New research may help explain why individuals with autism often fail to grasp the social and emotional elements of speech.

Scientists say they’ve spotted a weak connection in children with autism between the area of the brain tasked with responding to voices and the brain structures that release dopamine in response to rewards. They also found a disconnect between the brain’s voice processor and the area responsible for detecting emotional cues.

As a result, the sound of the human voice may not be pleasurable to those with the developmental disorder, researchers report in a study published this week in the Proceedings of the National Academy of Sciences.

“It is likely that children with autism don’t attend to voices because they are not rewarding or emotionally interesting, impacting the development of their language and social communication skills,” said Vinod Menon, a psychiatry and behavioral sciences professor at Stanford University and a senior author of the study.

For the research, Menon and his colleagues compared fMRI brain scans from 20 kids with high-functioning autism to those from 19 typically developing children. The more impaired the brain connections were in the children with autism, the more severe their communication difficulties were, the study found.

“The human voice is a very important sound; it not only conveys meaning but also provides critical emotional information to a child,” said the study’s lead author, Daniel Abrams of Stanford University. “We are the first to show that this insensitivity may originate from impaired reward circuitry in the brain.”

The finding could lead to the development of new treatments for autism, researchers said.

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