Baby’s Brain Takes Shape from Caregiver’s Speech

A team lead by a neurodevelopment researcher at the University of Texas at Dallas has discovered some of the most solid evidence yet that parents who chat to their infants boost the baby’s brain development.

The researchers used MRI and audio recordings to show that caregiver speech influences baby’s brain development in ways that benefit long-term language success. The study’s corresponding author is Dr. Meghan Swanson, assistant professor of psychology in the School of Behavioral and Brain Sciences. It was published online on April 11 and in the print version of Developmental Cognitive Neuroscience in June.

“This paper is a step toward understanding why children who hear more words go on to have better language skills and what process facilitates that mechanism,” Swanson said. “Ours is one of two new papers that are the first to show links between caregiver speech and how the brain’s white matter develops.”

White matter in the brain allows communication between distinct gray matter regions of the brain, where information processing occurs.

The Infant Brain Imaging Study (IBIS), a National Institutes of Health Autism Center of Excellence initiative encompassing eight institutions in the United States and Canada, as well as clinical locations in Seattle, Philadelphia, St. Louis, Minneapolis, and Chapel Hill, North Carolina, was used in the study. Home language recordings were obtained at 9 months and again six months later, and MRIs were performed at 3 months, 6 months, and ages 1 and 2.

“This timing of home recordings was chosen because it straddles the emergence of words,” Swanson said. “We wanted to capture both this prelinguistic, babbling time frame, as well as a point after or near the emergence of talking.”

It has long been recognized that an infant’s home environment, particularly the quality of caregiver speech, has a direct influence on language learning, but the mechanisms underlying this are unknown. Swanson’s team focused on creating neurological networks by imaging multiple sections of the brain’s white matter.

“The arcuate fasciculus is the fiber tract that everyone in neurobiology courses learns is essential to producing and understanding language, but that finding is based on adult brains,” Swanson said. “In these children, we looked at other potentially meaningful fiber tracts as well, including the uncinate fasciculus, which has been linked to learning and memory.”

The photos were utilized by the researchers to calculate fractional anisotropy (FA). This parameter for the freedom or limitation of water transport in the brain serves as a proxy for white matter development progress.

“As a fiber track matures, water movement becomes more restricted, and the brain’s structure becomes more coherent,” Swanson said. “Because babies aren’t born with highly specialized brains, one might expect that networks that support a given cognitive skill start out more diffuse and then become more specialized.”

Swanson’s team discovered that newborns who heard more words had lower FA values, indicating that their white matter structure developed more slowly. When the children started talking, they improved their linguistic performance.

The findings of the study are consistent with previous recent studies that suggest that slower maturation of white matter gives a cognitive benefit.

“As a brain matures, it becomes less plastic—networks get set in place. But from a neurobiological standpoint, infancy is unlike any other time. An infant brain seems to rely on a prolonged period of plasticity to learn certain skills,” Swanson said. “The results show a clear, striking negative association between FA and child vocalization.”

Sharnya Govindaraj, co-first author of the paper, a cognition and neuroscience doctoral student and a member of Swanson’s Baby Brain Lab, said at first she was surprised by the results.

“We initially didn’t know how to interpret these negative associations that seemed very counterintuitive. The whole concept of neuroplasticity and absorbing new knowledge had to fall into place,” she said. “Which ability we’re looking at also matters a great deal, because something like vision matures much earlier than language.”

Swanson was curious on how this link works for newborns exposed to more than one language as the parent of a toddler in a multilingual family.

“Raising a bilingual child, it is remarkable how she is not confused by languages, and she knows who she can use which language with,” Swanson said.

Swanson said she also has gained a deeper level of appreciation and gratitude for what she, as a researcher, asks parents in her studies to do.

“When participants sign up, I’m asking them to commit to a year and a half,” she said. “Because of the commitment of all the parents in prior studies, I and others have the knowledge that allows us to communicate with our children in a way that supports their development.”

Swanson said the take-home message is that parents have the power to help their children develop.

“This work highlights parents as change agents in their children’s lives, with the potential to have enormous protective effects,” Swanson said. “I hope our work empowers parents with the knowledge and skills to support their children as best they can.”

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