Canada

Loss-of-function variants in the human Zdhhc9 gene are identified in 2% of patients diagnosed with X-linked intellectual disability. These patients exhibit striking reductions in white matter volume and altered microstructure of white matter tracts. To further understand the role of Zdhhc9 in the brain and to elucidate how disrupting Zdhhc9 function contributes to phenotypes observed in patients, we have characterized a Zdhhc9 knockout mouse line. We demonstrate that Zdhhc9 is enriched in oligodendrocytes and is approximately two-fold higher in the corpus callosum than in any other region of the mouse brain. Zdhhc9 knockout mice exhibit significant reduction in myelin/oligodendrocyte associated markers, as well as reductions in the palmitoylation of these proteins, suggesting palmitoylation of myelin proteins may be required for their stability. RNA sequencing of different brain regions from control and Zdhhc9 knockout mice demonstrate differential expression of oligodendrocyte marker genes, suggesting a larger population of immature oligodendrocytes and fewer mature oligodendrocytes in knockout brains. This work provides a new perspective into the role of Zdhhc9 in oligodendrocytes and provides evidence that palmitoylation contributes to the development of white matter.

CAN-ACN 2021

The role of palmitoylating enzyme, zDHHC9, in intellectual disability

x-linked intellectual disability

dhhc

palmitoylation

Colleagues and Friends:

I am very happy to welcome you to the 14th annual Canadian Neuroscience Meeting, and to the first virtual edition of our meeting. I want to highlight the important work the CAN meeting chair, **Roger Thompson** and co-chair, **Alyson Fournier**, did to put together the great program we are offering this year. Moving to a virtual format required a complete re-design of the program, and both Roger and Alyson did a splendid job in providing us with an appealing and well adapted program for our first virtual event. I wish to thank them for this very important effort.

Highlights of this year’s scientific meeting include invited speakers **Michael Hausser, Franck Polleux, Gwyneth Card, Magdalena Götz**and Brain Prize winner **Huda Zoghbi**. Plenary and parallel symposia, proposed by our members complete our diverse [scientific program.](https://can-acn.org/meeting-2021/program-2021/)

The 2021 Advocacy session, chaired and organized by CAN advocacy committee chair **Karun Singh**, will feature a special lecture and question period with Member of Parliament and past Science Minister **Kirsty Duncan**. This will be followed by a short overview of CAN’s advocacy activities over the last year. We invite you to participate in this session for insight from Dr. Duncan on the workings of Parliament Hill, and to learn more about what CAN has been doing to promote neuroscience research in Canada.

We are also excited to host **Lisa Willis** in the Equity Diversity and Inclusion session, organized by EDI committee chair **Jibran Khokhar**.

A special highlight of our meeting will be the lectures by award-winning young neuroscientists. We are please to host the CAN 2020 Young Investigator Award winner **Mihaela Iordanova**, and CAN 2021 Young Investigator Award winners **Aaron Phillips** and **Tabrez Siddiqui**. Highlights will also include presentation by the top three winners of the CAN-CIHR-INMHA Brain Star Award winners, **Claire Gizowski, Nuria Daviu Abant** and **Lukas Tamayo-Orrego**.

Independently organized satellite symposia complement and complete this exciting program, check them out here: https://can-acn.org/meeting-2021/2021-satellite-symposia/

Some of the most engaging sessions are always the poster sessions featuring the work of our trainees, so make sure to log in to Gather Town during the poster sessions to chat with the presenters.
We hope you enjoy this program, and look forward to welcoming you, virtually.

Shernaz Bamji

President of the Canadian Association for Neuroscience

![](https://assets.underline.io/uploads/markdown_image/1/image/b9aea25343a87d5aac3b9367dc780974.jpg)



Please head to https://can-acn.org/meeting-2021/registration-2021/ to register. 

14th Canadian Neuroscience Meeting from August 23rd-25th

poster

Parkinson's Disease (PD) is the second most common neurodegenerative disease in the world. Characterized by motor and non-motor symptoms, PD is associated with the loss of dopaminergic neurons in the Subtantia Nigra (Kalia and Lang, 2015). One of the major pathological hallmarks of the disease is the aggregation of misfolded proteins called alpha-synuclein (α-syn), which will lead to the formation of cellular inclusion known as Lewy bodies (Spillantini et al., 1997). However, how these aggregates disturb neuronal homeostasis leading to neurodegeneration remains elusive. Several studies showed a correlation between alterations of the degradation systems (autophagic or proteasomal), implicated in the protein quality control, and a-syn aggregation (Lehtonen et al., 2019). It is then relevant to know how an alteration of the degradation systems is involved in the pathogenesis of PD. To this purpose, 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 called the LIPA (Light-Inducible Protein Aggregation) system nicely mimics key features of Lewy bodies (Bérard et al., under review). Using this cellular model, we were able to observe for the first time the effect of LIPA-induced aggregates on the proteasome and autophagy systems in living cells by using specific markers (Menéndez-Benito et al., 2005). Moreover, we also get interested in the inhibition of these systems and the effect on the aggregation. Taken together our observations reveal the impact of autophagy and proteasome dysfunctions in PD pathogenesis.

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

Stroke is one of the leading causes of death and disability in the world. Unfortunately, there is still no effective therapy to treat the disease. Therapeutic angiogenesis using potent pro-angiogenic agents has already been shown to provide therapeutic benefits. However, the use of such agents is a double-edged strategy because of the increased risk of exacerbation of vascular leakage. Pericytes are specialized mural cells that play a key role in stabilizing the angiogenic vasculature and possess plastic properties, as they are able to differentiate into endothelial cells by reprogramming. Because of their angiogenic and plastic properties, pericytes are an attractive target for developing new interventions to promote neurovascular repair after stroke. Using novel pharmacological and genetic approaches to target pericytes, our results indicate that a recently discovered platelet-derived growth factor, isoform D (PDGF-D), plays an important role in promoting pericyte plasticity contributing notably to a decrease in brain atrophy and a reduction in motor impairment. Furthermore, our data demonstrate that ex vivo pre-conditioned pericytes transplanted intra-nasally migrate to the lesion site and promote its vascularization, which leads to the regression of damage. The overall results therefore suggest that pericytes are an interesting target and a new tool for the development of new therapies against stroke

Exploration of the pro-angiogenic potential of pericytes in the repair of neurovascular unity following cerebrovascular accidents

Background: Experiencing child abuse (CA) is considered as one of the strongest predictors of depression and suicide. Childhood and adolescence are characterized by critical periods (CP) of heightened cerebral plasticity, in which neural circuits can be more easily modified by experience. The closure of these CP is driven by the development of perineuronal nets (PNNs) around certain neurons in the brain. We hypothesize that CA occurring during these CP alters the recruitment and maintenance of PNNs in brain regions involved in emotional regulation. Methods: Well-characterized brain samples of ventromedial prefrontal cortex (vmPFC) from adult depressed suicides with or without a history of CA and matched controls were provided by the Douglas-Bell Canada Brain Bank. Immunofluorescent staining was performed with different combinations of cellular markers (PV, NeuN, Westeria Floribunda Lectin). Fluorescent in situ hybridization (RNAScope®) was performed to identify the phenotype of neurons enwrapped by PNNs. Whole slide and confocal images were analyzed using QuPath and FIJI. Results: As previously reported, PNNs were found to be covering PV+ interneurons and, to a lesser extent, pyramidal neurons (SLC17A7+). CA was found to be associated with higher densities, intensity and coverage of PNNs in the lower layers of the vmPFC. Conclusions: These results suggest that a history CA has a lasting impact on vmPFC circuitry. This may represent a mechanism through which early-life adversity increases vulnerability to psychopathologies and suicide. Experiments are under way to determine the mechanisms underlying this phenomenon, namely through an examination of proximal microglia, which have been shown to be implicated in the regulation and maintenance of PNNs in animal models.

Perineuronal nets in the ventromedial prefrontal cortex of depressed suicides with a history of child abuse

A history of child abuse (CA) strongly increases the lifetime risk of suffering from major depression and predicts an unfavorable course for the illness. Severe CA has been specifically associated with a widespread, robust, and lasting inhibition of oligodendrocyte function, coupled with impaired myelination of small caliber axons in white matter of the human anterior cingulate cortex (ACC). Given that myelin is extremely lipid-rich, one possible explanation for this finding could be a disruption of the lipid profile that composes the myelin sheath. Furthermore, the composition of fatty acids (FA) in myelin phospholipids has been demonstrated to influence its stability and permeability. Therefore, the objective of this study was to quantify and compare FA concentrations in postmortem ACC white matter in the choline glycerophospholipid pool (ChoGpl), a key myelin phospholipid pool, between adult depressed suicides with a history of CA matched depressed suicides without CA and healthy non-psychiatric controls. Total lipids were extracted according to the Folch method and lipids were separated into respective classes using thin-layer chromatography. FA methyl esters from the ChoGpl fraction were quantified using gas chromatography. Our analysis revealed significant differences in FA concentrations between groups, primarily involving the FAs in the arachidonic acid synthesis pathway, which is further corroborated with ACC RNA-sequencing data. Furthermore, the concentration of most FAs was found to decrease with age. These findings are the first to associate a history of early-life adversity with ChoGpl dysregulation in the human brain.

A history of child abuse associates with fatty acid dysregulation in the anterior cingulate cortex of depressed suicides

Interictal epileptiform discharges (IEDs) and Sharp Wave ripples (SWR) are pathological and physiological events in patients with temporal lobe epilepsy. Although these two events may display similar temporal frequency patterns, they carry different energy in different frequency bands. We study a group of epilepsy patients with medically resistant epilepsy (MRE) at the Lawson Research Center at UWO, implanted with SEEG depth electrodes (DE) to identify interictal abnormalities IEDs and differentiate them from SWRs using a new algorithm. The data were cleaned, denoised, montaged and segmented, such as sleep intervals and observed Ictals. The signal waveform and its power were extracted symmetrically in non-overlapping intervals of 500 milliseconds for event detection. Each waveform's power across all detected spikes was computed and clustered based on their energy distributions. The recordings included more than 720 hours of extracellular recordings from three patients with 450 hours of non-sleep data extracted from four hippocampus electrodes anterior and posterior hippocampus. Results indicate that IEDs carrying the largest power in the bands [30-45] Hz, SWR, on the other hand, are distributed between and [25-40] and [90-110] Hz. Our algorithm detected and successfully distinguished IED from SWRs based on their carrying energy during non-sleep periods. The waveforms' energy is more significant in sleep than awake (non-ictal) periods, and was this characteristic was used as an informative feature to cluster these two events.

Physiological and Pathological transients in temporal lobe Epilepsy patients during intracranial recordings

Mutations in the ATP-dependent chromatin remodeller chromodomain, helicase, DNA binding (CHD) 7 are the primary cause of CHARGE syndrome (CS) and have been associated with autism spectrum disorder (ASD). CHARGE is an acronym for the most characteristic features presented by patients: coloboma of the eye, heart defects, atresia chonae, retardation in growth and development, genital abnormalities, and ear defects. Although not included in the diagnostic criteria CS features often include neurological and behavioural problems such as hyperactivity, seizure, intellectual disability and autism. Little is known about the molecular mechanisms that underlie these neurological symptoms. Further, there is no known treatment yet either for patients with CS or for the neurological symptoms shared between CS and ASD. To investigate this, we generated a novel CRISPR/cas9 zebrafish chd7−/− model. We show that chd7 knockout zebrafish larvae exhibit a small head phenotype, defects in craniofacial cartilage development and display aberrant axonal network development. Further the chd7 mutants have less GABAergic neurons and exhibit a hyperactivity behavioural phenotype. Using an unbiased whole transcriptomic approach, we found that the GABAergic neuron defect was at least in part due to the downregulation of a CHD7 target gene, paqr3b and the subsequent upregulation of the MAPK/ERK signalling pathway, which is also dysregulated in CHD7 mutant human cells. Through a phenotype-based screen in chd7−/− zebrafish and C. elegans, we show that the small molecule ephedrine restores MAPK/ERK signalling and improves both GABAergic defects and behavioural anomalies. This work provides insight into the neuropathogenesis in CS and identifies a promising compound for further preclinical studies.

Chd7 loss of function in zebrafish impairs GABAergic network development through MEK/ERK signalling: CHARGE syndrome and beyond

BACKGROUND Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease with cognitive, behavioral, and psychiatric symptoms, with depression and suicidality present in a large proportion of CTE cases. Pathologically CTE is defined by a distinctive accumulation of hyperphophorylated tau (pTau) predominately involving the frontal and temporal cortices, medial temporal lobe, and brainstem. However, the association between pathology in particular brain regions and psychiatric CTE symptoms is unknown. METHODS AND RESULTS Human postmortem brains from CTE cases and controls were obtained from the VA-BU-CLF Brain Bank. Trained neuropathologists examined each brain for gross and microscopic pathology, and provided semi-quantitative assessments. Regions of interest (including frontal, temporal, limbic, and brainstem structures) were sectioned and stained for pathological markers of interest (e.g. pTau, β-amyloid, α-synuclein, pTDP43, etc). Stained slides were scanned and traced digitally, with staining quantified using a Leica Aperio system. Preliminary analyses suggest alterations in specific cortical, limbic, midbrain, and white matter structures may associate with depressive and suicidal features in CTE. In particular, cortical white matter loss as well as hippocampal and midbrain pathology were associated with psychiatric features. We have also found myelination and inflammation-associated changes in the anterior cingulate cortex of depressed CTE cases. CONCLUSIONS This investigation is the first to explore associations between neuropathology in particular brain regions and specific psychiatric features in CTE. Preliminary results suggest neurodegenerative pathology, loss of white matter, neuroinflammation, and gliosis could underlie psychiatric phenotypes in CTE.

Pathological correlates of psychiatric phenotypes across brain regions in chronic traumatic encephalopathy

**AMajor depressive disorder (depression) involves different mechanisms and brain scales. Altered cortical inhibition is associated with treatment-resistant depression, and reduced dendritic inhibition by somatostatin-expressing (SST) interneurons is a key component of the pathology. Electroencephalography (EEG) is an important source of biomarkers for depression to improve diagnosis and inform personalized treatments. However, whether the effects of reduced SST inhibition on microcircuit activity have signatures detectible in EEG remains unknown. We used detailed models of human cortical layer 2/3 microcircuits with normal or reduced SST inhibition to simulate resting-state activity together with the EEG signals in health and depression. We show that the healthy microcircuit models had emergent properties that reproduced key features of resting-state EEG theta-alpha frequency bands. We found that simulated EEG from depression microcircuits showed a significant increase in theta rhythmic activity and increased broadband power. Neuronal spiking showed a spike preference of EEG peak phase, and did not differ between conditions. We also showed using a realistic head model that the EEG signal biomarkers were mostly localized. Our study thus used detailed computational models to identify EEG biomarkers of reduced SST inhibition in cortical microcircuits in depression, which may serve to improve the diagnosis and stratification of depression subtypes, and in monitoring the effects of pharmacological modulation for treating depression.

Biomarkers of reduced inhibition in human cortical microcircuit signals in depression

Only recently has the scope of parental research expanded beyond maternal contributions to include the paternal sphere. Epidemiological studies have suggested that paternal stress, nutrition, and alcohol consumption, all impact neurobiological and behavioural characteristics in offspring. Given their high prevalence and comorbid use, a severely understudied domain in paternal research includes caffeine, alcohol use, and exercise. In this experiment, sires received seven weeks of regular tap water (placebo) or caffeine and/or ethanol (drug) and were housed in regular static cages (no ex) or cages with running wheels attached (ex). Beginning at P40, offspring were administered RmTBIs or sham injuries, followed by a behavioural test battery designed to assess post concussive symptomology. Post-mortem qRT-PCR was used to assess gene expression in the prefrontal cortex (PFC) and nucleus accumbens (NAc). Paternal experience did not improve or exacerbate RmTBI outcomes. However, female and male offspring displayed unique responses to RmTBI and paternal experience, resulting in sex-dependent changes in physical, behavioural, and molecular outcomes. Injury and paternal exercise drove significant changes in female offspring, whereas male offspring were affected by paternal exercise and drug treatment. Our findings add valuable insight into paternal experience and epigenetic inheritance in offspring. While not directly exacerbating or improving recovery from RmTBI, paternal experience affected male and female offspring in a sexually dimorphic manner.

Rathletes do not give you wings: How paternal exercise, caffeine, and/or alcohol affects offspring pathophysiology and behaviour following repetitive mild traumatic brain injury (RmTBI)

Background Coronavirus disease 2019 (COVID-19) frequently disturbs the nervous system. However, COVID-19's neurological disease requires a detailed characterization. Furthermore, we do not know what predicts poor neurological outcomes in patients. Previous reports have linked neurological disturbances to COVID-19's increased mortality. Here, we describe the clinical alterations in COVID-19 patients presenting with neurological manifestations and correlate neurological outcomes with disease severity. Methods We retrospectively analyzed clinical, neurological, neuroimaging (CT or MRI scans) and cerebrospinal fluid (CSF) laboratory data from 33 confirmed COVID-19 hospitalized Brazilian patients subjected to CSF sampling as clinically indicated. Findings COVID-19 was associated with a broad spectrum of neurological diseases in mild and severe cases. Headache was the only symptom associated with mild disease. In a bivariate analysis, severe patients had an 18-fold increased risk of presenting neuroimaging alterations. CSF findings do not differ in severe and mild cases. Only four patients presented increased CSF white blood cell counts. CSF levels were high for protein in 12 patients and glucose in six patients. Interpretation These findings strengthen the notion that COVID-19-induced neurological disease is heterogeneous and manifests regardless of patient state. It will be most important to determine the time course of neurological disease and whether it is permanent or alleviated over time so that COVID-19 patients with neurological alterations can be adequately treated.

Next from CAN-ACN 2021

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

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Dynamic regulation of palmitoyltransferases by synaptic activity

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