The very first medical descriptions of autism, published in the 1940s, noted that children with autism don't respond normally to human voices. Picking up on the nuances of spoken communication is especially difficult for those with autism: Even if they can speak and read, they often struggle to hold a back-and-forth conversation or understand emotional cues in others' voices.
Now, new brain research from Stanford may explain why. Functional MRI scans showed that in kids with autism, brain regions specialized to respond to speech are poorly connected to the brain centers that process rewards and interpret emotions. The new study, which appears today in Proceedings of the National Academy of Sciences, also found that, for individual children, greater impairment in these brain connections translated into more severe communication deficits, as measured by the verbal portion of a standard test of autism severity.
From our press release about the new findings:
"Weak brain connectivity may impede children with autism from experiencing speech as pleasurable," said Vinod Menon, PhD, senior author of the study.
"The human voice is a very important sound; it not only conveys meaning but also provides critical emotional information to a child," said Daniel Abrams, PhD, a postdoctoral scholar in psychiatry and behavioral sciences who was the study's lead author. Insensitivity to the human voice is a hallmark of autism, Abrams said, adding, "We are the first to show that this insensitivity may originate from impaired reward circuitry in the brain."
The findings could help scientists improve existing autism therapies or design new ones. Now that they know that these particular circuits are weak, they can use brain scans taken before and after a child receives an autism therapy to check whether the treatment strengthens the child's brain.
Previously: A mother's story on what she learned from her autistic son, New imaging analysis reveals distinct features of the autistic brain and New public brain-scan database opens autism research frontiers
Photo by Kevin Shorter