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Developmental biology - Brain|
Conversation Strengthens a Child's Brain
Independent of parent income and education, a new finding suggests conversation with young children can promote their language skills regardless of that child's parents' socio-economic status.
Although decades of research have established a relationship between socioeconomic status and children's brain development, the specifics of this connection are not well understood.
The so-called "word gap" proposed by the influential 1990 findings that school-age children in lower socio-economic status (SES) households hear 30 million fewer words than more affluent classmates, along with other evidence that early language exposure influences later language ability - all suggest the strong influence practicing language phrasing has on brain structure.
Broca's and Wernicke's area of the human brain. Image credit: Wikipedia.org
In their neuroimaging study of 40 four to six year-old children and their parents of diverse socioeconomic (SES) backgrounds, Rachel Romeo and colleagues found that greater conversational turn-taking (measured over a weekend with an in-home audio recording device) was related to stronger connections between Wernicke's area and Broca's area - brain regions critical for the comprehension and production of speech.
Neuroscience research has elucidated broad relationships between socioeconomic status (SES) and young children's brain structure, but there is little mechanistic knowledge about specific environmental factors that are associated with specific variation in brain structure. One environmental factor, early language exposure, predicts children's linguistic and cognitive skills and later academic achievement, but how language exposure relates to neuroanatomy is unknown. By measuring the real-world language exposure of young children (ages 4-6 years, 27 male/13 female), we confirmed the preregistered hypothesis that greater adult-child conversational experience, independent of SES and the sheer amount of adult speech, is related to stronger, more coherent white matter connectivity in the left arcuate and superior longitudinal fasciculi on average, and specifically near their anterior termination at Broca's area in left inferior frontal cortex. Fractional anisotropy of significant tract sub-regions mediated the relationship between conversational turns and children's language skills and indicated a neuroanatomical mechanism underlying the SES “language gap.” Post-hoc whole-brain analyses revealed that language exposure was not related to any other white matter tracts, indicating the specificity of this relationship. Results suggest that the development of dorsal language tracts is environmentally influenced, specifically by early, dialogic interaction. Furthermore, these findings raise the possibility that early intervention programs aiming to ameliorate disadvantages in development due to family SES may focus on increasing children's conversational exposure in order to capitalize on the early neural plasticity underlying cognitive development.
Over the last decade, cognitive neuroscience has highlighted the detrimental impact of disadvantaged backgrounds on young children's brain structure. However, to intervene effectively, we must know which proximal aspects of the environmental aspects are most strongly related to neural development. The present study finds that young children's real-world language exposure, and specifically the amount of adult-child conversation, correlates with the strength of connectivity in the left hemisphere white matter pathway connecting two canonical language regions, independent of SES and the sheer volume of adult speech. These findings suggest that early intervention programs aiming to close the achievement gap may focus on increasing children's conversational exposure in order to capitalize on the early neural plasticity underlying cognitive development.
Authors: Rachel R. Romeo, Joshua Segaran, Julia A. Leonard, Sydney T. Robinson, Martin R. West, Allyson P. Mackey, Anastasia Yendiki, Meredith L. Rowe and John D. E. Gabrieli.
The authors declare no competing financial interests.
Research was funded by the Walton Family Foundation (to M.R.W.), National Institute of Child Health and Human Development (F31HD086957 to R.R.R.), Harvard Mind Brain Behavior Grant (to R.R.R.), and a gift from David Pun Chan (to J.D.E.G). We thank the Athinoula A. Martinos Imaging Center at the McGovern Institute for Brain Research (MIT); Atshusi Takahashi, Steve Shannon, and Sheeba Arnold for data collection support; Kelly Halverson, Emilia Motroni, Lauren Pesta, Veronica Wheaton, and Christina Yu for assistance in administering behavioral assessments; Megumi Takada for help with data collection/organization; Hannah Grotzinger for MRI quality assurance; Matthias Goncalves for data processing assistance; and Transforming Education, John Connolly and Glennys Sanchez from 1647 Families plus Ethan Scherer from the Boston Charter Research Collaborative for extensive recruitment support.
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The amount of adult-child conversation relates to the strength of white matter connections between two key language areas in the brain, seen above as colored differently between two study participants. Both children are the same age and gender and from the same SES. They differ in number of conversational turns experienced, which affects the strength of white matter connectivity between brain pathways. Image Credit: Romeo et al, Journal of Neuroscience (2018)