FRONTOSTRIATAL FUNCTIONS EXAMINED WITH OCULOMOTOR TASKS ARE ASSOCIATED WITH RESTRICTED AND REPETITIVE BEHAVIORS IN AUTISM

Background: Impaired executive functions are evident in autism and likely reflect frontostriatal dysfunction.  These impairments, which include failure to disengage attention and inhibit prepotent responses, may contribute to problems of cognitive inflexibility, impulsivity, and repetitive behaviors. Oculomotor tasks provide sensitive methods for assessing executive functions in a translational framework. 

Objectives: To investigate attentional disengagement and response inhibition in individuals with autism, and determine whether deficits in these functions are associated with repetitive behaviors. 

Methods: Eighteen individuals with autism and 15 age- and IQ- matched healthy control individuals performed a visually guided prosaccade task and an antisaccade task. During the prosaccade task, participants fixate on a central cross-hair and make reflexive saccades to novel peripheral targets.  During the antisaccade task, participants are instructed to inhibit attention to novel peripheral targets and instead make a saccade to the mirror location of the target.  Each task included gap and overlap conditions.  ‘Gap’ trials were characterized by extinction of the cross-hair at central fixation 200 ms prior to presentation of a peripheral stimulus. ‘Overlap’ trials were characterized by extinction of the cross-hair at central fixation 200 ms after presentation of a peripheral stimulus.  The latency and accuracy of prosaccades were examined.  Antisaccade error rates (the failure to inhibit prepotent responses) and latency of antisaccades were examined.  Repetitive behaviors were measured with the Autism Diagnostic Inventory – Revised.

Results: Individuals with autism showed prolonged latencies in shifting attention on overlap prosaccade trials, and more antisaccade errors on both conditions of the antisaccade task. Both increased latency on overlap trials of the prosaccade task and increased errors on the antisaccade task were associated with levels of repetitive behavior. 

Conclusions: These results indicate that disturbances in the ability to disengage attention and voluntarily inhibit prepotent responses may underlie repetitive and stereotyped behaviors in autism.