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Poster E64, Friday, November 10, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Changing our Brains and Minds: The effect of the bilingual experience on neural structure

Vincent DeLuca1, Christos Pliatsikas1, Jason Rothman1,2, Ellen Bialystok3;1University of Reading, 2UiT The Arctic University of Norway, 3York University

Current research suggests that speaking more than one language affects the structure of the brain and potentially cognitive processes related to executive control (Bialystok, 2016a, b). However, the connection between bilingualism and neurocognitive changes is not well understood, and results across studies are inconsistent regarding both neurological (García-Pentón et al., 2015; Pliatsikas & Luk, 2016) and cognitive effects (Valian, 2015). The variability in results between studies likely stems in small part from the fact that bilingualism is operationalized as a categorical variable, or only one experience-based factor is examined (e.g. age of second language acquisition), inevitably collapsing other factors across one another (Luk & Bialystok, 2013; Luk & Pliatsikas, 2016)). It is likely that changes in language behavior are linked to changes in the brain as an effect of second language (L2) acquisition and use (Abutalebi & Green, 2016) and these outcomes are modulated through time as non-native language experience and ability changes (Grundy, Anderson, & Bialystok, 2017). This ongoing project examines bilingualism as a spectrum, specifically assessing the effect of specific factors within the bilingual experience, using a combination of behavioral and neuroimaging (MRI) methods. Typically developing bilingual participants (current n=24, projected n= 60+; m age= 32.88yrs, SD= 6.86) were scanned, completed an English proficiency test (the Oxford QPT; Geranpayeh, 2003), and a language background questionnaire (LBQ) (Luk & Bialystok, 2013). T1-weighted and T2-weighted images were acquired. Demographics from the LBQ, including length of second language (L2) immersion, and L2 age of acquisition (L2 AoA), were run as predictors in analyses on the acquired structural data using the VBM (Ashburner & Friston, 2000), TBSS (Smith et al., 2006), and FIRST (Patenaude, Smith, Kennedy, & Jenkinson, 2011) pipelines in FSL. Not surprisingly, L2 proficiency was found to be highly predicted by L2 AoA (p<.0001), thus was not included in the model. Results of VBM analysis showed length of immersion and L2 AoA to significantly predict grey matter volume (GMV) change in several areas of the brain including bilaterally the VIIb and crus of the cerebellum, anterior cingulate cortex, and left inferior frontal gyrus (p<.004, corrected). TBSS analysis showed fractional anisotropy (FA) value increases across the brain to also significantly correlate with length of immersion including the bilateral posterior section of the corpus callosum (p<.002, corrected). Results of the FIRST analysis showed contractions in the left hippocampus and left globus pallidus were found to be significantly predicted by length of immersion (all ps<.05 corrected), but not L2 AoA. The GMV and FA value increases support the proposals of the Bilingual Anterior to Posterior and Subcortical Shift (BAPSS) model (Grundy et al., 2017), suggesting that increased/sustained exposure to the L2 results in increased and more efficient use of subcortical and posterior regions, including the corpus callosum and cerebellum. The contractions in the globus pallidus, related to immersion, suggest more efficient phonological control processes (Abutalebi and Green, 2016). The results also indicate that bilingualism is a dynamic process which crucially is modulated through time with changes to linguistic exposure and use.

Topic Area: Multilingualism

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