In most babies and kids, the sound of their mother's voice gets special treatment in the brain. But among children with autism, the distinctive brain response to mom's voice is lessened, a new Stanford study has found.
Communication problems are a hallmark of autism, a developmental disorder that affects 1 in 59 kids. The new study, published in eLife, helps explain some longstanding mysteries about how children with autism respond to voices. From our press release:
'Kids with autism often tune out from the voices around them, and we haven't known why,' said the study's lead author, Dan Abrams, PhD, clinical assistant professor of psychiatry and behavioral sciences at Stanford. 'It's still an open question how this contributes to their overall difficulties with social communication.'
The results suggest that the brains of children with autism are not wired to easily tune into mom's voice, Abrams said. The study also found that the degree of social communication impairment in individual children with autism was correlated with the degree of abnormality in their brain responses to their mother's voice.
The research team scanned the brains of children with and without autism using functional magnetic resonance imaging as they listened to three types of recorded sounds: the voice of their mom; the voices of women they did not know; and ambient noise that didn't include voices. The mothers and other women were recorded saying nonsense words to avoid activating the brain's language-processing centers.
Our press release explains what happened:
When comparing the brain response to mom's voice versus unfamiliar voices, children without autism had many more brain areas activated: Mom's voice preferentially lit up part of the hippocampus, a learning and memory region, as well as face-processing regions. Brain-connectivity patterns measured in a network that included auditory-processing regions, reward-processing regions and regions that determine the importance, or salience, of incoming information also distinguished children with autism from children without autism.
The findings support the social motivation theory of autism, which suggests that children with autism find social interactions inherently less rewarding and interesting than normal. With less built-in motivation to pay attention to voices and engage with other people, children with autism don't build as much experience with social interaction, the thinking goes.
Some existing treatments for autism involve motivating kids to engage socially. The Stanford researchers are interested in testing whether these treatments strengthen the brain responses and connections they studied.
Photo by S&B Vonlanthen