Autistic brain never 'rests'

By Megan Rauscher

NEW YORK (Reuters Health) - The typical brain activity that occurs when most people are resting or daydreaming is impaired or absent in individuals with autism, new research suggests.

The activity in this so-called "resting network" normally aids in the processing of emotional and social cues, "the very things that are abnormal in autism," lead investigator Daniel P. Kennedy noted in comments to Reuters Health.

The resting network is known to be highly active when an individual is at rest.

When someone is asked to perform a mentally demanding task that is not of a social or emotional nature -- like a math problem -- the resting network shuts down or is deactivated, "most likely reflecting a reduction in these unconstrained resting thoughts," explained Kennedy, a graduate student in the neuroscience PhD program at the University of California at San Diego in La Jolla.

Kennedy, along with Elizabeth Redcay, a UCSD graduate student in psychology, and Eric Courchesne, also at UCSD, report their findings in the Proceedings of the National Academy of Sciences, Early Edition.

Through brain imaging, Kennedy and his colleagues saw that the resting network of the autistic brain does not deactivate, likely because this high resting activity is not there during rest.

"We think that this finding makes sense in terms of understanding the social and emotional aspects of the disorder," Kennedy said. "We found that a network of brain regions important for social and emotional processing is abnormal in a disorder of social and emotional processing," he said.

The scientists also observed that the more abnormal the resting brain activity in the medial prefrontal cortex appeared, the more socially impaired the autistic subject was. Therefore, "it does seem that there is a clear relationship between this resting network and social impairment in autism," Kennedy said.

source: http://today.reuters.co.uk/news/newsArticle.aspx?type=healthNews&storyID=2006-05-12T162655Z_01_COL259177_RTRIDST_0_HEALTH-AUTISTIC-BRAIN-DC.XML