Study provides insights into early development of human voice processing
Voice processing in the brains of infants develops at an early stage in a child's life. A study by British and German scientists identifies the age of between four and seven months as the period when infants start demonstrating a sensitivity to the human voice, and the emotions it communicates, that is similar to that of adults. The study has now been published in Cell Press's journal Neuron. The results could prove useful in the early diagnosis of neurodevelopmental disorders such as autism. In adults with autism, the voice-sensitive regions in the temporal cortex fail to activate in reaction to speech and the recognition of emotion in the human voice is impaired. Aiming to shed light on the origins of voice processing, the researchers studied specific regions in the temporal cortex of baby's brains with the help of near-infrared spectroscopy. These cortical regions are essential to the processing of spoken language later in life. The test subjects were exposed to vocal and non-vocal sounds. The analysis revealed that the brains of seven-month olds reacted in much the same way to the human voice as those of adults. At four months, however, there was no such response. At the same time, activity was observed in the right temporal cortex of seven-month olds when they heard speech with a clear emotional character - angry or happy. This led the researchers to conclude that sensitivity to emotional prosody - the speech melody that conveys the speaker's emotional status and that is crucial to social communication - is already developed at this early age, too. While it is well-known that reaction to prosodic cues already occurs in newborns, previous studies have shown that only from the age of five months are infants capable of distinguishing reliably between happy, angry or sad prosody. 'Our findings demonstrate that voice-sensitive brain regions are already specialised and modulated by emotional information by the age of seven months and raise the possibility that the critical neurodevelopmental processes underlying impaired voice processing reported in disorders like autism might occur before seven months,' explains Dr Tobias Grossmann of the Centre for Brain and Cognitive Development at the University of London, UK, who led the study. 'Therefore, in future work the current approach could be used to assess individual differences in infants' responses to voices and emotional prosody and might thus serve as one of potentially multiple markers that can help with an early identification of infants at risk for a neurodevelopmental disorder.'
Countries
Germany, United Kingdom