Right temporoparietal junction underlies avoidance of moral transgression in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is characterized by a core deficit in theory-of-mind (ToM) ability, which extends to perturbations in moral judgment and decision-making. Although the function of the right temporoparietal junction (rTPJ), a key neural marker of ToM and morality, is known to be altered in autistic individuals, the neurocomputational mechanisms underlying its specific impairment in moral decision-making remain unclear. Here, we addressed this question by employing a novel fMRI task together with computational modeling and representational similarity analysis (RSA). ASD patients and healthy controls (HC) decided in public or private whether to incur a personal cost for funding a morally-good cause (Good Context) or receive a personal gain for benefiting a morally-bad cause (Bad Context). Compared with HC, individuals with ASD were much more likely to reject the opportunity to earn ill-gotten money by supporting a bad cause than HC. Computational modeling revealed that this resulted from unduly weighing benefits for themselves and the bad cause, suggesting that ASD patients apply a rule of refusing to serve a bad cause because they over-evaluate the negative consequences of their actions. Moreover, RSA revealed a reduced rTPJ representation of the information specific to moral contexts in ASD patients. Together, these findings indicate the contribution of rTPJ in representing information concerning moral rules and provide new insights for the neurobiological basis underpinning moral behaviors illustrated by a specific dysfunction of rTPJ in ASD patients.