Autism spectrum disorder is defined by deficits in social interactions and communication, and repetitive and restrictive behaviors. Individuals with ASD also commonly experience atypical auditory processing that presents in a wide range of different ways. Gaining a better understanding of auditory processing of speech in ASD is important as early speech and language ability in children with ASD has been shown to predict adaptive functioning, social skills, and communication abilities later in life.
Speech perception relies on the brain's ability to combine different sounds into words and sentences, or auditory scene analysis. When we listen to someone speaking, their words are made up of different sounds that come and go quickly, but we perceive them as a coherent stream of information. This is because our brain synchronizes the firing patterns of neurons that process different sound features, like pitch and timing. If this synchronization is disrupted, it could contribute to difficulties processing sounds.
We wanted to see if the way that the brain processes this basic acoustic information that helps bind speech together is different in children with ASD compared with typically developing children. We recorded brain activity using magnetoencephalography to record cortical responses while these two groups of children (ages 7 to 17) listened to speech with different levels of coherence.
In our study published in NeuroImage: Clinical, in early 2023, we found that individuals with ASD had different patterns of brain connectivity between areas involved in speech processing, particularly in the parietal region, which is important for combining different sounds into speech objects. We found that children with ASD had decreased local functional connectivity within the parietal cortex. This suggests that they may have difficulty integrating the different sounds of speech into a coherent whole.
These differences were also related to behavioral measures of auditory processing in individuals with ASD. Interestingly, the differences in brain connectivity were more pronounced in younger children with ASD, suggesting that speech processing may improve as they enter adolescence.
This is adapted from the paper in NeuroImage: Clinical, 2023. A 2015 Emerging Research Grants scientist, Hari Bharadwaj, Ph.D., is an assistant professor of communication science and disorders at the University of Pittsburgh School of Health and Rehabilitation Sciences. His 2015 grant was generously funded by Royal Arch Research Assistance.
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