A new study has found that areas of the brain that are linked to social behaviors are both underdeveloped and not networked enough in young people with high functioning autism spectrum disorder (ASD). The study may help show how the brains of children and adolescents with ASD may be organized differently than those without the disorder.
The brains of people with ASD are enlarged and have more than usual neurons. This is apparently because with ASD, the brain does not get rid of or "prune" synapses, a function that happens with other people's brains. To supply these extra neurons, ASD brains have extra blood flow to the frontal areas of the brain, which are the areas related to understanding social situations.
A team of researchers at the University of California, Los Angeles, hypothesized that ASD might be caused by increased or decreased connectivity within neural networks that form this social area of the brain. To test this, they used a new magnetic resonance imaging (MRI) technology called as arterial spin labeling perfusion. This technique tracks both brain blood flow and the organization and strength of connections within intrinsic neural networks. Arterial spin labeling perfusion has been used in other mental health disorders, including schizophrenia.
The researchers studied 17 young people between ages 7 and 17 who had high-functioning ASD and 22 typically developing young people. The groups were matched by age, gender, and IQ scores. The MRI revealed significant differences between the two groups. In children with ASD, a pattern of widespread increased blood flow was seen in frontal brain areas. They also had a reduction in connectivity between nodes located in the front and back of the brain, compared with typical brains. The findings support previous findings of both hyperperfusion and impairment in the default mode network in people with ASD.
ASD describes a range of related conditions that cause people to struggle with social communication; they may also have restricted areas of interest, and display repetitive behaviors, and be over-responsive to sensory experiences.
The study was published in the journal Brain and Behavior.