Conference Agenda

Symposium Proposals Genes, Brain and Behavior 2024

Abstract

Symposium Chair

Chair Name:
Katrina Choe

Co-Chair Name (Optional):
Susanne Schmid

Email:
choek@mcmaster.ca

Organization:

Department:
Psychology, Neuroscience & Behaviour

Position:
Assistant Professor

Species:
Mouse

Description

Title:
CNTNAP2 and its role in autism spectrum disorders - from mice to men

Abstract (500 word limit):
Autism spectrum disorder (ASD) is a highly heterogeneous neurodevelopmental disorder that has been linked with hundreds of distinct gene mutations. It still remains unclear how identified ASD genes are mechanistically linked to the behavioral symptoms, namely, difficulty with social communication and interaction; and restricted, repetitive patterns of behaviour. A loss-of-function mutation in the Contactin-associated protein-like 2 (CNTNAP2) gene, which encodes a neurexin-family cell adhesion molecule, causes a syndromic form of ASD (cortical dysplasia focal epilepsy (CDFE)). Each speaker in this symposium will talk about how they use a variety of species (e.g. mouse, rat, stem cell-drived human cortical organoids) as a genetic model to study the neurobiological and behavioral implications of CNTNAP2 gene disruption. Chairs are Katrina Choe and Susanne Schmid. Speakers include Peyman Golshani, Katrina Choe, Susanne Schmid, and Minyin Li. The speaker list is gender balanced, and features a variety of career stages encompassing postdoctoral trainee, early-career ,and established investigator. A diverse array of investigative approaches will be featured. 1) Peyman Golshani performs miniaturized microscopy and calcium imaging in the nucleus accumbens to track the activity patterns of neurons during social interaction in the CNTNAP2 model of autism. His group found unstable social representations, and that nucleus accumbens optogenetic inhibition can rescue social deficits in the model. 2) Katrina Choe uses functional brain mapping methods in the Cntnap2 KO mouse. Her group showed that a loss of functional coupling across social brain regions could underlie low social interest in Cntnap2 KO mice. Furthermore, oxytocin administration, which has a pro-social effect on Cntnap2 KO mice, strongly stimulated many brain areas and normalized connectivity patterns in nucleus accumbens (NAc)-associated brain networks, suggesting it as an underlying mechanism of the social rescue. 3) Susanne Schmid performs a battery of behavioural tests in the Cntnap2 KO rat across development and in adulthood. Her group showed many autistic symptoms in these rats, such as altered social recognition and communication, hyperlocomotions and stereotypic behaviours, as well as hyperreactivity to sound stimuli. Moreover, they found that some, but not all, of these behavioural traits as well as the underlying neuronal mechanisms are malleable in early postnatal life and can be modulated through cross-fostering, enhanced sensory stimulation, and time-limited drug treatments. 4) Minyin Li uses stem cell-derived human cortical organoids (hCOs) and ex vivo human primary tissue preparation. He discovered highly synchronous spontaneous calcium activity following CNTNAP2 knockout, and further found that loss of CNTNAP2 is associated with increased, non-synaptic, glutamate bulk transmission, and suggested that this adhesion molecule may function as a ‘brake’ on neural activity at early stages of cortical development.

Speaker 1

Name:
Peyman Golshani

Email:
pgolshani@mednet.ucla.edu

Organization:
UCLA

Department:

Position:
Professor

Species:
mouse

Speaker 2

Name:
Katrina Choe

Email:
choek@mcmaster.ca

Organization:
McMaster University

Department:

Position:
Assistant Professor

Species:
Mouse

Speaker 3

Name:
Susanne Schmid

Email:
susanne.schmid@schulich.uwo.ca

Organization:
Western University

Department:

Position:
Professor

Species:
Rat

Speaker 4

Name:
Minyin Li

Email:
minyin@stanford.edu

Organization:
Stanford University

Department:

Position:
Postdoctoral fellow

Species:
Stem-cell derived human brain organoid

Peyman Golshani

Impaired social interaction is a core deficit of autism spectrum disorder (ASD), and may result from social interactions being less rewarding. How the nucleus accumbens (NAc), as reward circuit hub, encodes social interaction and whether these representations are altered in ASD remain poorly understood. Using miniaturized microscopy, we identified NAc ensembles encoding social interactions by calcium imaging. NAc population activity, and specifically D1 receptor-expressing medium spiny neurons (D1-MSNs) activity predicted social interaction epochs at much higher accuracy than mPFC or CA1 ensembles. Despite a high turnover of NAc neurons modulated by social interaction, we found a stable population code for social interaction in NAc which was dramatically degraded in Cntnap2^-/- mouse model of ASD. Therefore, social interactions are preferentially, specifically and dynamically encoded by NAc neurons and social representations are degraded in an autism model.

University of California, Los Angeles

Min-Yin Li^1,2, Xiaoyu Chen^1,2, Se-Jin Yoon^1,2, Sabina Kanton^1,2, Kevin W. Kelley^1,2, Alfredo M. Valencia^1,2, Lucy K. Bicks³, Qiuyu Guo³, Li Li⁴, Mayuri V. Thete^1,2, Anca M. Paşca⁴, John R. Huguenard⁵, Daniel H. Geschwind^3,6,7,8 and Sergiu P. Paşca^1,2

Human cerebral cortical development is a protracted process that involves cell specification, migration, synaptogenesis and maturation. We surprisingly found that the neurexin superfamily member CNTNAP2, whose bi-allelic loss is associated with severe intellectual disability, language regression and early onset epilepsy is surprisingly expressed in newborn immature cortical glutamatergic neurons. Using stem cell–derived human cortical organoids (hCOs), we discovered highly synchronous spontaneous calcium activity following CNTNAP2 knockout. Similarly, acute application of a monoclonal antibody targeting the extracellular domain of CNTNAP2 was sufficient to induce a hypersynchronous phenotype in control hCOs. Pharmacological studies revealed that this defect is related to spiking activity and NMDA receptors. Functional studies further indicated that loss of CNTNAP2 is associated with increased, non-synaptic, glutamate bulk transmission, and suggested that this adhesion molecule may function as a ‘brake’ on neural activity at early stages of cortical development. To further explore this, we used an ex vivo human primary tissue preparation. Live imaging in organotypic slices showed that spontaneous calcium activity increased from the frontal to the occipital cortex, which was inversely correlated with CNTNAP2 gene expression. Application of a CNTNAP2 monoclonal antibody increased activity in frontal slices to parietal cortex levels. Taken together, these results suggest an early developmental, non-synaptic role in human cortical neuronal maturation for a synaptic cell adhesion molecule associated with severe disease.

Susanne Schmid^1,2, Ella Doornaert¹, Alaa El-Cheikh Mohamad¹, Dorit Moehrle¹

Homozygous loss-of-function mutation in the CNTNAP2 gene causes cortical dysplasia-focal epilepsy syndrome, which manifests with core symptoms of autism. Multiple studies have identified other CNTNAP2 mutations as risk factors for ASD. We used a homozygous Cntnap2 knockout (KO) rat, a validated genetic rat model for studying core symptoms of ASD, to explore the impact of interventions in early postnatal development on the autistic phenotype, focusing on sensory processing disruptions. The Cntnap2-KO rat has consistently shown to display increased startle and reduced prepulse inhibition (PPI), combined with hyperlocomotion and altered social behaviour. We exposed the offspring of Cntnap2 heterozygous breeders to a highly enriched environment during early postnatal life (preweaning) and compared them with offspring reared in conventional caging, and we also treated postnatal offspring with the GABA agonist R-baclofen during a one-week period of high plasticity in the auditory sensory pathway. Homozygous wildtype and KO animals were tested in juvenile and adult stages for startle, prepulse inhibition, locomotor activity and social behaviour. The results show that some, but not all phenotypes of Cntnap2 KO are malleable through interventions in early life, highlighting that there is a window of opportunity to change the developmental trajectory.

This work was supported by CIHR and NSERC

¹Anatomy & Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario; ²Psychology, University of Western Ontario

A Patwardhan1, A Abdul Rahiman1, KY Choe1

A clear mechanistic link between autism spectrum disorder (ASD)-linked gene mutations and associated lower sociability is yet to be established. Sociability is modulated by the activity of the Social Salience Network (SSN), a group of interconnected brain regions with the nucleus accumbens (NAc) serving as a hub. Mice lacking Cntnap2 (Cntnap2-null) are a well-established model of a syndromic form of ASD-risk gene mutation (Cortical Dysplasia-Focal Epilepsy), and exhibit lower social interest. We have previously reported that the NAc in Cntnap2-null mice exhibits aberrant activity and connectivity with other regions (Choe et al., 2022). The mechanisms underlying these NAc phenotypes are unknown. Furthermore, whether these activity differences persist in the NAc and other SSN regions during social interaction remain uninvestigated. To address these questions, we performed i) patch-clamp electrophysiology in acute brain slices containing the NAc and ii) c-Fos-immunostaining (as a proxy for cellular activity) of brain sections from Cntnap2-null and wildtype littermate mice and quantified cellular, synaptic, and regional activity differences. We found, in NAc shell medium spiny neurons (MSNs) from Cntnap2-null mice, lower cellular excitability as well as a lower frequency of spontaneous excitatory postsynaptic currents compared to wildtype controls. Furthermore, social interaction robustly increased the activity of the NAc and several other SSN regions in wildtype mice, but failed to do so in Cntnap2-null mice. These aberrant activity patterns within the SSN may serve as a potential mechanistic link between Cntnap2 and the low sociability phenotype in mice lacking this gene.

1 Department of Psychology, Neuroscience & Behaviour, Hamilton, ON, Canada. Funding Support: McMaster startup, CFI JELF, CIHR Project Grant, Canada Research Chair