Language Exposure and Brain Myelination in Early Development

Abstract

The language environment to which children are exposed has an impact on later language abilities as well as on brain development; however, it is unclear how early such impacts emerge. This study investigates the effects of children’s early language environment and socioeconomic status (SES) on brain structure in infancy at 6 and 30 months of age (both sexes included). We used magnetic resonance imaging (MRI) to quantify concentrations of myelin in specific fiber tracts in the brain. Our central question was whether Language ENvironment Analysis (LENATM) measures from in-home recording devices and SES measures of maternal education, predicted myelin concentrations over development. Results indicate that 30-month-old children exposed to larger amounts of in-home adult input showed more myelination in the white matter tracts most associated with language. Right hemisphere regions also show an association with SES, with older children from more highly educated mothers and exposed to more adult input, showing greater myelin concentrations in language-related areas. We discuss these results in relation with the current literature and implications for future research.SIGNIFICANCE STATEMENT:This is the first study to look at how brain myelination is impacted by language input and socioeconomic status early in development. We find robust relationships of both factors in language-related brain areas at 30 months of age.

Social Brain Perspectives on the Social and Evolutionary Neuroscience of Human Language

“…In light of the significance of child-parent interactions for acquiring language, neuroimaging research has recently begun to investigate how just this sort of communication may impact the developing brain. As previously discussed, studies have found that, during early maturation, the quantity of linguistic information, as calculated by infant exposure to the number of adult words, is strongly predictive of myelin in white matter association tracts related to adult language abilities-especially the left arcuate fasciculus (AF) and superior longitudinal fasciculus (SLF) in younger children at 30 months of age-as well as youngster's developing linguistic abilities [139]. On the other hand, the quality of linguistic information-word richness, dialogue experience, and mean length of utterance (MLU)appears to be more crucial for older youth 4-6 years of age, who show greater white matter connectivity involving left AF and SLF [140,141] and greater cortical volume in the left inferior frontal gyrus (IFG) and supramarginal gyri [142], as well as older children 5-9 years of age, who show increased cortical areas in the left perisylvian areas [143].…”