The size of language-related brain areas measured before a baby is born is related to the number of words the child can say at the age of two or three, according to a new study published in New York. developmental science.
Children’s ability to learn and use language begins long before they speak their first word. The superior temporal and inferior frontal gyri, the most important brain regions for language comprehension and production, begin to form around 24 to 25 weeks of pregnancy and are already partially formed in the second trimester.
After birth, the size and structure of these areas are related to language abilities in both children and adults. However, whether the size of these same areas before birth can predict the extent to which a child develops language skills in subsequent years has rarely been directly tested.
The team, led by Annika Verwach from Germany’s Max Planck Institute for Human Development, used brain scans obtained from fetuses between 30 and 33 weeks of gestation as part of the Cambridge Human Imaging and Longinal Development (CHILD) project.
Forty-one fetuses had usable brain scans, and language skills were then assessed using a parent-reported checklist of words the child could say at 18 months (25 children, 11 girls) and at around 24 to 36 months (24 children, 13 girls). The mean age of the children at subsequent evaluations was approximately 139 weeks, or approximately 2 years and 8 months.
At 18 months, Werwach’s team found no significant association between prenatal brain size and the number of words a child could say in either region. However, evaluations from 24 to 36 months revealed a clear pattern. Children with larger volumes in the superior temporal gyrus (the area most directly involved in processing sounds and words) before birth produced significantly more words as infants.
Importantly, this association was found on both the left and right sides of the brain, not just the left side where language is typically concentrated in adults. This is consistent with the fact that infants rely on both sides of the brain for early language processing.
The inferior frontal gyrus, an area more involved in higher-level language functions such as grammar and sentence structure, did not significantly predict early vocabulary.
The authors concluded, “This study shows that not only postnatal but also prenatal volume of language-related brain regions is associated with language development several years later. These findings suggest continuity in prenatal and postnatal neural networks for language development.”
However, there are some caveats to this study. The final sample size was very small (approximately 20 children in the final analysis), and participants were from predominantly White, middle- to high-income families. This means the findings need to be validated in a larger, more diverse group. Additionally, this study only examined one aspect of language development: expressive vocabulary, meaning the words a child can say, and did not assess receptive vocabulary (words a child can understand) or other language skills.
The study, “Prenatal volume of bilateral superior temporal gyri is associated with expressive vocabulary in children aged 24 to 36 months,” was authored by Annika Werwach, Alex Tsompanidis, Luca Villa, Roger Tait, John Suckling, Topun Austin, Sarah Hampton, Carrie Allison, Rosemary Holt, Simon Baron-Cohen, and Gesa Schaadt.
