Social Brain Is Functionally Impaired in Autism Spectrum Disorder

A novel imaging study shows that brain areas linked to social behavior are both underdeveloped and insufficiently networked in youths with high functioning autism spectrum disorder (ASD).

Researchers the University of California Los Angeles (UCLA; USA) conducted a study to investigate the neurobiological underpinnings of ASD. To do so, they used functional magnetic resonance imaging (fMRI) to assess resting cerebral blood flow (CBF) and functional connectivity (FC) of intrinsic brain networks in 17 youth with ASD and 22 matched typically developing children. The groups were matched by age (7 to 17 years old), gender, and IQ scores.

The researchers utilized a novel MRI tool known as pseudo-continuous arterial spin labeling (ASL) perfusion with background suppression to magnetically label the water content of blood so that it could serve as a tracer to quantify brain blood flow. The researchers also refined for the study an existing technology that assesses how well separate brain areas are functionally interconnected. Both techniques are noninvasive, requiring no injections of radioactive tracers.

The results showed a pattern of altered resting perfusion in ASD children, including frontotemporal hyperperfusion and hypoperfusion in the dorsal anterior cingulate cortex. They also found increased local FC in the anterior module of the default mode network (DMN), accompanied by decreased CBF in the same area. Reduced long-range FC between anterior and posterior modules of the DMN in children with ASD was also demonstrated. These were associated with greater social impairments, as assessed with the social responsiveness scale (SRS) score. The study was published in the September 2015 online issue of Brain and Behavior.

“The brain controls most of our behavior, and changes in how brain areas work and communicate with each other can alter this behavior and lead to impairments associated with mental disorders,” said Kay Jann, PhD, a postdoctoral researcher in the UCLA department of neurology. “When you match physiologic changes in the brain with behavioral impairment, you can start to understand the biological mechanisms of this disorder, which may help improve diagnosis, and, in time, treatment.”

“ASD might be caused by increased or decreased connectivity within specific neural networks that form the ‘social brain.’ This connectivity can be measured by the amount of blood flow and activity patterns between brain nodes, or neural networks,” added senior author associate Prof. Danny J. J. Wang, PhD. “One major brain network, the DMN, has become a focus of such research, because it is important for social and emotional processes, self-referential thought, and in 'Theory of Mind,' which is the ability to attribute mental states to one-self and to others.”

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