Atypical brain activation in adults with ASD during gestural interaction

Individuals with Autism Spectrum Disorder (ASD) have trouble in gestural interaction such as automatic mimicry and perceiving being imitated by other. We hypothesized that these troubles are caused by impairment of automatic, spontaneous transition from perceptual to motor representation (inverse model) and vice versa (forward model). We conducted a functional MRI with 19 adults with high-functioning ASD and 22 normal adults, where the subjects execute and observed finger gestures. We manipulated the congruency and the order of executed and observed action. When the subjects executed incongruent action based on the visually presented other’s action, activation in the left insula of the ASD group was significantly less prominent than that of the normal group in Autism Quotient (AQ) dependent manner. Considering that the left insula is the part of the executive system and is related to the response inhibition, this may represent the reduced workload for inhibition of the automatic mimicry of visually presented action, because of the less prominent generation of inverse model for adults with high-functioning ASD. When the subjects executed action based on observed action, congruency effect was observed in the bilateral extrastriate body area (EBA) of both groups. By contrast, when subjects observed other’s action after execution of an action, congruency effect in the left EBA was specifically attenuated in the ASD group in AQ dependent manner. As there was no intentional imitation process, this attenuated congruency effect is attributed to less prominent automatic generation of the forward model in adults with high-functioning ASD. These findings suggest that adults with high-functioning ASD have abnormality in linkage between motor and perceptual action representation that are automatically and bi-directionally induced, which may be related to atypical behaviors of ASD during gestural interaction