Across a crowded room, your mother calls out your name and within milliseconds your brain fires, recognizing her voice as innately familiar. But what can explain these neurons igniting, and what does it tell us about how well a child might communicate with others? A team of researchers from Stanford University Medical Center are the first to look at what happens inside babies’ brains the moment they hear their mother’s voice. Their findings, published in the Proceedings of the National Academy of the Sciences, reveal the importance of hearing mom’s voice within less than a second after birth.

"Nobody had really looked at the brain circuits that might be engaged," said the study’s senior author Vinod Menon, a psychiatry and behavioral sciences professor, in a statement. "We wanted to know: Is it just auditory and voice-selective areas that respond differently, or is it more broad in terms of engagement, emotional reactivity, and detection of stimuli?"

To see the inner-workings of a child’s brain, researchers scanned 24 healthy children who were all around 10 years of age using a magnetic resonance imaging (MRI) machine. While they were being scanned, the children listened to short clips of recordings of nonsensical words — some were from their own mothers while the others came from two different women who had never met any of the children involved in the study. Although the clips were less than a second long, children could identify their own mother’s voices with nearly perfect accuracy (over 97 percent of the time).

"The extent of the regions that were engaged was really quite surprising," Menon said. "In this age range, where most children have good language skills, we didn't want to use words that had meaning because that would have engaged a whole different set of circuitry in the brain."

Researchers found when a child heard their own mother’s voice, it activated the  part of the brain responsible for emotions, or the primary auditory cortex. Another activated region plays a role in processing information about ourselves and recognizing faces. However, when babies heard either of the two unfamiliar women’s voices, the areas didn’t light up with activity.

Some children's brains showed stronger degrees of connection between each of the regions that lit up, suggesting they were better communicators compared to those with weaker degrees of connectivity. Menon explained that because of this, their research will be important for laying the foundation for understanding social communication problems in children with disorders, such as autism.

"Many of our social, language, and emotional processes are learned by listening to our mom's voice," said the study’s lead author Daniel Abrams, a psychiatry and behavioral sciences professor, in a statement. "We know that hearing mother's voice can be an important source of emotional comfort to children. But surprisingly little is known about how the brain organizes itself around this very important sound source. We didn't realize that a mother's voice would have such quick access to so many different brain systems."

Researchers have known for years that a child is acutely aware of their mother’s voice from the time they are born. But this is the first time researchers have been able to demonstrate how their voice resonates within the neurological networks of their brain’s circuitry.

According to Menon, he and his research team plan to conduct further studies that include children with autism as well as adults in order to compare the differences in how the brain lights up within individuals in each group. Menon concluded: "Voice is one of the most important social communication cues. It's exciting to see that the echo of one's mother's voice lives on in so many brain systems."

Source: Menon V, Abrams DA, and Chen T. Neural circuits underlying mother’s voice perception predict social communication abilities in children. Proceedings of the National Academy of Sciences. 2016.