The brains of males with autism contain unusually few neurons in the amygdala, an inner-brain structure involved in emotion and memory, a new study finds.
Although previous research had suggested that wayward amygdala development contributes to autism, the new investigation shows for the first time that the disorder features low numbers of neurons in that part of the brain, say neuroscientists Cynthia M. Schumann of the University of California, San Diego and David Amaral of the University of California, Davis.
Schumann and Amaral used a computer-aided microscopic device to count neurons from representative sections of the amygdala in the preserved brains of 9 males who had been diagnosed with autism and of 10 males who had no psychiatric or developmental disorders. The individuals ranged in age from 10 to 44. In both groups, brains were obtained within 2 days after death.
Autism, which usually becomes apparent by around age 3, interferes with a person's ability t