Neural responses to biological motion distinguish autistic and schizotypal traits

Abstract Difficulties in social interactions characterize both autism and schizophrenia, and are correlated in the neurotypical population. It is unknown whether this represents a shared etiology or superficial phenotypic overlap. Both conditions exhibit atypical neural activity in response to the perception of social stimuli and decreased neural synchronization between individuals. This study investigated if neural activity and neural synchronization associated with biological motion perception are differentially associated with autistic and schizotypal traits in the neurotypical population. Participants viewed naturalistic social interactions whilst hemodynamic brain activity was measured with fMRI, which was modelled against a continuous measure of the extent of biological motion. General Linear Model analysis revealed that biological motion perception was associated with neural activity across the action-observation network. However, inter-subject phase synchronization analysis revealed neural activity to be synchronized between individuals in occipital and parietal areas, but de-synchronized in temporal and frontal regions. Autistic traits were associated with decreased neural activity (precuneus, middle cingulate gyrus) and schizotypal traits were associated with decreased neural synchronization (middle and inferior frontal gyri). Biological motion perception elicits divergent patterns of neural activity and synchronization, which dissociate autistic and schizotypal traits in the general population, suggesting they originate from different neural mechanisms.