In a study being published today, researchers in Pittsburgh, New York and Israel have identified problems in the brains of people with autism that could help explain why they engage in repetitive behaviors and have certain learning problems.
The study, in the journal Neuron, shows that adults with autism had erratic responses to basic visual, auditory and touch stimuli while in a brain scanner, compared with people who don't have the disorder.
It was conducted by researchers from Carnegie Mellon University, the University of Pittsburgh, New York University and the Weizmann Institute of Science in Rehovot, Israel.
Marlene Behrmann, a CMU autism expert, said the group wanted to see how high-functioning adults with autism responded to very basic sensory stimuli.
While staring at a fixed point on a computer screen while inside a magnetic resonance imaging machine, the 28 subjects -- half with autism and half without -- were shown a series of dots while the scanner looked at activity in parts of their brain.
The scientists also looked at brain activity in response to a series of beeps as well as puffs of air on the hand.
In people who did not have autism, the responses were generally the same for the different stimuli. In the people with autism, the responses were all over the landscape, she said.
Some autistic individuals had strong reactions to sounds but weak ones to visual stimuli. Others had varied reactions to the same stimulus from one trial to the next.
This "unreliable" brain response to sights, sounds and touch might explain why people with autism are much more likely to have epilepsy than others are, she said. It also could explain the well-known hypersensitivity that many people with autism have to sounds or touch.
Many severely affected children with autism engage in repetitive behaviors like rocking or spinning objects.
David Heeger, a researcher from New York University who participated in the study, said these repeated motions might be one way autistic people deal with their erratic brain responses.
"Imagine you have the experience that your world is completely unreliable -- every time you look at something it looks slightly different or every time you hear something you hear it slightly differently," he said. "One way to deal with that is you might repeat an activity that you can do over and over, and that might be comforting."
In addition, Mr. Heeger said, the tendency of higher functioning autistic people to be attracted to certain subjects and learn lots of details about them could also be an attempt to make their worlds more predictable and less anxiety-provoking.
The importance of the study, Ms. Behrmann said, is that it may be a marker for a general disorganization in the brains of people with autism.
"If you can see changes at the front door [of the brain]," she said, "it's not surprising you would see changes downstream."education - homepage - neigh_city - breaking - science
Mark Roth: firstname.lastname@example.org or 412-263-1130. First Published September 19, 2012 12:15 AM