Saccade adaptation in autism and Asperger's disorder.

Autism and Asperger's disorder (AD) are neurodevelopmental disorders primarily characterized by deficits in social interaction and communication, however motor coordination deficits are increasingly recognized as a prevalent feature of these conditions. Although it has been proposed that children with autism and AD may have difficulty utilizing visual feedback during motor learning tasks, this has not been directly examined. Significantly, changes within the cerebellum, which is implicated in motor learning, are known to be more pronounced in autism compared to AD. We used the classic double-step saccade adaptation paradigm, known to depend on cerebellar integrity, to investigate differences in motor learning and the use of visual feedback in children aged 9-14 years with high-functioning autism (HFA; IQ>80; n=10) and AD (n=13). Performance was compared to age and IQ matched typically developing children (n=12). Both HFA and AD groups successfully adapted the gain of their saccades in response to perceived visual error, however the time course for adaptation was prolonged in the HFA group. While a shift in saccade dynamics typically occurs during adaptation, we revealed aberrant changes in both HFA and AD groups. This study contributes to a growing body of evidence centrally implicating the cerebellum in ocular motor dysfunction in autism. Specifically, these findings collectively imply functional impairment of the cerebellar network and its inflow and outflow tracts that underpin saccade adaptation, with greater disturbance in HFA compared to AD.