By using MRI and audio recordings, a team of scientists led by the University of Texas at Dallas has recently found that caregiver speech is positively linked to infant brain development in ways that improve long-term language skills. The study, published in the journal Developmental Cognitive Neuroscience, suggests that children who hear more words during infancy will likely have better language skills.
The experts enrolled 52 infants from the Infant Brain Imaging Study (IBIS) – a project involving eight universities in the US and Canada and focused on developmental disorders such as autism – and collected home language recordings when children were nine months old and again six months later. In addition, the researchers performed a series of MRI scans at three months, six months, one year, and two years of age.
“This timing of home recordings was chosen because it straddles the emergence of words,” said study senior author Meghan Swanson, an assistant professor of Psychology at UT Dallas. “We wanted to capture both this prelinguistic, babbling time frame, as well as a point after or near the emergence of talking.”
Although scientists have long known that infants’ home environment – particularly the quality of caregiver speech – significantly influences language skills and acquisition. The neural mechanisms behind these processes were not clear. The current study revealed major links between caregiver speech and how the brain’s white matter – which facilitates communication between various gray matter regions (where information processing takes place) – develops in children.
“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. 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,” Swanson explained.
The scientists used the MRI scans to measure fractional anisotropy (FA), a metric for the freedom or restriction of water movement in the brain that can be 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.”
The analysis revealed that infants who heard more words had lower FA values, suggesting that the structure of their white matter was slower to develop. This finding aligns with previous research showing that slower maturation of white matter confers cognitive advantages, leading to better language skills.
“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. The results show a clear, striking negative association between FA and child vocalization,” Swanson explained.
“This work highlights parents as change agents in their children’s lives, with the potential to have enormous protective effects. I hope our work empowers parents with the knowledge and skills to support their children as best they can,” she concluded.
Language development and language skills in babies is an incredible process that involves a combination of natural growth processes, imitation, and learning. It usually unfolds in stages and varies significantly among individuals, but generally follows a similar pattern.
Newborns start their communication through crying, but soon start to experiment with their vocal cords to produce different sounds, which is referred to as cooing. These are usually vowel sounds such as “ah”, “eh”, “uh”.
As they grow, babies start to add consonants to their sounds, creating babbling noises like “ba-ba” or “da-da”. This is an important stage in language development because it represents the beginning of intentional vocalization.
Babies at this stage may appear to be talking in a language of their own as they start using different tones and sounds. They might also start using gestures to communicate, like waving for “bye-bye” or pointing at something they want.
At around their first birthday, language skills begin to develop more rapidly, with many babies say their first recognizable word. Common first words often refer to parents (“mama”, “dada”) or everyday objects.
Children start rapidly learning new words. At 18 months, they may know between 20-50 words, and by 2 years, they often have a vocabulary of around 200 words. They also start to combine words into two-word phrases, such as “more milk”.
Toddlers begin stringing words together to form short sentences, initially typically 2-3 words long. They begin using pronouns like “I”, “me”, and “you”.
Children start forming complex sentences and significantly improve their ability to narrate events in a logical sequence. Their vocabulary expands rapidly during this time, and they become better at communicating complex thoughts and ideas.