Is Autism a Disconnection Syndrome

Reduced cortical connectivity has been implicated as the underlying cause of cognitive and behavioral deficits associated with autism spectrum disorders (ASD). This research used two stimulus-response experiments to compare connectivity across hemispheres in boys with ASD to neurotypical boys. Experiment 1 recorded reaction times to bilaterally and unilaterally presented stimuli. Only the ASD group benefited greatly in bilateral conditions and, for unilateral conditions, when the stimulus appeared in the visual field across from the response hand. These condition types only affected reaction times for the ASD group, suggesting compromised interhemispheric transfer. Experiment 2 compared accuracy and efficiency for processing simultaneously presented patterns in both visual fields. When these patterns were the same, the task was easier for the neurotypical group, while the ASD group performed comparably whether the patterns were the same or different, suggesting greater isolation in each hemisphere. Impaired interhemispheric transfer supports overall cortical underconnectivity as the cause of cognitive impairments associated with this disorder.