Bengaluru: A child’s brain finds a mother’s voice very rewarding, but only until age 12, says a study by researchers from Stanford. According to the study, teenagers’ brains offer a similar response to “nonfamilial” or newer voices.
This potentially explains the shift in behaviour that makes teenagers more sociable with peers than with family around this age, and even their “teenage rebellion”, the researchers say.
Published in The Journal of Neuroscience last week, the findings suggest that, until the age of 12, a mother’s voice lights up multiple parts of a child’s brain uniquely, including the reward circuit.
After the age of 13, neuroanatomical changes cause this phenomenon to cease, resulting in children responding similarly to newer voices — especially those outside the family.
The study was conducted using functional MRI or fMRI, which tracks blood flow in the brain and can trace neural activity.
Apart from providing insights into understanding social cognition and dynamic changes that occur in an adolescent brain, the findings are expected to further research about pronounced social impairments such as autism.
Development of ‘social brain’
As part of two studies, researchers from Stanford enrolled volunteers aged 7 to 16, all currently raised by their biological mothers, to study their brain activity.
Recordings of gibberish words in different voices, lasting just under a second, were played to the children and teenagers as researchers observed their brains, imaging them using fMRI.
The team had previously found that between the ages of 7 and 12, children’s brains are tuned in to their mother’s voice, and that infants, toddlers, and pre-adolescents can identify their mothers’ voices with extremely high accuracy. Their mother’s voice can even lead to certain regions of the child’s brain — associated with reward, emotion-processing, and information-prioritising — getting activated, the findings revealed.
In the new study, researchers found that this phenomenon does not occur once the child attains the age of 13, and, instead, the child’s brain starts to tune in to unfamiliar voices, finding them more rewarding.
The authors note that adolescent brains tune in to all voices as their social cognition expands. Even as teenagers, the children continue to identify their mother’s voice with precise accuracy, but the reward circuitry is activated only for novel voices that lie outside the family, they say.
(Edited by Amrtansh Arora)