Attenuated activation of the anterior rostral medial prefrontal cortex on self-relevant social reward processing in individuals with autism spectrum disorder.

The social motivation hypothesis posits that people with autism spectrum disorder (ASD) find social stimuli less rewarding and are therefore less motivated towards social interaction than people with neuro-typical development (TD). However, the less rewarding social stimuli characteristics during social interaction for people with ASD are largely unknown. The contingent positive responsiveness of others relevant to self-action motivates the early development of social interaction, thus representing a social reward. As individuals with ASD often exhibit atypical responses to self-relevant stimuli in their early life, we hypothesized that the self-relevant responses of others are less rewarding for individuals with ASD. To test this hypothesis, we conducted a functional magnetic resonance imaging study using a social contingency task. During the task, the participants attempted to make the audience laugh by telling funny jokes and thus activating the anterior rostral medial prefrontal cortex (arMPFC) of TD individuals (Sumiya et al., 2017). We explicitly predicted that the atypical activation of the arMPFC is related to the reduced reward value of self-relevant responses to others in individuals with ASD. Thirty-one adults with ASD and 24 age- and intelligence quotient-matched TD adults participated in the study. Participants with ASD reported significantly lower pleasure after the audience's responses to their own actions than those in the TD group. Correspondingly, the self-related activation of the arMPFC, defined by the results of our previous study, was attenuated in the ASD group compared to the TD group. The present findings indicate that weak self-relevant outcome processing mediated by the arMPFC of individuals with ASD dampens the rewarding nature of social interaction.