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Neural correlates of morphosyntactic processing in Spanish-English bilingual children: An fNIRS study

Poster E9 in Poster Session E, Saturday, October 8, 3:15 - 5:00 pm EDT, Millennium Hall

Alisa Baron¹, Neelima Wagley², Ioulia Kovelman; ¹The University of Rhode Island, ²Vanderbilt University, ³University of Michigan

Introduction. Between the ages of 2 and 10 (Brown, 1973; de Villiers & de Villiers, 1973; Jackson-Maldonado & Maldonado, 2017) children undergo substantial changes in their language development, especially their syntactic competences. The neurodevelopment that underlies these changes remain largely unexplored, especially in linguistically diverse learners who speak more than one language. We used functional Near Infrared Spectroscopy (fNIRS) to examine the neuro-cognitive mechanisms of syntactic processing in children who were bilingual in Spanish and in English. In a pre-registered study (OSF), we assessed the neural correlates of -ing, -ed, and -s grammatical morphemes and how they may vary as a function of age or current language use. Based on prior literature (Friederici, 2009; Friederici et al., 2017; Skeide, 2012; Xiao et al., 2016) we predicted strongest activation in the inferior frontal gyrus (IFG) opercularis and triangularis and posterior half of the left superior temporal gyrus (STG)/medial temporal gyrus (MTG) to primarily be recruited for morphosyntactic processing during sentence comprehension. Methods. Eighty-one participants were included in the final analyses. Participants were grouped based on age into a younger (6;0-8;11: n=40) and older groups (9;0-11;11: n=41). All participants completed a language background questionnaire, standardized assessments of language and literacy in Spanish and English, and an English sentence judgement task during fNIRS imaging. The focus of the grammatical task was on a developmentally early acquired morphosyntactic structure, the present progressive -ing, and the later acquired structures of regular past -ed and third person singular -s. Analyses were completed using generalized linear models in the NIRS AnalyzIR toolbox in MATLAB. Results. Younger children had significantly greater activation in the left dorsolateral prefrontal cortex (DLPFC; β=-0.51, q < .001) and superior temporal gyrus (STG; β=0.27, q=.004) for -ing than -ed&s. Older children showed greater activation in the left IFG pars opercularis (β=-0.94, p=.02) for -ing when compared to -ed&s. For sentences with an -ing omission, the between-group comparisons revealed that younger children had greater activation in left IFG opercularis (β=1.91, q=.01) and primary auditory cortex (PAC; β=2.27, q=.01). For sentences with -ed&s omissions, the younger children had greater activation in the left IFG opercularis (β=1.63, p=.007) than older children. Analyses of how grammatical morphemes vary as a function of current language use are currently ongoing. Conclusion. Complementary to prior studies, results suggest that the left IFG region is a central processing hub of grammatical morphemes, where complex morphosyntactic features recruit greater activity in this region. The findings confirmed our initial prediction in that Spanish-English bilinguals had strongest left IFG activation for -ing, -ed and -s grammatical morphemes. However, this was mediated by age as younger children showed significantly greater activation than the older children. Our findings contribute to our understanding of the neurodevelopment of syntactic processing in bilingual children.

Topic Areas: Multilingualism, Syntax