Action semantic deficits are associated with impaired motor skills in autistic adults without intellectual impairment.

Abstract

Several studies indicate the functional importance of the motor cortex for higher cognition, language 24 and semantic processing, and place the neural substrate of these processes in sensorimotor action25 perception circuits linking motor, sensory and perisylvian language regions. Interestingly, in 26 individuals with autism spectrum disorder (ASD), semantic processing of action and emotion words 27 seems to be impaired and is associated with hypoactivity of the motor cortex during semantic 28 processing. In this study, the relationship between semantic processing, fine motor skills and clinical 29 symptoms was investigated in 19 individuals with ASD and 22 typically-developing matched 30 controls. Participants completed two semantic decision tasks involving words from different semantic 31 categories, a test of alexithymia (the Toronto Alexithymia Scale), and a test of fine motor skills (the 32 Purdue Pegboard Test). A significant Group x Word Category interaction in accuracy (p < .05) 33 demonstrated impaired semantic processing for action words, but not object words in the autistic 34 group. There was no significant group difference when processing abstract emotional words or 35 abstract neutral words. Moreover, our study revealed deficits in fine motor skills as well as evidence 36 for alexithymia in the ASD group, but not in neurotypical controls. However, these motor deficits 37 did not correlate significantly with impairments in action-semantic processing. We interpret the 38 data in terms of an underlying dysfunction of the action-perception system in ASD and its specific 39 impact on semantic language processing.