Disrupted Brain Circuits in Autism Spectrum Disorder
Autism Spectrum Disorder is a complex developmental brain disorder that affects an individualís ability to communicate and interact with others socially. In a recent study, conducted at the National Institute of Mental Health, scientists have identified a circuit in the brain which plays a key role in social processing and which is disrupted in autistic individuals.
Hamidi: We often take our ability to understand a subtle joke, to pick up on sarcasm and to relate to others socially for granted. Individuals who are affected by autism are unable to process these social cues. Recent findings have uncovered some key brain areas that may be essential in processing this social information and which are disrupted in autistic individuals.
Dr. Martin: What's been termed the "social brain" has been based on about 20 years of research.
Hamidi: Dr. Alex Martin is a senior investigator at the National Institute of Mental Health and the chief on the Section of Cognitive Neuropsychology in the Laboratory of Brain and Cognition.
Dr. Martin: And these areas all seem to work together as a circuit to allow us kind of to negotiate our social world and it's that circuitry that seems to be most dysfunctional, certainly in our so-called high-functioning individuals on the autism spectrum.
Hamidi: Different people with autism can have very different symptoms. Health care providers think of autism as a "spectrum" disorder, a group of disorders with similar features. One person may have mild symptoms, while another may have serious symptoms. Dr. Martin says, the high-functioning individuals are still able to use these brain circuits to process non-social information. The deficits, he explains, are restricted to the ability to process social information.
Dr. Martin: What we've been finding with our research is that this particular group of individuals have certain types of deficits in the domain of social processing, that has to do with the way they orient to the social world and their ability to kind of understand what’s going on socially and it's really restricted to kind of social interactions as opposed to interactions with other kinds of objects.
Hamidi: Although only individuals on the high-functioning end of the autism spectrum were selected for the study, the results from the brain scans can still give some information about what brain circuits might be affected across the autism spectrum. Dr. Martin explains.
Dr. Martin: So, with our high-functioning individuals we take advantage of analyses where we just record data when people are simply resting in the scanner not really doing anything but lying there and we've been able to show—we could pick out the dysfunctional network by comparing what are these "resting-state scans" in these individuals and compare them to their control group.
Hamidi: Dr. Martin continues that the results of these studies, not only provide insight into what circuits are dysfunctional in high-functioning autistic individuals, but may provide some clues about which brain areas may be affected in all autistic individuals.
Dr. Martin: So in other words, these analyses suggest that one might be able to detect abnormalities in specific circuits in the brain in individuals that would normally be way too impaired to perform our task.
Hamidi: Dr. Martin spoke recently at the Clinical Center Grand Rounds lecture. To hear his presentation, titled "Cognition and Brain Functional Connectivity in Autism" visit the Clinical Center website: clinicalcenter.nih.gov. For more information regarding this study and autism research, visit www.nimh.nih.gov. This is Anahita Hamidi, National Institutes of Health, Bethesda, Maryland.