Neurophysiological correlates of bilingual advantage and its contribution to cognitive reserve

Studies reported that bilingualism strengths executive functions in elderly and delays the Alzheimer’s disease (AD) onset for five years. These findings suggest that bilingualism enhances the cognitive reserve (CR). CR is a construct that includes a set of cognitively stimulating experiences (e.g. high education level, high occupational status) that enhance brain functional connectivity, leading to better cognitive functioning and delayed clinical AD onset. Since brain functional modulations maintained for a long period of time result in structural changes, studies suggested that enhanced functional and structural connectivity provide to persons with high CR greater resilience against changes related to physiological and pathological ageing. Considering the European population ageing, study of variables related to CR is crucial to prevent the cognitive decline in elderly and for the maintenance of public health systems. The aim of this project is studying the specific cognitive processes related to bilingual advantage in executive functions and the underlying neural correlates. Studies often failed to find a relationship between bilingualism and better executive functions. These studies often focused on cognitive control to inhibit irrelevant information but recent research suggested that bilingualism is mainly related to better attentional switching abilities. Also, high CR of the participants or low difficulty of the performed task could mask a bilingual advantage due to a ceiling effect in cognitive performance. Four samples of healthy elderly (monolinguals and bilinguals with low and high CR) will perform two cognitive tasks during an electroencephalogram (EEG) recording. Neural correlates of cognitive processes occurring during the tasks performance will be studied by using event-related potentials. Functional connectivity will be studied through EEG coherence and graph theory whereas structural connectivity will be studied by using diffusion weighted imaging.