différences de genre existent concernant l’importance accordée au principe de non-nuisance. Il était attendu que les individus s’identifiant au genre féminin accordent une plus grande importance au principe de non-nuisance que les individus s’identifiant au genre masculin. 111 adolescentes (M = 16,33 ans, ET = 1,30) et 80 adolescents (M = 15,91 ans, ET= 1,47) âgés entre 14 et 18 ans ont rempli le questionnaire mesurant les cinq principes moraux (Questionnaire des fondateurs morales). La sous-échelle utilisée dans la présente étude représente la sensibilité ainsi que le niveau d’importance que les individus accordent au principe de non-nuisance dans leur jugement du bien et du mal. Les résultats obtenus suggèrent que les adolescentes accorderaient significativement plus d’importance que les adolescents au principe de non-nuisance (F(1, 185) = 4,35, p = ,038, d = ,31). Les résultats de cette étude suggèrent que les adolescentes tendent à s’appuyer plus fortement sur le principe de non-nuisance dans leur jugement du bien et du mal que leurs pairs masculins. Concrètement, ceci pourrait se manifester dans leurs comportements par une plus grande considération pour les autres ainsi que par plus de compassion et de sympathie.

EEG and behavioral correlates of intermodal time prediction in a motor task

Alana Arrouet, PhD^1,2, Eduardo Marques-Carneiro¹, Pierre Marquet², Anne Giersch¹
¹Institut National de la Santé et de la Recherche Médicale, Cognitive Neuropsychology and Pathophysiology of Schizophrenia, University of Strasbourg, Strasbourg, France
²Research Centre, Centre intégré universitaire de santé et des services sociaux de la Capitale-Nationale, Laval University, Faculty of Medicine, QC, Canada
Corresponding Author: Alana Arrouet, email alana.arrouet@hotmail.com

Abstract

Patients with schizophrenia suffer from disturbances in their bodily self and time disorders. To objectify them, we explore how the passage of time can be used to process information in the future. Using the variable foreperiod paradigm which consists in a signal followed at variable delays by a target, we can quantify this ability. In neurotypicals, more the participant waits for the target, the faster he is to respond to it. This is called ‘hazard function’ and it is altered in patients, in relation with disorders of the self. We developed a variable foreperiod paradigm with a playful purpose, to be adapted to a young at-risk population. We decided to investigate it in the tactile domain, which might be especially important for schizophrenia. Here we present the results aimed at validating our protocol in neurotypicals. Our task consists in the exploration of a maze without seeing it. Participant’s exploration is guided by a visual start signal, and a tactile stop vibration. We use two delays: short and long. In addition, we measure an electrophysiological marker which correlates with the benefit of the passage of time. We replicated the hazard function with faster reaction times (RTs) in response to long delays vs short delays. Indeed, participants stopped their movement faster in long vs short trials. Interestingly, participants movement started to decelerate at the same time in short and long trials. Regardless of the delay, we highlight the presence of a CNV whose amplitude increased with time. The current study validates our tactile hazard function approach in a playful environment. The movement recordings allow us to measure responses directly related to prediction. The labyrinth is adapted to the target population and allows us to acquire behavioral and EEG temporal prediction markers. The next step would be to test patients and at-risk subjects.

Protocole de prise en charge clinique des déficits de production de phrases chez les personnes aphasiques

Sarah-Ève Poirier^1,2, Marion Fossard^2,3, Laura Monetta^1,2
¹Université Laval, Québec, QC, Canada
²Centre de recherche CERVO, Québec, QC, Canada
³Université de Neuchâtel, Neuchâtel, Suisse
Corresponding Author: Sarah-Ève Poirier, email sarah-eve.poirier.1@ulaval.ca

Abstract

Véritable handicap « invisible », l’aphasie est présente chez le tiers des victimes d’accident vasculaire cérébral (AVC) et en représente l’une des conséquences les plus invalidantes, entrainant des difficultés souvent sévères et durables pour l’intégration sociale et la qualité de vie. Les personnes aphasiques peuvent éprouver, entre autres, une difficulté à produire des phrases (DPP), ce qui réduit la quantité et la qualité de l’information transmise par la personne et la rend moins compréhensible pour ses interlocuteurs. Différents traitements ayant été développés en anglais pour améliorer la production de phrases auprès de cette population ont démontré une efficacité. Toutefois, aucun traitement pour les DPP n’a été développé en français. L’objectif de la présente étude est donc adapter un traitement pour la rééducation de phrase mais en ciblant les verbes en franco-québécois et établir son efficacité auprès de la population aphasique en termes d’amélioration des items entrainés, de généralisation à des items non entrainés, de transfert au contexte conversationnel et de maintien des acquis dans le temps. Une étude de cas unique sera réalisée afin de déterminer l’efficacité – en termes d’amélioration des items travaillés, de généralisation à des items non travaillés, de maintenance des acquis dans le temps et de transfert à d’autres contextes – d’un traitement franco-québécois inspiré du Verb Network Strengthening Treatment. Le participant sera rencontré à 28 reprises afin d’évaluer ses habiletés initiales, établir les lignes de base, appliquer le traitement et évaluer le maintien des acquis post-traitement. Il est attendu que ces quatre mesures d'efficacité soient améliorées à la suite du traitement. En plus de l'efficacité attendue, les résultats permettront d'améliorer les pratiques cliniques des orthophonistes intervenant auprès de la clientèle adulte ayant une aphasie.

Inférence de profils cognitifs au Five-Point Test chez l’enfant neurotypique à l’aide de réseaux de neurones artificiels

Myriam Sahraoui¹, Karim Jerbi¹, Bruno Gauthier¹
¹Université de Montréal, Montréal, QC, Canada
Corresponding Author: Myriam Sahraoui, email myriam.sahraoui@umontreal.ca

Abstract

L’intelligence artificielle est en expansion dans le domaine médical et a récemment fait son entrée en neuropsychologie (Stamatis et al., 2021; Treviño et al., 2021). Toutefois, l’apprentissage machine a peu été utilisé pour analyser les résultats de tests neuropsychologiques dans l’étude de la cognition normale. L’objectif de ce projet était de dégager des profils cognitifs obtenus à partir d’un test de fluidité graphique (par ex., Fournier et al.,2020), à l’aide du SOM (Self-Organizing Maps), un algorithme d’apprentissage machine non supervisé. Un échantillon de 113 participants neurotypiques de 7 à 13 ans ont effectué le Five-Point Test (Regards et al., 1982) sur tablette numérique, d’une durée de cinq minutes. Dans le but d’identifier des profils cognitifs distincts, le nombre de dessins, de répétitions et de stratégies par minute ont ensuite servi d’entrée au SOM (Kohonen, 1989, 1995) qui a permis la distribution des données sur un réseau de neurones. Étant donné que le SOM est un algorithme d’apprentissage non supervisé, ce qui permet la distribution des données sans connaissances préalables de groupes ou de profils distincts. Finalement, les neurones du SOM ont été regroupés à l’aide d’un clustering hiérarchique agglomératif. Le clustering des neurones du SOM a permis de dégager deux groupes principaux. Les groupes se différenciaient en termes de nombre de dessins, de stratégies et de répétitions, qui étaient tous supérieurs pour le premier groupe comparé au second. Une autre différence a été trouvée dans l’évolution de la production dans le temps. Le premier groupe avait un patron de production en forme de cloche alors que le second avait un patron de production descendant. Ces résultats préliminaires suggèrent une distribution catégorielle des profils cognitifs en fluidité graphique chez l’enfant neurotypique. Ces profils semblent être caractérisés par deux éléments principaux. Premièrement des compromis quantité/qualité différents basés sur la production de dessins et le nombre de répétitions, qui pourraient être le résultat d’une distribution différente des ressources cognitives. Deuxièmement des patrons de production différents dans le temps (en cloche versus descendant) qui pourraient indiquer des approches différentes de la tâche. Les résultats soulignent l’utilité du SOM pour identifier des profils cognitifs distincts à partir de données neuropsychologiques, qui pourraient ouvrir de nouvelles voies dans l’exploration des modes de fonctionnement cognitif des enfants neurotypiques, permettant potentiellement de mieux comprendre le développement atypique.

Methods, Experimental Models and Preclinical Studies

Sex Differences in Response to Chronic Social Defeat Stress

Andrea Smith¹, Lindsay Hyland¹, Bethany Watts¹, Hiyam Al Ansari¹, Miski Dahir¹, Aleyna Akgun¹, Zachary Silver¹, Alfonso Abizaid¹
¹Department of Neuroscience, Carleton University, Ottawa, ON, Canada
Corresponding Author: Andrea Smith, email andreasmith3@cmail.carleton.ca

Abstract

The chronic social defeat stress paradigm is commonly used to study the physiological and behavioral effects of psychosocial stressors in rodents. This model is particularly relevant as it recapitulates many stress-induced pathologies observed in humans, including metabolic and behavioral disturbances. This paradigm is limited by its sex-specific design, as males only exhibit territorial aggression towards other males, creating a barrier to studying the effects of stress in females. Currently, the effects of chronic stress on metabolism in females has yet to be fully investigated. In this study we implemented a new model of chronic stress known as the non-discriminatory social defeat stress paradigm. In this protocol, a male and a female C57 mouse are introduced to a territorial CD-1 mouse. The presence of a C57 intruding male into the CD-1 territory provokes aggressive behaviors towards both C57 mice. Males and females were exposed to the social defeat stressor for 21-days while being given access to standard chow and a high fat diet ad libitum. Both males and females display similar metabolic phenotypes in response to this social stressor. This reduces their weight gain while increasing their caloric intake of the standard chow, rich in carbohydrates. Females, unlike males, exhibited an increase in pro-social behaviors during the social interaction test. The results from this study highlight that there are sex specific differences exhibited by females in response to social stressor and future research needs to continue to investigate these differences.

Nitric oxide, a retinal neuromodulator, uncouples horizontal cell gap junctions

Tareq Yousef^1,2, William Baldridge, PhD^1,2,3
¹Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada
²Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, NS, Canada
³Department Ophthalmology and Visual Sciences, Nova Scotia Health, Halifax, NS, Canada
Corresponding Author: Tareq Yousef, email ty@dal.ca

Abstract

The vertebrate retina uses various circuits for visual processing. Horizontal cell (HC) feedback to photoreceptors contributes to the receptive-field surrounds of ganglion cells, facilitating contrast detection. The magnitude of the surround varies depending on background illumination intensity. This may be mediated by changes in HC receptive-field size produced by alterations of gap junction coupling. A triphasic model of HC coupling suggests that coupling decreases during prolonged darkness (dark-suppression), increases after moderate exposure to light (light-sensitization) and is also decreased after bright light (light-adaptation). It is hypothesized that dopamine and retinoic acid promote uncoupling of HCs during dark-suppression and light-adaptation, dopamine being strongly driven by flickering light. Less understood are the contributions of nitric oxide (NO) and its predicted effector, protein kinase G (PKG). This work investigates NO and PKG’s role on HC GJ coupling in a model vertebrate retina, the goldfish, using high-throughput bulk injection of Neurobiotin tracer. DETA NONOate, an NO donor, reduced HC coupling (as indicated by decreased spread of Neurobiotin) under light sensitization while L-NAME, an NO synthase inhibitor, increased coupling in light-adapted retinas as compared to controls. There was no noticeable increase in Neurobiotin spread due to L-NAME in dark-suppressed retinas. KT5823, a PKG inhibitor, increased coupling in both light-adapted and dark-suppressed retinas as compared to controls. RKRARKE, another PKG inhibitor increased coupling in light-adapted retinas but produced no effect on dark-suppressed retinas. These results suggest that NO and PKG contribute to the uncoupling of HCs during dark-suppression and light-adaptation. It is yet to be determined how NO interacts with other neuromodulators to modulate HC coupling but preliminary results indicate a relationship between the action of PKG and protein kinase A, the effector of dopamine.

Noninvasive neurostimulation in Parkinson’s disease to reduce dyskinesia: translational studies from non-human primates to patients

Estelle Gouriou^1,2,3, Thérèse Di Paolo^2,4, Cyril Schneider ^1,2,3,5
¹Noninvasive neurostimulation laboratory, Université Laval, Québec, QC, Canada
²Axe Neurosciences du Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec, QC, Canada
³Faculty of medicine, Université Laval, Québec, QC, Canada
⁴Faculty of pharmacy, Université Laval, Québec, QC, Canada
⁵Dept rehabilitation of faculty of medicine, Université Laval, Québec, QC, Canada
Corresponding Author: Estelle Gouriou, email Estelle.gouriou@crchudequebec.ulaval.ca

Abstract

Parkinson's disease (PD), the second most common neurodegenerative disease worldwide presents with motor and cognitive symptoms. Levodopa or L-Dopa is the standard medication which, over time, can unfortunately favor the development of disabling involuntary movements, referred to as L-Dopa induced dyskinesia (LID). LID may result from glutamatergic-related hyperactivation of the primary motor cortex (M1) with erratic NMDA-receptors function. Thus, amantadine (NMDA-receptor antagonist) is in-taken to treat LID but debilitating side effects are induced. In that vein, there is a growing interest in nonpharmacological and noninvasive approaches that could normalize for instance glutamatergic brain function without any side effects. In line, painless transcranial stimulation, magnetic (rTMS) and electrical (tDCS) are used in the present project for their influence on M1 plasticity, LID and motor symptoms in the non-human primate (MPTP, animal model of PD) and in people living with PD. The proposed studies will contribute to the advancement of knowledge in PD and LID faulty M1 function and may clinically impact the patients’ quality of life (e.g., by the intent to reduce amantadine in-take). The rationale of the studies is supported by our pilot results in the dyskinetic MPTP primate and people with PD. In the former rTMS reduced LIDs without deteriorating the beneficial effect of L-Dopa on motor symptoms, in the latter motor symptoms were improved. The project furthermore proposes an approach that could be adapted (personalized) to the clinical profile and the neurophysiological status (M1 function), which is a pivotal point in the context of a neurodegenerative disease.

Anxious-depressive phenotype in an acute and chronic stress model in BALB/C and C57BL/6NCrl mice

Carlos Medina¹, Sergio Cruz¹, Grace Pardo¹, Luis Pacheco¹
¹Centro de Investigaciones Biomédicas, Laboratorio de Investigación en Neurociencias, Universidad Andina del Cusco, Cusco, Peru
Corresponding Author: Carlos Medina Saldivar, email carlos.medina.s@upch.pe

Abstract

Behavioral studies in preclinical depressive models using mice show behavioral variations that seem dependent on sex and strain. However, it is unknown whether these variables have the same contribution or interact together in the variation of these behaviors. Our objective was to evaluate the existing interactions between the variables "strain", "sex" and "group" (control vs. chronic stress) in an acute and chronic depression model. BALB/c (n= 51) and C57BL/6NCrl (n= 92) mice strains of both sexes were used. An acute depressive and 1-month chronic mild stress (CMS) model was applied. The anxious-depressive phenotype was evaluated by using light-dark box test (LDB), elevated plus maze (EPM), forced swim test (FST) and tail suspension test (TST). Apathy was assessed by splash test (ST). The results were evaluated using a linear model and multivariate analysis. In the acute model and independent of sex, significant differences were observed between the strains in the results for immobility time in FST and TST, as well as in number of transitions and latency for the LDB test (p <0.0001). In the chronic model, both strains respond differently in most behavioral tests (p <0.05), independent of sex and group, with the exception of TS (p <0.05). However, a significant effect in CMS group was found in the anxiety tests (p <0.01). The difference between strains was significant in the acute and chronic depression model. Exposure to ECL seems to contribute mainly to the appearance of an anxious but non-depressive or apathetic phenotype, with no clear sex differences.

Effect of antibodies against TDP-43 protein in mice model of amyotrophic lateral sclerosis

Amélie Poulin-Brière¹, Silvia Pozzi¹, Jean-Pierre Julien¹
¹CERVO Brain Research Center, Université Laval, Quebec City, QC, Canada
Corresponding Author: Amélie Poulin-Brière, email amelie.poulin-briere.1@ulaval.ca

Abstract

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease for which there is currently no cure. Numerous studies suggest a role of TDP-43 protein. Mutated in the majority of ALS cases, the protein is mislocalised in the cytoplasm and forms aggregates involved in motoneurons (MN) degeneration. TDP-43 interacts with p65 (sub-unit of NFκB), inducing glial cells activation. Our laboratory has shown that E6 antibody directed against RRM1 domain of TDP-43 reduced its mislocalisation in ALS mouse models and that cerebrospinal fluid (CSF) from ALS patients induces TDP-43 mislocalisation in neurons. This projects aims to study the effect of E6 antibody on cytoplasmic aggregation of TDP-43 and NFκB activity in cells exposed to human CSF, as well as on motor and cognitive performances, and on tissues pathology in mice models of ALS induced by chronic infusion of human CSF. E6 antibody is tested on cell and mouse models exposed to human CSF. In vitro, microglial and neuronal cells were exposed to human CSF for 48h and to an antibody treatment for 24h. NFkB activity is analysed on cells transfected with p65 binding site upstream of the luciferase gene. TDP-43 mislocalisation was analysed on cells transfected with human TDP-43 (TDP-43-WT) by immunofluorescence and by western blot in nuclear and cytoplasmic fractions, as well as soluble and insoluble fractions. In vivo, mice overexpressing TDP-43-WT were treated with E6 by intrathecal injection and were submitted to an intraventricular infusion of human CSF for two weeks, during which they were submitted to motor and cognitive tests. E6 effect on TDP-43 proteinopathy and neuroinflammation is analysed by biochemistry and immunofluorescence on collected tissues. Results on neuronal cells show a reduction of cytoplasmic levels of TDP-43 in cells treated with E6 antibody compared to cells treated with control antibody. Moreover, E6 treated mice show a significantly increased stride length compared to PBS treated mice. Cognitive tests show no difference between groups. E6 antibody shows a beneficial effect on pathology induced by CSF infusion since it reduces levels and mislocalisation of TDP-43 in cells, and rescues gait deficits in mice. Preliminary analysis of mice spinal cords shows a reduction in TDP-43 mislocalisation in motoneurons of mice treated with E6 antibody.

Impact of alpha-synuclein aggregation on protein degradation systems and its implication in Parkinson’s Disease pathogenesis

Walid Idi¹, Morgan Bérard¹, Razan Sheta¹, Abid Oueslati¹
¹Université Laval, Quebec City, QC, Canada
Corresponding Author: Walid Idi, email walid.idi@crchudequebec.ulaval.ca

Abstract

In Parkinson Disease (PD), the aggregation of misfolded proteins called alpha-synuclein (a-syn), represents one of the major cellular hallmarks of the disease. Insoluble propriety of these aggregates makes difficult their degradation, disturbing the neuronal homeostasis and leading to neurodegeneration. Several studies shown a correlation between alterations of degradation systems (autophagic or proteasomal), implicated in the protein quality control, and a-syn aggregation. It’s relevant to know how an alteration of degradation systems is involved in the pathogenesis of PD. Our group recently created a new cellular model in which we control optogenetically and observe in real time the aggregation of a-syn. This system is called the LIPA (Light-Inducible Protein Aggregation) system. This system combined to proteasomal and autophagic markers allow us to investigate in vitro how a-syn aggregates impact the degradation systems. Using this cellular model, we were able to observe for the first time the effect of LIPA-induced aggregates on the proteasomal system in cells. Moreover, we also get interested in the inhibition of proteasomal and autophagic systems and the effect on the aggregation. Taken together our observations reveal the ability of our LIPA system to mimic potential effects of a-syn aggregation on degradation systems in PD pathogenesis.

Anti-seizure activity of curcumin derivatives in different zebrafish models of epilepsies.

Uday Praful Kundap¹, Brandon Choo², Mohd Farooq Shaikh², Siti Munirah Mohd Faudzi³, Faridah Abas⁴, Éric Samarut^1,5
¹Department of Neurosciences, Research Center of the University of Montreal Hospital Center, Université de Montréal, Montréal, QC, Canada
²Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
³Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Selangor, Malaysia
⁴Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, Selangor, Malaysia
⁵Modelis Inc., Montreal, QC, Canada
Corresponding Author: Uday Kundap, email uday.kundap@umontreal.ca

Abstract

Epilepsy is a broad term used to sum-up frequent and intense seizures that cause uncontrolled firing of neurons inside the brain. Seizures are the outward manifestation of abnormally excessive or synchronous brain activity and is a persistent problem for those afflicted. There are wide range of treatment and techniques available to reduce the intensity of seizures which are limited to drug treatment, alteration of diet (ketogenic diet) and surgery etc. The anti-epileptic drug treatment limited to available 28 compounds which shows different mechanism of action depending upon its property, chemical structure and receptor binding ability. While seizures can be somewhat symptomatically managed with anti-epileptic drugs (AEDs), many patients are still refractory to the currently available AEDs. Curcumin is the principle curcuminoid of Curcuma longa or colloquially, turmeric and has been experimentally proven to have anti-seizure properties despite its poor bioavailability. Hence, this study aims to ask if structural analogues of curcumin could also have an anti-seizure effect in a pentylenetetrazol induced acute seizure zebrafish larvae model and two genetic zebrafish models (gabra1 and gabrg2 loss-of-function) as a precursor to future pharmacokinetic studies with these derivatives. Overall, from the 68 analogues tested, we found 13 different derivatives that had significant anti-seizure activity against chemically-induced acute seizures. From those, only 3 analogue were found to be depict anti-seizure activities both at the behavioural and neuronal levels. These are good candidates as potential future anti-seizure therapeutics for the treatment of generalised tonic-clonic seizures and generalized epilepsy with febrile seizures. Further work is needed in deciphering its mechanisms of actions and their pharmacodynamic/pharmacokinetic profiles before human clinical trials can become a reality.

Automatisation des expériences d’imagerie in vivo chez la souris pour les neurosciences de la vision

Ismaël Djerourou¹, Enzo Delamarre², Solenn Tissier¹, Maurice Ptito^1,3, Matthieu Vanni¹
¹Université de Montréal, Montréal, QC, Canada
²Polytechnique Montréal, Montréal, QC, Canada
³University of Copenhagen, Copenhague, Danemark
Corresponding Author: Ismaël Djerourou, email ismael.djerourou@umontreal.ca

Abstract

En neuroscience, la technique la plus efficace pour cartographier l’activité cérébrale chez la souris est actuellement l’imagerie calcique. Elle se réalise généralement sur la souris éveillée tête fixée. Pour ce faire, les souris sont implantées avec une barre en titane et une fenêtre crânienne chronique donnant accès au cerveau. Les souris sont manuellement fixées via la barre pour réaliser diverses tâches comportementales tout en observant ou en manipulant l’activité cérébrale. Ces protocoles demandent beaucoup de temps à l’expérimentateur, causent beaucoup de variabilité et ne permettent pas d’acquérir beaucoup de données. Notre but a donc été de concevoir un dispositif permettant d’automatiser ce processus de sorte que les souris se fixent d’elles-mêmes pour réaliser les tâches tout en permettant l’acquisition massive de données. En collaboration avec Labeotech Inc, nous avons créé des cages automatiques composées de deux compartiments séparés par un tunnel de pesée afin de suivre l’état de santé de chaque souris. Sur l’un des compartiments est attaché le tunnel de fixation, au bout duquel se trouve le seul point d’eau. Lorsque les souris entrent dans le tunnel de fixation, elles sont identifiées via un lecteur RFID et si elles atteignent le fond du tunnel, le système de fixation s’enclenche en parallèle de l’imagerie et des tâches visuelles. L’eau est alors distribuée à la souris. Le principal défi réside dans la procédure d’apprentissage de cette tâche par la souris. Après la chirurgie d’implantation, les souris ont été placées dans des cages d’entraînement où elles ont été habituées à boire au fond d’un tunnel passif. Ensuite, les souris ont été placées dans les cages automatiques. Elles sont entraînées et habituées au système de fixation d’abord par une activation du son de fixation, puis de la fixation partielle et enfin de la fixation complète permettant de stabiliser la tête des souris pour l’imagerie mésoscopique. Au sein de la cage automatique, 4 souris sur 6 ont effectué des fixations volontaires (42/jour/souris) sur une période de 42 jours. Le temps de fixation était de 20s ce qui permettra dans le futur d’offrir une durée suffisante pour permettre la cartographie. Les cages automatiques permettent la fixation initiée volontairement par les souris. Ce système a beaucoup de potentiel pour les études longitudinales en imagerie optique chez la souris éveillée. La grande quantité de données générées pourra facilement être partagée et ainsi accélérer les découvertes dans le domaine des neurosciences de la vision.

The Reliability of Risk of Bias Tools for Nonrandomized Studies

Kalaycioglu I¹, Rioux B^{2, 3}, Neves Briard J^{2, 3}, Nehme A^{2, 3}, Touma L^{2, 3}, Dansereau B^{2, 3}, Veilleux-Carpentier A^{2, 3}, Keezer MR^{2, 3, 4}
¹Faculty of Medicine, University of Montreal, Montreal, QC, Canada
²Department of Neurosciences, University of Montreal, Montreal, QC, Canada
³Centre hospitalier de l’Université de Montréal, Montreal, QC, Canada
⁴School of Public Health, University of Montreal, Montreal, QC, Canada
Corresponding Author: Isabel Kalaycioglu, email Isabel.kalaycioglu@umontreal.ca

Abstract

There are currently no standard risk of bias (ROB) tools to assess the internal validity of systematic reviews involving exposure or frequency studies. We aimed to compare the interrater reliability of the American Academy of Neurology (AAN) ROB criteria with other commonly used tools for observational exposure (Newcastle-Ottawa, SIGN50) and frequency studies (Gyorkos, Loney). Six raters independently assessed the ROB of 30 exposure and 30 frequency studies, selected from published AAN guidelines. Articles were rated on a 3-level summary measure of ROB (low, intermediate, or high). We calculated an intra-class coefficient (ICC) for each tool and compared them with Fisher's Z-tests. Our results are preliminary, with 81.5% of assessments completed. The interrater reliability was moderate for the AAN exposure tool and almost perfect for the AAN frequency tool (Table 1). All tools had an interrater reliability that was significantly greater than our threshold for a non-useful tool (ICC ≤ 0.2), except for the Newcastle-Ottawa scale (p-value=0.102). The ICCs of the AAN tools did not differ significantly from others except for the Gyorkos tool, which trended towards a lower ICC as compared to the AAN frequency tool (p-value=0.061). The six ROB tools assessed in our study surpassed the benchmark for a non-useful tool, except for the Newcastle-Ottawa scale. The AAN ROB tools, in addition to their simplicity, had substantial to almost perfect interrater reliability. Our findings suggest that the AAN ROB tools may be used in systematic reviews of exposure and frequency studies in neurology.

Neuroimaging

Developing a brain signature of the facial expression of pain

Marie-Eve Picard^1,2, Miriam Kunz³, Jen-I Chen², Étienne Vachon-Presseau^4,5, Pierre Rainville^1,2
¹Université de Montréal, Montreal, QC, Canada
²Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada
³University of Augsburg, Augsburg, Germany
⁴McGill University, Montreal, QC, Canada
⁵Alan Edwards Centre for Research on Pain, Montreal, QC, Canada
Corresponding Author: Marie-Eve Picard, email marie-eve.picard.2@umontreal.ca

Abstract

The facial expression of pain is an important element of non-verbal communication, allowing us to signal an immediate threat and a potential need for help. Only a few studies have examined the neural correlates of the facial expression of pain. By using a multivariate approach, this study aims to predict facial responsiveness in response to painful stimuli through fMRI data. Data from 55 participants were analyzed using a multivariate approach. Participants were exposed to a total of 16 non-painful trials and 16 painful trials where a phasic stimulus, sufficiently painful to evoke a facial expression without causing any damage, was applied while they were in the MRI machine. Their facial expression was also recorded with an MRI-compatible camera. From the facial activity, we derived a composite score, called the FACS score. We then used the LASSO-PCR algorithm to predict these FACS scores from the fMRI contrast images. Our results showed that we can predict the FACS scores using brain activity (R2 = 0,19) with a performance above the chance level (p = 0,01). The activity from regions of the thalamocortical pathways, namely the thalamus, the insula, and the somatosensory cortex, and motor areas (M1, SMA) were involved in this prediction. By integrating the activity within nociceptive pathways and motor areas, we were able to predict the facial expression of pain. Additional analyses will be conducted to further investigate the generalizability of our model to other populations and its specificity to facial expression compared to other manifestations of pain.

Cortical and Subcortical Markers of Longitudinal Risk for Internalizing Psychopathology during COVID-19 in High-Risk Adolescents

McKinley Pawlak ^1,3,10, Kyla Franco ⁷, Emily Bernier ⁷, Signe Bray ^1,2,3,4,5, Sneha Chenji ⁶, Melanie Noel ^1,3,7, Kathryn A. Birnie ^8,11, Frank P. MacMaster ^6,9, Daniel C. Kopala-Sibley ^1,3,6,10
¹Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
²Child and Adolescent Imaging Research Program, University of Calgary, Calgary, AB, Canada
³Alberta Children Hospital Research Institute, University of Calgary, Calgary, AB, Canada
⁴Department of Radiology, University of Calgary, Calgary, AB, Canada
⁵Department of Pediatrics, University of Calgary, Calgary, AB, Canada
⁶Department of Psychiatry, University of Calgary, Calgary, AB, Canada
⁷Department of Psychology, University of Calgary, Calgary, AB, Canada
⁸Department of Anesthesiology, Perioperative, and Pain Medicine, University of Calgary, Calgary, AB, Canada
⁹University of Calgary Strategic Clinical Network for Addictions and Mental Health, University of Calgary, Calgary, AB, Canada
¹⁰Mathison Centre for Mental Health Research and Education, University of Calgary, Calgary, AB, Canada
¹¹Department of Community Health Sciences, University of Calgary, Calgary, AB, Canada
Corresponding Author: Daniel C. Kopala-Sibley, email daniel.kopalasibley@ucalgary.ca

Abstract

We examined how individual differences in cortical and subcortical brain structure in adolescents at high familial risk for internalizing psychopathology are related to the development of internalizing psychopathology during the COVID-19 pandemic. Participants were 88 adolescents aged 11-17 with one parent with a history of depressive or anxious disorders, but with no such history themselves. In the year prior to the pandemic (2019), youth completed the Mini International Neuropsychiatric Interview-Kid, the Youth Self Report (YSR) internalizing, affective, and anxiety symptoms scales, and T1-weighted MRI scans. During the pandemic (August-September 2020), 71 youth completed the YSR and a measure of COVID-19-related stress. Adjusting for pre-pandemic symptoms and stress from COVID-19, decreased bilateral nucleus accumbens (B = -.270 p = .003), pallidum (B = -.276 p = .003) and thalamus volumes (B = -.270 p = .008), and increased bilateral rostral ACC thickness (B = .209 p = .017) at baseline predicted increased anxiety scores at follow-up. Alterations in subcortical and cortical brain structure may identify which youth are vulnerable to depression and anxiety during the COVID-19 pandemic, and further our knowledge of how altered brain structure may confer risk for psychopathology.

Object Recognition in Emerging Images

Marleen Bakker^1,2, Hinke Halbertsma¹, Barbara Nordhjem¹, Frans Cornelissen¹
¹Universitair Medisch Centrum Groningen, Groningen, The Netherlands
²Polytechnique Montréal, Montréal, QC, Canada
Corresponding Author: Marleen Bakker, email marleenbakkermarleen@gmail.com

Abstract

Recognizing objects is vital for daily life, yet the underlying mechanisms are poorly understood. The lateral occipital complex (LOC) is regarded as an object-sensitive area, while the roles of the early visual areas (V1, V2 and V3) in object recognition are unclear. Most objects are recognized within milliseconds and thus the underlying brain mechanisms cannot be captured by fMRI. However, recognition can be delayed with emerging images (EI), which contain a “hidden” object that people recognize belatedly, thus enabling fMRI analysis of involved brain areas. We investigated the roles of the early visual areas and the LOC in object recognition with EI. Early visual areas have a retinotopic organization, meaning that adjacent stimuli in the visual field stimulate brain voxels that are next to each other in the brain. This enabled us to project the changes in activity that occurred in early visual areas back onto the visual field, and see to which places in the visual field they correspond. During an fMRI scan, participants looked at an EI. Next, we aided recognition by showing the hidden object’s silhouette (disambiguation) and presented the EI again. We compared BOLD responses before and after disambiguation, where the stimulus was the same but the level of object recognition differed. We used a retinotopic paradigm to obtain the parameters needed for the backprojection onto the visual field, and a scrambled images paradigm to locate the LOC. V1 and V2 (but not V3) showed a significantly stronger BOLD response after disambiguation than before, indicating involvement of these areas in object recognition. The back-projection of cortical activity in the visual field revealed no pattern, indicating a non-spatial based role of these areas. Interestingly, the LOC showed no significant difference. Thus, V1 and V2 show an increase of activity during object recognition, but this change is not specifically taking place in voxels responding to the location of the object. We found no significant difference before and after disambiguation in the LOC, which may be explained by repetition suppression counteracting the effect of recognition in the LOC. This study indicates that early visual areas might be more involved in object recognition than originally thought, and that the EI paradigm can shed new and interesting light on the mechanisms behind object recognition.

Altérations de l’Intégrité de la Matière Blanche avec l’Obésité: Méta-Analyse des Études d’Imagerie par Tenseur de Diffusion (DTI)

Justine Daoust^1,2, Joelle Schaffer³, Alain Dagher³, Isabel García-García⁴, Andréanne Michaud^1,2
¹Centre de recherche de l’institut universitaire de cardiologie et de pneumologie de Québec, QC, Canada
²Université Laval, Québec, Canada
³Université McGill, Montréal, QC, Canada
⁴Université de Barcelone, Barcelone, Espagne
Corresponding Author: Andréanne Michaud, email Andreanne.Michaud@fsaa.ulaval.ca

Abstract

Des études d’imagerie par tenseur de diffusion (DTI), une technique d’IRM permettant d’évaluer l'intégrité des faisceaux de la matière blanche (MB) par la mesure d’anisotropie fractionnelle (FA) et la moyenne de diffusion (MD), ont montré une perte d'intégrité de la MB chez les individus souffrant d’obésité. Toutefois, les études dans le domaine ne sont pas unanimes. Nous avons donc mené une méta-analyse afin d’identifier les faisceaux de la MB qui présentent des changements significatifs avec l’obésité. Une revue systématique des études de DTI évaluant la relation entre l’obésité et l’intégrité de la MB, rapportée avec la FA et la MD, a été réalisée dans la base de données PubMed. Nous avons effectué une méta-analyse basée sur les coordonnées significatives des études rapportant la FA en utilisant le logiciel Anisotropic Effect Size-Signed Differential Mapping. Dix-huit bases de données ont été incluses représentant 4453 participants (18 à 92 ans, 55% de femmes). Les résultats obtenus montrent que les individus obèses sont caractérisés par une réduction de l’intégrité de la MB dans la partie antérieure droite du corps calleux (SDM-Z = -3.282; MNI = 26, 32, 22; p < 0.001). Nos analyses indiquent que nos résultats ont un niveau élevé de reproductibilité (Jackknife, 15/18) et aucun biais de publication (p=0.218). Neuf bases de données rapportant la MD ont été identifiées, ce qui était insuffisant pour effectuer une méta-analyse. Bien que les mécanismes expliquant ces résultats ne soient pas complètement élucidés, nos résultats suggèrent que l’obésité est associée à une réduction de l’intégrité de la MB, rapportée avec la FA, dans une zone du cerveau qui relie les cortex préfrontal et orbitofrontal, des régions impliquées dans les processus cognitifs. Des études futures sont nécessaires pour valider les mécanismes et vérifier si ces changements cérébraux peuvent être renversés à la suite d’une perte de poids.

Unfolding the Effects of Aging on Beta Burst Characteristics During Unimanual & Bimanual Movements

Rahul Chatterjee¹, George Lungoci¹, Xuanteng Yan², Georgios Mitsis², Marie-Hélène Boudrias³
¹Department of Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
²Department of Bioengineering, McGill University, Montreal, QC, Canada
³School of Physical & Occupational Therapy, McGill University, Montreal, QC, Canada
Corresponding Author: Rahul Chatterjee, email rahul.chatterjee@mail.mcgill.ca

Abstract

Beta oscillations in the primary motor cortex emerge as epochs of higher amplitude known as bursts. There is compelling evidence suggesting that beta bursts are a strong predictor of motor performance. The primary objectives of the study were to investigate the age-related changes in burst characteristics (i.e. burst amplitude, rate & duration) in the motor area (M1) of the dominant hemisphere during unimanual and bimanual grips. In this study, we have used previously collected MEG data from 12 younger (18 to 30 years) and 12 older (60 to 74 years) healthy individuals. To detect beta bursts, we first applied a threshold corresponding to the power of the signal followed by a second threshold reflecting the duration of the fluctuations or bursts. We found increased burst rate during pre-movement intervals compared to movement intervals for both the groups. This can be explained by the relative decrease in average beta band power during movement production. Moreover, we detected an increase in burst amplitude following both the grip tasks. Our study reveals that older subjects exhibit higher burst amplitude across all intervals. This result aligns with previous studies that reported higher absolute beta power in older adults throughout the movement execution. Also, we found that burst duration in older adults were significantly lower than younger subjects across all intervals for the bimanual task. This could suggest that the increased beta synchrony which is required during sustained hand grips, decreases with aging. Further, we found that burst characteristics were more variable in older compared to the younger participants across all intervals for both the tasks. This study is an important step towards a better understanding of healthy aging and the development of subject-specific neurofeedback systems using neuromagnetic signals.

Neurodegenerative Disorders

Defining the Caprin-1 interactome in unstressed and stressed conditions

Lucas Vu¹, Asmita Ghosh^2,3, Chelsea Tran^1,4, Walters Tebung², Hadjara Sidibé^2,3, Stephen Moore^1,4, Krystine Garcia Mansfield⁵, Victoria David-Dirgo⁵, Ritin Sharma⁵, Patrick Pirrotte⁵, Robert Bowser¹, and Christine Vande Velde^2,3
¹Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ, USA
²Department of Neurosciences, Université de Montréal, Montreal, QC, Canada
³CHUM Research Center, Montréal, QC, Canada
⁴School of Life Sciences, Arizona State University, Tempe, AZ, USA
⁵Tgen Collaborative Center for Translational Mass Spectrometry, Phoenix, AZ, USA
Corresponding Author: Christine Vande Velde, email c.vande.velde@umontreal.ca

Abstract

Cytoplasmic stress granules (SGs) are dynamic non-membranous foci containing translationally arrested mRNA and RNA binding proteins (RBPs) which form in response to a variety of cellular stresses. Previous studies have utilized over-expression of G3BP1 as a bait to get a glimpse of the SG proteome. While this has generated a rich resource and helps in understanding the complexity of SGs, later studies have confirmed that such over-expression of RBPs can alter the stoichiometry and result in aberrant granule formation in the cell. This prompted us to understand the SG proteome using endogenous immunoprecipitation of a candidate SG protein. We utilized Caprin-1 as a candidate as it is known to strongly interact with G3BP1 and G3BP2 – two core SG proteins. Further, the interacting partners of Caprin-1 remain largely uncharacterized although this protein is associated with aggregate inclusions in amyotrophic lateral sclerosis (ALS). Recent studies within our group demonstrated the presence of Caprin-1 cytoplasmic inclusions in ALS patient neurons. Additionally, others determined that Caprin-1 co-localizes with pTDP-43 in ALS spinal cord motor neurons. To gain insight into the proteome of Caprin-1 containing inclusions, we employed immunoprecipitation of endogenous Caprin-1, which is not impacted by TDP-43 localization or mutation, to further define the stress granule proteome. We identified 1500 proteins that interacted with Caprin-1 in basal and stressed conditions. Based on gene ontology analyses, interactors under stressed conditions were annotated to the ribosome, spliceosome, and RNA transport. Of the interactors, we found ANKHD1, TALIN-1, SNRNP200 and GEMIN5 to co-localize with arsenite-induced SGs in HeLa cells. As the proteome of SGs can vary with different stress inducers, we validated our results in thermal and osmotic stress conditions. We further validated our findings in neuronal-like cells, SH-SY5Y cell line and differentiated SH-SY5Y cells and found SNRNP200 to be a novel SG component across different stresses. Since Caprin-1 is found to be present as aggregates in spinal motor neurons of ALS patients, we checked if its strongest interactors would also be sequestered and be part of inclusion bodies in patient neurons. We found SNRNP200 to be aggregated in 23% of motor neurons in ALS patient tissue which starkly contrasted to only 1.5% of control neurons bearing similar inclusions of SNRNP200.

Caractérisation des agonistes de NOD2 in vitro dans le contexte de la maladie d’Alzheimer

Morgan McLaughlin¹, Paul Préfontaine¹, Marie-Michèle Plante¹, Vincent Pons¹, Serge Rivest¹
¹Centre de Recherche du Centre Hospitalier Universitaire, Universitaire de Québec, Québec, QC, Canada
Corresponding Author: Morgan Mclaughlin, email morgan.mclaughlin.1@ulaval.ca

Abstract

La maladie d’Alzheimer (MA) et l’angiopathie amyloïde cérébrale (AAC) sont fortement associées et cette dernière est caractérisée par l’accumulation de Aβ dans la paroi des vaisseaux sanguins cérébraux. En outre, les cellules du système immunitaire inné tel que les monocytes patrouilleurs, peuvent phagocyter l’Aβ vasculaire. Des recherches antérieures ont indiqué que les monocytes peuvent être convertis du phénotype inflammatoire au phénotype patrouillant en utilisant la liaison du muramyl dipeptide (MDP) à NOD2 (Lessard et al., 2017). Nous postulons que le développement d'analogues de la MDP avec une activité de phagocytose plus élevée que la MDP et avec le même effet immunomodulateur que la MDP peut être un médicament préventif pour la MA. Nous avons utilisé les lignées de cellules HEK-Blue NOD2 et HEK-Blue TLR2 pour détecter quels analogues se lient à NOD2. Les analogues du MDP ont été mélangés au milieu de détection HEK-Blue à des concentrations variables pour nous assurer que les analogues de MDP activaient sélectivement la voie NOD2. En outre, nous avons utilisé le test MTS pour détecter la toxicité des analogues. Des essais de phagocytose ont permis de caractériser le taux de phagocytose de chaque analogue et la méthode CBA (cytometric bead array) a été réalisé pour voir quels facteurs inflammatoires étaient générés après que les cellules mononucléaires du sang périphérique (CMSPs) ont été exposées à ces analogues. Certains analogues du MDP se lient à NOD2 de manière dépendante de la concentration tandis que d'autres ne se lient pas du tout à NOD2. Les analogues de NOD2 peuvent provoquer un taux accru de phagocytose par rapport au véhicule et au contrôle positif (MDP). Nous avons constaté que certains analogues sont capables d'augmenter la phagocytose des monocytes patrouilleurs à un taux supérieur à celui du MDP. Nous avons également constaté que les analogues de NOD2 ne provoquent pas la libération de facteurs pro-inflammatoires. Les analogues de la MDP ont le potentiel de devenir un médicament préventif pour la MA en augmentant le taux de phagocytose des Aβ et en diminuant l’Aβ vasculaire. Des recherches supplémentaires sont nécessaires pour mieux comprendre le rôle exact des monocytes patrouilleurs dans la MA.

Evaluating the mannose receptor C-type 2 as a putative therapeutic target in multiple sclerosis

Bettina Zierfuss, PhD¹, Antoine Fournier, PhD¹, Olivier Tastet, MSc¹, Lyne Bourbonnière, MSc¹, Sandra Larouche, DCS¹, Boaz Lahav, BSc¹, Stephanie Zandee, PhD¹, A Prat, MD, PhD, FRCPC¹
¹Department of Neuroscience, Université de Montréal, Montréal, QC, Canada
Corresponding Author: Bettina Zierfuss, PhD, email bettina.zierfuss@gmail.com

Abstract

Multiple sclerosis (MS) is an idiopathic autoimmune disease of the central nervous system (CNS). It is characterized by a disturbance of the blood-brain barrier (BBB) integrity, and infiltration of immune cells attacking the host’s own CNS tissue. The proteomics analysis of the encephalitogenic MCAM+Th17 cells showed increased protein levels of the mannose receptor C-type (MRC) 2. Here, we present preliminary results evaluating the relevance of MRC2 in MS disease. Flow cytometry to determine the abundance of MRC2 on the surface of peripheral blood mononuclear cells (PBMCs) in untreated relapsing remitting (RRMS) patients in comparison to healthy donors. Immunohistochemistry of active MS lesions on postmortem brain tissue. Analysis of human in vitro polarized Th1, Th2 and Th17 cells regarding MRC2 expression by flow cytometry, western blotting and immunofluorescence microscopy. Immunohistochemistry on spinal cord derived from the experimental autoimmune encephalomyelitis (EAE) mouse model. Flow cytometry analysis of PBMCs from untreated RRMS patients showed tendentially increased numbers of MRC2+ CD4+ and CD8+ T cell subpopulations when comparing to healthy donors. Preliminary data showed co-localization of MRC2 expression with MS-relevant immune cells entering acute CNS lesions when analyzing postmortem brain tissue derived from MS patients. In vitro polarized pro-inflammatory Th1 and Th17 showed higher abundance of MRC2 expression in comparison to anti-inflammatory Th2 cells. To determine the therapeutic effect of MRC2 blockage, we first needed to characterize Mrc2 expression in EAE. Similar to human MRC2 expression, preliminary data showed Mrc2 co-localization with infiltrating MS-relevant immune cells at the peak of EAE development. Our preliminary results indicate a role for MRC2 in CNS-resident cells and in peripheral immune cells particularly when entering MS / EAE lesions. Future analysis will elucidate whether MRC2 indeed represents a novel therapeutic target to interfere with MS disease development and progression.

NKG2D and its ligand ULBP4 contribute to MS pathobiology

Ana Carmena Moratalla¹, Yves Carpentier Solorio¹, Florent Lemaître¹, Negar Farzam-Kia¹, Stephanie Zandee¹, Alexandre Prat¹, Catherine Larochelle¹, Elie Haddad², Nathalie Arbour¹
¹Centre de Recherche du Centre Hospitalier de l’Université de Montréal, QC, Canada
²Centre de Recherche du Centre Hospitalier Universitaire Sainte-Justine, Montréal, QC, Canada
Corresponding Author: Ana Carmena, email anacarmena3@gmail.com

Abstract

Extensive evidence points to pathogenic roles for immune mediators in the pathobiology of multiple sclerosis (MS); nevertheless, the contribution of specific immune mediators remains incompletely resolved. We have identified NKG2D as a relevant player in MS and its animal models. Our goal is to uncover the contribution of NKG2D and its ligands (NKG2DL) to the typical tissue injury observed in the brain of MS patients. For our investigation, we used primary cultures of human neural and immune cells, as well as post-mortem tissue from controls and MS patients. Expression of proteins was analyzed by flow cytometry, western blotting and immunofluorescence. To investigate the functional implications of our discoveries, we performed diverse methods including ELISAs, migration assays and in vitro live imaging. We found that ULBP4 (one NKG2DL) is expressed in brain lesions of MS patients and absent in the brain of controls. Using post-mortem tissue, we identified astrocytes as the main population expressing this ligand and interestingly, this expression was higher in the astrocytes end feet that form the blood brain barrier. Using primary cultures of human astrocytes we observed that various cellular stress involved in MS pathobiology, such as inflammation, induced an upregulation of ULBP4. Finally, we observed a shed form of ULBP4 in the CSF of MS patients compared to controls. To evaluate the role of ULBP4, we co-cultured our ULBP4-expressing astrocytes with activated CD8 T cells and discovered a reduction of ULBP4 in the surface expression of astrocytes, as well as NKG2D from CD8 T cells, suggesting an interaction via this receptor. To investigate this further, we imaged our co-culture by spinning disc microscopy. We discovered that soluble ULBP4 induced a reduction of the coefficient of arrest of CD8 T cells, and induced a scanning behavior in these cells. This increase in motility suggest that soluble ULBP4 might impair the establishment of stable interactions, acting as a decoy for CD8 T cells. In conclusion, our results support the involvement of NKG2D and its ligand ULBP4 in MS pathology.

Identification of WDR35 as a novel gene conferring resistance to oxidative stress in an in vitro model of Parkinson’s disease

Bolduc Cyril¹, Metzakopian Emmanouil², Lévesque Martin¹
¹Department of Psychiatry and Neurosciences, Université Laval, Québec, QC, Canada
²Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
Corresponding Author: Cyril Bolduc, email cyril.bolduc.1@ulaval.ca

Abstract

One of the main histologic hallmarks of Parkinson’s disease (PD) is the loss of dopaminergic (DA) neurons from the substantia nigra pars compacta (SNpc) and the apparition of Lewy bodies mainly composed of aggregated α-synuclein (α-syn). There is still no cure for PD and the development of neuroprotective therapies is needed. Furthermore, we still don’t know the reasons of the degeneration of dopaminergic neurons, but some evidence indicates that mitochondrial dysfunctions might play a role by inducing a high production of reactive oxygen species (ROS) leading to oxidative stress. Those effects may result from the toxicity of α-syn which might accumulate into the mitochondria and thus alter their functions. We aimed to discover novel genes that might confer resistance against oxidative stress using a genome-wide CRISPR-Cas9 loss of function screening approach with an in vitro model of PD. Pitx3-GFP mouse embryonic stem cells (ESC) were transduced with a Lentivirus encoding a Cas9 before being expanded and transduced with a gRNA loss of function library containing approximately 90,000 gRNA. The embryonic stem cells were then differentiated into midbrain dopaminergic neurons which express GFP under the Pitx3 gene locus. Finally, the cells were treated with an IC50 concentration of rotenone and compared to their untreated controls. GFP positive cells were sorted by flow cytometry before performing a high throughput sequencing to identify the gRNA enrichment associated with resistance to rotenone. Our CRISPR-Cas9 screening studies have identified a group of genes which confer resistance to rotenone when knocked-out (KO) and WDR35 was among the most enriched gRNA. We confirmed our results by measuring the effect WDR35 KO on the survival rate of mouse embryonic stem cells derived dopaminergic neurons in response to increasing concentrations of rotenone. To validate our preliminary results, the next step will be to KO WDR35 in vitro in dopaminergic neurons derived from two lines of induced pluripotent stem cells of PD patients carrying a triplication (3xSNCA) or a mutation into the SNCA gene (A53T), but also in vivo with a mouse model of PD overexpressing the human mutated A53T form of α-syn. Using respirometry, markers of synucleinopathy, ROS production and mitochondrial permeability as well as super resolution imaging to observe the morphology of mitochondria, we expect that WDR35 KO will protect dopaminergic neurons against the α-syn toxicity by rescuing mitochondrial functions. Inactivating WDR35 confers resistance against rotenone in dopaminergic neurons derived from embryonic stem cells and might be used as a neuroprotective gene target for Parkinson’s disease. Further validations are required in vitro and in vivo.

Effects of an anti-alpha-synuclein intrabody to reduce alpha-synuclein pathology in hippocampal neurons

Sabrina Armstrong¹, Lilia Rodriguez Moya¹, Anurag Tandon¹
¹Tanz Centre for Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada
Corresponding Author: Sabrina Armstrong, email sabrina.armstrong@mail.utoronto.ca

Abstract

Synucleinopathies, such as Parkinson’s disease (PD), are characterized by the intracellular accumulation of aggregated alpha-synuclein (a-syn). This aggregated a-syn is present in intracellular inclusions called Lewy bodies/neurites and can spread in a prion-like manner by propagating pathology to connected brain regions. Therapeutics that target a-syn to prevent it from misfolding and aggregating may be a viable strategy in halting the progression of PD. Small functional domains of antibodies, called nanobodies, are being investigated as therapeutics to target a-syn. VH14 is a human single domain nanobody with high-affinity for the non-amyloid component domain of a-syn, the region critical for its aggregation. Previous studies have shown when VH14 is fused with a proteasome-targeting sequence (PEST), it reduces intracellular a-syn in vitro and in vivo. We hypothesized that VH14-PEST could reduce intracellular monomeric a-syn and rescue pathology in primary hippocampal neurons. To test this hypothesis, we treated primary hippocampal neurons with a-syn pre-formed fibrils (pff), which seed endogenous a-syn aggregation, and induced expression of VH14-PEST using a Tet-ON system. We used both confocal microscopy and biochemical analysis to assess the formation of phosphorylated serine-129 a-syn (pS129 a-syn) pathology after 7 and 14 days. Exposure to a-syn pffs for 7 days produced pS129 a-syn fibrils along the axons and cell body inclusions in neurons. The a-syn pathology was further increased after 14 days of pff exposure. Expression of VH14-PEST in these neurons significantly reduced pathological pS129 a-syn levels at both 7 and 14 days, compared to a control nanobody not targeted to a-syn. Furthermore, treatment of neurons with synucleinopathy sourced mouse brain homogenate, also caused pS129 a-syn pathology in primary neurons, and this was also significantly reduced by expression of VH14-PEST. Thus, our results demonstrate the ability of intracellular a-syn nanobody expression to reduce a-syn pathology.

Epigenetic and transcriptomic signatures associated with autoimmunity in Parkinson’s Disease

Lovatiana Andriamboavonjy¹, Camille Michaud¹, Diana Matheoud¹, Martine Tétreault¹
¹Université de Montréal, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada
Corresponding Author: Lovatiana Andriamboavonjy, email lovatiana.andriamboavonjy@umontreal.ca

Abstract

The correlation between autoimmunity and Parkinson's disease pathogenesis tend to be confirmed. In the familial form of PD, genetic analysis has confirmed the association between PD-linked genes and autoimmune diseases. The autoimmune basis in PD has led us to the hypothesis of a peri-genetic modification in autoimmunity associated genes for sporadic PD. Besides, transcriptomic and epigenomic alteration can occur after a viral infection or downstream to the activation of immune cells. In Guadeloupe, where flaviviruses infections are endemic, the prevalence of atypical parkinsonism is much higher compared to North America and Europe. We suspect a link between the flaviviruses infection and atypical parkinsonism due to a peri-genetic alteration. Our objectives are: To characterize the transciptomic and/or epigenomic modulation of autoimmunity associated genes in PD, and to identify the potential omics signature involved in parkinsonism clinical expression (Parkinson's Disease vs. other parkinsonism). Three specific groups, PD patients, atypical parkinsonism patients, control patients, will constitute our research population, from two geographical region (Montreal and Guadeloupe). Our approach will consist of: (1) Establishing a transcriptomic signature: Peripheral blood mononuclear cells' (PBMC) RNA will be extracted and subject to a bulk RNA-seq. A bioinformatic pipeline will align the transcripts and identify: variants, alternative splicing, differential expression, specific isoforms and differential polyadenylation. (2) Establishing an epigenomic signature: PBMC's DNA will be extracted and subjected to a methyl-ATAC-seq, which will allow for one time to determine the opened chromatin regions and the methylation profile. Expected result is identification of epigenetic and transcriptomic markers to differentiate typical and atypical parkinsonism. The path of autoimmunity has to be deepened in PD. Exploring the genetic and peri-genetic differences between PD and other parkinsonism can lead us to a more accurate diagnosis between these pathologies and consequently help us to a better understanding of these diseases.

Délétion de tau dans modèle murin de la malade d'huntington

Eva Lépinay^1,2, Melanie Alpaugh^1,2, Martine Saint-Pierre¹, Francesca Cicchetti^1,2
¹Centre de Recherche du CHU de Québec, Axe Neurosciences, Québec, QC, Canada
²Département de Psychiatrie & Neurosciences, Université Laval, Québec, QC, Canada
Corresponding Author: Eva Lepinay, email eva.lepinay@crchudequebec.ulaval.ca

Abstract

La protéine tau associée aux microtubules est essentielle à la formation et à la stabilisation des réseaux de microtubules neuronaux et une fonction altérée a été associée à la maladie. En effet, l'hyperphosphorylation de la protéine tau et les anomalies de conformation sont les caractéristiques des tauopathies - une sous-classe de maladies neurodégénératives caractérisées par le dépôt de protéines tau anormales dans le tissu cérébral. Ces dernières années, une accumulation d’évidences suggèrent que la protéine tau contribue également à la pathologie de la maladie de Huntington (MH). Plus précisément, des études ont rapporté que (i) des agrégats de tau se forment dans plusieurs structures cérébrales chez les patients atteints de MH, (ii) dans un modèle de souris transgénique MH, les comportements étaient améliorés suite à une délétion de tau et donc que (iii) cette maladie pourrait être une tauopathie secondaire. Nous supposons que la protéine tau pourrait aggraver et/ou accélérer l'apparition du phénotype comportemental et neuropathologique de la MH. En particulier, nous supposons que la réduction de l'expression de la protéine tau améliorera le phénotype comportemental du modèle murin zQ175 de la MH. Des souris zQ175 ont été croisées avec des souris délétées tau (mTKO) (wt/wt, wt/mTKO, zQ175/wt, zQ175/mTKO) et des tests comportementaux comprenant le Barnes maze, l'open field, le rotarod et le narrow beam ont été réalisés à 3, 6, 9 et 12 mois pour évaluer l'évolution de l'anxiété, la cognition et la motricité de nos animaux en fonction de la présence ou de l'absence de tau. Nos résultats préliminaires suggèrent que la perte de tau induit une aggravation des comportements chez les souris zQ175/mTKO. Pour comprendre nos résultats, nous avons ciblé deux hypothèses : (1) la protéine huntingtine mutée pourrait bloquer le mécanisme de compensation après délétion de tau (MAP, microtubule-associated proteins) ou (2) l'interaction entre MAP et la protéine tau serait nécessaire à la fonction des microtubules dans la MH. D'après ces résultats, la protéine tau jouerait un rôle essentiel dans la MH. Ce projet contribuera à une meilleure compréhension des relations entre la protéine tau, la huntingtine mutée et le développement des déficits dans la MH.

Identifier la voie de signalisation responsable sous-jacente à la metaplasticité induit par la protéine précurseur de l'amyloïde (APP)

Arsenii Prozorov¹, Jannic Boehm¹
¹Université de Montréal, Montréal, QC, Canada
Corresponding Author: Arsenii Prozorov, email okkamokulus@gmail.com

Abstract

Les cellules nerveuses communiquent entre elles via des synapses. Changer la force de la transmission synaptique est appelé plasticité synaptique et c'est le processus cellulaire sous-jacent à l'apprentissage et à la formation de la mémoire. Les deux formes importantes de plasticité synaptique sont la potentialisation à long terme (LTP, le renforcement de la transmission synaptique) et la dépression à long terme (LTD, l'affaiblissement de la transmission synaptique).Et ces processus sont notre meilleure compréhension des mécanismes de mémoire. L'induction de la plasticité synaptique est étroitement contrôlée par l'activation de voies de signalisation intracellulaires spécifiques. Cependant, ces dernières années, il a été montré que certaines molécules pouvaient influencer et modifier l'induction de la plasticité synaptique, un phénomène appelé métaplasticité. Dans une étude récente, le laboratoire de mon superviseur le Dr Boehm pourrait montrer que la protéine précurseur amyloïde (APP), est une molécule effectrice de la métaplasticité. L'APP a pris de l'importance puisque son clivage produit le peptide amyloïde-bêta (A-bêta), qui est considéré comme l'un des facteurs majeurs du développement de la maladie d'Alzheimer. La présence conjointe d'agrégats de ß-amyloïde et de protéines tau sont les signes caractéristiques de la maladie d'Alzheimer. Le rôle de cette protéine reste largement insaisissable. Jusqu'à présent, on sait que l’APP joue un rôle essentiel dans le développement des connexions synaptiques et la régulation de la force synaptique, cependant, les voies et mécanismes moléculaires impliqués restent inconnus. Pour les expériences proposées suivantes, j'utiliserai des cultures organotypiques de tranches d'hippocampe de souris âgées de 6 jours. Je vais cultiver ces cultures pendant 6 à 10 jours, puis analyser les changements de plasticité synaptique avec une approche patch-clamp. Les résultats préliminaires montrent que la faible concentration de l’APP oligomérisé n’affecte pas la plasticité synaptique. cependant surexpression de AICD (domaine intracellulaire de l'APP) renverse cet effet, et induit la dépression synaptique. Les résultats de ce projet mettra en lumière: 1) le rôle de la protéine précurseur amyloïde dans la physiologie synaptique, 2) L’effet endogène de l’APP sur la plasticité synaptique et la métaplasticité, et 3) Le développement de la maladie d'Alzheimer et l'altération de la mémoire sous-jacente observée chez les patients atteints de la maladie d'Alzheimer.

The development of the humanized antibodies against TDP-43 Proteinopathy

Edris Rezaei^1,2, Silvia Pozzi², Jean-Pierre Julien^1,2
¹Department of Psychiatry and Neuroscience, University of Laval, Québec City, QC, Canada
²CERVO Brain Research Centre, Québec, QC, Canada
Corresponding Author: Jean-Pierre Julien, email jean-pierre.julien@fmed.ulaval.ca

Abstract

Introduction: Amyotrophic lateral sclerosis (ALS) is a life-threatening and neurodegenerative disease characterized by degeneration of motoneurons in the motor cortex brainstem and spinal cord. The first symptom of the disease is accompanied by main muscle-related symptomatology. The disease then progresses to muscle atrophy followed by complete paralysis, and death generally occurs by respiratory failure 3 to 5 years after symptom onset. Diagnosis, which is still based on clinical evaluations, aims to exclude other disorders that resemble ALS and is thus often delayed by about 1 year from the first appearance of symptoms. Ninety percent of patients with ALS have sporadic-origin ALS (sALS), while ten percent have familial inherited mutations (fALS). TAR DNA binding protein (also known as TDP43) is a DNA/RNA binding protein with main localization in the nucleus of cells. In 2006, Neumann & et.al discovered abnormal cytoplasmic aggregates of TDP-43 in the cytoplasm are a pathological feature of neurons degenerative, including frontotemporal dementia (DFT), amyotrophic lateral sclerosis (ALS), and Alzheimer's disease (AD). In this regard, Pozzi & et al reported that intrathecal injection of AAV encoding a single-chain antibody (scFv) against RRM1 domain of TDP-43 attenuated pathological changes in models transgenic ALS / DFT mice caused by TDP-43 mutations. The results provided proof of the principle that the antibody approach can be used to target the pathology of the TDP-43. However, the use of a viral vector in the clinic carries certain risks because the treatment is irreversible. They also found that there is effective penetration into the neurons, especially motor neurons, following intrathecal injection of antibodies. Injection antibodies in cerebrospinal fluid (CSF) to target neuronal cytoplasmic proteins offer new perspectives for the treatment of neurodegenerative diseases. Purpose: We aim to produce humanized antibodies that target cytoplasmic aggregates of TDP43 proteins which would be a more specific therapeutic approach for patients. Three important features of humanized antibodies compared to mouse monoclonal antibodies are: the immunogenicity is reduced; their constant domain allows for human effector functions to take place and increases the half-life of mAbs. Results: Obtaining variable heavy chain and the light chains by PCR from pscFv9 plasmid Insert the purified PCR products into TOPO Blunt vector Digestion of TOPO+sequences plasmids with EcoRI and NheI for VH and EcoRI and BsiWI for VK Digestion of fragments: EcoRI-VH7-NheI, EcoRI-VH-NheI and EcoRI-VH4-NheI with EcoRI and NheI EcoRI-Vk9-BsiWI, EcoRI-Vk-BsiWI and EcoRI-Vk3-BsiWI with EcoRI and BsiWI The human recombinant full length antibodies against TDP-43 RRM1 domain have been produced by cloning the variable heavy chain and the light chains from the pscFv9-VH7Vk9 , VH4VK3 and VHVK (control) plasmid into pFUSEss-CHIg-hG1 and pFUSE2ss-CLIg-hG1 plasmids (InVivoGen).The two plasmids contain all the elements to obtain a full length human IgG1 and a hIL2 signal sequence for release of the antibody in the extracellular space. Immunoblots of high chain and low chain humanized Abs expressed in HEK293 cells after transfection Experimental plan for future: The effects of humanized antibodies will be examined in model cells with TDP-43 aggregation. The formation of cytoplasmic aggregates of TDP-43 may be induced in cell culture (NSC34 cells) by overexpression of TDP-43, exposure to an oxidant (ethacrynic acid), or by LPS from ALS patients. TDP-43 immunofluorescence microscopy will be performed to measure the effect of antibodies on the formation of TDP-43 protein aggregates. Conclusion: Currently, there is no effective cure for neurodegenerative diseases such as ALS, FTD, and Alzheimer's disease. The only drugs for ALS are Riluzole and Edaravone, which prolong the life of patients by a few months. The cytoplasmic aggregation of TDP-43 is one of the pathological features of the disease and recent findings suggest that antibodies targeting TDP-43 can stimulate the breakdown of this protein and slow down the disease in vivo. Here, it is proposed to create and test humanized antibodies targeting TDP-43. If the results show that antibodies can attenuate the formation of TDP-43 aggregates in model cells, this will encourage the development of an immunotherapy approach for ALS and other neurodegenerative diseases.

Investigating the contribution of tau to Huntington’s disease pathology

Shireen Salem^1,2, Melanie Alpaugh^1,3, Martine Saint-Pierre¹, Ronald Melki⁴, Francesca Cicchetti^1,2,3
¹Axe Neurosciences, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec, QC, Canada
²Département de Médecine Moléculaire, Université Laval, Québec, QC, Canada
³Département de Psychiatrie & Neurosciences, Université Laval, Québec, QC, Canada
⁴Commissariat à l’énergie atomique et aux énergies alternatives, Institut François Jacob (Molecular Imaging Research center) and Centre national de la recherche scientifique, Laboratory of Neurodegenerative Diseases, Fontenay-aux-Roses, France
Corresponding Author: Shireen Salem, email shireen.salem@crchudequebec.ulaval.ca

Abstract

The tau protein is implicated in microtubule stabilization and axonal transport in physiological conditions and exists in six isoforms resulting of alternative splicing of the tau gene. In several conditions, collectively referred to as tauopathies, tau becomes hyperphosphorylated and accumulates into various pathological forms (i.e. neuronal inclusions, neurofribrillary tangles and neuropil threads). More recently, it has been reported that the expression of tau isoforms containing 4 repeats is also increased in patients with Huntington's disease (HD), suggesting that this disorder may be a secondary tauopathy. We hypothesize that the introduction of 3R or 4R tau to cell and animal models of HD leads to an exacerbation of intracellular huntingtin (HTT) aggregation, with consequences on cellular and behavioral functions. Human synthetic recombinant tau (monomers and fibrils of 3R and 4R tau) are introduced to an HD neuronal cell line – StHdh cells containing 7 or 111 polyglutamine repeats – and various aspects of toxicity and dysfunction are assessed. The uptake of tau is observed by immunocytochemistry, metabolic activity using an MTT toxicity assay and HTT aggregation is measured by filter retardation assays. To evaluate the influence of tau on behavioral impairments, 3-month old wild-type and HD (zQ175) mice received bilateral intracerebral stereotaxic injections of tau forms into the hippocampus and prefrontal cortex. Several behavioral tests were performed at 2, 5, 7 and 9 months to assess cognitive, motor and anxiety-like measures. Low dose tau fibrils significantly decrease the metabolic activity of both healthy and HD StHdh cells while the 3R forms of tau increase HTT aggregation in HD StHdhQ111 cells. In vivo, 4R monomers and 3R fibrils exacerbate behavioral phenotypes in WT mice, notably anxiety-like behavior as indicated by less time spent in the center and increased freezing time in the open field as well as motor deficits shown by a reduction in the distance travelled in the open field. In zQ175 mice, 4R monomers tend to worsen cognition, as observed in the intrasession habituation of the open field. Although preliminary, tau seems to alter cellular features associated to HD such as increased HTT aggregation, and to worsen behavioral phenotypes in mice. Ongoing experiments will allow us to link the cellular alterations to the behavioral aspects observed, shedding light on the role of tau in this disease.

Defining the Caprin-1 Interactome in stressed and unstressed conditions

Asmita Ghosh^1,2, Lucas Vu³, Chelsea Tran^3,4, Walters Aji Tebung^1,2, Hadjara Sidibé^1,2, Krystine Garcia-Mansfield⁵, Victoria David-Dirgo⁵, Ritin Sharma⁵, Patrick Pirrotte⁵, Robert Bowser³, Christine Vande Velde^1,2
¹Centre Hospitalier de l'Université de Montréal Research Center, Montréal, QC, Canada
²Department of Neurosciences, Université de Montréal, Montreal, QC, Canada
³Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ, USA
⁴School of Life Sciences, Arizona State University, Tempe, AZ, USA
⁵Collaborative Center for Translational Mass Spectrometry, Translational Genomics Research Institute, Phoenix, AZ, USA
Corresponding Author: Asmita Ghosh, email asmita.beas@gmail.com

Abstract

Cytoplasmic stress granules (SGs) are dynamic non-membranous foci containing translationally arrested mRNA and RNA binding proteins (RBPs) which form in response to a variety of cellular stresses. Previous studies have utilized over-expression of G3BP1 as a bait to get a glimpse of the SG proteome. While this has generated a rich resource and helps in understanding the complexity of SGs, later studies have confirmed that such over-expression of RBPs can alter the stoichiometry and result in aberrant granule formation in the cell. This prompted us to understand the SG proteome using endogenous immunoprecipitation of a candidate SG protein. We utilized Caprin-1 as a candidate as it is known to strongly interact with G3BP1 and G3BP2 – two core SG proteins. Further, the interacting partners of Caprin-1 remain largely uncharacterized although this protein is associated with aggregate inclusions in amyotrophic lateral sclerosis (ALS). Recent studies within our group demonstrated the presence of Caprin-1 cytoplasmic inclusions in ALS patient neurons. Additionally, others determined that Caprin-1 co-localizes with pTDP-43 in ALS spinal cord motor neurons. To gain insight into the proteome of Caprin-1 containing inclusions, we employed immunoprecipitation of endogenous Caprin-1, which is not impacted by TDP-43 localization or mutation, to further define the stress granule proteome. Cells were subjected to immunoprecipitation with either Caprin-1 or IgG-coated dynabeads, followed by mass spectrometry. Proteomics analyses were used to interrogate the Caprin-1 interactome. We validated interactors to co-localize to SGs, using various stressors. We identified 1500 proteins that interacted with Caprin-1 in basal and stressed conditions. Based on gene ontology analyses, interactors under stressed conditions were annotated to the ribosome, spliceosome, and RNA transport. Of the interactors, we found ANKHD1, TALIN-1, SNRNP200 and GEMIN5 to co-localize with arsenite-induced SGs in HeLa cells. As the proteome of SGs can vary with different stress inducers, we validated our results in thermal and osmotic stress conditions. We further validated our findings in neuronal-like cells, SH-SY5Y cell line and differentiated SH-SY5Y cells and found SNRNP200 to be a novel SG component across different stresses. Since Caprin-1 is found to be present as aggregates in spinal motor neurons of ALS patients, we wondered if its strongest interactors would also be sequestered and be part of inclusion bodies in patient neurons. We found SNRNP200 to be aggregated in 23% of motor neurons in ALS patient tissue which starkly contrasted to only 1.5% of control neurons bearing similar inclusions of SNRNP200. Our findings demonstrate the Caprin-1 interactome, and reveal novel cytoplasmic stress granule components. One of these, SNRNP200, being implicated in potential pathogenic aggregates in ALS patient neurons.

Memory and Dementia

The challenges of treating Alzheimer’s disease (AD): BACE1 inhibitors on trial

Nicole Palacio^1,2, Miguel Parra, PhD^1,3, and Maria Claudia Lattig, PhD¹
¹Department of Biological Sciences, Universidad de Los Andes, Bogotá, Cundinamarca, Colombia
²Present Address: Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
³Present Address: Faculty of Medicine, Universidad El Bosque, Bogotá, Cundinamarca, Colombia
Corresponding Author: Nicole Palacio, email maria.palacioprada@mail.mcgill.ca

Abstract

BACE1 inhibitors were promising alternatives for the treatment of Alzheimer’s disease (AD). However, clinical trials have shown heterogeneous results, and several have stopped for futility reasons. Thus, our purpose was to differentiate the cognitive and physiological effects of BACE1 inhibitors with a meta-analysis. We searched for double-blind randomized clinical trials indexed in PubMed. The chosen functional and cognitive measures were the difference in ADCS-ADL, ADAS-cog, and MMSE scores before and after treatment. The physiological measures were the change in Aβ1-40 and Aβ1-42 in cerebrospinal fluid. Fixed and random effect meta-analyses were used to determine the standardized mean difference (SMD) and confidence interval (CI) when comparing placebo and treatment groups. To distinguish the effects in preclinical and clinical AD samples with various genetic risks, we included subgroup analyses and meta-regressions in RStudio. The high heterogeneity decreased after separating the population diagnosed with AD. BACE1 inhibitors did not improve the capacity to do daily activities measured by ADCS-ADL (SMD= -0.09; 95% CI= -0.42 to 0.23; p= 0.42). There was no benefit in cognitive measures like ADAS-cog (SMD= 0.08; 95% CI= -0.11 to 0.27; p=0.28) or MMSE (SMD= -0.07; 95% CI= -0.22 to 0.08; p= 0.31). Despite the limited number of studies, BACE1 inhibition could worsen some MMSE cognitive measures in preclinical samples (SMD= -0.15; 95% CI= -0.28 to -0.02; p= 0.02). Nevertheless, BACE1 inhibition led to reductions of Aβ1-40 (SMD= -4.32; 95% CI= -6.36 to -2.27; p<0.01) and Aβ1-42 (SMD= -3.93; 95% CI= -5.17 to -2.69; p<0.01). The percentage of APOE4 carriers per study did not clearly impact the overall reduction of Aβ1-40 and Aβ1-42 in the trial. Although BACE1 inhibitors reduce Aβ1-40 and Aβ1-42 in cerebrospinal fluid, they do not bring cognitive benefits. It is important to analyze other therapeutic alternatives for AD besides BACE1 inhibition.

Evaluation of semantic memory using famous people tests in Mild Cognitive Impairment

Émilie Delage^1,2, Jessica Cole^2,3, Marie-Joëlle Chasles^2,3, Isabelle Rouleau^3,4, Sven Joubert^1,2
¹Département de psychologie, Université de Montréal, Montréal, QC, Canada
²Centre de recherche de l’Institut universitaire de gériatrie de Montréal, Montréal, QC, Canada
³Département de Psychologie, Université du Québec à Montréal, Montréal, QC, Canada
⁴Centre de Recherche du Centre Hospitalier de l’Université de Montréal, Montréal, QC, Canada
Corresponding Author: Emilie Delage, email emilie.delage.1@umontreal.ca

Abstract

Difficulty remembering the names of famous people is a common complaint among older people. Theses difficulties are frequent in normal aging and are even more so in Alzheimer’s disease (AD), affecting not only access to names, but also semantic knowledge related to famous people. However, few studies have investigated this type of memory in the preclinical stage of AD, the Mild Cognitive Impairment (MCI). A group of healthy elderly people aged between 60 and 90 years (N = 43) and a group people the same age meeting the criteria for MCI (N = 32) completed two Quebec tests measuring the memory of famous people: the POP-10 (multiple choice question about the life of a famous person after presentation of the name), and the mini-PPMS (free recall of the name plus a multiple choice question about the life of a famous person, after presentation of the picture). The results indicate that memory for famous people is significantly reduced in the MCI group compared to the healthy elderly group, for the ability to name photographs of famous faces (t (69) = 5.173, p <0.01) , as well as for the ability to answer biographical questions about these people (e.g. profession, nationality, etc.) (t (65) = 3.488, p <0.01 and t (69) = 4.849, p <0.01). There is no difference between visual (photos) and verbal (names) presentation of stimuli (t (30) = 0.928, p> 0.05). In summary, semantic memory for famous people is impaired in older people in the preclinical phase of AD (MCI), both when assessing denomination and biographical knowledge. The use of clinical tools developed and validated in Quebec is therefore an accessible way to assess the integrity of semantic memory in the elderly and to distinguish between people who are in a preclinical phase of dementia and healthy people.

Investiguer le rôle mes micro-occlusions multifocales dans la pathobiologie de la maladie d’Alzheimer

Sarah Lecordier^1,2, Vincent Pons^1,2, Romain Menet^1,2, Serge Rivest^1,2, Ayman ElAli^1,2
¹Department of Psychiatry and Neuroscience, Faculty of Medicine, Université Laval, Quebec City, QC, Canada
²Research Center of Centre Hospitalier Universitaire de Québec-Université Laval, Quebec City, QC, Canada
Corresponding Author: Sarah Lecordier, email sarah.lecordier@crchudequebec.ulaval.ca

Abstract

Les micro-occlusions sont présentes chez près de 40% des patients atteints de la maladie d'Alzheimer (MA). Elles sont associées à des micro-angiopathies cérébrales (MAC) provoquant une réduction chronique du flux sanguin cérébral, entraînant des troubles de la mémoire, anxiété et dépression, désorientation et perte des fonctions exécutives. L'accumulation de micro-infarctus causés par les MAC tout au long de la vie favorise le développement progressif des troubles cognitifs d’origine vasculaires, communément appelé démence vasculaire (DVa). Les mécanismes pathologiques qui associent les MAC à la MA ne sont pas entièrement élucidés. Les microglies qui constituent les cellules immunitaires du cerveau, répondent rapidement aux lésions cérébrales, surtout au sein des lésions ischémiques suite à un accident vasculaire cérébral (AVC). En effet, le dysfonctionnent des microglies avec l’âge exacerbe la réponse inflammatoire ce qui entrave la réparation tissulaire. En fait, de nombreuses études proposent que le dysfonctionnent des microglies augmentent les risques de développer des démences et la MA, qui se manifeste de façon plus sévère chez la femme. Ainsi, nous postulons que la dérégulation de l'activité des microglies au sein des micro-infarctus après des micro-occlusions cérébrales pourrait accélérer l'apparition de la MA. À cette fin, nous avons utilisé une nouvelle approche pour induire des micro-infarctus dans un modèle de souris de la MA pour évaluer l'impact sur la démence en fonction du sexe. En utilisant des analyses moléculaires, d'imageries et neurocomportementales, nous avons constaté que la MA se développe de façon sexe spécifique d’où un impact différent des micro-occlusions sur la pathologie. Les micro-infarctus sont associés à une dégénérescence cellulaire précoce accompagnée d’une activation soutenue des microglies qui diminuent le volume et le nombre de plaques chez le mâle et la femelle respectivement. Ce résultat serait accompagné d’une augmentation des oligomers d’amyloides beaucoup plus toxiques à l’origine de déficits cognitifs précoces. Nos résultats préliminaires suggèrent que les micro-angiopathies exacerbent la progression de la MA en aggravant les déficits structurels et fonctionnels du cerveau dépendamment de l’âge et du sexe biologique.

Postsynaptic protein Shank3 deficiency synergizes with Alzheimer’s disease neuropathology to impair cognitive performance in the 3xTg-AD murine model

Olivier Landry^1,2, Arnaud François^1,2, Méryl-Farelle Oye Mintsa Mi-Mba^1,2, Marie-Thérèse Traversy^1,2, Cyntia Tremblay², Vincent Emond², David A. Bennett³, Karen H. Gylys⁴, Joseph D. Buxbaum⁵, Frédéric Calon^1,2
¹Faculté de pharmacie, Université Laval, Québec, QC, Canada
²Axe Neurosciences, Centre de recherche du CHU de Québec-Université Laval, Québec, QC, Canada
³Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, United States
⁴School of Nursing, University of California, Los Angeles, CA, United States
⁵Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, United States
Corresponding Author: Frédéric Calon, email frederic.calon@crchudequebec.ulaval.ca

Abstract

The loss of synapses is intrinsically linked to Alzheimer’s disease (AD) neuropathology and symptoms. However, it remains elusive to what extent the decrease of a synaptic protein translates into clinically significant effects. The postsynaptic protein Shank3 (SH3 and multiple ankyrin repeat domains) may be an exception because the loss of a single SHANK3 allele is sufficient to cause profound cognitive symptoms in children. We sought to determine whether a Shank3 deficiency occurs in AD and whether it contributes to the emergence or worsening of AD neuropathology and symptoms. We investigated postmortem Shank3 concentrations in the parietal cortex of individuals classified as Controls, MCI or AD using Western Blot technique. We next crossed the 3xTg-AD mouse model of AD with Shank3 deficient mice (Shank3Δex4-9) to generate 4 groups of hemizygous mice. We performed behavioral tests (novel object recognition, light & dark box and open field) to assess the cognitive impact of a Shank3 deficiency. We then investigated AD-related neuropathology (amyloid-β and tau accumulation) based on ELISA and Western Blot analyses. A 30-50% postmortem loss of Shank3 was found in the brain of people with a diagnosis of AD and associated with cognitive impairment. In the Shank3Δex4-9-3xTg-AD model, we observed a synergistic effect of Shank3 deficiency and AD neuropathology on memory from 9 months of age. We also observed a worsening of the anxious behavior in Shank3-deficient 3xTg-AD mice. Levels of other synaptic proteins, such as PSD-95, cortactin and septin3, remained unchanged in the parietotemporal cortex and hippocampus. Finally, Shank3 deficiency increased levels of soluble amyloid-β42 and human tau in the parietotemporal cortex of 18-month-old 3xTg-AD mice. These results in human samples and in transgenic mice are consistent with the hypothesis that Shank3 deficiency plays a causal role in the apparition of cognitive impairment in AD, in synergy with canonical AD neuropathology.

Excitotoxicity in Aβ-burdened neurons triggers an exacerbation of early Alzheimer’s-like amyloid deposition

Maya Mikutra-Cencora¹, Rowan Pentz², A. Claudio Cuello^1,2,3,4
¹Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
²Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
³Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
⁴Department of Pharmacology, Oxford University, US (visiting professor)
Corresponding Author: Maya Mikutra-Cencora, email maya.mikutra-cencora@umontreal.ca

Abstract

Amyloidosis in Alzheimer’s disease has been shown to trigger neuronal excitotoxicity with implications for AD symptomology and a potential disease-aggravating role in AD pathogenesis. Recent evidence suggests that AD neurons are burdened with increasing levels of soluble and oligomeric Aß (known to be the most toxic amyloid species within the brain) prior to the onset of plaques, leading to neuronal dysfunction and disease aggravation. We propose that such neurons may be uniquely vulnerable to excitotoxic stress, and that such stress might trigger the release of intracellular Aß, leading to extracellular amyloid accumulation, as well as proinflammatory processes important for disease progression. We induced excitotoxic stress by intrahippocampal NMDA injection in heterozygous McGill-R-Thy1-APP transgenic rats expressing autosomal dominant Alzheimer’s disease-conferring mutations at ten months, a model characterized by extensive intracellular amyloid but no plaque deposition. At one day post-injection, immunohistochemical analysis revealed a co-localized increase in intracellular amyloid accumulation and cytokine signaling previously shown to characterize early stages of Alzheimer’s pathology, as well as a paradoxical inhibition of glial response. After 2.5 months, treated rats exhibited plaque pathology despite the absence of such aggregates in normally aging animals. Excitotoxicity is a possible causal agent of disease progression and may act early in disease progression, prior to the onset of plaque pathology and concurrently with intracellular amyloidosis.

Modulation de la réponse immunitaire comme traitement contre la Maladie d’Alzheimer

Pierre-Alexandre Piec¹, Vincent Pons¹, Marie-Michèle Plante¹, Paul Préfontaine¹, Serge Rivest¹
¹Centre de Recherche du Centre Hospitalier de Université Laval, Québec, QC, Canada
Corresponding Author: Pierre-Alexandre Piec, email pierre-alexandre.piec.1@ulaval.ca

Abstract

La maladie d’Alzheimer (MA) est une maladie neurodégénérative dans laquelle les patients perdent progressivement leurs facultés cognitives. Cette pathologie est associée à une forte inflammation chronique due à la présence d’amyloïde bêta (Aß) dans le cerveau. Cependant on trouve des dépôts amyloïdes dans les vaisseaux sanguins cérébraux provoquant une angiopathie amyloïde cérébrale (AAC), touchant jusqu’à 93 % des patients atteints de la MA. L’accumulation vasculaire d’Aß est considérée comme un facteur de risque lié à la maladie, entrainant des microhémorragies ainsi que des accidents vasculaires cérébraux, accélérant et aggravant la MA. À ce jour aucun traitement efficace n’est disponible pour guérir ou ralentir la maladie. Le système immunitaire y joue un rôle important, or avec la propagation de cette pathologie, les cellules immunitaires ne sont plus capables d’éliminer l’Aß correctement. En 2013 nous avons montré chez la souris que certains monocytes vasculaires sont capables de phagocyter activement l’amyloïde dans les vaisseaux. Il existe chez la souris comme chez l’Humain deux sous-populations monocytaires. Les monocytes classiques respectivement caractérisés par l’expression Ly6Chi (murins), CD14++ CD16 — (humain) et les monocytes non classiques/patrouilleurs Ly6Clow et CD14+ CD16++. Des études montrent que les Ly6Clow sont plus efficaces pour phagocyter l’Aß vasculaire grâce à leurs phénotypes capables de parcourir la vasculature pour phagocyter l'Aß vasculaire. Démontrant le fort potentiel thérapeutique de ces monocytes, plusieurs molécules ont la capacité de stimuler la production de Ly6Clow dont le muramyl-dipeptide (MDP). Ce dernier permet la conversion des monocytes Ly6Chi vers Ly6Clow en se liant au récepteur NOD2. Nous supposons que l’augmentation du nombre des Ly6Clow par le MDP entraine une élimination de l'Aß au niveau vasculaire. Ainsi par effet d'équilibre entre la vasculature et le parenchyme cérébral, l'élimination au niveau vasculaire d'Aß va induire une diminution au niveau cérébrale et ainsi retarder la physiopathologie d'Alzheimer. Différents techniques ont été réalisés pour étudier l'impact du MDP sur la pathologie d'Alzheimer. Nous avons étudier au stade précoce de la pathologie (correspondant de 3 jusqu'à 6 mois) l'effet bénéfique du MDP sur des souris transgéniques Alzheimer APP/PS1 ♀ et ♂. Pour permettre un changement de population nous avons injecté en IP à 10mg/kg de MDP pendant trois jours (pour permettre une induction de notre population d'intérêt) puis 1X/semaine pendant 3 mois. Nous avons déterminé la dose minimale d'activation nécessaire du MDP pour induire la conversion monocytaire. Nous avons étudié modulation monocytaire dans le temps par cytométrie en flux avant et après le traitement jusqu'à 5 jours après l'induction. Un test de comportement Novel Object recognition task a été effectué pour évaluer la variation de la mémoire à court terme de nos souris à 3 et à 6 mois. Une analyse de la toxicité et de l'inflammation de notre composé a été évaluée sur des PBMC de sang de patient Alzheimer grâce à un Cytometric Bead Array. Nous avons finalement évalué l'environnement cérébral en comptant les microglies et les plaques d'Aß (nombre et volume) de l'hippocampe et du cortex. Le MDP permet une modulation des monocytes en stimulant la conversion Ly6Chigh en Ly6Clow et est conservé dans le temps. Il semble réduire le nombre de plaques ainsi que leurs volumes sans sur-activer les cellules microgliales au niveau de l'hippocampe et du cortex. Une faible dose semble nécessaire pour activer la conversion monocytaire. Le MDP semble favoriser la conservation de la mémoire des souris Alzheimer en retardant l'apparition des symptômes de la pathologie. Le MDP semble avoir un fort potentielle thérapeutique en retardant les symptômes d'Alzheimer par la modulation de l'immunité périphérique.

L’effet d’une expérience de mémoire sur le système vasculaire du cerveau

Alice Cadoret¹, Laurence Dion-Albert¹, Mathilde Théberge¹, Sarah Amrani¹, Manon Lebel¹, Caroline Ménard¹
¹Université Laval, Québec, QC, Canada
Corresponding Author: Alice Cadoret, email alice.cadoret.1@ulaval.ca

Abstract

Des expériences liées aux émotions, positives comme négatives, altèrent la mémoire et ont un impact sur plusieurs régions du cerveau reliées à cette fonction cognitive. Le stress posttraumatique est un exemple d’émotions négatives très fortes affectant la mémoire par des flashbacks et souvenirs récurrents de traumatismes vécus. Les personnes atteintes du trouble de dépression majeur présentent également des difficultés de mémoire. La barrière hémato-encéphalique (blood brain barrier, ou BBB) subit des changements morphologiques et fonctionnels suite à différentes émotions, tel que le stress. Le lien entre la formation de la mémoire avec ou sans valence émotionnelle et l’intégrité de la BBB est peu connu puisque la plupart des études se penchent sur les fonctionnements neuronaux de l’acquisition de la mémoire. Pourtant, tant l’intégrité de la BBB que les capacités cognitives diminuent avec le vieillissement. Mon projet s’intéresse donc aux effets d’une expérience de mémoire avec ou sans impact émotionnel sur le système vasculaire de différentes régions du cerveau chez la souris. Le test de reconnaissance d’un nouvel objet (novel object recognition, ou NOR), un test à impact émotif neutre qui évalue l’apprentissage et la mémoire, a été réalisé dans différentes conditions expérimentales. Le comportement des animaux lors de ce test a été évalué avec le programme d’analyse Ethovision. Les cerveaux ont ensuite été collectés puis nous avons investigué le changement d’expression de gènes liés aux cellules endothéliales formant la BBB par PCR. Nos résultats démontrent que le comportement des animaux varie selon les différentes conditions expérimentales du test NOR, notamment en lien avec l’anxiété, soulignant l’importance de ces dernières. De plus, l’expression de certains gènes est modulée selon la région du cerveau, le sexe et l’âge des souris. Les changements transcriptionnels sont validés au niveau protéique par immunofluorescence et microscopie. Ces résultats suggèrent que la BBB est affectée lors d’un test de mémoire même si celui-ci est à impact émotif neutre, à tout le moins chez la souris. Les changements comportementaux observés pourraient corréler avec les changements d’expression des gènes et pourraient ainsi être associé à une modulation de l’étanchéité de la BBB. Pour la suite du projet, des expériences de mémoire avec valence émotionnelle positive (récompense) et négative (peur) seront réalisés afin de comparer les effets de ces dernières sur la BBB.

Amelioration of some olfactory system deficits with DHA treatment in APOE4 transgenic mice

Laura Martínez González^1,2, Adam Bourissai³, Mélissa Lessard-Beaudoin^1,2, Réjean Lebel³, Luc Tremblay³, Martin Lepage³, Rona K. Graham^1,2
¹Research Centre on Aging CIUSSS de l’Estrie, Sherbrooke, QC, Canada
²Department of Pharmacology and Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
³Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, QC, Canada
Corresponding Author: Laura Martínez González, email Laura.Martinez.Gonzalez@USherbrooke.ca

Abstract

Olfactory system deficits are observed early in Mild Cognitive Impairment (MCI) and Alzheimer disease (AD). Numerous studies have shown neuroprotective effects in MCI/AD with treatment of docosahexaenoic acid (DHA), an omega-3 fatty acid. However, few studies have assessed DHA and effects on the olfactory system deficits. The objectives of our project were to determine if DHA treatment in a murine model of MCI improves cognitive and olfactory system deficits and establish if inflammation and/or excitotoxicity are early events in the olfactory regions in MCI. . Structural (MRI), functional (olfactory behaviour, novel object recognition and sucrose preference test) and molecular (markers of neurogenesis and inflammation) assessments of APOE4 and wild type mice (WT) +/- DHA treatment at 3, 6 and 12 months of age have been performed. Our results show that APOE4 mice treated with the control diet showed recognition memory deficits at all ages, which was rescued with a DHA diet. In the olfactory behavior test, an abnormal habituation and discrimination abilities were observed in APOE4 mice on control diet, which was rescued with DHA. In the sucrose preference test, a measure of depression, APOE4 mice on the DHA diet had less preference for sucrose than WT mice. Early atrophy of the olfactory bulb (OB), olfactory tubercle, piriform cortex, amygdala was observed in APOE4 mice, and showed no rescue with DHA. Moreover, no rescue of increased NR2B positive cells in the APOE4 OB on the control diet was found in the DHA treated mice. However, a significant increase in the number of microglia was observed in the OB of APOE4 mice, which was ameliorated with a DHA diet. Conclusion: The consumption of a diet rich in DHA may prevent the olfactory behavioral deficits and recognition memory decline observed in the APOE4 mice. The early brain region atrophy observed in the APOE4 mice could be due to caspase activation and/or alterations in neurogenesis. NR2B expression is altered in the APOE4 OB, which could lead to excitotoxicity and consequently, cell death. IBA-1 expression is upregulated in OB of APOE4 mice at early age suggesting there is microglia activation and a neuroinflammatory response, which is alleviated with DHA treatment. Overall, the data suggest that high intake of DHA may provide some rescue of olfactory system deficits in E4 carriers.

Brain uptake studies of fibroblast growth factor 21 by in situ cerebral perfusion

Manon Leclerc^1,2,3, Tra-My Vu^1,2,3, Vincent Emond², Frédéric Calon^1,2,3
¹Faculté de Pharmacie, Université Laval, Québec, QC, Canada
²Axe Neurosciences, Centre de recherche du centre Hospitalier de l’Université Laval, Québec, QC, Canada
³Institut sur la Nutrition et les Aliments Fonctionnels, Québec, QC, Canada.
Corresponding Author: Manon Leclerc , email manon.leclerc.4@ulaval.ca

Abstract

Fibroblast growth factor 21 (FGF21) is a hormone mainly secreted by the liver, with pleiotropic effects on glucose and lipid homeostasis and insulin sensitivity. The effect of FGF21 in the central nervous system (CNS) is begging to be explored as well. FGF21 interacts with the FGF21 receptor, which is composed of the co-receptors FGF receptor 1 (FGFR1) and ß-Klotho, both present in the CNS. In addition, a previous report indicates that FGF21 crosses the blood-brain barrier (BBB), but given its size, FGF21 is likely to use specific transport mechanism. Objective: To determine the mechanism of transport of FGF21 through the BBB. In situ cerebral perfusion (ISCP) was used to quantify and characterize the transport of 3H-recombinant human FGF21 (3H-rhFGF21) through the BBB in the mouse. FGF21 uptake was also investigated in the triple transgenic mice model of Alzheimer’s disease neuropathology (3xTg-AD) fed or not a high-fat diet (HFD). 3H-rhFGF21 had a brain uptake coefficient (Clup) of 0.30 ± 0.03 µl.g-1.s-1, similar to compounds ferried by receptor-mediated transport (RMT), and approximatively 61 ± 2% of the tritium signal was extravascular. However, its uptake was not impacted by an FGFR1 phosphorylation inhibitor (ASP5878). Coperfusion with PSC833 (a P-glycoprotein (P-gp) inhibitor) increased the Clup by +200%, consistent with an efflux of 3H-rhFGF21 through P-gp at the BBB level. Moreover, 3H-rhFGF21 transport across the BBB was saturable with Clup decreasing when competing with increasing amounts of non-radiolabeled rhFGF21. Finally, the brain transport of 3H-rhFGF21 was not impacted by AD neuropathology in aged 3xTg-AD mice nor by a HFD. In all ISCP experiments, no change in permeability was detected with co-perfused 14C-sucrose, a marker of brain vasculature volume. Our studies show that the FGF21 transport is saturable, but independent of the FGFR1 phosphorylation. Our data are consistent with P-gp acting as an efflux BBB transporter of FGF21. The transport of FGF21 through the BBB was not affected by HFD or AD neuropathology. Studies are ongoing to identify BBB FGF21 influx transporters.

Molecular Biology and Neurogenetics

Electrophysiological properties of glutamatergic reticular and reticulospinal tract neurons of the medullary reticular formation important to locomotion

Yacine Haili¹, Josée Seigneur¹, Narges Karimi¹, Frédéric Bretzner^1,2
¹Axe Neurosciences du Centre de recherche du Centre Hospitalier Universitaire de Québec–Université Laval, Québec, QC, Canada
²Université Laval, Faculty of Medicine, Department of Psychiatry and Neurosciences, Québec, QC, Canada
Corresponding Author: Yacine Haili, email yacine.haili.1@ulaval.ca

Abstract

Recently, it has been shown that glutamatergic neurons of the medullary reticular formation integrate cortical and mesencephalic inputs and have access to the spinal locomotor circuit through the descending reticulospinal pathway. Although these neurons contribute to motor, locomotor, and postural functions, less is known about their electrophysiological properties and their network connectivity. Brainstem were harvested from 3-4-week-old mice for living tissue slice preparation. In a 1st series of experiments, we performed whole-cell patch-clamp recordings of VGluT2-cre expressing reticular neurons. In a 2nd series of experiments, a AAV2-retro-DiO-FP (fluorescent protein) was injected in the lumbar spinal cord of VGluT2-cre mice to patch-clamp glutamatergic reticulospinal tract neurons. In our first experiments, 42 neurons were recorded in the medulla, 30 of those neurons were located in the gigantocellular reticular nucleus (Gi). 24 out of these 30 neurons displayed a regular-spiking pattern (RS) with spike frequency adaption, and 6 out of 30 cells displayed a fast-spiking firing pattern (FS) without spike frequency adaptation. Moreover, RS neurons displayed a mean initial firing frequency of 24 +/- 2.2 Hz with a sag in response to a hyperpolarizing current in 30% of these RS neurons, whereas FS neurons displayed a mean initial firing frequency of 40.82+/- 8.3 Hz and no sag. Mean membrane resistance was 388 +/- 47 MΩ for RS neurons and 285 +/- 22 MΩ for FS neurons. The morphology of RS neurons was round, whereas that of FS neurons was ovoid. Finally, immunohistochemistry experiments on brainstem slices confirmed that RS pattern neurons were glutamatergic. To investigate the network connectivity, we next performed stereotaxic injections of AAV-retro-DiO-FP in the lumbar spinal cord to label glutamatergic reticulospinal tract neurons. We identified and recorded 39 reticulospinal tract neurons projecting to the lumbar spinal cord. All these neurons showed a RS pattern with spike frequency adaptation, with a mean initial spiking frequency of 14.16 +/- 4.5 Hz. In addition, 62% of these neurons displayed a sag in response to a hyperpolarizing current. Interestingly, the membrane resistance of these neurons was heterogeneous ranging from 94.2 to 936.8 MΩ, arguing the presence of small and large glutamatergic reticulospinal tract neurons. Our results reveal the presence of reticulospinal tract neurons with small and large soma exhibiting regular firing pattern and spike frequency adaptation that could contribute to the descending motor command.

Early life adversity and a sex-specific polygenic risk for fasting insulin are associated with executive functioning

Aashita Batra^1,2, Lawrence Chen^1,2, Zihan Wang², Carine Parent², Irina Pokhvisneva², Sachin Patel², Michael J. Meaney^2,3,4, Patricia Pelufo Silveira^2,3
¹Integrated Program in Neuroscience, McGill University, QC, Canada
²Douglas Mental Health University Institute, McGill University, QC, Canada
³Ludmer Centre for Neuroinformatics and Mental Health, Douglas Research Centre, McGill University, Montreal, QC, Canada
⁴Translational Neuroscience Programme, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
Corresponding Author: Aashita Batra, email aashita.batra@mail.mcgill.ca

Abstract

As insulin is an important hormone for childhood growth and development and has implications for adult psychopathology in both males and females, we hypothesized that 1) the genetic background associated with altered fasting insulin (FI) and ADHD would be shared; 2) if (1) is rejected, the genetic background associated with altered fasting insulin would perform better in interaction models, G by E (childhood adversity), as opposed to main effect models to predict child psychosocial problems and adult psychopathology. Using conjunctional false discovery rate (FDR), we saw that no SNPs were shared between the FI GWAS and ADHD GWAS. (2) We calculated polygenic risk scores (PRS) from the sex-specific FI GWAS at different thresholds and identified one that best predicted peripheral insulin levels in male and female children in the ALSPAC cohort, further refining it to only include SNPs significantly associated with the peripheral insulin levels (p-refined<0.05). As hypothesized, there was an interaction between FI PRS and early life adversity exposure on executive functions measured by CBCL Total Problems Assessment [Nmales = 4037, pmale = 0.00038; Nfemales = 3684, pfemale = 0.00049] and measured by CBCL ADHD Assessment [Nmales = 1929, pmale = 0.042; Nfemales = 1697, pfemale = 0.006], in which higher PRS is linked to lower Total/ADHD problems while the lower PRS is linked to higher Total/ADHD problems in males and females exposed to early adversity. As predicted, there were no main effects of FI PRS on executive functions measured by the CBCL Total Problems Assessment or measures by the CBCL ADHD Assessment. The genetic background associated with higher fasting insulin levels is linked to psychopathology, but this effect is dependent on the exposure to adversity. The findings reported here have implications for identification and treatment of psychopathology at different ages.

Mechanistic studies of FUS regulating local protein synthesis at synapses

Yousri Benchaar¹, Chantelle F. Sephton¹, Myriam Sévigny¹
¹Université Laval, Québec, QC, Canada

Corresponding Author: Yousri Benchaar, email yousri.benchaar.1@ulaval.ca

Abstract

Neurons are polarized cells that have numerous dendritic processes and an axon that extend away from the cell body. The requirement for regulated protein synthesis at specific locations in neurons is a logistical hurtle that must be overcome to maintain synaptic plasticity and proper neurological functions. To meet the demands of local translation within neurons, mRNAs are bound by RNA binding proteins (RBPs) forming ribonucleoprotein (RNP) complexes that are targeted to specific sites of local translation. We hypothesize that some RBPs have an integral role in regulating local translation in response to intracellular signal transduction pathways. Using imaging, subcellular fractionation and biochemical approaches we will investigate how pharmacological inhibition of mTORC1 and mTORC2 regulates FUS association with eIF4F and polyribosomes at the synapse. We will use a continuous sucrose gradient (15% - 45%) and a Brandel Density fractionation system to isolate polyribosomes from primary cortical neuron treated with a pharmacological inhibitor of the mTOR kinase, torin1. The polyribosme are split in fraction using the Brandel Density fractionation system. We first investigate with Western blot to targetting FUS to see if its associated with light or heavy polysome fractions. We use super-resolution imaging looking at the localisation of Fus in primary cortical neurons treated with Torin1. Also, using commercially available antibodies towards FUS, we will immunoprecipitated (IP) and purify it from monosome and polysome fractions from primary cortical neurons to proceed with a unbiased mass-spectrometry to identify sites of PTMs. Our preliminary findings show that FUS activity is controlled by the activity of the mammalian target of rapamycin (mTOR) signaling pathway, the major signaling pathway that regulates mRNA translation. We observed that pharmacological inhibition of mTOR kinase stimulates the association of FUS with the translation initiation complex (eIF4F) as well as polyribosomes, the molecular complex that translates mRNA into protein. We have further examined the functional association of FUS with polyribosomes and found that it associates with stalled polyribosomes. Consistent with this effect, when we blocked neuronal activity in primary neuron cultures, we observed more co-localization of FUS with ribosomal subunits by super-resolution imaging. Based on our findings, we hypothesize that FUS activity at synapses is regulated by the mTOR pathway and that misregulation of FUS would negatively impact translation and neuronal function. We investigate for post-translational modifications of FUS that promote its association with polyribosomes. Using commercially available antibodies towards FUS, we will immunoprecipitated (IP) and purify it from monosome and polysome fractions from primary cortical neurons. Polyribosomes will be isolated using a continuous sucrose gradient (15% - 45%) and a Brandel Density fractionation system. We will perform unbiased mass-spectrometry to identify sites of PTMs (methylation, phosphorylation, etc.). Also, we will perform RNA-seq for the identification of RNA targets that are differentially regulated by FUS. The findings from my research will provide novel insights into the regulatory mechanisms that control local protein synthesis in neurons and further our understanding about synaptic plasticity and brain physiology.

Human skin and nerve derived Schwann cells exhibit subtle transcriptomic and functional differences

Kabita Baral¹, Tak-Ho Chu³, Elodie Labit¹, Nicole Rosin¹, Sarthak Sinha¹, Daniel Umansky³, Rajiv Midha³, Jeff Biernaskie^1,2,3
¹Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine
²Alberta Children’s Hospital Research Institute
³Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary
Corresponding Author: Kabita Baral, email kabita.baral1@ucalgary.ca

Abstract

Schwann cells (SCs) support peripheral nerve regeneration, but the efficacy of this regeneration is limited. Introducing exogenous SCs to the site of peripheral nerve injury is an ongoing avenue of investigation as a cellular therapy to enhance regeneration. Approaches that utilize an accessible source of a patient’s own cells would greatly facilitate clinical translation. Previous work demonstrates that skin-derived SCs are able to promote axonal growth and remyelination in murine models of nerve injury, however, it is not clear whether skin-derived and nerve-derived SC are functionally equivalent. To this end, we isolated SCs from small skin samples and then subjected them to high resolution single-cell mRNA sequencing (scRNA-seq) followed by battery of in vitro and in vivo assays. Our genomic analyses revealed close to 95% similarity between skin and nerve SCs at differential gene level while gene network analysis showed mostly overlapping profiles between the two cell types with the exception of immune regulatory family (eg. IRF) upregulated in skin SCs. In vitro assays revealed similarity in proliferation, migration and expression of epidermal growth factor between the two cell types, which is in alignment with our genomic analysis. However, we observed subtle difference such as higher expression of VEGF and collagen content in skin SCs and higher expression of TGF-alpha in nerve SC. Overall, our results showed that skin and nerve Schwann cells share mostly identical properties with subtle differences, suggesting that skin may be a viable source of Schwann cells to improve nerve repair.

HnRNP A1B, un isoform alternatif de HNRNPA1, est spatialement et temporellement régulé

Myriam Gagné^1,2, Gurleen Litt², Yousri Benchaar³, Hadjara Sidibé^2,4, Jade-Emmanuelle Deshaies², Danielle Arbour⁴, Alicia Dubinski^2,4, Sarah Peyrard², Richard Robitaille⁴, Chantelle Sephton³, Christine Vande Velde^2,4
¹Department of Biochemistry, Université de Montréal, Montréal, QC, Canada
²Centre de Recherche du Centre Hospitalier de l’Université de Montréal, Montréal, QC, Canada
³Department of Psychiatry and Neuroscience, CERVO Brain Research Centre, Laval University, Quebec City, QC, Canada
⁴Department of Neurosciences, Université de Montréal, Montréal, QC, Canada
Corresponding Author: Myriam Gagné, email myriam.gagne1@hotmail.com

Abstract

HnRNP A1 est une protéine clé dans le métabolisme des ARN qui peut être épissé alternativement pour former soit hnRNP A1 ou hnRNP A1B via l’inclusion de l’exon 7B (expansion du domaine IDR). Malgré la variété de rôles connus pour hnRNP A1, la contribution de hnRNP A1B a été négligée. Nous avons découvert qu’hnRNP A1B à une plus grande propriété d’agrégation et qu’il s’accumule et forme des agrégats dans des neurones moteurs de patient atteint de sclérose latérale amyotrophique (SLA). Du a sa forte expression préférentielle dans le système nerveux central (SNC), nous anticipons qu’hnRNP A1B joue une fonction distincte importante pour le SNC. Nous avons produit un anticorps spécifique pour hnRNP A1B et l’avons utilisé pour caractériser le niveau d’expression et la distribution de hnRNP A1B dans le SNC de souris C57B6/N de différents âges du développement au vieillissement. De plus, nous avons utilisé notre anticorps spécifique pour effectuer un essai de spectrométrie de masse pour identifier des intéracteurs spécifiques pour hnRNP A1B dans le SNC. Nous avons découvert que l’expression de hnRNP A1B devient graduellement spécifique aux neurones moteurs de la moelle épinière avec le vieillissement. De plus, nous avons montré qu’hnRNP A1B à une distribution cellulaire différente de hnRNP A1 en niveau basal. Nous avons, de plus, identifié des partenaires d’interactions pour hnRNP A1B qui nous indique qu’hnRNP A1B pourrait jouer un rôle dans le transport d’ARN, une nouvelle fonction non répertoriée pour hnRNP A1. Nos résultats soutiennent qu’hnRNP A1B joue une fonction distincte d’hnRNP A1 qui est particulièrement importante les neurones moteurs. Nos travaux démontrent que des isoformes peuvent être régulées différemment et jouer des fonctions spécifiques. Cette caractérisation de hnRNP A1B nous permet de formuler des hypothèses sur sa fonction et nous permet de mieux comprendre comme elle est dérégulée en contexte pathologique.

L'exploration du potential pro-angiogénique des péricytes dans la réparation de l'unité neurovasculaire à la suite d'accidents vasculaires cérébraux

Maxime Bernard^1,2, Romain Menet^1,2, Sarah Lecordier^1,2, Ayman ElAli^1,2
¹Department of Psychiatry and Neuroscience, Faculty of Medicine, Université Laval, Quebec City, QC, Canada
²Research Center of Centre Hospitalier Universitaire de Québec–Université Laval, Quebec City, QC, Canada
Corresponding Author: Maxime Bernard, email maxime.bernard.4@ulaval.ca

Abstract

Les accidents vasculaires cérébraux (AVC) constituent une cause majeure de décès et de handicap au Canada. Les AVC ischémiques constituent la majorité des cas et sont causés par une interruption du flux sanguin cérébral. Malheureusement, aucun traitement efficace n’est encore disponible. Plusieurs mécanismes de restauration endogène sont induits après un AVC afin de tenter de restaurer le tissu lésé, incluant l’angiogenèse et la neurogenèse. En induisant l’angiogenèse, le cerveau essaie d’améliorer la vascularisation de la région endommagée afin d’augmenter l’apport en oxygène et nutriments. De plus, les nouveaux vaisseaux permettent aux cellules inflammatoires d’éliminer les débris cellulaires et agissent comme échafaudage pour les progéniteurs neuronaux. Suite à ces observations, il a été suggéré qu’en améliorant l’angiogenèse, il serait possible de réduire les dommages après un AVC. Des études se sont intéressées au vascular endothelial growth factor (VEGF), un agent pro-angiogénique afin de promouvoir la vascularisation du tissu lésé. Malheureusement, le VEGF engendre des effets néfastes en exacerbant la perméabilité vasculaire. Récemment ce fut proposé que la promotion de l'intégrité de l’unité neurovasculaire, qui comprend des éléments vasculaires et non vasculaires, pourrait conduire à des percées dans les traitements de l'AVC. Au sein de l’unité neurovasculaire, les péricytes coordonnent et traitent les signaux des cellules voisines afin de générer des réponses neurovasculaires critiques dans le cerveau, notamment la régulation du flux sanguin cérébral, l’angiogenèse, et la neurogenèse. Dans un contexte angiogénique, les cellules endothéliales sécrètent le ligand platelet-derived growth factor B (PDGF-B) qui lie son récepteur PDGFRß exprimé dans les péricytes. PDGFRß contrôle la survie, la prolifération et le recrutement des péricytes aux vaisseaux naissants afin de les stabiliser. Nous postulons que les péricytes activés contribuent à la restauration neurovasculaire en stimulant une réponse angiogenèse stable suite aux AVC. Des cellules primaires, « Human Brain Vascular Pericytes » (HBVP) sont utilisées dans le but de comprendre les mécanismes cellulaires mis en place après un AVC. Pour ce faire, une hypoxie est réalisée sur les cellules PDGFRß+ afin de simuler les effets obtenus après un AVC. De plus, mon projet vise aussi à différencier les péricytes en cellules endothéliales puis à les transplanter dans le but de favoriser l’angiogenèse. Des souris transgéniques adultes dans lesquelles la signalisation d'hypoxie peut être désactivée conditionnellement dans les péricytes seront aussi utilisées via un système Cré-Lox. L'AVC sera induit chez la souris via l'occlusion transitoire de l'artère cérébrale moyenne (MCAo). Les déficits neurologiques sont ensuite examinés et des tests de comportements sont réalisés à différents temps. De plus, après chirurgie, une injection de péricytes est effectuée par voie intranasale. Les souris sont par la suite sacrifiées à différents temps, permettant ainsi d’étudier l’effet de cette transplantation sur le tissu lésé au cours du temps. Plusieurs injections de PDGF-D seront ensuite effectuées après MCAo afin de vérifier le potentiel régénérateur de ce traitement. Suite au traitement au PDGF-D, une diminution de l’atrophie cérébrale est observée ainsi qu’une meilleure récupération motrice. On devrait également observer une augmentation de la survie cellulaire, médié par une augmentation de l’angiogenèse. Des péricytes seront également transplantés par voie intranasale à des souris après un AVC. Les péricytes migrent rapidement et spécifiquement jusqu’au site de la lésion en utilisant le système vasculaire comme échafaudage. On s’attend ainsi à observer une augmentation significative de l’angiogenèse spécifiquement au site de la lésion, et plus particulièrement dans le cas où les péricytes auront déjà été exposés à des conditions hypoxiques. L’angiogenèse induite par la transplantation des péricytes devrait ainsi permettre une meilleure perfusion du tissu cérébral favorisant ainsi la réduction des lésions après un AVC. Les résultats globaux suggèrent donc que les péricytes constituent une cible intéressante et un nouvel outil pour le développement de nouvelles thérapies contre les accidents vasculaires cérébraux.

Impact of ependymal cell metabolic perturbation on brain function

Nilesh Sharma¹, Jeff Biernaskie^1,2,3
¹Department of Comparative Medicine and Experimental Biology, University of Calgary, Calgary, AB, Canada
²Alberta Children’s Hospital Research Institute, Calgary, AB, Canada
³Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
Corresponding Author: Nilesh Sharma, email nilesh.sharma@ucalgary.ca

Abstract

Metabolic regulation is thought to be an important feature within stem cell niches. Recent work suggests that ependymal cells (ECs), that line the ventricular system of the brain, could be critical players in regulating the ventricular-subventricular zone (V-SVZ). ECs are multi-ciliated glial cells that are responsible for regulating the neural stem cell niche and propelling the cerebrospinal fluid. Transcriptional profiling of the adult SVZ niche showed that ECs are highly enriched in glucose transporter 1 (GLUT1) and leading us to hypothesize that ECs may regulate NSC behavior by modulating metabolism within the V-SVZ. To test this, I performed a conditional deletion of GLUT1 in adult ECs in vivo using aSMACreERT2:ROSATdTomato:GLUT1flox/flox mice to delete GLUT1 in aSMA+ ECs. At 1-month post-GLUT1 deletion, an increase in overall proliferation (marked with Ki67) was observed within the V-SVZ niche. A sex dimorphic effect was observed on neurogenesis; with females displaying a reduction in the number of DCX+ neuroblasts, while males exhibited no change. Interestingly, this reduction was more pronounced in the anterior V-SVZ compared to posterior V-SVZ, suggesting sensitivity to GLUT1KO might be spatially dependent. There was also a marked increase in GFAP staining and an accumulation of lipid droplets within the V-SVZ post-GLUT1 deletion suggesting that disruption in glucose metabolism may perturb local lipid metabolism. Altogether, these results indicate that EC metabolism regulates the NSC niche and may play a broader role in maintaining brain homeostasis.

Systems Neuroscience

Theta-gamma phase amplitude coupling in human hippocampus supports auditory short-term memory retention.

Arthur Borderie^1,2, Anne Caclin³, Barbara Tillmann³, Phillippe Albouy^1,2
¹Centre de Recherche CERVO, Laval University, Quebec City, QC, Canada
²International Laboratory for Brain, Music and Sound Research and Centre for Research on Brain, Language and Music, Montreal, QC, Canada
³Lyon Neuroscience Research Center, Lyon University, Lyon, France
Corresponding Author: Arthur Borderie, email arthur.borderie.1@ulaval.ca

Abstract

Phase Amplitude Coupling between theta and gamma oscillations has been hypothesized to implement the retention of information during short-term memory. However, the role of theta-gamma coupling in short-term memory functions, still needs to be confirmed. In this study, we investigated if hippocampal theta-gamma PAC supports memory retention, as compared to simple perception, and if theta-gamma coupling strength increases with increasing duration of the memory retention period. Stereotaxic EEG recordings were obtained in 16 pharmaco-resistant epileptic patients who performed delayed match-to-sample tasks for tone sequences, and a passive listening control condition with the same material. To investigate working memory functions, the duration of the silent retention period between the to-be-compared sequences was manipulated (2000, 4000, 8000 ms). Time frequency analyses during the encoding period of the task show that each tone was encoded by a transient gamma burst in the auditory cortex, while the entire sequence elicited sustained theta oscillations in the ventral auditory stream. During the retention period, theta-gamma coupling increased in bilateral hippocampi in memory trials as compared to perception trials. Finally, increasing theta-gamma coupling was observed with increasing duration of the retention period during memory. This result suggests, in line with Lisman and Jensen’s model, that hippocampal theta-gamma coupling supports the retention of memorized items in short-term memory. This expands our knowledge of the general role of cross-frequency coupling as a global biological mechanism for brain information processing and integration in the human brain.

Ipsi- and Contralateral Corticospinal Influences in Uni- and Bimanual Movements in Humans

Laura Duval^1,2, Lei Zhang³, Anne-Sophie Lauzé⁴, Yuqi Zhu⁵, Mindy Levin⁶, Dorothy Barthélemy^2,7, Numa Dancause¹, Anatol Feldman^1,2
¹Department of Neuroscience, University of Montreal, Montreal, QC, Canada
²Centre for Interdisciplinary Research in Rehabilitation, Montreal, QC, Canada
³Institut für Neuroinformatik, Ruhr-Universität Bochum, Bochum, Germany
⁴Faculty of Medicine, McGill University, Montreal, QC, Canada
⁵Faculty of Medicine, University of Montreal, Montreal, QC, Canada ^6.School of Physical & Occupational Therapy, McGill University, Montreal, QC, Canada
⁶Ecole de Readaptation, University of Montreal, Montreal, QC, Canada
Corresponding Author: Laura Duval, email lduv666@aucklanduni.ac.nz

Abstract

There are both contra- (c) and ipsilateral (i) corticospinal (CS) projections to motoneurons (MNs). There is evidence that cCS influences on wrist MNs are modulated by wrist position and cutaneous afferents. Thus, we aimed to test whether these findings are valid for iCS influences as well. Using transcranial magnetic stimulation applied over the right primary motor cortex, we first compared iCS influences on wrist flexor MNs at actively maintained flexion and extension wrist positions in one uni- and two bimanual tasks in right-handed subjects (n=23). We further compared iCS influences in four bimanual holding tasks in which subjects had to hold a smooth or coarse block between their hands, with or without its weight being supported, in flexion position (n=21). A position-dependent modulation of the short-latency motor evoked potential (iMEP) was observed, but only in the bimanual task when the two hands interacted through a block (p=0.01). A texture-dependent modulation was present regardless of the weight supported, and the smooth block was associated with larger iMEPs in comparison to the coarse block (p=0.001). Hence, iCS influences on MNs were modulated only in bimanual tasks and depended on how the two hands interacted. Furthermore, cutaneous afferents modulated facilitatory iCS influences and thus may participate to grip forces scaling and maintaining. It is concluded that the left and right cortices cooperate in bimanual tasks involving holding an object between the hands, with possible participation of mono- and poly-synaptic, including transcallosal projections to MNs. Results might be essential for the understanding of the role of intercortical interaction in healthy and neurological subjects.

Information-theoretic investigation of sound to spike encoding algorithms

Ahmad El Ferdaoussi¹, Éric Plourde¹, Jean Rouat¹
¹Neurosciences Computationnelles et Traitement Intelligent des Signaux Research Group, Department of Electrical and Computer Engineering, Université de Sherbrooke, Sherbrooke, QC, Canada
Corresponding Author: Ahmad El Ferdaoussi, email Ahmad.El.Ferdaoussi@usherbrooke.ca

Abstract

The problem of the neural coding of sound, that is, transforming a sound waveform into spike representations, is of interest in many domains, including audio-based spiking neural networks, where it is the first and one of the most important stages of processing. Spike encoding can be done with many algorithms, but there is no clear picture as to which one is the best. To make progress on this question, we tackle the specific problem of encoding a cochleagram representation of sound into spikes, and we use information theory to study the performance of spike encoding algorithms on a simple task that consists of coding the time-dependent instantaneous frequency of a sound stimulus in the population response of a group of neurons in time. The sound stimulus consists of segments of frequency modulations, and the algorithms investigated are: Independent Spike Coding, Send-on-Delta coding, Ben's Spiker Algorithm, and Leaky Integrate-and-Fire coding. By estimating the mutual information between the instantaneous sound frequency and the neuron population response, we find disparities in the coding efficiency of the different algorithms. We also find that they peak in coding efficiency at different mean firing rates. The information-theoretic analysis of spike encoding algorithms on this simple frequency coding task reveals that their performance varies. This suggests that they could also perform differently on more complex inputs, like speech and environmental sounds. Therefore, there is a need to further study these encoding methods with respect to the application at hand, such as the use of spiking neural networks, computational modeling of the auditory system, and neuromorphic silicon cochleae implementations.

Developing an ERP paradigm to assess conceptual processing in DoC patients: A proof of principle study

Netri Pajankar¹, Adianes Herrera-Diaz¹, John Connolly¹
¹McMaster University
Corresponding Author: Netri Pajankar, email pajankan@mcmaster.ca

Abstract

The purpose of this study was to develop a protocol capable of inducing event-related potentials (ERPs) exhibiting semantic or conceptual processing without taxing working memory or focused attention excessively in patients with Disorders of Consciousness (DoC). Currently, there is a small and subjective database of findings on the N400 ERP component which reflects several cognitive mechanisms such as concept formation and semantic processing from patients with DoC. We examined the N400 ERP component in response to related and unrelated environmental sound and spoken word pairs in healthy participants. Our results showed the N400 effect - a significantly higher N400 peak in response to the unrelated pairs compared to the N400 peak for the related pairs. The presentation of the N400 effect in these participants suggests that such an auditory priming paradigm composed of verbal and non-verbal but meaningful stimuli could be used to evaluate cognitive processing in patients with DoC.

On the longevity of changes in feedforward limb control after observing perturbed reaching

Natalia Mangos^1,2,3, Christopher J. Forgaard^1,2, Paul L. Gribble^1,2,4,5
¹The Brain and Mind Institute, Western University, London, ON, Canada
²Department of Psychology, Western University, London, ON, Canada
³Graduate Program in Neuroscience, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
⁴Department of Physiology & Pharmacology, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
⁵Haskins Laboratories, New Haven, CT, USA
Corresponding Author: Natalia Mangos, email nmangos@uwo.ca

Abstract

Motor learning is based on the brain learning new representations of the forces required for movement. While this process typically involves extensive physical practice, recent evidence suggests that motor learning can also occur by observing the movements of others—an influential idea that could have implications for stroke neurorehabilitation. Despite the longevity of changes in the motor system being a defining characteristic of motor learning, studies to date have only examined observation-related effects immediately after observation has occurred. None have addressed how long the effects of observation might last, leaving unknown whether such effects are transient phenomena or products of durable, learned changes in the motor system. Using a forcefield learning paradigm, we measured human subjects' force generation patterns before and at various time points (one, 10, 30, or 60 minutes) after they had either performed or observed reaching movements that were perturbed by novel, robot-generated forces (i.e., a velocity-dependent forcefield). Our preliminary findings show that after physical practice or observation of perturbed movements, subject-generated forces adapted to match the distinct, temporal pattern of forces required to oppose the forcefield. Although adaptive changes in force control appeared to be more durable following physical practice than following observation, both practice and observation of perturbed movements gave rise to alterations in limb control that remained present after a 60-minute delay period. These results demonstrate that the effects of observation on the human motor system can persist for at least an hour after observing. This is consistent with the idea that neural representations of the forces required for movement can be learned by observing.

Real-time neural feedback of mesoscale cortical GCAMP6 signals for training mice

Pankaj K. Gupta¹, Timothy H. Murphy¹
¹University of British Columbia, Vancouver, BC, Canada
Corresponding Author: Pankaj Gupta, email guptapg@tcd.ie

Abstract

Mice can learn to control specific neuronal ensembles using sensory (eg. auditory) cues or even artificial optogenetic stimulation (Prsa et al. 2017). In the present work, we measure mesoscale cortical activity with GCaMP6s and provide graded auditory feedback (within ~100 ms after GCaMP fluorescence) based on changes in dorsal-cortical activation within specified regions of interest (ROI)s with a specified rule. We define a compact, low-cost optical brain-machine-interface (BMI) capable of image acquisition, processing, and conducting closed-loop auditory feedback and rewards, using a Raspberry Pi. The changes in fluorescence activity (ΔF/F) are calculated based on a running baseline (eg. 5 sec.). Two ROIs (R1, R2) on the dorsal cortical map were selected as targets. We started with a rule of ‘R1-R2’ (ΔF/F of R1 minus ΔF/F of R2) where the activity of R1 relative to R2 was mapped to frequency of the audio feedback and if it were to cross a set threshold, a water drop reward is generated. To investigate learning in this context, water-deprived tetO-GCaMP6s mice (N=8) were trained for 30-minutes every day on the system for several days, with a task to increase audio frequency leading to reward. We found that mice could modulate activity in the rule-specific target ROIs to get an increasing number of rewards over days. Analysis of the reward-triggered ΔF/F over time indicated that mice progressively learned to activate the cortical ROI to a greater extent. We developed an open-source system for closed-loop feedback that can be added to experimental scenarios for brain activity training and could be possibly effective in inducing neuroplasticity.

Changes in the mu and theta rhythms during the acquisition phase of a unilateral motor learning task

Xuanteng Yan¹, Rahul Chatterjee¹, George Lungoci¹, LinXin He¹, Georgios Mitsis¹, Marie-Hélène Boudrias¹
¹McGill University, Montreal, QC, Canada
Corresponding Author: Xuanteng Yan, email xuanteng.yan@mail.mcgill.ca

Abstract

Electroencephalogram (EEG) is a non-invasive technique for monitoring brain activities. With the use of EEG, previous studies have reported a general decrease within the mu (8–12Hz) as well as beta (13–30Hz) frequency band during motor task execution [1], [2]. This phenomenon is termed event-related desynchronization (ERD). Moreover, it has been found that the coupling between the theta (4 – 8Hz) and gamma (31 – 70Hz) frequency band is closely associated with motor memory consolidation [3]. However, it is still unclear how would mu and theta rhythms change during motor learning process. Therefore, the objective of the present study is to investigate the power changes in terms of the mu and theta frequency band within the motor cortex area (M1) during a unilateral motor learning task. Experimental paradigm and data collection: Twenty-five healthy, young adults (aged 19–33 years) were involved in the present study. The proposed motor learning task consisted of 5 blocks of hand grips with each block containing 20 trials. During the motor learning process, participants were instructed to adjust the force applied to a gripper using their dominant hand (right hand) so that the force level controlled visual cursor could be kept within a series of red rectangular targets. Along with the motor learning process, EEG data were collected with a 64-channel EEG system (Brain Vision). Data analysis: We selected eight channels that covered the M1 area for analyzing changes in brain rhythms during motor learning process, namely: C3, C4, CP1, CP2, C1, C2, CP3, CP4. The collected EEG recordings were down-sampled to 500Hz and band-pass filtered for extracting mu and theta oscillations. The mu and theta band power were calculated for assessing relative power changes during motor learning process. A decrease in power within the theta frequency band was found within the M1 area and significant decrease was detected in almost all electrodes covering ipsilateral M1 area (channel CP2, C2 and CP4) and also contralateral M1 hemisphere (CP1 and C1). Furthermore, there was an increase in the mu band power in both the ipsilateral (C2) and contralateral (C3, CP1 and CP3) M1 electrodes. In the present study, we investigated how mu and theta oscillations change during the motor learning process. We found increased mu band power and decreased theta band power. This will help investigate changes in neural plasticity underlying motor learning process and design non-invasive brain stimulation therapy for enhancing motor memory consolidation in the long term.

Recovery of the glutamatergic descending drive from the gigantocellular reticular nucleus after spinal cord injury in mice

Narges Karimi¹, Maxime Lemieux¹, Frédéric Bretzner¹
¹Centre de recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
Corresponding Author: Narges Karimi, email narges.karimi.1@ulaval.ca

Abstract

Locomotion is a voluntary function involving various descending projections to the spinal cord. Following a spinal cord injury (SCI), several of these projections are severed. Among these projections are those arising from the gigantocellular reticular nucleus (Gi) which is mainly a glutamatergic relay to the spinal cord of supraspinal structures. Although previous studies have shown anatomical plasticity of reticulospinal axons following incomplete SCI, little is known about the extent of the functional plasticity. Using optogenetic tools and in vivo electromyographic (EMG) activity in VGluT2-cre mice, we have investigated changes in motor efficacy of glutamatergic Gi neurons following a unilateral SCI. We have recorded EMG activity of the ankle flexor Tibialis anterior (TA) and extensor Gastrocnemius lateralis (GL). Short pulses (10ms) of photostimulations were delivered randomly during treadmill locomotion to probe the ability of the Gi to modify the ongoing locomotor pattern. Before SCI, photostimulations of the Gi increased activity in muscles during their relaxed phase (the stance phase for the TA and the swing phase for the GL) and decreased activity of the GL during stance. After SCI, the excitatory response during locomotion was depressed in the ipsilesional TA of 50% of mice and in the ipsilesional GL of 42% of mice. There was also some depression on the contralesional side (in 36% of mice for the TA and 38% for the GL). We observed a recovery of motor efficacy in ipsilesional TA in 70% of mice with an initial depression. A similar pattern was found in the ipsilesional GL with a recovery in 83% of mice. On the contralesional side, we found that 80% of mice recovered motor efficacy for both TA and GL. Finally, a positive correlation was found between changes in the locomotor performance and motor responses in ipsilesional flexor and extensor hindlimb muscles but not in the contralesional hindlimb. Altogether, these results show that there is a good rate of recovery after incomplete SCI and that this motor recovery correlates with locomotor improvement.

Functional contribution of midbrain nuclei to locomotor recovery after spinal cord injury

Marie Roussel¹, Maxime Lemieux¹, Frédéric Bretzner¹
¹Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
Corresponding Author: Marie Roussel , email marie.roussel.1@ulaval.ca

Abstract

Recently, electrical stimulation of the mesencephalic locomotor region has been shown to improve locomotor recovery after spinal cord injury (SCI). The cuneiform nucleus (CNF), a cluster of glutamatergic and GABAergic neurons, and the pedunculopontine nucleus (PPN), a cluster of glutamatergic, cholinergic, and GABAergic neurons, are part of this functional region. It has been recently shown that these neuronal populations exhibit distinct effects on locomotor control: glutamatergic neurons of the CNF can initiate and accelerate locomotion, whereas glutamatergic neurons, and to a lesser degree cholinergic neurons, of the PPN decelerate and stop locomotion. Here, we propose to identify and characterize the functional contribution of these distinct midbrain neuronal populations to locomotor recovery after SCI. Using transgenic mice expressing a photoactivator (ChR2) in glutamatergic (VGluT2) neurons, we photostimulated glutamatergic neurons of either the CNF or PPN before and after a thoracic lateral hemisection in freely behaving mice. 7 weeks after SCI, the ipsilesional limb still showed functional deficits including a slower locomotor rhythm and a decrease in the amplitude of the intralimb coordination and step height. During treadmill locomotion, long trains of photostimulations (10 ms pulses at 20 Hz for 1 s) of glutamatergic expressing CNF neurons accelerated the locomotor rhythm, increased postural tone, and improved step height, whereas photostimulations of glutamatergic expressing PPN neurons evoked decelerations and locomotor arrests. Furthermore, long photostimulations of glutamatergic expressing CNF neurons also improved the fluidity and amplitude of intralimb coordination in contrast to glutamatergic PPN neurons during swimming. Our results argue that glutamatergic CNF neurons could be a neurological target to improve functional locomotor recovery in SCI patients. Funding: Wings for Life Foundation and Craig H. Neilsen Foundation.

Neuroinflammation

Sex- specific impact of manipulation of the methionine cycle on disease progression, T cell activation and gut microbiota in neuroinflammation

Florence Millette¹, Victoria Hannah Mamane¹, Rutger Koning¹, Jocelyn Chen², Dominic Roy², Audrey Daigneault¹, Meriem Messaoudene¹, Corentin Richard¹, Florent Cauchois¹, Hélène Jamann¹, Oumarou Ouedraogo¹, Renaud Balthazard¹, Bertrand Routy¹, Russell Jones^2,3, Catherine Larochelle¹
¹Centre de Recherche du Centre hospitalier de l'Université de Montréal, Montreal, QC, Canada
²McGill University, Montreal, QC, Canada
³Van Andel Institute, Grand Rapids, MI, USA
Corresponding Author: Florence Millette, email florence.millette@umontreal.ca

Abstract

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) with a sex bias towards women. Proinflammatory TH1 and TH17 cells are considered pathogenic in MS and its animal model, experimental autoimmune encephalomyelitis (EAE). Obesity, western diet and gut dysbiosis increase inflammation and influence MS course. Dietary methionine restriction (MR) is associated with lower weight gain and reduced inflammation. T cells upregulates components of methionine metabolism upon activation and MR reduces expansion of TH17 cells. We hypothesize that limiting the activity of the methionine cycle will improve EAE by modulating TH17 cells through sex-specific epigenetic mechanisms and modification of the gut microbiota. Active EAE is induced in male and female C57BL/6 mice exposed to MR or control diet by immunization with MOG35-55. Clinical scores, flow cytometry and 16S rRNA sequencing are used to characterize the properties of immune cells and the gut microbiota. Our preliminary results show that dietary MR is associated with a significantly delayed onset of neurological symptoms, with clinical differences in disease evolution between male and female. This is associated with a reduced number of immune cells and pathogenic T cells in the spleen and CNS respectively at presymptomatic, and at onset and peak stages. MR diet is associated with modification of the gut microbiota suggesting a shift towards an anti-inflammatory profile. MR ameliorates the clinical course and neuroinflammatory processes in EAE in a sex-dependent manner, and could represent a new therapeutic avenue to improve MS.

Activation of microglial transcriptomic and epigenomic programs after systemic pro-inflammatory stimulus

Félix Distéfano-Gagné¹, André Machado Xavier¹, Sarah Belhocine¹, Stéphanie Fiola¹, David Gosselin¹
¹Université Laval, Québec, QC, Canada
Corresponding Author: Félix Distéfano-Gagné, email felix.distefano-gagne@crchudequebec.ulaval.ca

Abstract

Systemic immune response syndrome (SIRS) is a critical medical condition caused by diverse infections, including several bacterial infections and potentially COVID-19, and associated to long-term complications. SIRS is accompanied by a functional breakdown of multiple organs, including the brain. This results in a neuroinflammatory response orchestrated by microglia, the brain’s resident macrophage. However, the transcriptional and epigenetic mechanisms underlying this response remain under-characterized. To study the aforementioned mechanisms, we used a systemic inflammation murine model in which SIRS is induced by injection of bacterial lipopolysaccharides (LPS). At several time points following LPS injection, microglia were extracted in order to perform massively parallel sequencing, more specifically RNA-seq to evaluate the transcriptome and ChIP-seq targeting histone mark H3K27ac to assess activity at promoter regions and distant genomic regulatory elements. Results show that microglia’s transcriptomic and epigenomic activities during neuroinflammatory response follow different dynamic profiles. RNA-seq data indicate a wave of pro-inflammatory gene transcription starting 3h after induction of SIRS. This initial wave is followed by increased activity at distant genomic regulatory regions that is regulated by transcription factors Nf-κB, AP-1 and Irf. Furthermore, the pro-inflammatory transcriptional profile progressively makes way for a program linked to mitosis which is associated with a peak in proliferation 48h post-injection. These results define the progression of intrinsically connected transcriptional and epigenetic programs of microglia during SIRS. As such, they provide potential therapeutic targets that could be exploited to lessen brain sequelae in SIRS.

Long-term impacts of Kawasaki disease on brain’s electrophysiological signals: a pilot study

Audrey-Ann Fauteux^1,2, Kristian Agbogba^2,3, Mickael Rolland-Déry², Inga Sophia Knoth², Audrey-Rose Charlebois-Poirier^1,2, Eve Lalancette^1,2, Rocio Gissel Gutierrez-Rojas^2,4, Nagib Dahdah^2,4, Sarah Lippé^1,2
¹Department of Psychology, University of Montreal, Montreal, Qc, Canada
²Department of Pediatrics, Research Center, Sainte-Justine University Health Center, Montreal, Qc, Canada
³École de Technologie Supérieure, Université du Québec, Montreal, Qc, Canada
⁴Division of Pediatric Cardiology, Sainte-Justine University Health Center, Montreal, Qc, Canada
Corresponding Author: Audrey-Ann Fauteux, email audrey-ann.fauteux@umontreal.ca

Abstract

Kawasaki disease (KD), an acute transitory immune vasculitis of early childhood, affects the central nervous system. It causes excessive irritability, transitory sensorineural hearing loss, and central nervous system inflammation (cerebral imaging and cerebrospinal fluid) during the acute phase. Despite attentional and behavioral concerns following KD, few inconclusive studies provide limited information on neurophysiological development consequences. This pilot study on primary school-aged children investigated long-term signature of KD on electrophysiological markers associated with attention deficit (theta/beta ratio; TBR) and brain maturation (alpha peak; AP). A 3-minute eyes-open resting EEG was recorded in 14 children (8.5±2.4 years, 9 males) 5.2±2.7 years after KD and compared to 32 matched controls (8.9±2.1 years, 23 males). Fast-Fourier transformations were calculated from 0 to 90 Hz in six scalp regions to obtain total spectral density power, TBR and AP frequency, amplitude and amplitude ratio (AP salience compared to neighbouring±1Hz frequencies). Global intellectual quotient was measured with the French-Canadian version of Wechsler Intelligence Scale for Children. Intellectual abilities were comparable between KD and Controls (full-scale IQ 104±13 vs. 107±12), with 2 KD participants’ global IQ-score 1 SD below national norms. There was however a significantly lower AP amplitude ratio in KD compared to controls in 4/6 regions (frontocentral, central, parietal and occipital; <0.05). Thus, a weaker and less salient AP in midline regions was identified in KD group (Cohen’s r showing medium to large effect size [r range: -0.33 to -0.46]). The attenuated alpha peak in children with past KD represents long-term impact of the disease on spontaneous electrophysiological signals. As this neuro-biomarker indexes the maturation and integrity of neural networks, results suggest that KD could impact cerebral mechanisms years after the onset of the disease. This first EEG-based study merits large-scale longitudinal studies following KD to better characterize patients’ developmental trajectory.

Functional Crosstalk Between Microglial Purinergic and Adrenergic Signaling

Thomas Deluc¹, Ariel Ase¹, Philippe Séguéla¹
¹Department of Neurology and Neurosurgery, Montreal Neurological Institute and Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada
Corresponding Author: Thomas Deluc, email thomas.deluc@mail.mcgill.ca

Abstract

Neuropathic pain induced by nerve injury is characterized by its persistence, with no effective treatment. Microglia have received much attention in the past decade due to their importance in chronic pain. Microglia are in constant survey of their environment and are the first elements to respond after any kind of disturbance in the CNS. Adenosine triphosphate (ATP), which is released after damage, acts as a danger signal and is sensed by the microglia due to the presence of purinergic receptors. Microglial purinergic receptors are involved in key pathways such as release of pro-inflammatory cytokines (P2X7), chemotaxis (P2Y12) or phagocytosis (P2Y6). It has been shown that the main purinergic receptors expressed in microglia, P2X4, P2X7, P2Y6 and P2Y12, play an important role in pain sensitization and in the maintenance of neuropathic pain. However, how these receptors are modulated is still poorly understood. As the expression of the Gs-coupled ß2 adrenergic receptor in the CNS is mainly limited to microglia, it represents a promising candidate regarding a functional modulation of microglial purinergic receptors relevant to pain mechanisms. In order to investigate a possible modulatory effect of ß2 adrenergic receptors on purinergic signaling in microglia, we used the murine BV2 cell line and primary microglia isolated from the mouse forebrain (P1-P4). Fura2-based ratiometric calcium imaging experiments were performed in order to validate the expression of the different P2 receptor subtypes in microglia and to assess quantitatively their modulation by ß2 adrenergic receptors (agonist: isoproterenol). We finally used human IPSC-derived microglia to confirm our results. Focusing on P2Y6 UDP receptors, we are currently optimizing a phagocytosis assay protocol. Our calcium imaging results show that activation of the ß2 adrenergic receptor modulates purinergic microglial receptors. We show that ß2 adrenergic receptors a) potentiate the response of the ionotropic P2X7 ATP receptors involved in release of proinflammatory cytokines and; b) inhibit the response of the metabotropic P2Y6 UDP receptors involved in phagocytosis. We confirmed that the inhibition of P2Y6 by ß2 adrenergic receptor is conserved in human microglia. We are currently investigating if phagocytosis induced by P2Y6 is impacted by ß2 adrenergic modulation. We demonstrated that the norepinephrine/ß2 adrenergic receptor signaling regulates the function of at least two types of purinergic receptors in microglia. Further, we plan to investigate if key microglial functions such as cytokine release or phagocytosis are impacted by these crosstalks.

Oral and Regular Presentations

Select oral and regular presentation recordings can be found online at: Neurosymposium.ca

Reduce chronic inflammatory state of microglial cells exposed to perinatal insults by a neuroprotective approach such as Melatonin

Marianne Mengus^1,2, Roqaya Imane¹, Sophie Tremblay^1,2
¹Centre de Recherche du Centre Hospitalier Universitaire Sainte-Justine, Montréal, QC, Canada
²Université de Montréal, Montréal, QC, Canada
Corresponding Author: Marianne Mengus, email marianne.mengus@outlook.fr

Abstract

Extreme preterm infants are exposed to multiple inflammatory stressors over their neonatal period including perinatal cerebellar hemorrhage(CBH) and postnatal infection, known as two major risk factors for neurodevelopmental impairments. Given microglia involvement in inflammatory functions across the central nervous system, they may play a central role in the pathogenesis of cerebellar injury in developing brains. To date, there is still no available treatment offered to these vulnerable population. Conditional transgenic mice dependent on diphtheria toxin intracerebellar injection to deplete CX3CR1-positive cells(microglial cells) were bred and exposed to CBH at P2 combined with early inflammation(EIS). Using this transgenic mouse model allows microglial cells depletion prior to cerebellar insult, microglia phenotypic changes across time will be analyzed by flow cytometry after insults and treatment. Melatonin treatment was administered for three consecutive days starting 2 hours after insult exposure. Our preliminary data showed an equal number of microglial cells identified by flow cytometry expressing activated microglia profile from M1 pro-inflammatory or M2 pro-repair phenotypes prior to insult without any sex differences(n=3-5). Two weeks after exposure to perinatal insults(P15), mice showed a significant change of M1/M2 ratio compare to controls favoring a M1 pro-inflammatory phenotype at 72.5%(n=6-8; ****P<0.0001) after LPS-exposure compare to 17.5%(n=8; **P=0,0025) after exposure to the combined insult(CBH+LPS). Control mice also have a lower ratio of M1 pro-inflammatory activated microglia(22.3%; n=8). Moreover, melatonin treatment after perinatal insults attenuates significantly percentage of activated microglial cells exhibiting M1 pro-inflammatory profile at P15 to 48,7%(n=8; ****P<0,0001) in pups exposed to CBH+LPS and 45,6%(n=6; ****P<0,0001) in pups exposed to LPS compare to controls. Perinatal systemic inflammatory stress exposure promotes a persistence of the pro-inflammatory M1 phenotype of activated microglial cells over time. Melatonin treatment administered soon after perinatal insults reduces this chronic pro-inflammatory predominance from microglia phenotype ratio.

Harnessing Complex Photophysical Interactions of Amyloid Probes BSB and MCAAD-3 for Sensitive Detection of Protein Aggregation in Alzheimer’s Disease

Anastasiia A. Stepanchuk¹, Jeffrey T. Joseph², Peter K. Stys¹
¹Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
²Department of Pathology, Cumming School of Medicine, University of Calgary, Calgary, AB,
Corresponding Author: Anastasiia Stepanchuk, email anastasiia.stepanchu@ucalgary.ca

Abstract

Protein misfolding and aggregation into amyloid fibrils are characteristic of a number of disorders, including systemic amyloidoses, Alzheimer’s disease (AD) and prion diseases. When the protein switches from a soluble native conformation and self-associates into beta-sheet-rich structures, the resulting assemblies can be easily visualized in tissue samples using small organic fluorophores that preferentially bind to the hydrophobic pockets in the fibrils. In this study, we aimed to develop an approach for more sensitive detection of misfolded protein pathology in 5xFAD Alzheimer’s mouse and human AD samples using two amyloid dyes, BSB and MCAAD-3, combined with spectral imaging and advanced spectral analysis. This new approach outperforms conventional single-probe or immunohistochemical labeling, providing information about heterogeneities in protein aggregates that would not be revealed by conventional means. Brain sections from 5xFAD mice and human AD cases were incubated in sub-micromolar concentrations of BSB and MCAAD-3 for 24 hours and imaged on a spectral confocal microscope. Detailed analysis and quantification of protein pathology was performed using advanced custom-written spectral analysis tools. Each probe used in the study had different variability of emission signatures depending on the nanostructure of the amyloid fibrils. The intra- and inter plaque spectral differences were amplified by the combined conformational sensitivity of BSB and MCAAD-3, as well as different affinities of these dyes to different aggregates. Quantitative spectral analysis of the images revealed unique spectral signatures associated to distinct types of aggregates, such as senile plaques, diffuse plaques, vascular amyloid and neurofibrillary tangles. Moreover, our staining, imaging, and analysis paradigm allowed for interrogation of possible interactions between the dyes bound to amyloid pockets. Our study shows how complex photochemical behavior of the amyloid dyes can be studied and harnessed using advanced spectral imaging and analysis modalities to reveal the full picture of the protein misfolding pathology in mouse and human brain tissue sections. Compared to conventional well-established techniques, our approach has great potential to improve the detection of subtle pathological changes involving protein misfolding, identification of different structural subtypes of deposits and to further our understanding of the factors contributing to the pathophysiology of protein misfolding disorders. Importantly, these novel quantitative methods are likely to have utility in other neurodegenerative and even in diseases involving other organ systems.

Dysregulation of Brain-Derived Extracellular Vesicle Cargo in Major Depressive Disorder

Pascal Ibrahim^1,2, Prakroothi Danthi², Jean-Francois Theroux², Corina Nagy^1,2, Gustavo Turecki^1,2
¹McGill University, Montreal, QC, Canada
²McGill Group for Suicide Studies, Montreal, QC, Canada
Corresponding Author: Gustavo Turecki, email gustavo.turecki@mcgill.ca

Abstract

Major Depressive Disorder (MDD) is one of the leading causes of disability worldwide. Environmental factors are thought to play a role in disease development via epigenetic mechanisms. MicroRNA’s (miRNA) are well known epigenetic regulators that are disrupted in MDD and are packaged into extracellular vesicles (EVs). EVs have emerged as means of intercellular communication. They are thought to transfer miRNA and other molecules, such as proteins, between cells, altering gene expression in recipients. Therefore, we hypothesize that EV cargo from the anterior cingulate cortex will have a disease specific profile that could mediate disease development in MDD subjects compared to healthy controls. EVs were isolated from post-mortem human brain tissue from the anterior cingulate cortex of using size exclusion chromatography. RNA was extracted and a small-RNA library was constructed and sequenced using the Illumina Platform. Proteins were also extracted and profiled using LC-MS/MS. Differential expression analysis was then performed. Western blots showed little to no contamination with cellular debris, along with enrichment of the exosomal marker CD9. TEM images showed the typical cup-shaped morphology with sizes mostly between 30 and 200 nm. Preliminary differential analyses revealed that both the miRNA and proteomic profiles of the EVs are dysregulated in MDD. This will be the first study to profile brain-derived EV miRNA and protein in the context of depression. This could provide novel mechanistic insights into the pathophysiology of MDD, which could be a starting point for the development of targeted therapeutic strategies and prevention measures.

Understanding the role of SYNGAP1 in GABAergic circuit development and function

Vidya Jadhav^1,2, Maria I. Carreno-Munoz^1,2, Théo Badra^1,2, Graziella D. Cristo^1,2, Bidisha Chattopadhyaya¹, Jacques Michaud^2,3
¹Centre Hospitalier Universitaire Sainte-Justine Research Center, Montreal, QC, Canada
²Department of Neurosciences, Université de Montréal, QC, Canada
³Department of Paediatrics, Université de Montréal, QC, Canada
Corresponding Author: Vidya Jadhav , email vidyujadhav1191@gmail.com

Abstract

Haploinsufficiency of Syngap1 gene encoding the Synaptic Ras- GTPase Activating protein is associated with intellectual disability, autism spectrum disorder and epilepsy. Syngap1 is a negative regulator of Ras and of AMPA receptor trafficking to the postsynaptic membrane, thereby regulating the process of synaptic plasticity and neuronal homeostasis. Loss of Syngap1 leads to alterations in synaptic plasticity, behavioral abnormalities and cognitive deficits in mouse models. In particular, several studies have shown that Syngap1 regulates the time course of the maturation of dendritic spines and glutamatergic synapses in excitatory neurons; In contrast, the role of Syngap1 in inhibitory, GABAergic neurons is relatively uncharted. GABAergic neurons are a diverse class of neurons with different morphology, connectivity and physiological properties. They play an important role in neural circuit development and plasticity. Parvalbumin (PV)-expressing interneurons, one of the major classes of cortical GABAergic interneurons, form synapses onto the soma and proximal dendrites of pyramidal cells and are involved in the synchronization of the firing rate of pyramidal cell populations. Previous in-vitro studies suggest that haploinsufficiency of Syngap1 affects the formation of PV cell synaptic connectivity with reduced inhibitory synaptic activity. Aim: In continuation with these previous observations, here we study the role of Syngap1 in PV cell development In vivo, in establishing balanced synaptic connectivity and proper network. To this end, we used germline heterozygous Syngap1 mice to characterize both the excitatory (VGlut1+PSD95+) and inhibitory (PV+ Geph+) synaptic connectivity affecting PV+ cells in the sensory cortices. We further characterized cognitive behavior such as Cued contextual fear conditioning and attention set shifting task behavior in these mice. We observed reduced excitatory inputs marked by VGlut1+PSD95+ punctas on perisomatic PV cells in sensory cortices of germline Syngap1 haploinsufficient mice. However no significant change was observed in terms of inhibitory output marked by PV+Geph+ punctas onto pyramidal cells in sensory cortices. Syngap1 heterozygous mice showed deficits in contextual learning post 7 days and showed mild cognitive deficits in attention set shifting task. Preliminary data suggest that alteration in synaptic connectivity of PV cells in different cortical regions do contribute to observed overall behavioral and cognitive deficits. A better understanding of the role of Syngap1 in GABAergic cell development may shed light on the involvement of GABAergic circuit alterations in the cognitive deficits caused by Syngap1 haploinsufficiency in humans.

A Bi-cortical Neuroprosthesis to Control Locomotion After Spinal Cord Contusion in the Cat

Maude Duguay^1,2, Marco Bonizzato^1,2, Hugo Delivet-Mongrain¹, Nicolas Fortier-Lebel¹, Marina Martinez^1,2
¹Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
²Centre Intégré Universitaire de Santé et de Services Sociaux du Nord-de-l’Île-de-Montréal, Montréal, QC, Canada
Corresponding Author: Marina Martinez, email marina.martinez@umontreal.ca

Abstract

Traumatic spinal cord injury (SCI), which impairs control of movement and sensory functions, is one of the leading causes of paralysis. Most SCIs are anatomically “incomplete”, meaning that some connections between the cortex -which is essential for planning, controlling and executing voluntary movements- and the spinal circuits, which generate them, are spared. Despite several studies supporting the concept that targeting supraspinal centers is a valuable approach to restore walking, most rehabilitation interventions do not directly engage the motor cortex. To address this need, we developed a neuroprosthesis that allows timely delivery of the stimulation to the motor cortices during locomotion. We used a cat model of thoracic spinal cord contusion (T10) which induces transient paralysis of both hindlimbs and long-term locomotor impairments, such as foot drag. In three cats, we bilaterally implanted chronic intracortical electrode arrays in both motor cortices’ hindlimb representation. Before and after a spinal cord contusion, we enhanced the evoked motor response by optimizing the amplitude, timing, duration and site of stimulation. In n=3 cats walking on a treadmill, we delivered brief (100ms) bursts of cortical stimulation, synchronized with the hindlimb lift. Both before and after SCI, we modulated the hindlimb trajectory during gait, as shown by a significant increase in step height and velocity of flexion that correlated with the increase in stimulation amplitude. Two weeks post-SCI, our bi-cortical stimulation intervention decreased dragging by 40% compared to spontaneous locomotion. These data provide a proof of concept that cortical stimulation protocols can be deployed to improve locomotion acutely after SCI and could be used for movement assistance therapies to promote recovery. This research has important clinical potential because the cortex is an accessible structure that can be targeted in humans. Similar stimulation protocols could be used to promote recovery in other neurotrauma, including stroke.

Capturing T lymphocytes’ dynamic interactions with human neural cells using time-lapse microscopy

Florent Lemaître^1,2, Ana Carmena Moratalla^1,2, Negar Farzam-kia^1,2, Yves Carpentier Solorio^1,2, Olivier Tastet², Aurélie Cleret-Buhot², Jean Victor Guimond³, Elie Haddad⁴, Nathalie Arbour¹
¹Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
²Centre de Recherche du Centre Hospitalier de l’Université de Montréal, Montreal, QC, Canada
³CLSC des Faubourgs. CIUSSS du Centre-Sud-de-l’Ile-de-Montréal, Montréal, QC, Canada
⁴Department of Microbiology, Infectious Diseases, and Immunology and Department of Pediatrics, Faculty of Medicine, Université de Montréal, Centre de Recherche du Centre Hospitalier Universitaire Sainte-Justine, Montreal, QC, Canada
Corresponding Author: Florent Lemaitre, email grdflo.lemaitre@gmail.com

Abstract

To fully perform their functions, T lymphocytes migrate within organs’ parenchyma and interact with local cells. Infiltration of T lymphocytes within the central nervous system (CNS) is associated with numerous neurodegenerative disorders. Nevertheless, how these immune cells communicate and respond to neural cells remains unresolved. To investigate the behavior of T lymphocytes that reach the CNS, we have established an in vitro co-culture model and analyzed the spatiotemporal interactions between human activated CD8+ T lymphocytes and primary human astrocytes and neurons using time-lapse microscopy. By combining multiple variables extracted from individual CD8+ T cell tracking, we show that CD8+ T lymphocytes adopt a more motile and exploratory behavior upon interacting with astrocytes than with neurons. Pretreatment of astrocytes or neurons with IL-1β to mimic in vivo inflammation significantly increases CD8+ T lymphocyte motility. Using visual interpretation and analysis of numerical variables extracted from CD8+ T cell tracking, we identified four distinct CD8+ T lymphocyte behaviors: scanning, dancing, poking and round. IL-1β-pretreatment significantly increases the proportion of scanning CD8+ T lymphocytes, which are characterized by active exploration, and reduces the proportion of round CD8+ T lymphocytes, which are less active. Blocking MHC class I on astrocytes significantly diminishes the proportion of poking CD8+ T lymphocytes, which exhibit synapse-like interactions. Lastly, our co-culture time-lapse model is easily adaptable and sufficiently sensitive and powerful to characterize and quantify spatiotemporal interactions between human T lymphocytes and primary human cells in different conditions while preserving viability of fragile cells such as neurons and astrocytes.

Development of a novel optogenetic based model of alpha-synuclein aggregation to study Parkinson’s disease

Razan Sheta¹, Morgan Bérard¹, Maxime Teixeira¹, Walid Idi¹, Roxanne Turmel¹, Jérome Lamontagne¹, Denis Soulet¹, Francesca Cicchetti¹, Edward A. Fon², Abid Oueslati¹
¹Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Quebec, QC, Canada
²Montreal Neurological Institute, McGill University, Montreal, QC, Canada
Corresponding Author: Razan Sheta, email Razan.sheta.1@ulaval.ca

Abstract

Parkinson’s disease (PD) is characterized by dopaminergic neuronal loss and the presence of proteinaceous inclusions known as Lewy bodies. These inclusions are constituted of a pre-synaptic protein, referred to as alpha-synuclein (alpha-syn). Evidence suggest for a central role of alpha-syn aggregation in PD. However, how these aggregates precipitate DA neuronal loss remain elusive. This is mainly due to the lack of proper models to undertake such investigations. To overcome this limitation, our group created a cellular and animal model of PD mimicking authentic LBs features. Using our new optogenetic-inducible alpha-syn aggregation, we aim to dissect how these inclusions interfere with physiological functions of DA neurons leading to neuronal loss. Our optogenetic versatile strategy allows for spatiotemporal control of alpha-syn aggregation both in vivo and in living cells. This approach is based on the use of a mutant form of the Arabidopsis thaliana photoreceptor cryptochrome 2 (CRY2). When stimulated with blue light, CRY2 undergoes reversible and robust protein clustering. Fusing this system to alpha-syn, CRY2 clustering triggered aggregation of alpha-syn prompting formation of LB-like inclusions in living cells. We refer to this system as light-inducible protein aggregation (LIPA). The LIPA system has allowed for real-time induction of alpha-syn inclusions with remarkable spatial and temporal resolution both in vitro and in vivo. Results showed that LIPA-induced aggregates auto-perpetuate for several days, and faithfully mimicking authentic features of LBs. Additionally, optogenetically induced alpha-syn aggregation in mice induced significant dopaminergic neuronal loss and behavioural impairment. In conclusion, the LIPA system provides a dependable and invaluable tool to generate, visualize and dissect the role of protein aggregation in neurodegenerative disorders.

Integrated Transcriptomic and Neuroimaging Brain Model Decodes Biological Mechanisms in Aging and Alzheimer’s Disease

Quadri Adewale^1,2,3, Ahmed F. Khan^1,2,3, Felix Carbonell⁴, Yasser Iturria-Medina^1,2,3, for the Alzheimer’s Disease Neuroimaging Initiative
¹Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
²McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
³Ludmer Centre for Neuroinformatics and Mental Health, McGill University, Montreal, QC, Canada
⁴Biospective Inc., Montreal, QC, Canada
Corresponding Author: Quadri Adewale, email quadri.adewale@mail.mcgill.ca

Abstract

Both healthy aging and Alzheimer’s disease (AD) are characterized by concurrent alterations in several biological factors. However, generative brain models of aging and AD are limited in incorporating the measures of these biological factors at different spatial resolutions. Here, we propose a personalized bottom-up spatiotemporal brain model which accounts for the direct interplay between hundreds of RNA transcripts and multiple macroscopic neuroimaging modalities (PET, MRI). In normal elderly and AD participants, the model identifies top genes modulating tau and amyloid-β burdens, vascular flow, glucose metabolism, functional activity, and atrophy to drive cognitive decline. 1. We pre-processed 6 longitudinal neuroimaging data (beta-amyloid and tau proteins, cerebral blood flow, glucose metabolism, R-fMRI, and grey matter volume) of 151 healthy and 309 diseased subjects from ADNI database. 2. Using gene expression (GE) data of 6 neurotypical brains from Allen Human Brain Atlas, we derived brain-wide GE of 976 landmark genes with leading roles in central biological functions. 3. We developed a novel mathematical model that incorporates: (i) disease- and aging-related longitudinal changes in neuroimaging data, (ii) GE-modulated interactions between the different neuroimaging modalities, (iii) propagation of alterations resulting from (ii) across brain networks. 4. By evaluating the latent relationship between the gene-imaging interactions and cognitive measures (MMSE, ADAS, executive function, memory score), we identified causal genes and pathways driving healthy aging and AD progression. We identified 8 and 111 genes driving cognitive changes in healthy aging and AD, respectively. The biological factors (measured by imaging modalities) causally modulated by each gene, and factor alterations resulting from the modulation were also identified, e.g. our model revealed that APBB2 (amyloid beta A4 precursor protein-binding, family B, member 2) modulates glucose metabolism to cause longitudinal alteration of neuronal activity. Pathway analysis of the identified genes suggested that AD and healthy aging share specific biological mechanisms, even though AD is a separate entity with considerably more altered pathways. We developed a mathematical model to investigate the influence of gene expression on multifactorial alterations of biological processes in aging and AD progression. Our results are strongly consistent with previously reported studies and provided further insight into the molecular mechanism underlying healthy and pathological aging process. Overall, this personalized model offers novel insights into the multiscale alterations in the elderly brain, with important implications for identifying effective genetic targets for extending healthy aging and treating AD progression.

Mitochondrial Antigen Presentation could point the way to the establishment of Parkinson's disease-like symptoms.

Moustafa Nouh ELemeery^1,2, Renaud Balthazard¹, Annie Laplante¹, Diana Matheoud¹
¹Département de Neurosciences, Centre de Recherche du Centre Hospitalier de l’Université de Montréal, Montréal, QC, Canada
²Medical Biotechnology Department, National Research Centre, Dokki, Giza, Egypt
Corresponding Author: Diana Matheoud, email diana.matheoud@umontreal.ca

Abstract

Parkinson’s disease (PD) is a neurodegenerative disorder with motor symptoms linked to the loss of dopaminergic neurons in the substantia nigra compacta. Although the mechanisms that trigger the loss of dopaminergic neurons are unclear, inflammation and mitochondrial dysfunction are thought to have key roles. Moreover, we recently discovered that part of the immune dysregulation observed in PD originates from mitochondrial dysfunction through the activation of mitochondrial antigen presentation (MitAP). This new antigen presentation pathway promotes the exposure of normally hidden mitochondrial antigens to the immune system by antigen presenting cells (APC) and leads to mitochondrial autoimmunity through the generation of autoreactive T cells that can target cells exposing mitochondrial antigens. MitAP is negatively regulated by PINK1 and Parkin, two proteins encoded by PD-related genes that have been shown to control mitophagy and inflammation. Furthermore, in a murine model of PD, MitAP activation, through intestinal infection, leads to the generation of autoreactive mitochondrial-specific T cells that specifically attack dopaminergic neurons and leads to a PD-like phenotype. However, mitochondrial-specific T-cells were not directly assessed for their ability to target dopaminergic neurons in vivo and their phenotype in a PD-susceptible model (PINK1 deficiency) is not known. Here we show that mitochondrial-specific T cells promote PD-like symptoms associated with dopaminergic neurons loss in the substantia nigra pars compacta and in the striatum. In the absence of PINK1, immunisation with LPS-treated PINK1-KO dendritic cells induced mitochondrial-specific T-cells with the phenotype of Th1, Th17 and Tc17 cells that strongly correlating with the phenotype of mitochondrial-specific T cells we found in PD patients. Moreover, we showed that even in the presence of PINK1 in Dopaminergic neurons (DAn), once this mitochondrial autoimmunity is launched, DAn degeneration is achieved. Therefore, these data confirm the major role of PINK1 in the regulation of the immune system and suggest a poor role of this protein in the direct protection of DAn because these events take place very early compared to motor symptoms. So, we suggest that mitochondrial-specific T cells are a valuable early PD biomarker and opens new therapeutic avenues in PD research.

Longitudinal Study on Hippocampal Volume and Verbal Memory in Patients with First-Episode Psychosis: Effects of Dopaminergic and Anticholinergic Burden of Antipsychotics

Agnes Belkacem¹, Katie M. Lavigne^1,2, Carolina Makowski³, Mallar Chakravarty¹, Ridha Joober¹, Ashok Malla¹, Jai Shah¹, Martin Lepage¹
¹Douglas Research Centre, McGill University, Montreal, QC, Canada
²Montreal Neurological Institute-Hospital, McGill University, Montreal, QC, Canada
³Department of Radiology, University of California San Diego, La Jolla, CA, United States
Corresponding Author: Agnes Belkacem, email agnes.belkacem@mail.mcgill.ca

Abstract

Antipsychotics help reduce positive symptoms of psychosis, but have limited impact on cognitive deficits and negative symptoms and have been associated with structural changes in the brain. Studies have shown that antipsychotic dosage can be associated with hippocampal volume, with reduced volumes in areas with dense dopamine receptors, such as in the dentate gyrus subfield. In addition, the literature also suggests considering anticholinergic burden of antipsychotics as it is associated with deficits in verbal memory in First-Episode Psychosis. As part of a longitudinal study over an 18-month period with 4 time points, our objectives were to examine changes in verbal memory performance and hippocampal subfield volumes in patients versus controls over time and to determine the extent to which antipsychotic treatment may partly account for changes over time. (1) We hypothesized that patients would have poorer verbal memory performance and reduced hippocampal subfield volumes over time relative to controls. (2) a. We expected that dopaminergic burden would be negatively associated with subfields with denser dopaminergic receptors. (2) b. We expect anticholinergic burden to be negatively associated with cognition, especially verbal memory performance in First-Episode Psychosis patients. First-Episode Psychosis patients, followed by the PEPP-Montréal clinic (N = 74), and non-clinical controls (N = 53) completed a 3T MRI scan and a neurocognitive evaluation (CogState) at 3, 9, 12 and 18 months after admission. (1) Generalized Estimating Equations analysis revealed a significant timepoint by group interaction for verbal memory performance and for the right CA1, left CA4/dentate gyrus subfield. (2) a. Significant negative correlations were found between dopaminergic burden and left CA1, left CA4/dentate gyrus, left fimbria and left hippocampus subfields volumes change over time in patients. (2) b. A significant negative correlation was found between anticholinergic burden and verbal memory performance over time in patients. Knowledge of a significant reduction in hippocampal volume in the early stages of the disease shows that it is crucial to provide treatment at the onset of the first psychotic symptoms, which may not only reduce cognitive deficits but also eventually restore damaged neuronal pathways. In addition, the associations found between medications, brain volume, and cognitive performance provide evidence in favor of prescribing the minimum effective dose of antipsychotics.

Étude des mécanismes de maturation de l'interleukine-1 bêta chez un modèle murin d'encéphalomyélite auto-immune expérimentale

Maxime Kusik¹, Benoit Mailhot¹, Felipe Da Dama Monteiro¹, Martine Lessard¹, Steve Lacroix¹
¹Axe Neurosciences du Centre de Recherche du Centre Hospitalier Universitaire de Québec–Université Laval et Département de médecine moléculaire de l’Université Laval, Québec, QC, Canada
Corresponding Author: Maxime Kusik, email maxime.kusik.1@ulaval.ca

Abstract

La sclérose en plaques (SEP) est une maladie inflammatoire chronique du système nerveux central caractérisée par une réaction immunitaire anormale contre la gaine de myéline, une membrane impliquée dans la conduction de l’influx nerveux et la protection neuronale. Les mécanismes moléculaires sous-jacents cette réaction anormale restent toutefois inconnus. Le laboratoire du Dr Lacroix met de l’avant l’importance de l’interleukine (IL)-1β dans la SEP chez un modèle murin mimant la SEP, soit l’encéphalomyélite auto-immune expérimentale (EAE). En effet, le Dr Lacroix et son équipe ont démontré que des souris invalidées en IL-1β (Il1b-/-) sont protégées contre le développement de l’EAE. À la lumière de ce résultat, nous avons formulé l’hypothèse que l’inactivation de l’inflammasome, un complexe multiprotéique stimulant la maturation de l’IL-1β grâce à la protéine adaptatrice ASC empêchera le développement de la maladie EAE chez la souris. La maladie EAE a été induite chez des souris n’exprimant pas ASC (ASC-KO) et les mécanismes moléculaires menant à l’activation de l’IL-1β ont été caractérisés dans un modèle in vitro de transmigration de la barrière hémato-encéphalique. Nous avons observé que l’absence d’ASC chez les souris EAE ne fait que retarder l’initiation de la maladie, suggérant que l’IL-1β mature est produite malgré l’inhibition des inflammasomes dans un contexte EAE. Subséquemment, nous avons déterminé chez les souris ASC-KO que les monocytes sont la principale source d’IL-1β mature durant l’EAE dans un contexte indépendant des inflammasomes. De plus, nous avons démontré que ces monocytes doivent être en contact avec des cellules endothéliales pour produire la forme mature de l’lL-1β sans la protéine ASC. Considérant le rôle crucial de l’IL-1β dans le modèle murin de la SEP, une meilleure compréhension des interactions protéiques menant à l’activation et la sécrétion de l’IL-1β ouvrirait la porte à de nouvelles approches thérapeutiques prometteuses contre la SEP.

Apprentissage Profond pour la Microscopie de Localisation Ultrasonore en 3D

Brice Rauby¹, Jonathan Porée¹, Hatim Belgharbi¹, Chloé Bourquin¹, Maxime Gasse^1,2, Jean Provost^1,3
¹Polytechnique Montréal, Montréal, QC, Canada
²Montreal Institute of Learning Algorithm, Montréal, QC, Canada
³Montreal Heart Institute, Montréal, QC, Canada
Corresponding Author: Brice Rauby, email brice.rauby@polymtl.ca

Abstract

La microscopie de localisation ultrasonore (ULM) repose sur la localisation de microbulles (MB) injectées dans le flux sanguin pour dépasser la limite de diffraction en imagerie du réseau vasculaire. Cette modalité est particulièrement prometteuse car non-ionisante, non invasive et hautement résolue. De plus, l’ULM 3D permet de s’affranchir des contraintes liées au choix du plan d’imagerie. Par ailleurs, l'utilisation d'une concentration élevée de MB pourrait surmonter les limitations actuelles de l'ULM dynamique et réduire le temps d'acquisition. La modélisation spatio-temporelle des trajectoires de MB a permis de multiplier par dix les concentrations lors de l'utilisation de l'apprentissage en profondeur en ULM 2D. Dans ce travail, nous présentons LightST-ULM, un réseau neuronal convolutif multidimensionnel (CNN) allégé qui distingue avec succès les vaisseaux sanguins dans des acquisitions 3D hautement concentrées. LightST-ULM a été entrainé sur des trajectoires de MB basées sur des simulations anatomiquement réalistes et la réponse ultrasonore correspondante en utilisant une implémentation GPU de SIMUS. Les paramètres de simulation correspondaient à une sonde matricielle à matrice de 8 MHz. La formation et la sélection de modèles ont été effectuées avec 5 sections de cerveau de souris différentes. De plus, une 6ème section de cerveau de souris a été utilisée pour la validation et l'évaluation. Pour localiser précisément les trajectoires des MB, le modèle proposé utilise uniquement la dimension temporelle dans les premières couches de convolution. Cela permet au CNN de détecter les trajectoires MB en utilisant leur contexte temporel tout en réduisant la dimensionnalité et la consommation de mémoire des couches suivantes. De plus, l'utilisation de blocs résiduels inversés permet au modèle de capturer des représentations riches à un coût de calcul réduit. Par rapport à l'ULM conventionnel, LightST-ULM améliore le dice (la métrique de qualité) des angiogrammes 3D reconstruits de 17,9% à 38,4% et sépare les vaisseaux à moins de 20 µm. LighST-ULM est également robuste à une multiplication par dix de la concentration de MB. Le modèle proposé permet d’imager avec succès le réseau vasculaire en 3D et à haute concentration. Les travaux futurs se concentreront sur les applications in vivo de la méthode dans le cerveau des rongeurs. Nous reconnaissons le soutien d'IVADO, RBIQ, FRQNT, TransMedTech, Apogée, NFRF et CFREF.

Sharp wave ripples modulation by glutamatergic projections from raphe to hippocampus

Justine Fortin-Houde^1,2, Guillaume Ducharme², Anne-Sophie Simard^1,2 and Bénédicte Amilhon^1,2
¹Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
²CHU Sainte-Justine Research Center, Montréal, QC, Canada
Corresponding Author: Justine Fortin-Houde, email justine.fortin-houde@umontreal.ca

Abstract

The hippocampus has an important role in memory. Sharp wave ripples (SWR) oscillation in the hippocampus during slow wave sleep contribute directly to memory consolidation. The median raphe play a central role in emotion-related processes and is known to modulate hippocampal rhythms. The median raphe contains a glutamatergic long-range projecting population, characterized by the expression of type 3 vesicular glutamate transporter (VGLUT3), whose functions remain largely unexplored. In this study, we aim to provide the first exhaustive characterization of this raphe-hippocampus glutamatergic pathway and its contribution to SWR activity. To specifically target VGLUT3 expressing neurons, we combine the use of VGLUT3-CRE mice and Cre-dependent viral vector. We injected Cre-dependent retrograde virus in the hippocampus to label the glutamatergic neurons projecting to this structure. We also explored the roles of glutamatergic neurons in modulating sharp wave ripples using electrophysiological recordings in the hippocampus combined with optogenetic activation of median raphe VGLUT3 neurons. We established a detailed cartography of hippocampus-projecting glutamatergic neurons within raphe nuclei. We show that the dorsal and ventral part of the hippocampus are targeted by distinct glutamatergic neuron populations. Our in vivo recordings demonstrate that optogenetic activation of glutamatergic median raphe neurons strongly suppress SWR activity in the dorsal hippocampus (n=3). Control experiments showed that light delivery in the median raphe with no opsin expression (YFP only) had no effect on SWR oscillations. Our results suggest that glutamatergic inputs from the median raphe modulate hippocampus sub-regions and associated functions independently. We reveal a powerful inhibitory control of SWR through median raphe glutamatergic neurons, suggesting a strong impact on memory formation. Taken together, the results of our study provide insight into the anatomy and functions of a novel median raphe-hippocampus glutamatergic pathway well positioned to modulate memory formation in response to emotion-related information.

The interplay of B cells and T cells in a transgenic model of CNS autoimmunity

Reda Fazazi¹, Prenitha Doss¹, Asmita Yeola¹, Joanie Baillargeon¹, Benoit Mailhot¹, Steve Lacroix^1,2, Manu Rangachari^1,2
¹Axe Neurosciences du Centre de Recherche du Centre Hospitalier Universitaire de Québec, Quebec City, QC, Canada
²Department of Molecular Medicine, Université Laval, Québec, QC, Canada
Corresponding Author: Reda Fazazi, email mohamed-reda.fazazi@crchudequebec.ulaval.ca

Abstract

La sclérose en plaques (SP) est une maladie auto-immune du système nerveux central (SNC) qui est traditionnellement considérée comme médiée par les lymphocytes T. Cependant, une accumulation de preuves indique un rôle crucial pour les lymphocytes B dans le processus pathologique. L'encéphalomyélite auto-immune expérimentale (EAE) est un modèle bien établi pour étudier les aspects immunitaires de l'auto-immunité du SNC. Afin d'examiner la relation des lymphocytes B et T dans l'EAE, nous avons étudié les souris transgéniques IgH^MOG, dont les cellules B expriment une chaîne IgH dérivée d'un anticorps spécifique contre le peptide de la myéline (MOG35-55). Nous avons immunisé ces souris et les contrôles NOD WT avec le peptide MOG35-55 qui est intégré par le CMH de classe II, induisant une réponse des cellules T CD4+. L'inflammation et la démyélinisation des tissus du SNC ont été évaluées par histopathologie, et le phénotype des cellules mononucléées infiltrant le SNC a été étudié par cytométrie en flux. La capacité des lymphocytes B IgH^MOG à présenter un antigène aux lymphocytes T CD4+ a été évaluée en utilisant des tests in vitro et ex vivo. Les souris IgH^MOG ont rapidement développé une EAE sévère caractérisée par une infiltration leucocytaire et une démyélinisation dans le SNC. Tandis que la fréquence des lymphocytes T CD4 + était augmentée dans le SNC des souris IgH^MOG, aucune différence n'a été observée en ce qui concerne la fréquence des lymphocytes B. En outre, les cellules T CD4 + infiltrant le SNC par IgH ^MOG ont produit des niveaux significativement plus élevés de cytokines GM-CSF et IL-17 associées aux lymphocytes Th17 par rapport à ceux des témoins. Mécanistiquement, les cellules B IgH^MOG étaient plus aptes que les cellules B WT à favoriser la production de cytokines inflammatoires des cellules T CD4 + dans des tests in vitro et menaient à une plus grande activation cellulaires de cellules T CD4+. Ces données montrent que les cellules B spécifiques au peptide MOG35-55 contribuent à l'EAE en favorisant l'inflammation des cellules T CD4+ et leur recrutement au SNC.

Protecting the newborn brain in the context of asphyxia: can sildenafil (Viagra™) improve outcomes achievable beyond total body cooling

Zoe Ward¹, Pia Wintermark, MD^1,2
¹Research Institue of McGill University Health Center, Montreal, QC, Canada
²Faculty of Medicine and Health Sciences, McGill University, Montreal, QC, Canada
Corresponding Author: Zoe Ward, email zoe.ward@mail.mcgill.ca

Abstract

Birth asphyxia is the leading cause of neonatal mortality and long-term neurologic deficits. The only available treatment for birth asphyxia is therapeutic hypothermia (TH) (i.e., whole body cooling, administered within 6 hours of birth and continued for 72 hours). Despite its neuroprotective effects, many asphyxiated newborns develop brain injury and neurological disabilities. As an alternative treatment, our lab demonstrated possible neurorestorative effects of sildenafil (Viagra®) following hypoxia-ischemia (HI) in an animal model of birth asphyxia. Sildenafil decreased the size of brain injury and increased the number of neurons. However, the synergistic effect(s) of a combined treatment of hypothermia and sildenafil on brain injury following HI are not yet characterized. The Vannucci rat model was used to replicate the neurologic damage following birth asphyxia in human term newborns. Rats were randomized to five groups: sham-operated rats treated with vehicle, HI rats treated with vehicle, HI rats treated with hypothermia, HI rats treated with sildenafil, and HI rats treated with hypothermia and sildenafil. Rats were sacrificed at three times points: P12, P17 (i.e., acute changes), and P30 (i.e., subacute changes). Cortex and hippocampus were evaluated to assess the treatment effects of hypothermia and sildenafil on neurogenesis, apoptosis and neuroinflammation after initial injury. I anticipate that (A) sildenafil administered after hypothermia will further prevent and repair brain injury compared to each treatment separately, and (B) this synergistic effect is due to the differential effects of each treatment on neurons, oligodendrocytes and inflammatory cells, with hypothermia preventing apoptosis, and sildenafil promoting neurogenesis, oligodendrogenesis and decreasing neuroinflammation. The proposed experiments will elucidate the potential synergistic effects of sildenafil and hypothermia following neonatal HI at term-equivalent age, compared to either treatment alone. Preclinical data obtained from these experiments will provide relevant information to guide future clinical trials of sildenafil in asphyxiated newborns.

Combining the effects of cortical and spinal stimulation to improve walking after spinal cord injury

Roxanne Drainville^1,2,3, Marco Bonizzato^1,2,3, Rose Guay Hottin^1,2,3, Alexandre Sheasby^1,2,3, Marina Martinez^1,2,3
¹Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
²Groupe de Recherche sur le Système Nerveux Central and Centre Interdisciplinaire de Recherche sur le Cerveau et l’Apprentissage, Montréal, QC, Canada
³CIUSS-NIM Hôpital du Sacré-Cœur de Montréal, Montréal, QC, Canada
Corresponding Author: Roxanne Drainville, email drainville.roxanne@gmail.com

Abstract

Spinal cord injuries (SCI) are associated with chronic motor deficits. When the injury preserves some nerve fibers, recovery of locomotion can occur with time and rehabilitation, but is often incomplete. Neuroprostheses are medical technologies of increasing popularity for the treatments for SCI. Neurostimulation of the spinal cord below the injury reactivates the dormant spinal networks, allowing weak residual motor commands from the brain to result in overt leg movement. Our lab recently developed a novel cortical neuroprosthesis. Electrical stimulation is delivered in synchrony with the locomotor behavior to activate specific cortical networks and support movement (Bonizzato & Martinez, Science Translational Medicine, accepted). After SCI, our technology helps the brain to produce and sustain effective motor commands. Thus, foot flexion is improved and dragging is immediately alleviated. Moreover, we demonstrated that daily locomotor training using cortical stimulation results in improved recovery of voluntary foot control (ladder walking task). Cortical and spinal stimulation are complementary in treating walking deficits. We propose that cortical and spinal neuromodulation can be combined to maximize the benefits of intervention. We already validated a rat model of cortico-spinal intervention after SCI. In several rats, we combined cortical and spinal stimulation during treadmill walking and characterized the optimal spatiotemporal stimulation characteristics (site, amplitude, duration and frequency). Our preliminary data suggest that combining cortical and spinal stimulation is more effective in reducing foot drop caused by SCI than delivering cortical or spinal stimulation as a single therapy.

Targeting Polo-like kinase 2, a new guilty in Alzheimer's disease pathogenesis

Laura Martínez-Drudis^1,2, Razan Sheta^1,2, Rémi Pellegrinato^1,2, Frédéric Calon^2,3, Serge Rivest^1,2, Abid Oueslati^1,2
¹Department of Molecular Medicine, Faculty of Medicine, Université Laval, Quebec, QC, Canada
²Neuroscience Axis, Centre Hospitalier Universitaire de Québec-Université Laval Research Center, Quebec, QC, Canada
³Faculty of Pharmacy, Université Laval, Quebec, QC, Canada
Corresponding Author: Laura Martínez-Drudis, email laura.martinez-drudis@crchudequebec.ulaval.ca

Abstract

Increasing evidence suggest that phosphorylation plays an important role in the aggregation and toxicity of amyloid beta (Aβ) resulting from amyloid precursor protein (APP) cleavage and tau, the major neuropathological hallmarks of Alzheimer’s disease (AD). Our laboratory has reported a dramatic accumulation of Polo-like kinase 2 (PLK2) in the brains of AD patients. This observation, in association with the recent notion of a direct interaction between PLK2 and APP, suggests that the aberrant accumulation and activity of PLK2 may contribute to AD. Our goal is focused on examining the effect of PLK2 pharmacological inhibition on APP and tau accumulation and toxicity in cells and transgenic mouse models of AD. HEK293T cells were used to examine the effect of PLK2 and its inhibition on APP and Tau protein levels by immunoblotting. In vivo, behavioral analysis incorporated evaluation of different learning and memory task. Biochemical and histological analysis of AD neuropathology (APP, tau, their phosphorylated forms, and synaptic dysfunction) were performed using immunoblotting and immunohistochemistry. We observed that PLK2 overexpression decreases APP and tau levels in a PLK2-concentration dependent manner, counteracted by PLK2 pharmacological inhibition in cells. In vivo, our results showed cognitive decline and AD hallmarks in symptomatic mice, as well as a decrease in some aspects of APP and tau pathology upon PLK2 inhibition both at the behavioral and molecular levels in a sex-dependent manner. Overall, this project will shed light onto novel mechanisms by which phosphorylation regulates tau and APP aggregation and toxicity, providing a novel therapeutic target for AD and related dementia. In addition, our study highlights the importance of considering gender- and sex-specific responses when assessing AD therapeutics.

Characterizing human cerebellar perineuronal nets in depression and child abuse

Refilwe Mpai^1,2, Maria A. Davoli¹, Naguib Mechawar^1,3
¹McGill Group for Suicide Studies, Douglas Mental Health University Institute, Verdun, QC, Canada
²Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
³Department of Psychiatry, McGill University, Montreal, QC, Canada
Corresponding Author: Refilwe Mpai, email refilwe.mpai@mail.mcgill.ca

Abstract

Child abuse (CA) is a leading risk factor for various types of psychopathologies, including major depressive disorder (MDD). MDD affects around 300 million people worldwide and is a major cause of disability. During childhood, there are critical periods during which brain circuits display enhanced plasticity. Adverse experiences that occur during these critical periods result in deviances from typical neurodevelopment increasing one’s predisposition to mental disorders. Perineuronal nets (PNNs), a mesh-like structure of condensed extracellular matrix surrounding certain neuronal subtypes, play an important role in the closure of critical periods. PNNs develop during childhood and increase in density as the brain reaches maturity. As shown in animal models, the formation of PNNs can be altered by experience and have been implicated in the permanence of fear memories. We hypothesize that, in humans, PNNs may stabilize neuronal populations involved in the encoding of aversive memories and experiences associated with CA. The cerebellum is increasingly implicated in MDD, however, the cellular and molecular mechanisms through which it is altered by MDD and CA have not yet been elucidated. In this study, we use immunofluorescence staining and microscopy to characterize PNNs in post-mortem human cerebellum and, as the study progresses, we will examine how they may be altered in samples from MDD patients with or without CA vs matched healthy controls. Results from a recent study conducted in our laboratory indicate an increase in the density of PNNs in the ventromedial prefrontal cortex (vmPFC) of depressed suicides with a history of CA compared to depressed suicides and controls with no history of CA. Our preliminary characterization suggests an overall cerebellar PNN distribution in humans that is comparable to that previously described in rodents. I am currently optimizing my immunofluorescence staining to visualize PNNs and have begun characterizing them in human cerebellar samples.

Modeling Amyotrophic Lateral Sclerosis with iPSC-derived Motor Neurons Expressing Mutations in TARDBP

Sarah Lépine^1,2, Eric Deneault¹, Xiuqing C. Chen¹, Mathilde Chaineau¹, Gilles Maussion¹, Thomas Durcan¹
¹Early Drug Discovery Unit, Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal, QC, Canada
²Faculty of Medicine and Health Sciences, McGill University, Montreal, QC, Canada
Corresponding Author: Sarah Lépine, email sarah.lepine2@mail.mcgill.ca

Abstract

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the death of motor neurons, causing a progressive paralysis that is fatal generally within 2 to 4 years after disease onset. A recognized pathological hallmark of ALS is the presence of cytosolic aggregates containing TAR DNA-Binding Protein 43 (TDP-43) in motor neurons in >95% of cases. In addition, missense mutations TARDBP, the gene encoding TDP-43, are known to be causative for ALS in a small subset of patients. Elucidating the pathological roles of TDP-43 will facilitate the identification of pathways involved in neurodegeneration. Over the last decades, induced pluripotent stem cells (iPSCs) became a powerful tool to study neurodegenerative disorders in human disease-relevant cells. By using the CRISPR-Cas9 genome-editing technology, we generated two homozygous knockin iPSC lines carrying point mutations in TARDBP that encode the A382T and G348C variants, two frequent ALS variants in TDP-43. Successful introduction of the mutations was confirmed by digital droplet PCR and Sanger sequencing. Both iPSC lines express pluripotency markers Nanog, TRA-1-60, SSEA-4 and Oct-3/4 and display a normal karyotype. Using a well validated differentiation protocol that mimic motor neurogenesis, our group is able to reproducibly differentiate iPSCs into motor neuron progenitor cells (MNPCs) and motor neurons (MNs). Using quantitative PCR and immunofluorescence, we show that these TARDBP mutations do not impair normal differentiation. TARDBP A382T/A382T and TARDBP G348C/G348C iPSCs differentiate into MNPCs that express progenitor markers Nestin, PAX6 and OLIG2 at similar levels than wild type MNPCs. As MNPCs further mature into MNs, mutant and control cells upregulate MN transcription factors HB9 and ISL1, as well as cholinergic markers ChAT and VAChT. This model will be used to dissect the molecular and cellular effects of TARDBP mutations in human MNs, which may aid in the identification of new therapeutic targets.

All-Optical Investigation of Nucleus Accumbens Circuits That Elicit Compulsive Behaviour

Houman Azizi¹, Christopher Lafferty², Jonathan Britt^3,4
¹Department of Neuroscience, McGill University, Montreal, QC, Canada
²Department of Psychology, McGill University, Montreal, QC, Canada
³Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
⁴Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, QC, Canada
Corresponding Author: Houman Azizi, email houman.azizi@mail.mcgill.ca

Abstract

Compulsions are a core feature of numerous psychiatric disorders, including OCD and Tourette syndrome. Previous research suggests that dysregulation of the basal ganglia may drive compulsive behaviors. In rodents, overactivation of certain striatal inputs can elicit excessive self-grooming. It remains unclear, however, whether activation of striatal inputs influences other measures of compulsion and how repeated stimulation affects plasticity in downstream circuits. We measured cognitive flexibility of male and female mice using a reversal learning task and tested the effect of repeated optogenetic stimulation of thalamic (PVT) or hippocampal (HPC) inputs to the nucleus accumbens (NAc) on their performance. We also performed calcium imaging coupled with optogenetics to record evoked activity from D1 neurons of the NAc following repeated PVT afferent stimulations. Repeated PVT stimulation decreased the cognitive flexibility of animals in long-term while HPC stimulations resulted in the same effect in both short- and long-term. Evoked population response of D1 neurons of the NAc to photostimulation of HPC inputs did not alter after performing long-term potentiation (LTP) plasticity protocol stimulations on this pathway. However, the natural and intrinsic activation of D1 neurons on the onset of locomotion increased after undergoing our LTP plasticity protocol. Our data demonstrate that distinct striatal inputs can affect different aspects of compulsive behavior while PVT to the NAc pathway can be the main circuit underlying OCD-like behaviors. Lastly, these data suggest that potentiation of HPC to the NAc inputs can happen through optogenetics, even though it is not visible in evoked responses of D1 neurons.

The He(ART) of Dyslexia: How Can Listening to Music Improve Verbal Memory?

Bre-Anna Owusu¹, Elisabet Service¹
¹McMaster University, Hamilton, ON, Canada
Corresponding Author: Bre-Anna Owusu, email kingb10@mcmaster.ca

Abstract

It is estimated that, 6% to 17% of school aged children have dyslexia—the most prevalent of learning disabilities, characterized as an inability to read fluently. Apart from literacy issues, dyslexic children also have difficulties memorizing novel spoken words, a deficiency that underlies their poor reading and oral language skills. Previous research demonstrates that regular musical rhythmic primes benefit subsequent literacy learning in children with dyslexia. Neural oscillations synchronize to musical rhythms as they orient listeners’ attention over time—facilitating predictive processing; allowing children to read likely words at expected points in sentences. To test the presence of a rhythm attending effect on verbal memory in dyslexic children, we adapted the methodology of a rhythmic-priming paradigm. In this, dyslexic children’s performance on grammar judgement tasks is measured after they have heard a variety of varied rhythms. In our adapted procedure, the child will listen to 32-second regular or irregular rhythms. Following each prime, a grammatically correct or incorrect spoken sentence containing a novel word will be presented in which recognition of the novel word and grammatical judgment are measured. Verbal memory performances of children with dyslexia and their grammaticality judgments should improve after children listened to regular musical rhythms compared to memory performances after listening to irregular rhythms. In addition to previous findings on impaired verbal memory processing in children with dyslexia, our anticipated results point to the benefit of using musical rhythms to boost verbal memory skills helping children with dyslexia improve their vocabulary.

Tissue engineering repair of peripheral nerve transections

Alexane Thibodeau, MSc^1,2, Todd Galbraith¹, Chantal M. Fauvel¹, Hélène T. Khuong, MD^1,2, François Berthod, PhD^1,2
¹Centre de Recherche en Organogénèse Expérimentale de l’Université Laval – Centre de Recherche du CHU de Québec, QC, QC, Canada
²Department of Surgery, Faculty of Medicine, Université Laval, Québec, QC, Canada
Corresponding Author: François Berthod, email francois.berthod@fmed.ulaval.ca

Abstract

Peripheral nerve damage is still a challenge even with all the recent technologies. Nerve injuries can cause severe loss of sensibility and paralysis. Autologous nerve transplantation, the gold standard in clinic, induces a deficit to the donor site and a poor functional recovery in most cases. An alternative is to use nerve tube to guide axonal migration through the distal nerve stump, but there are several clinical limitations to this technic. Our goal is to produce a fully autologous viable nerve tube (NT), i.e. solely from patient own cells. NT contain a capillary network developed by seeding endothelial cells (ECs) and enriched in Schwann cells (SC) for faster recovery in patients with major peripheral nerve transections. NT are made from a rolled human fibroblasts sheet seeded with EC and SC’s. NT were implanted in immunodeficient RNU rats for 22 weeks to repair a 15 mm sciatic nerve defect. Innervation was observed by immunofluorescence and the myelin thickness was obtained with toluidine blue staining. The gastrocnemius muscle weight was measured as a reliable reinnervation status. The horizontal ladder rung test monitor the functional outcome. NT support an axonal migration through the entire nerve gap, i.e. rat axons re-innerved sciatic distal stump. Toluidine blue staining revealed mature myelinated fibers after 22 weeks with similar G-ratio in NT vs autograft (p>0.05). NT and autograft showed equivalent gastrocnemius muscle mass (p>0.05). A partial motor function recovery was observed in rats with similar efficiency in NT vs autograft (p>0.05). A pre-vascularized and SC enriched living nerve tube allows motor function recovery. EC may increase the vascularization process and provide a well-oxygenated environment. Primary SC release nerve growth factors that will improve nerve regeneration. A living pre-vascularized nerve tube could provide a new clinical tool to repair much larger lesions.

Development of a novel optogenetic based model of alpha-synuclein aggregation to study Parkinson’s disease

Razan Sheta¹, Morgan Bérard¹, Maxime Teixeira¹, Walid Idi¹, Roxanne Turmel¹, Jérome Lamontagne¹, Denis Soulet¹, Francesca Cicchetti¹, Edward A. Fon², Abid Oueslati¹
¹Centre de Recherche du CHU de Québec, Université Laval, Quebec, QC, Canada.
²Montreal Neurological Institute, McGill University, Montreal, QC, Canada
Corresponding Author: Razan Sheta, email Razan.sheta.1@ulaval.ca

Abstract

Unveiling the Role of the Endolysosomal System in the Pathogenesis of Parkinson's disease

Teixeira Maxime¹, Bérard Morgan¹, Sheta Razan¹, St-Pierre Marie-Kim¹, Tremblay Marie-Ève^1,2, Vallières Luc¹, Oueslati Abid¹
¹Axe Neurosciences du Centre de Recherche du Centre Hospitalier Universitaire de Québec–Université Laval, Québec, QC, Canada
²Division of Medical Sciences University of Victoria, Victoria, BC, Canada
Corresponding Author: Maxime Teixeira, email maxime.teixeira@crchudequebec.ulaval.ca

Abstract

While progress has been made in understanding the neurodegenerative mechanisms that lead to cell death in Parkinson’s disease (PD), early causal pathogenic events are not clear. Converging findings point at endolysosomal system (ELS) dysfunction as the early mechanism and key pathway affected in PD. However, the exact mechanism by which alpha-synuclein aggregates, also called Lewy Bodies (LBs), disrupt the ELS remain elusive. To answer this question, our group created a new optogenetic-based model of PD that allows for the real-time induction of α-syn aggregates, under the blue light control, that mimics all cardinal LBs features. This system is referred to as Light-Inducible Protein Aggregation (LIPA) and allows us to explore unsolved questions related to early interactions between the ELS, LBs and PD pathogenesis. Using the LIPA system inside living cells, we were able to study the direct impact of our aggregates on vesicle homeostasis. To specifically investigate the interactions between our LIPA aggregates and the ELS, we decided to use the super-resolution microscopy STED in combination with transmission electron microscopy (TEM) to cross-confirm the results observed. The combination of immunocytochemistry and STED offered us a better understanding of the interactions between LBs and trafficking vesicles while showing several different. Our LIPA aggregates showed ultrastructural features of authentic LBs, showing interactions with vesicles such as the early/late endosomes (EEA-1/Rab7) but also the degradation vesicles (LAMP1/2A) characterized by multiple co-localization with those markers. Interestingly, those vesicles were specifically interacting with alpha-synuclein and were not co-localizing in the same way with aggregates. Those results were confirmed using TEM on our LBs, showing that they are composed of multiple vesicles and shown distorted organelles (mitochondria, Golgi apparatus or reticulum endoplasmic). Those results allowed us to observe and to better understand how alpha-synuclein aggregates impact the trafficking of the vesicles inside the cell overtime.

Abnormal Lateralization in infants at risk for Autism

Gabriel Blanco¹, Christian O"Reilly¹, Mayada Elsabbagh¹
¹McGill University, Montreal, QC, Canada
Corresponding Author: Gabriel Blanco Gomez, email gabriel.blancogomez@mail.mcgill.ca

Abstract

Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental condition characterized by impaired social and communication skills, with language impairments affecting over 50% of children. In the last decade, various studies have shown that children with ASD display structural and functional differences which lead abnormal lateralization patterns during development. For instance, the incidence of left-handedness is thought to be around 8-10% in the general population compared to 40-60% in the ASD population. Typically developing children also display leftward activation during various language tasks while children with ASD show rightward activation. Moreover, it remains to be seen whether these patterns emerge early during development (infancy) or later in childhood. The goal of this study is to explore lateralization patterns during infancy to further our understanding of brain connectivity in ASD and create a more detailed characterization of ASD subgroups. Using data from the International Infant EEG Data Integration Platform (EEG-IP), ), a multi-site longitudinal cohort of 196 infants (ages 6-18 months) at risk for autism and neurotypical controls, we computed brain lateralization from resting state high-density EEG recordings. Our results showed that at six months, infants at risk for autism displayed increased leftward lateralization in the frontal lobe compared to control groups. Similarly, while typically developing infants showed leftward lateralization at the superior temporal gyrus, middle temporal gyrus and superior parietal gyrus and pericalcarine regions, infants at risk showed a lack of dominance (p’s < 0.05).These regions are associated with language processing, suggesting that language development is disrupted early on. The next step is to compare lateralization scores with language outcomes to better understand how abnormal brain asymmetry can lead to language deficits.

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