Imaging Study Shows Autistic Brain Fails to Rest
Regional metabolic deactivation observed during rest is absent in autism
TUESDAY, May 16 (HealthDay News) -- Metabolic activity in certain regions of the brain normally associated with resting and daydreaming is absent in patients with autism, according to a report published online May 15 in the Proceedings of the National Academy of Sciences Early Edition.
Daniel P. Kennedy, of the University of California at San Diego, and colleagues used functional magnetic resonance imaging to examine brain activity in 15 subjects with autism spectrum disorder and 14 healthy control subjects. Periods of rest consistently activate a medial cortical network that is suppressed during cognitively demanding tasks -- an effect called "deactivation."
Imaging studies showed that regions in the medial prefrontal cortex and rostral anterior cingulate cortex deactivated after control subjects went from a word counting test to a resting state. Deactivation in these areas were completely absent in most autistic subjects, and there was a high clinical correlation between level of deactivation and social and functional impairment.
"We speculate that the lack of deactivation in the autism group is indicative of abnormal internally directed processes at rest, which may be an important contribution to the social and emotional deficits of autism," the authors conclude.