Atypical Brain Functioning in Siblings of Autistics


Relative to the other groups, there was reduced activity in specific brain regions in children with ASD when they were watching biological motion compared with scrambled motion.

These included the right amygdala and the ventromedial prefrontal cortex, areas which other research has identified as having changed activity in adults with ASD.

The researchers found additional brain regions that showed reduced activity in both the siblings group and the ASD group, relative to the typically developing group.

They interpreted this result as a reflection of the underlying genetic vulnerability that the siblings group might have to ASD.

The scientists also found what they called “compensatory activity” in the siblings group – brain regions that were working harder than normal and might be helping the children overcome their increased genetic risk of ASD.

These included the right posterior temporal sulcus and the ventromedial prefrontal cortex, which have been implicated in social perception and social cognition. [...]

“More controversially, the authors also propose that other brain regions are under-responsive to biological motion in siblings of children with autism, as well as in those with autism.”

“Yet other regions are reported to be overactive in the siblings, and this is interpreted as compensatory activity.
“Since these siblings had no subclinical symptoms of autism, and were selected to have no other relatives with any autistic features, they are unlikely to constitute a group with strong genetic risk for autism, and so this aspect of the results is puzzling and it would be important to replicate it in another sample.” (via.)

It’s interesting that while autistics show below normal activation in the ventromedial prefrontal cortex, that their siblings showed above normal activation in the same region while viewing “biological motion.”

It’ll be interesting to see what mysteries of the human mind will be revealed as the diagnostic criteria for what exactly defines the autistic spectrum becomes more refined. Supposedly these autistic children didn’t have any other relatives showing symptoms of autism, however, wouldn’t it be interesting to find out whether their relatives show this same abnormal overactivation in said regions.