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Exploring Resting State Networks on a continua of Bilingualism and Age
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Poster B35 in Poster Session B, Tuesday, October 24, 3:30 - 5:15 pm CEST, Espace Vieux-Port
Tanya Dash1,2, Yves Joanette1,2, Ana Ines Ansaldo1,2; 1Centre de recherche de l’Institut Universitaire de Gériatrie de Montréal, 4565 Queen-Mary Road, Montreal, Quebec H3W 1W5, Canada, 2École d’orthophonie et d’audiologie, Faculté de médecine, Université de Montréal, Montreal, Quebec H3N 1X7, Canada
The phenomenon of bilingualism provides a neural protective mechanism towards age-related cognitive decline called cognitive reserve (Gallo & Abutalebi., 2023). A putative functional neural substrate underlying bilingualism-related reserve is stronger internal functional connectivity in the Default mode network (DMN; Grady et al., 2015), language network (Berker et al., 2016), and frontoparietal network that can result in better cognitive performance (Grady et al., 2015). We anticipated that with increasing levels of bilingualism, bilinguals will demonstrate more intact brain functional networks, which may be a sign of cognitive reserve. Resting-state fMRI-assessed ROI to ROI connectivity is associated with protective factors (bilingualism) and better maintenance of attention across the lifespan. We assessed the resting-state fMRI of 79 healthy controls (HC). ROI-to-ROI connectivity of resting-state networks (specifically frontoparietal, language, and default mode) was computed, and the reserve was quantified as different measures of bilingualism (Dash et al., 2022) and measures of cognitive reserve (Nucci et al., 2012; Education, work, leisure). The contribution of gender was factored out. Partial least square regression (PLSR) was conducted to yield sets of four orthogonal latent variables (LVs) assessing the association between: a) functional connectivity within the resting state networks; specifically, DMN, frontoparietal and language networks, b) measures of cognitive reserve – age, measures of bilingualism, education, leisure work. Different measures of cognitive reserve (age, bilingualism, work, leisure, education) showed an interactive factor loading that predicted resting-state functional connectivity (rsFC) differently. L2 exposure and proficiency variables, along with a negative loading of CRIq, formed LV1, which predicted positive rsFC within the salience and language networks. Additionally, as LV1 scores increased, there was a decrease in inter-network connectivity for the DMN and language networks. Greater task-based proficiency (LV2) predicted stronger connectivity in the salience and dorsal attentional networks. Interestingly, CRIq also showed positive loading in LV2, along with L2 language task proficiency. Finally, chronological age, along with negative loading of L2 age of acquisition and L2 exposure, formed LV3 and predicted a negative relationship with intrinsic connectivity for the language and salience networks. In other words, as age increases, intra- and inter-network functional connectivity decreases. These novel results extend our previous findings on task-based measures of bilingualism having better potential to predict functional connectivity (Dash et al 2022). Also, PLSR allowed us to look at the individual contribution of measures of bilingualism along with other cognitive reserve variables in unison as these variables are highly collinear.
Topic Areas: Multilingualism, Control, Selection, and Executive Processes