Autism and the brain

Kennedy Krieger Institute’s Center for Autism and Related Disorders (CARD) hosts an annual continuing education conference to foster understanding of autism spectrum disorders and to provide information about strategies aimed at promoting learning in young children with autism spectrum disorders.  Brainjogging’s founder, Shirley Pennebaker, M.Ed.; cognitive therapist Katie Cyphers, M.A.; and Columbus Learning Center Director Sellers Cook will attend this year’s conference October 28-29, 2010.  In honor of this, Brainjogging’s blog posts this week will be devoted entirely to autism.

In the 1980s, researchers examined the entire brain of a man with autism.  This individual died at age 29.  His brain was sliced into thousands of thin sections and then examined. The brain from a typical man, or one without autism, who died at age 25 was similarly examined as a control brain.

Harvard University’s Dr. Margaret Bauman participated in the research group.  She reported that one main “difference was in the amygdalae, two almond-shaped clumps of cells deep in the brain, one on each side” (NPR).    The amygdalae are vital in processing certain emotional responses, especially fear.  Bauman also pointed out that the brain cells in the amygdala from the autistic brain were “smaller and more densely packed,” indicating that they were underdeveloped (NPR).

In 2006, scientists examined nine brains from people with autism and ten brains from typical people.  The individuals to whom the brains belonged ranged in age from 10-44.

The MIND Institute’s Dr. Amaral stated that brains of people with autism were clearly different in that they had “a decreased number of neurons in the amygdala, and then particularly in one subdivision of it called the lateral nucleus” (NPR).  The lateral nucleus communicates with a part of the brain that controls perception, which might explain why people with autism tend to process information by relying heavily on their own internal sense of body position, rather than visual cues.

Additionally, an underdeveloped amygdala might explain the tendency of an individual with autism to exhibit anxiety; his or her amygdala doesn’t properly regulate fear. Interestingly, “in boys with autism, the amygdala develops early and stops growing around the age of eight, [but] in typical boys, the amygdala continues to grow until age 18” (NPR).

Dr. Amaral says early development in the amygdala accounts for the reduced number of neurons later: while typical brains have about 12 million neurons, brains from individuals with autism average about 11 million.

*Listen to NPR’s podcast of Jon Hamilton’s “New Autism Study Shows Discrepancy in Autistic Brains.”

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