A new MRI study of autistic kids has discovered unique patterns of neural communication in the area of the brain involved in processing social information.
After studying MRI scans of school-age children’s brains, researchers at San Diego State University discovered that in children with autism, the mid-brain structure called the amygdala only weakly connects with some regions of the brain — and more strongly with others — when compared with typically developing children of the same age.
A region of the brain showing marked differences connecting with the amygdala was the occipital cortex, located in the rear of the brain. It is involved in encoding facial expressions, gaze, and other facial cues, said SDSU psychologist Dr. Inna Fishman, who led research.
The findings point to possible brain “markers” for autism spectrum disorders to further characterize the condition in biological and not just behavioral terms, according to Fishman.
She said these markers could potentially become a tool in identifying autism in children.
“The patterns of amygdala connections are very unique in autism,” said Fishman. “What we found is not necessarily something I would predict. We measured connections of the amygdala with the entire brain, and the findings with the visual cortex kind of surprised me.”
The study’s findings were based on brain imaging from 55 children, between the ages of 7 and 17, identified with autism spectrum disorder (ASD) and then compared with 55 typically developing children of the same age.
The functional MRI used in the research measures how brain activity changes over time — in this case, a period of six minutes, the researchers explain. It provides a picture of ongoing communication between different brain regions, known as “functional connectivity,” showing how synchronized the amygdala’s activity is with other brain areas.
The MRIs revealed weaker connections between the amygdala and the occipital cortex, according to Fishman. The MRIs also showed that the expected strengthening of connections between the amygdala and the frontal cortex that takes place during adolescence in typically developing youth was entirely absent in the autistic children.
This absence of a continuing brain maturation associated with typical adolescence could contribute to the social communication difficulties experienced by those with ASD as they reach their teenage years and young adulthood, Fishman said.
Fishman added there may be some form of disrupted coordination between the amygdala and other points in the brain, though it’s not yet possible to say whether this causes any of the differences in social functioning seen in children with ASD.
That is partly because of the age of the children in the study.
“Having scanned kids who are 10, 12 or 14 years old, and having found differences at this age doesn’t allow us to make inferences about what might have caused these differences to emerge in the first place,” she said. “By that point, the connections in the brain are formed and already quite established.”
Fishman is now studying brain connectivity and organization in toddlers and preschoolers with ASD, when their autism symptoms first manifest. She said she hopes to learn more about whether the early behaviors seen in children with ASD lead to the atypical connection patters or the other way around.
Overall, understanding the biology behind ASDs “brings us closer, incrementally” to improved clinical decisions concerning diagnosis or prognosis of autism, and possibly to more targeted, tailored interventions focusing on specific brain circuits based on the level of unique brain connections identified in the brain, Fishman said.
The study was published in the Journal of the American Academy of Child & Adolescent Psychiatry.
Source: San Diego State University
Photo: Sarah Reynolds, a research coordinator on Dr. Inna Fishman’s team at San Diego State University, and a participant reviewed the child’s brain images after the scan. Sarah Reynolds, a research coordinator on Dr. Inna Fishman’s team, and a participant reviewed the child’s brain images after the scan. Credit: San Diego State University Center for Autism.