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Does structural neural connectivity mediate the relationship between bilingual exposure and language/executive function outcomes in young children? A DTI study
Poster Session D, Saturday, September 13, 5:00 - 6:30 pm, Field House
This poster is part of the Sandbox Series.
Gavkhar Abdurokhmonova1, Rachel Romeo1; 1University of Maryland
Extensive research finds that specific features of children’s early language environments (e.g., number of adult words, conversational turns, etc.) strongly relate to their later language and cognitive outcomes (Hart & Risley, 1995; Weisleder & Fernald, 2013). There are also studies finding associations between monolingual children’s language environments and functional activation in temporal and prefrontal cortical regions, thus, relating early language exposure to brain regions supporting children’s language and executive functioning (EF) development (Garcia-Sierra et al., 2016; Romeo et al., 2018a). However, there is limited evidence on functional as well as structural connectivity in young bilingual children who are exposed to two and/or more languages. Given critical role of early language environments in shaping the neuroanatomy of key white matter tracts (e.g., superior longitudinal fasciculus (SLF)/arcuate fasciculus (AF)) in monolinguals (Romeo et al., 2018b; Skeide et al., 2016), it is important to examine how early bilingual environments affect the microstructure of white matter tracts connecting the main language- and EF-related cortical regions. This study aims to examine how early bilingual experiences, independent of socioeconomic status (SES), relate to the microstructure of the SLF/AF. Specifically, we hypothesize that (1) SLF/AF might act as critical neuroanatomical mechanisms (mediation analysis) by which children’s bilingual environments shape their language and EF skills. Furthermore, we hypothesize that (2) there might be specific regions of both SLF and AF that show microstructural differences (sub-tract analysis) in how they relate to early language development in bilingual children. Lastly, given the evidence on bilinguals’ bilateral hemispheric recruitment of neuronal resources in language-based tasks as opposed to left-lateralized brain activation in monolinguals (Hull & Vaid, 2007), we will also conduct (3) exploratory analysis examining whether the structural architecture of SLF/AF in bilinguals is left-lateralized or hemispherically balanced (laterality analysis). Participants are n=47 4-6-year-old children from diverse SES, racial/ethnic, and linguistic backgrounds with usable DTI and LENA data. From the total sample (n=47), 25 children were categorized as bilingual based on their caregivers' responses to the LSBQ (Luk & Bialystok, 2013). Their LENA data were annotated for whether it contained only English, only non-English language(s), both English and non-English languages, or no speech. Thus, we derived a continuous measure of bilingualism such that 0 indicated equal amounts of English and non-English (balanced bilingual), and 1 indicated either fully English or fully non-English (monolingual). Upcoming DTI data analyses: data will be preprocessed using the robust QSIPrep 0.12.1 pipeline (Cieslak et al., 2021). Hypotheses #1 and #2 will be tested using the Automated Fiber-Tract Quantification (AFQ; Yeatman et al., 2012; 2018). Lateralization (hypothesis #3) will be examined by creating an average fractional anisotropy index across bilateral SLF and AF, and, subsequently, estimating the leftward asymmetry of activation in SLF/AF correspondingly. This will be first, known to us, study examining how early bilingualism shapes the neuroanatomy of language-supporting white matter tracts in SES-, racial/ethnically-, and linguistically diverse children as young as 4-6 years old. The findings will deepen our understanding of white matter development during critical period of early childhood in bilingual children.
Topic Areas: Multilingualism, Language Development/Acquisition