Slide Slam Q11
The efficiency of the Functional Networks in the Bilingual Ageing Brain
Tanya Dash1,2, Pierre Berroir1, 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
Introduction: Life-long experience of using two or more languages has been shown to enhance cognitive control abilities in young (Bialystok et al., 2012; Costa et al., 2008) and elderly (Berroir et al.,2017; Luk et al., 2011; Dash et al., 2019) bilinguals. By frequently practicing the language control mechanism, bilinguals tend to be faster and more accurate in tasks of attention, working memory, and cognitive control. The bilingual advantage is also evident in the structural and functional differences in the regions related to bilingual language control. Thus, bilingualism can be considered to build a cognitive reserve that supports the maintenance of cognitive function, despite brain decline. The current study examines the effect of bilingualism on the resting-state functional connectivity (rsFC) for young and elderly bilinguals. Methods: 27 young bilinguals (YB; Mean age = 35.34 years, 12 F) and 28 elderly bilinguals (EB; Mean age = 69.7 years, 19 F) participated in the study. All participants were French speakers who spoke English as a second language (L2). Measures of bilingualism were assessed using the LEAPq (Marian et al., 2007) and objective language tasks (Dash et al., 2019). In addition, the cognitive reserve index questionnaire (Nucci et al., 2012) was also completed by the participants. The rsFC between individuals varying in age and measures of bilingualism were compared to explore the changes in functional connectivity using ROI to ROI analysis. Data were preprocessed and analyzed using the CONN toolbox with SPM12. Results: Brain-wide, YB showed stronger rsFC within network connectivity for the salience (ventral attention), visual, somatomotor, and frontoparietal control network compared to EB, consistent with the idea of a reduction in age-related functional connectivity. Our results indicate that the brain-behavioral relationship demonstrates a positive correlation between the strength of within-network rsFC and the behavioral effect of alerting, orienting, and executive control. Also, L2 proficiency and exposure – defined as a continuous variable – impacts brain plasticity by modulating the rsFC within the salience network only. Conclusion: Together, our findings highlight the age-related reduction in rsFC in EB when compared to YB. Furthermore, our results indicate that bilingual experience when other proxies of the cognitive reserve are controlled for modulates the functional connectivity within salience network, i.e., with increasing L2 proficiency and exposure, there is an increase in the strength of connectivity within salience network. Salience network – left frontal opercular areas – are related to establishing relevant stimuli in the environment and is typically associated with error processing. It is likely that with more L2 proficiency and usage, the bilingual brain tends to tap into salient cues in the environment to perform more efficiently. These findings shed new light on the importance of modeling bilingualism as a continuous variable rather than dichotomous.