Some children with autism have weak brain connections in regions that link speech with emotional rewards, possibly signalling a new pathway in treatment, researchers say.
The study in the Proceedings of the National Academy of Sciences on Monday is the first to suggest that the reason why children with autism display an insensitivity to human speech may be linked to faulty circuitry in the brain's reward centres.
'Weak brain connectivity may impede children with autism from experiencing speech as pleasurable,' said Vinod Menon, senior author of the study and professor of psychiatry and behavioural sciences at Stanford University.
Researchers took magnetic resonance imaging brain scans of 20 children with a high-functioning type of autism; they had normal range IQs and could speak and read, but had a hard time in conversation or understanding emotional cues.
By comparing the scans to those of 19 children without autism, they found that the brains of youngsters with autism showed poor connections to brain regions that release dopamine in response to rewards.
On the left side of the brain, the autistic children showed weak connections to the nucleus accumbens and the ventral tegmental area.
And on the right side, in the voice-selective cortex where vocal cues and pitch are detected, there was a weak connection to the amygdala, which processes emotional cues.
Researchers also found that weaker connections meant worse communication abilities.
'The human voice is a very important sound; it not only conveys meaning but also provides critical emotional information to a child,' said lead author Daniel Abrams, a postdoctoral scholar in psychiatry at Stanford.
'We are the first to show that this insensitivity may originate from impaired reward circuitry in the brain.'
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Autism study looks at brain