Action execution and observation in autistic adults: A systematic review of fMRI studies

Motor impairments are common in individuals with autism spectrum disorder (ASD) although less is known about the neural mechanisms related to such difficulties. This review provides an outline of functional magnetic resonance imaging (fMRI) findings associated with execution and observation of naturalistic actions in autistic adults. Summarized outcomes revealed that adults with ASD recruit similar brain regions as neurotypical adults during action execution and during action observation, although with a difference in direction and/or magnitude. For action execution, this included higher and lower activity bilaterally in the precentral cortex, the parietal cortex, the inferior frontal gyrus (IFG), the middle temporal gyrus (MTG), the occipital cortex, and the cerebellum. For action observation, differences mainly concerned both higher and lower activity in bilateral IFG and right precentral gyrus, and lower activity in MTG. Activity overlaps between action execution and observation highlight atypical recruitment of IFG, MTG, precentral, and parieto-occipital regions in ASD. The results show atypical recruitment of brain regions subserving motor planning and/or predictive control in ASD. Atypical brain activations during action observation, and the pattern of activity overlaps, indicate an association with difficulties in understanding others' actions and intentions.