Research may unlock mystery of autism's origin in the brain

August 22, 2007

In the first study of its kind, researchers have discovered that in autistic individuals, connections between brain cells may be deficient within single regions, and not just between regions, as was previously believed.

Tony Wilson, Ph.D., lead researcher and assistant professor of neurology at Wake Forest University School of Medicine, said he hopes this study will eventually lead to earlier diagnosis and more targeted medications for autism.

Using magnetoencephalography (MEG) brain imaging technology to measure brain electrical activity, the researchers administered a test called the 40 hertz (cycles per second) auditory steady-state response test. The test measures electromagnetic wave cycles and indicates brain cell discharges at the 40 hertz frequency.

“This test measures the brain’s capacity to mimic what it’s hearing. A healthy brain’s cells will fire back at 40 hertz,” said Wilson. “We chose this test because it is a robust metric of how well individual circuits are functioning.”

The results were reported in this month’s issue of Biological Psychiatry.

A group of 10 children and adolescents with autism, and 10 without autism, listened to a series of clicks occurring every 25 milliseconds (ms) for a duration of 500 ms. The MEG measured the brain’s responses to these clicks.

In the right hemisphere of the brain, which controls attention and spatial processing, there was no significant difference in the groups. But the results showed a considerable discrepancy between the two groups in the left hemisphere, the area of the brain that controls language and logic.

In the auditory area of the left hemisphere, the group without autism delivered a brain response to the 40 hertz stimulation 200 ms after it began. However, the group with autism failed to respond entirely at the same 40 hertz frequency.

“Our results made sense. Both anecdotal and behavioral evidence suggest children with autism have significantly disturbed brain circuits on the local-level within an individual brain area,” said Wilson. “For example, they tend to restrict their visual gaze to a part of someone’s face, like a nose or an eye, but not the person’s whole face.”

The results also support previous research that showed disconnections between two or more brain regions, known as long-range connectivity. This new study supports the idea that the network as a whole is broken, but shows the disconnection in long-range connectivity may actually start within individual brain regions, known as local connectivity.

Wilson explains the difference between local and long-range connectivity using vision as an example. “With vision, one part of your brain identifies color, another perceives motion. Within each of these areas of your brain, there is local connectivity between brain cells that allow the region to do its job. When you see a red ball flying across the room, both of these areas of your brain start communicating with each other and put together flying and red as qualities of the same ball. That’s long-range connectivity.”

Wilson conducted the autism research while at the University of Colorado, but says he hopes to continue his autism research at Wake Forest.

“I chose Wake Forest because it has one of the most advanced MEGs in the country. Here, we can study the brain at a very precise level,” said Wilson.

Source: Wake Forest University

Explore further: How to manipulate the brain to control maternal behavior in females and reduce aggression in males

Related Stories

Children with autism more likely to have handwriting problems

November 9, 2009

Children with autism may have lower quality handwriting and trouble forming letters compared to children without autism, according to a study published in the November 10, 2009, print issue of Neurology, the medical journal ...

Brain imaging may help diagnose autism

January 8, 2010

Children with autism spectrum disorders (ASDs) process sound and language a fraction of a second slower than children without ASDs, and measuring magnetic signals that mark this delay may become a standardized way to diagnose ...

Children with autism show slower pupil responses, study finds

November 10, 2009

Autism affects 1 in 150 children today, making it more common than childhood cancer, juvenile diabetes and pediatric AIDS combined. Despite its widespread effect, autism is not well understood and there are no objective medical ...

Scientists crack brain's codes for noun meanings

January 13, 2010

Two hundred years ago, archaeologists used the Rosetta Stone to understand the ancient Egyptian scrolls. Now, a team of Carnegie Mellon University scientists has discovered the beginnings of a neural Rosetta Stone. By combining ...

Recommended for you

How the finch changes its tune

August 3, 2015

Like top musicians, songbirds train from a young age to weed out errors and trim variability from their songs, ultimately becoming consistent and reliable performers. But as with human musicians, even the best are not machines. ...

Machine Translates Thoughts into Speech in Real Time

December 21, 2009

( -- By implanting an electrode into the brain of a person with locked-in syndrome, scientists have demonstrated how to wirelessly transmit neural signals to a speech synthesizer. The "thought-to-speech" process ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.