Monday, October 23, 2006

The Mirror Theory of Autism

Scientific American's November cover story, "Broken Mirrors: A Theory of Autism," explains ongoing research into the social impairment demonstrated by children with autism spectrum disorders. The article, by researchers from the University of California, San Diego, is a science paper written for laypeople. Spending half an hour reading it gives you a decent grounding in a couple of areas of autism-related medical studies.

Researchers have been using different types of brain scans to explore why people with autism don't learn how to imitate others' movements, or mimic others' behaviors the way typically developing people do. Studies have shown that certain neurons in the brain fire when a person makes a voluntary movement, and that so-called "mirror neurons" also fire in similar ways in response to observed stimuli. For example, the researchers write of typically developing people studied, "investigators found that certain neurons that typically fire in response to pain also fired when the person saw someone else in pain." People with autism, however, do not show this kind of neurological response, the researchers write. (There's good background information on mirror neurons at the PBS show NOVA which you can find here.)

The Scientific American authors, Vilayanur S. Ramachandran and Lindsay M. Oberman, write that more work needs to be done, both in understanding what's going on and figuring out if there are medical treatments possible. "Scientists do not yet know which genetic and environmental risk factors can prevent the development of mirror neurons or alter their function, but many research groups are actively pursuing the hypothesis because it predicts symptoms unique to autism." (They say one drug candidate for study is the methamphetamine "ecstasy.")

The article also touches on research into another aspect of autism, the tendency of people to be overwhelmed by their surroundings and appear to seek solace in self-stimulatory behaviors. The authors say they are looking into the brain region called the amygdala "which acts as a portal to the emotion-regulating limbic system." Studying children's' responses to stimuli leads to the authors to suggest kids with autism have a distorted view of the sensory landscape around them. Self-stimulating activities, like repetitive motions, have a calming effect on the kids. As with mirror neurons, research continues into the causes and potential treatments.

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