Impaired social function is a cardinal symptom of autism spectrum disorders (ASDs). One of the brain circuits that enable us to relate to other people is the “mirror neuron” system. This brain circuit is activated when we watch other people, and allows our brains to represent the actions of others, influencing our ability to learn new tasks and to understand the intentions and experiences of other people.

This mirror neuron system is impaired in individuals with ASD and better understanding the neurobiology of this system could help in the development of new treatments.

In their new study, Dr. Peter Enticott at Monash University and his colleagues used transcranial magnetic stimulation to stimulate the brains of individuals with ASD and healthy individuals while they observed different hand gestures. This allowed the researchers to measure the activity of each individual’s mirror neuron system with millisecond precision in response to each observed action.

They found that the individuals with ASD showed a blunted brain response to stimulation of the motor cortex when viewing a transitive hand gesture. In other words, the mirror neuron system in the ASD individuals became less activated when watching the gestures, compared to the healthy group. In addition, among people with ASD, less mirror neuron activity was associated with greater social impairments. This finding adds to the evidence that deficits in mirror neuron system functioning contribute to the social deficits in ASD.

This finding also directly links a specific type of brain dysfunction in people with autism spectrum disorder to a specific symptom. This is important because “we do not have a substantial understanding of the brain basis of autism spectrum disorder, or a validated biomedical treatment for the disorder,” said Dr. Enticott. “If we can develop a substantial understanding of the biology of specific symptoms, this will allow us to develop treatments targeted specifically to the symptoms.”

“This study is an example of the effort to break down the component problems associated with autism spectrum disorder and to map these problems on to particular brain circuits,” commented Dr. John Krystal, editor of Biological Psychiatry.

Enticott added, “We are currently investigating whether non-invasive brain stimulation can be used to improve mirror neuron activity in autism spectrum disorder, which would have substantial potential therapeutic implications.”

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The article is “Mirror Neuron Activity Associated with Social Impairments but not Age in Autism Spectrum Disorder” by Peter G. Enticott, Hayley A. Kennedy, Nicole J. Rinehart, Bruce J. Tonge, John L. Bradshaw, John R. Taffe, Zafiris J. Daskalakis, and Paul B. Fitzgerald (doi: 10.1016/j.biopsych.2011.09.001). The article appears in Biological Psychiatry, Volume 71, Issue 5 (March 1, 2012), published by Elsevier.

Notes for editors
Full text of the article is available to credentialed journalists upon request; contact Rhiannon Bugno at +1 214 648 0880 or .(JavaScript must be enabled to view this email address). Journalists wishing to interview the authors may contact Peter Enticott at +61 3 9076 6594 or .(JavaScript must be enabled to view this email address).

The authors’ affiliations, and disclosures of financial and conflicts of interests are available in the article.

John H. Krystal, M.D., is Chairman of the Department of Psychiatry at the Yale University School of Medicine and a research psychiatrist at the VA Connecticut Healthcare System. His disclosures of financial and conflicts of interests are available here.

About Biological Psychiatry
Biological Psychiatry is the official journal of the Society of Biological Psychiatry, whose purpose is to promote excellence in scientific research and education in fields that investigate the nature, causes, mechanisms and treatments of disorders of thought, emotion, or behavior. In accord with this mission, this peer-reviewed, rapid-publication, international journal publishes both basic and clinical contributions from all disciplines and research areas relevant to the pathophysiology and treatment of major psychiatric disorders.

The journal publishes novel results of original research which represent an important new lead or significant impact on the field, particularly those addressing genetic and environmental risk factors, neural circuitry and neurochemistry, and important new therapeutic approaches. Reviews and commentaries that focus on topics of current research and interest are also encouraged.

Biological Psychiatry is one of the most selective and highly cited journals in the field of psychiatric neuroscience. It is ranked 4th out of 126 Psychiatry titles and 15th out of 237 Neurosciences titles in the Journal Citations Reports® published by Thomson Reuters. The 2010 Impact Factor for Biological Psychiatry is 8.674.

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Rhiannon Bugno
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214-648-0880
Elsevier