Study shows link between caregiver speech and infant brain development

TEXAS: Some of the most convincing evidence to date that parents who talk to their newborns more, improve their brain development has been identified by a team led by a neurodevelopment researcher from the University of Texas at Dallas. The researchers showed that caregiver speech is connected to newborn brain development in ways that enhance long-term language development using MRI and audio recordings.

The study was released online on April 11 and in the print issue of Developmental Cognitive Neuroscience in June. Its lead author is Dr. Meghan Swanson, an assistant professor of psychology in the School of Behavioral and Brain Sciences.

"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 facilitates communication between various gray matter regions, where information processing takes place in the brain.

The research included 52 infants from the Infant Brain Imaging Study (IBIS), a National Institutes of Health-funded Autism Center of Excellence project involving eight universities in the U.S. and Canada and clinical sites in Seattle, Philadelphia, St. Louis, Minneapolis, and Chapel Hill, North Carolina. Home language recordings were collected when children were 9 months old and again six months later, and MRIs were performed at 3 months old and 6 months old, and at 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's long been known that an infant's home environment -- especially the quality of caregiver speech -- directly influences language acquisition, but the mechanisms behind this are unclear. Swanson's team imaged several areas of the brain's white matter, focusing on developing neurological pathways. "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 researchers used the images to measure fractional anisotropy (FA). This metric for the freedom or restriction of water movement in the brain is used as a proxy for the progress of white matter development. "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 found that infants who heard more words had lower FA values, indicating that the structure of their white matter was slower to develop. The children went on to have better linguistic performance when they began to talk. The study's results align with other recent research showing that slower maturation of white matter confers a cognitive advantage.

"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."