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Poster E9, Friday, November 10, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Language exposure is associated with the cortical thickness of young, low-SES children

Rachel Romeo1,2, Julia Leonard2, Sydney Robinson2, Meredith Rowe3, Allyson Mackey2,4, John Gabrieli2,3;1Harvard Medical School, 2Massachusetts Institute of Technology, 3Harvard Graduate School of Education, 4University of Pennsylvania

Children’s early life experiences are associated with their neuroanatomy and corresponding cognitive functions. One such experience is language exposure; the quantity and quality of the language children hear during these early years is associated with their overt language abilities throughout childhood and into adulthood. Furthermore, linguistic input varies with by socioeconomic status (SES), such that children from lower SES families typically hear fewer words than their higher-SES peers. Despite this strong behavioral literature, there is currently no evidence that directly relates children’s language experience to brain structure. Here, we examined how variation in spoken language experience at home is related to children’s language skills and cortical thickness. An SES-diverse group of families with typically-developing, native English-speaking children (n = 55) in pre-Kindergarten and Kindergarten (ages 4 to 6 years) were recruited. SES was measured by a composite of parental education and income. Children completed standardized behavioral assessments of their verbal skills (vocabulary and grammar) and non-verbal cognitive abilities, as well as a high-resolution MRI scan. Families then completed two full days of real-world audio recordings from the child’s perspective (via a child-worn audio recorder), from which three measures were estimated: the number of words spoken by an adult, the number of utterances by the child of interest, and the number of time-locked conversational turns between the child and an adult. As expected, SES was significantly correlated with children’s language scores (r = 0.62) and both language exposure measures (adult words: r = 0.32, and conversational turns: r = 0.27) were also correlated with SES. However, whole brain correlations revealed significant associations between language exposure measures and cortical thickness throughout much of the temporal lobe, while SES alone was not significantly correlated with thickness of any regions. This suggests that language exposure is more strongly related to cortical structure than SES and may be the factor driving SES differences in language-related brain development. Furthermore, an interaction was found between SES and the correlation between the number of adult words and thickness of a posterior region of the left superior temporal sulcus (“Wernicke’s area”). Lower-SES children displayed a strong positive relationship between the number of adult words and the thickness of Wernicke’s area, whereas higher-SES children exhibited no significant relationship between adult words and Wernicke’s thickness. To our knowledge, this is the first evidence that directly relates measures of language exposure to measures of brain structure. Results indicate that that the amount of words children hear is related to the thickness of regions subserving speech and language processing, and that language experience is more strongly related to brain structure in low SES environments. This suggests that that children from lower SES families may be more sensitive to their proximal language exposure than their higher SES peers. This may be in part due to a lack of other environmental protective factors in lower SES families, such as access to libraries and high-quality preschool. This highlights the importance of family-based early interventions to bolster the language environments for lower SES children.

Topic Area: Language Development

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