Neural and cognitive changes in aging and bilingualism: Implications for language production and executive function

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This award was provided as part of NSF's Social, Behavioral and Economic Sciences Postdoctoral Research Fellowships (SPRF) program. The goal of the SPRF program is to prepare promising, early career doctoral-level scientists for scientific careers in academia, industry or private sector, and government. SPRF awards involve two years of training under the sponsorship of established scientists and encourage Postdoctoral Fellows to perform independent research. NSF seeks to promote the participation of scientists from all segments of the scientific community, including those from underrepresented groups, in its research programs and activities; the postdoctoral period is considered to be an important level of professional development in attaining this goal. Each Postdoctoral Fellow must address important scientific questions that advance their respective disciplinary fields. As people live longer, their lives are more impacted by age-related cognitive changes. Older adults cite word-finding difficulties as their number one memory complaint, making communication increasingly difficult for them. Research on the source of age-related word retrieval problems has focused on changes in the mapping between word meaning and word form. The planned research explores how cognitive abilities, such as executive function, and the pathways in the brain supporting language and cognitive functions contribute to language production in older age. Taking advantage of the unique language demands placed on bilinguals, this interdisciplinary project combines theories and methods from linguistics, psychology, and cognitive neuroscience to examine the long-term effects of lifelong bilingualism on language production, executive functions, and the neural structures supporting them. The proposed research will advance our understanding not only of age-related changes in language production, but also of the the neural structures supporting executive function and language. As a community with a large Hispanic and bilingual population, Riverside, California is an ideal setting for studying younger and older bilingual adults and for training and mentoring undergraduate students who come from groups that are underrepresented in science. The goals of the proposed research are to investigate factors reflecting lifelong language experiences and their effects on cognitive and language functioning in older bilingual and monolingual adults. A specific goal is to investigate the effects of bilingualism on white matter pathways in the brain, particularly those involved in language and higher-order cognitive processes. Past research has demonstrated that the unique cognitive demands imposed by the lifelong use of two languages results in enhancements in executive control and protections against the symptoms of cognitive impairment and dementia in the elderly. Little is known about the long-term effects of these executive control enhancements on language production. In the proposed research, we investigate how lifelong bilingualism affects word retrieval processes in older adults and ask if the potential advantages observed for cognitive control also serve to help older bilingual adults compensate for language declines in aging. Using behavioral and structural neuroimaging methods, we explore the neural substrates of lexical retrieval and executive control in older adults who have used two languages throughout their lives and those who have used a single language. The project integrates research on bilingualism that considers the consequences of dual language use for spoken language and for cognition, together with research on cognition, language, and neural change in aging.