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Postdoctorial Fellowship Award Winner 

Longitudinal mapping of social brain development in common marmosets

Poster Session B - Sunday, March 8, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom
Also presenting in Data Blitz Session 2 - Saturday, March 7, 2026, 10:30 am – 12:00 pm PST, Salon D.

Maëva Gacoin¹ (), Tyler Cook¹, Justine Clery^1,2; ¹McGill University, ²Azrieli Center for Autism Research

Primate species, including humans, navigate complex social environments by interpreting relationships through cooperative (e.g., grooming) and competitive (e.g., chasing) behaviors that reveal social hierarchies. Understanding the neural mechanisms underlying such interactions is key to elucidating the basis of adaptive behavior and its disruption in neurodevelopmental disorders such as autism. The common marmoset (Callithrix jacchus), a highly social New World primate, provides a unique opportunity to study the development of social cognition due to its rich social repertoire, rapid maturation, and translational relevance to humans. This project investigates how social cognition emerges in marmosets through a combination of functional and structural Magnetic Resonance Imaging (fMRI, sMRI) and behavioral assessments. Four marmosets (two males) were scanned awake longitudinally from 9-month-old (mo, juvenile) to adulthood while viewing videos of conspecific social behaviors (e.g., grooming, fighting, nursing). Complementary T1- and T2-weighted MRI from 6 mo (i.e. late infancy) onward tracked cortical myelination and frontoparietal functional connectivity, while behavioral tasks using touchscreen and eyetracking assessed social categorization. Results reveal progressive cortical myelination and strengthening of frontoparietal connectivity across development. Emotional valence of observed social interactions modulated brain activity: competitive interactions engaged the amygdala, while friendship and kinship behaviors elicited weaker responses and a similar brain pattern until 15 mo. With maturation, prefrontal activation patterns became increasingly distinct across social contexts, paralleling improved behavioral discrimination. These findings advance our understanding of how the primate brain supports the development of social cognition and establish the marmoset as a powerful preclinical model for investigating social deficits in autism.

Topic Area: EMOTION & SOCIAL: Development & aging