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Brain scans reveal autism's signature

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Using fMRI, researchers have identified a pattern of brain activity that characterizes a child's genetic vulnerability for developing autism.

Using fMRI, researchers have identified a pattern of brain activity that characterizes a child's genetic vulnerability to developing autism spectrum disorder (ASD). This discovery could lead to earlier diagnoses.

ASD is a strongly genetic condition that affects brain development and is characterized by certain social impairments. It can disrupt the brain’s ability to perceive other people’s movements and emotions.

Researchers from the Child Study Center at Yale School of Medicine examined the functional magnetic resonance imaging of three categories of children – autistic children, unaffected siblings of autistic children, and ‘typically developing’ children – as they watched videos of a man moving around.

They found patterns of brain activity that were unique to the children with autism.

They also found similar reduced brain activity in autistic children and their siblings who showed no behavioral traits of ASD – suggesting an underlying genetic risk for developing autism. But more controversially, they found that certain brain regions of unaffected siblings are overactive, possibly compensating for their genetic risk.

“This study may contribute to a better understanding of the brain basis of ASD, and the genetic and molecular origin of the disorder,” said study author Martha Kaiser. According to the researchers, the simplest and potentially most powerful signature of autism will be found at the level of brain systems. The study was published yesterday in Proceedings of the National Academy of Sciences.

Pat-a-cake and compensation

Sixty-two children between the ages of 4 and 17 were shown about five minutes of movie clips while their brains were scanned. The silent movies were of an adult male actor performing childhood experiences, like pat-a-cake. The videos were created using a method called point-light display, where lights were placed on the major joints of the man who was then filmed in the dark. The clips they watched alternated between coherent motion and scrambled versions of the movements.

When comparing brain scans during the coherent versus scrambled motions, the fMRI revealed three distinct kinds of brain activity, or neural signatures:

1. State activity – reduced activity found only in children with autism. This signifies active ASD.

2. Trait activity – reduced activity found in both children with autism and unaffected siblings. This signifies an underlying genetic susceptibility to ASD.

3. Compensatory activity – enhanced activity found only in unaffected siblings. This may signify some kind of mechanism that allowed these children to compensate for and actually overcome their genetic predisposition for ASD.

“We were able to still find something unique about being an unaffected sibling,” said lead author Kevin Pelphrey. This study could explain how some children who are genetically predisposed do not develop the clinical behaviors of autism, and it could lead to targeted treatments.

“It may be that training up social-perception abilities, and focusing on the compensatory regions could improve social perception and cognition in children with autism,” Kaiser added.

Image: Yale Office of Public Affairs

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Janet Fang

Contributing Editor

Janet Fang has written for Nature, Discover and the Point Reyes Light. She is currently a lab technician at Lamont-Doherty Earth Observatory. She holds degrees from the University of California, Berkeley and Columbia University. She is based in New York. Follow her on Twitter. Disclosure