The Cognitive Neuroscience of Bilingual Advantages in Executive Control

Executive control refers to a set of supervisory processes that enable humans to flexibly shape thoughts and behavior in order to accomplish internal goals. Recent evidence suggests that bilingual adults are advantaged at executive control processes relative to their monolingual peers. Bilingual advantages appear to be most pronounced in late adulthood, when executive control processes begin to decline. These findings suggest that bilingualism may promote neuroplasticity and/or compensatory brain reserve. However, large knowledge gaps exist in this field. First, little is known about which specific executive functions receive a boost from bilingualism. Second, almost no information exists on the neurobiological mechanisms underlying bilingual advantages. Third, it remains unknown whether the degree of experience with the second language correlates with bilingual advantages. The focus of this proposal is to use behavioral and imaging methods to address these issues. At the behavioral level, the present proposal will provide detailed information about the extent and limits of bilingual influences on executive control processes. Results from the behavioral studies will determine if bilingualism strengthens only processes that directly replicate the bilingual experience or serves to bolster executive control processes more broadly. In addition, the present proposal will use cutting-edge functional magnetic resonance imaging (fMRl) and diffusion tensor imaging (DTI) methods to understand the neurobiological bases of bilingual performance advantages. The fMRl methods will be used to identify variations in bilingual brain activation patterns that correlate with their advantages in executive control accuracy. The DTI methods will identify variations in bilingual white matter microstructure that correlate with their advantages in executive control speed. Characterizing the neurobiological bases of bilingual advantages in executive control will further our understanding about how an accessible lifestyle variable can influence neuroplasticity and/or compensatory brain reserve in aging. This project will provide research training and mentoring to a number of students, including a graduate student, a research assistant, and several undergraduates. There will also be a broader impact of the present work. Although research relevant to understanding the consequences of second language use is an issue of fundamental importance in our increasingly multilingual society, bilinguals have typically been excluded from cognitive neuroscience research in the US. Results from the present proposal will help highlight reasons for including bilinguals in cognitive neuroscience research in the US.