Researchers have identified a difference in brain activity that may explain why many people with autism struggle to pick up on social cues and to screen out distracting sights, sounds and other sensations.
The difference – a slowness in the brain activation and habituation involved learning patterns – increased with autism severity. Importantly, the findings suggest areas where people with autism may benefit from tailored teaching approaches and other supports.
The findings appear this week in the journal NeuroImage.
The study, conducted by Sarah Schipul and Marcel Just, of Carnegie Mellon University, involved 16 adults affected by autism spectrum disorder (ASD) and 16 adults unaffected by the condition.
A simple task – for some…
The researchers asked the participants to repeatedly view a pattern of dots. With each presentation, the dots varied slightly but the overall pattern remained the same. At the end of the exercise, the participants were asked to correctly identify the pattern, presented alongside a different pattern.
This type of pattern familiarization – which occurs largely beyond conscious awareness – is called implicit learning. Implicit learning is likewise thought to be crucial for learning language and social cues, as well as screening out distracting sights, sounds and other sensations.
The researchers used functional magnetic resonance imaging (fMRI) to track how quickly each participant’s brain became familiar with the dot pattern. They could see this familiarization process as a decrease in active brain responses to the pattern over multiple viewings. This decrease in brain activity, the researchers say, indicates that the brain is learning the pattern and requires less energy to process it on subsequent viewings.
They found that the brains of the control subjects (unaffected by autism) adapted more quickly when they repeatedly saw the pattern. With each subsequent exposure, their brains responded less and less – indicating that the pattern had been learned and become “old news.”
"This finding provides a tentative explanation for why people with ASD might have difficulty with everyday social interactions,” Dr. Just says. Social rules and cues – like background patterns – tend to be learned implicitly, or without conscious awareness, he explains.
So the study’s findings support the idea that many people with autism need extra support and coaching to consciously learn social rules and responses.
Brain adaptation and autism severity
What’s more, the results showed that the slowness in brain adaptation increased with the severity of the participant’s autism symptoms.
"Seeing that individuals with more atypical neural responses also had more severe ASD symptoms suggests that these neural characteristics underlie or contribute to the core symptoms of ASD," Just says. "For example, the ability to learn implicit social clues may be affected in ASD, leading to impaired social processing."
Decreased brain synchronization
A second finding of the study involved brain synchronization – that is, how well brain activity coordinated across different regions of the brain while the study volunteers learned the dot pattern.
The researchers had specifically designed the implicit learning exercise to engage both the frontal and posterior regions of the brain. But the brain scans showed that brain synchronization between these regions was significantly lower in the participants who had autism.
"This alteration of brain synchronization,” Just explains, may lead to symptoms of the disorder that involve processes that require brain coordination between frontal and other areas, such as language processing and social interaction.”
By increasing understanding of the brain differences behind autism symptoms, such research may guide the development of tailored teaching methods that help those with autism master skills that most people learn unconsciously.
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