SEATTLE, WA--Individuals with autism have been shown to have a difficult time recognizing faces, but two University of Washington researchers now suggest that the problem may be due to a lack of practice, rather than to abnormal functioning of the affected region of the brain.
Previous research, using an electroencephalogram (EEG) to measure brain activity, had shown that autistic 3- and 4-year-olds failed to show normal brain response when viewing their mother's picture. However, a recent study released at the AAAS (Triple-A-S) Annual Meeting indicates that with time, a mother's image does activate the part of the temporal lobe implicated in face recognition, even when an unfamiliar face does not. AAAS is the American Association for the Advancement of Science.
"These results suggest that lack of normal activation of the fusiform gyrus in persons with autism may be due to their lack of familiarity and experience with faces rather than an inherent problem with the fusiform," said Geraldine Dawson, who directs the University of Washington Autism Center and who was among the first researchers to suggest that an impairment in face recognition might be one of the earliest signs of autism.
The researchers are seeking to understand the nature of brain dysfunction in autism, focusing specifically on brain regions involved in face processing. The MRIs allow them to examine patterns of brain activity while the subjects process information from faces. The project also examines whether interventions can be used to effectively train dysfunctional brain regions to better process information from the face.
The current study compared activation of the fusiform gyrus (the face area) and inferior temporal gyrus (a part of the brain that recognizes objects not faces) in 11 high-functioning adolescents and adults with autism and 10 matched controls, recording the way the brains of each individual responded when viewing faces and when viewing cars.
"As previously demonstrated, the brain area activated by unfamiliar faces in the individuals with autism was the same as the area that is normally used during visual processing of objects," said Elizabeth Aylward, UW professor of radiology and co-director of the UW Autism Research Team. "However, the fusiform was activated in response to the mother's face."
In earlier work, Dawson had established that children with autism had problems with face recognition, when compared with normally developing children and children with developmental delay. She and Aylward note that the ability to recognize faces may be similar to the ability to comprehend language.
"In the beginning babies can distinguish between all types of language sounds," said Aylward. "But language processing later becomes fine tuned to the sounds of the child's own language. Similarly, in normal children, the area of the brain involved in face processing may require fine tuning in order for it to respond specifically to human faces."
Aylward and Dawson wondered whether this particular area of the brain was developmentally "broken," or did it fail to activate in response to faces because it has not had sufficient experience? And would more exposure (or more directed exposure) to faces lead to normal patterns of brain activation? If the latter were the case, the researchers hypothesized that a face with which the child has had the most experience, usually that of a parent, would be the face most likely to result in normal activation of the fusiform.
Dawson is working with another University of Washington researcher, Gerard D. Schellenberg, Research Professor of Medicine and Neurology Adjunct Research Professor of Pharmacology, on an ongoing study of families with siblings diagnosed with autism. With 300 families signed up, the UW multiplex family study, which Schellenberg will describe at the AAAS meeting, is one the largest worldwide efforts aimed at identifying the location of autism genes. The researchers believe that there are at least five genes that come together to make a person vulnerable to the disorder.
"There is strong evidence that inheritance is a major player in autism," said Schellenberg. "We are using autism as a trait and trying to do a genetic map that will help us to understand whether the deletions we see in autism are affecting genes and causing autism, or whether the genome in autism is unstable, and the deletions are a symptom of that instability."
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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