The proposed project is designed to investigate how language status and genetic variation is associated with cognitive control. To achieve this, the proposed project will use functional Magnetic Resonance Imaging (fMRI), which measures deoxyhemoglobin, is correlated with blood flow and energy metabolism, and serves as an indirect measure of neural activity. Work in many laboratories including our own has identified neural and behavioral differences in bilinguals and monolinguals during cognitive control tasks. Furthermore, recent studies suggest that differences in the ability to perform control tasks with verbal and no explici verbal response exist within the bilingual population. Finally, an independent study found an advantage on switching tasks with no explicit verbal response for carriers of the A1 allele of the DRD2/ANKK1 taq1A polymorphism. These individuals have a reduced number of dopamine D2 receptors, show a decrease in switching costs, and have decreased activity in neural areas devoted to cognitive control. A second study using a DRD2 agonist, found increased switching-related activation in the same areas in the agonist condition compared to placebo. In the proposed study, a group of bilinguals and monolinguals will be screened for their genetic makeup. From these a subset of each group that is a carrier or not will be placed in an MRI scanner while performing a cognitive control task. The results from the proposed study will help to elucidate whether carriers of the A1 allele outperform non-carriers in both monolingual and bilingual populations. It will also elucidate whether the magnitude of any advantage seen in bilinguals is moderated by a group's genetic status. As such it should serve as the springboard for future studies with children learning a second language. The results may also shed light on theoretical accounts of bilingualism as well as inform clinicians and educators who work with bilinguals by revealing whether genetic variation is also associated with performance on cognitive control tasks.
The proposed project is designed to investigate how variation in language status (bilingual or monolingual) and genetic status (carrier or non-carrier of the A1 allele of the DRD2/ANKK1 taq1A polymorphism) can be associated with the neural activity observed when performing a cognitive control task. The results from this study should help break new ground by informing researchers, educators and clinicians about the ways in which individual genotypic differences and language experience differences are associated with cognitive control abilities.
