The brains of people with autism spectrum disorder (ASD) show significant differences in their learning abilities, say scientists Carnegie Mellon University. The research study was announced on Nov. 20, 2015, and was published in the journal Neuroimage.
Researchers analyzed how the brains of autistic and non-autistic people gradually learn to adapt to visual patterns without being aware of the pattern, a process which is also known as implicit learning. Magnetic resonance (fMRI) imaging was used to monitor brain activation. Participants with autism were slower than their typical peers to become familiar with the pattern that they saw repeatedly. This indicates that the brains of the autistic participants did not register the “oldness” of the patterns to the same level as those of the control participants.
The control group demonstrated that they had adapted to the patterns being learned by decreasing their brain activation levels. The decreases shown by the autistic participants were significantly less than the control group. The researchers found an association between the autistic person’s degree of adaptation to the patterns and the severity of their autism symptoms. These findings may provide insight into why autistic people struggle with implicit learning situations such as the ability to interpret facial expressions.
“This finding provides a tentative explanation for why people with ASD might have difficulty with everyday social interactions, if their learning of implicit social cues has been altered,” said Marcel Just, the D.O. Hebb University Professor of Psychology in the Dietrich College of Humanities and Social Sciences.
Both the control group and ASD group became familiar with the type of activity that would be used in the scanner. During the brain scan, 16 typical adults and 16 high-functioning adults with autism were trained to perform an implicit dot pattern-learning task. The target pattern was a random array of dots that underwent minor changes. The autistic participants took longer than the control group to learn the task, showing that people with autism have altered implicit learning.
When both groups learned a new dot pattern, the fMRI scanner showed that their brain activation levels were different. The brain activation levels were similar in the beginning, but at the end of the learning session, the typical participants showed a decrease in activation in the posture regions. The autistic participants’ brain activation did not decrease over time, and actually increased in the frontal and parietal regions.
The participants also participated in an exercise designed to engage the frontal and posterior regions of the brain to determine how well the brain can synchronize. Brain synchronization was lower in people with autism, and was related to the severity of the participants’ ASD symptoms.
“This lack of synchronization with frontal regions in ASD – an impairment in brain connectivity – 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,” Just said. “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. It is possible that reduced neural adaptability during learning in ASD may lead to the behavioral symptoms of the disorder. For example, the ability to learn implicit social clues may be affected in ASD, leading to impaired social processing.”