A specific type of neuron in the amygdala performs differently in individuals with autism spectrum disorder than in those without the disorder, according to a new study by researchers at Cedars-Sinai Medical Center in New York.
“The amygdala — which is critical for face recognition and processing of emotions — is thought to be one of the principal areas where dysfunction occurs, but this is the first time single neurons in the structure have been recorded and analyzed in patients with autism,” said first author Ueli Rutishauser, Ph.D., assistant professor of neurosurgery and director of Human Neurophysiology Research at Cedars-Sinai.
For the study, researchers recorded the firing activity of individual nerve cells in the amygdalae of two patients with high-functioning autism as they viewed pictures of faces expressing emotion, either fear or happiness. The patients were asked to look at the pictures and report which emotion they saw.
The researchers then compared the recordings of neurons in participants with autism to those without the disorder, which led to the discovery that a specific type of neuron performed abnormally in those with autism.
In the amygdala, which is known for its role in emotional memory, certain neurons fire when a person looks at a whole face; other types respond when viewing parts of a face or certain facial features, such as an eye or mouth. In the two patients with autism, “whole-face” neurons responded typically, but the “face-part” neurons were much more active when the patients were shown the mouth region compared to when they were shown the eyes.
“A subpopulation of neurons in these patients with autism spectrum disorder showed abnormal sensitivity to the mouth region. The amygdala neurons appeared normal from an electrical point of view, and the whole-face-sensitive neurons responded normally. Thus, the subset of face-part-sensitive neurons was specifically abnormal in autism,” Rutishauser said.
Senior author Ralph Adolphs, Ph.D., Bren Professor of Psychology and Neuroscience at Caltech, said the research offers new insights into mechanisms underlying the symptoms of autism and opens the door for further studies.
“Are there genetic mutations that lead to changes in this one population of neurons? Do the cell abnormalities originate in the amygdala or are they the result of processing abnormalities elsewhere in the brain? There are many questions yet to be answered, but this study points us in a specific direction that we believe will help understand autism,” he said.
The study is published in the journal Neuron.
Source: Cedars-Sinai Medical Center