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Atypical Brain Connectivity Seen in Autism Spectrum Disorder
Medscape Psychiatry & Mental Health
April 28, 2014

NEW YORK (Reuters Health) - Autism spectrum disorder (ASD) is associated with increased functional connectivity between two brain networks, according to a study using functional MRI.

"Children and adolescents with ASD are equipped with different brains, which can be characterized as noisier, less efficient, and less mature," said Dr. Inna Fishman from San Diego State University in California, who led the research.

"These findings specifically demonstrate that the neural circuitry subserving understanding of others has aberrant patterns of connections, which explains, at least partially, their social deficits," she told Reuters Health by email.

The theory of mind (ToM) and mirror neuron system (MNS) networks of the brain are putatively impaired in ASD and involved in social processing, Dr. Fishman and colleagues note in JAMA Psychiatry, online April 16.

The team used resting-state functional MRI to assess connectivity between these two brain networks in 25 adolescents with ASD and 25 typically developing adolescents matched for age, handedness, and nonverbal IQ.

Compared with typically developing adolescents, adolescents with ASD showed a mixed pattern of both over- and underconnectivity in the ToM network, and this pattern was associated with greater social impairment.

Similarly, greater connectivity in the MNS network was associated with more social symptoms of ASD, although ASD patients as a group did not show significant differences in MNS connectivity from typically developing adolescents.

Greater connectivity between the ToM and MNS networks was also associated with more severe social impairment.

"While suggesting links between ToM and MNS connectivity and social impairment in ASD, our findings cannot establish causality," the researchers caution. "Atypical functional connectivity of these networks could reflect neurobiological abnormalities contributing to the emergence of social impairment. However, alternatively, abnormal social development in children with ASD may result in aberrant connectivity."

"We are currently testing whether this phenomenon can be detected in younger children as well," Dr. Fishman said. "This should allow us to draw conclusions about the developmental trajectory of these atypical connectivity patterns thus far observed in adolescents with ASD."

"Early interventions have a real impact in this population, so we are hopeful that interventions such as neurofeedback training, targeted directly at those networks, could make a real difference in the organization of these so-called social brain networks," she concluded.

Dr. Robert Coben from Neurorehabilitation and Neuropsychological Services in Massapequa Park, New York, said it is already well-known that social problems in autism are caused by differences in brain connectivity.

"By understanding this it is now possible to deploy interventions that have the ability to augment and enhance connectivity patterns in an individual," said Dr. Coben, who was not involved in the new study. "Such techniques are often referred to as neuromodulation and may include techniques such as rTMS (repetitive transcranial magnetic stimulation) and a technique called neurofeedback. Our research has shown the effectiveness of this approach with our first data to support this being published in 2007."

SOURCE: JAMA Psychiatry 2014 | Atypical Cross Talk Between Mentalizing and Mirror Neuron Networks in Autism Spectrum Disorder
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