Most children react to their mother’s voice. It is an important social cue and it’s vital for children’s social-emotional learning. Babies find their mother’s voice soothing and previous research shows that teenagers are comforted by words spoken by their mother compared to when the words are delivered via text message. However, children with autism often tune out voices around them and now recent research suggests that the brains of children with autism are not wired to easily tune into their mother’s voice which contributes to difficulties in social communication.
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Researchers from the Stanford University School of Medicine performed the first comprehensive brain network analysis of voice processing in children with Autism Spectrum Disorder (ASD). The study included 42 children ages 7 to 12. Half the children had autism, and the other half didn’t. The brains of the children were scanned using fMRI imaging while they listened to three different recorded sounds: their mother’s voice; the voices of unfamiliar women; and non-vocal environmental sounds. In the voice recordings, the women said nonsense words to avoid activating language comprehension regions in the brain. The researchers compared brain activation patterns and brain network connectivity between the two groups of children. They also asked the children to identify whether each voice recording they heard came from their mother or an unfamiliar woman.
Children without autism correctly identified their mothers’ voices 97.5 per cent of the time. Children with autism identified their mothers’ voices 87.8 per cent of the time which is a statistically significant difference. When comparing brain response to unfamiliar voices with the response to environmental sounds, the researchers found that the brain responded similarly in children with and without autism, although children with autism had less brain activity in one area of the auditory association cortex. When comparing the brain response to mother’s voice versus unfamiliar voices, children without autism had many more areas of the brain activated. The sound of their mother’s voice-activated part of the hippocampus, a learning and memory region, as well as face-processing regions. Brain connectivity patterns were also different between children without autism and those with autism in other areas of the brain including the auditory-processing regions, reward-processing regions and regions that determine the importance of incoming information. The researchers found that the network impairment in individual children with autism was also linked to their individual level of social communication impairment.
The study shows that brain responses to a mother’s voice are vital for building social communication ability in children. But these responses are different in children with autism, supporting the social motivation theory of autism, which suggests that social interaction is less engaging for children with the disorder than those without it.
Source: eLife
