Teenagers start tuning out their mothers’ voices

Children younger than 12 can identify their mothers’ voices with extremely high accuracy. Moreover, rather than cuing only their brains’ auditory-processing networks, the specific sound of these voices activates many other key neural areas, including reward centers, emotion-processing regions, visual processing centers, and neural networks parsing which incoming information is salient.

However, a new study led by Stanford Medicine has found that around age 13, children’s brains shift from focusing on their mothers’ voices to favor new voices, as a part of a biological signal driving them to separate from their parents and enlarge their social spheres. 

“Just as an infant knows to tune into her mother’s voice, an adolescent knows to tune into novel voices,” said study lead author Daniel Abrams, an associate professor of Psychiatry and Behavioral Sciences at Stanford. “As a teen, you don’t know you’re doing this. You’re just being you: You’ve got your friends and new companions and you want to spend time with them. Your mind is increasingly sensitive to and attracted to these unfamiliar voices.”

By analyzing fMRI scans of teenagers’ brains recorded while they listened to their mothers’ voices and several unfamiliar ones, the researchers discovered that, although teens’ brains were more receptive to all voices (including their mothers’) than those of younger children, in teenagers aged 13 or older, the reward circuits and the brain networks that prioritize important stimuli were activated more strongly by unfamiliar voices than by those of their mothers. According to the scientists, the brain’s shift towards new voices is a sign of healthy maturation.

“A child becomes independent at some point, and that has to be precipitated by an underlying biological signal,” said study senior author Vinod Menon, a professor of Psychiatry and Behavioral Sciences at Stanford. “That’s what we’ve uncovered: This is a signal that helps teens engage with the world and form connections which allow them to be socially adept outside their families.”

As Professor Abrams argues, the voices in our environment represent an extremely rewarding sound source, allowing us “to feel connected, included, part of a community, and part of a family.” Since children’s social interactions undergo major transformations during adolescence, revealing the neurobiological roots of these changes is essential not only for better understanding healthy maturation processes, but also for clarifying what goes wrong in children with neurodevelopmental disorders such as autism. 

The study is published in the Journal of Neuroscience.

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By Andrei Ionescu, Earth.com Staff Writer