Thackery Ian Brown, Ph.D. - US grants

Project Summary The aged population is growing, and aging brings with it functional decline that can lead to a loss of independence, with significant financial, health, and quality-of-life consequences. Two hallmarks of both healthy aging and age-related disease are 1) memory and navigation deficits, and 2) increased neural and cognitive susceptibility to stress. However, there are marked individual differences in these age-related changes. This proposal will help characterize factors that contribute to that variability. Age-related memory and navigation deficits manifest in fundamental difficulties with orienting towards goal locations and planning how to navigate to them. Such future-oriented navigational thought relies on complex interactions between memory, attention, and cognitive processes which are affected in aging. Critically, stress can act on these faculties and their underlying neural mechanisms, and may strongly influence the ability to engage in effective planning in many settings. Therefore, aging and stress may interact to powerfully influence brain function and cognition, and the fundamental ability of aging individuals to navigate their daily lives. It is imperative that we understand 1) the complex neural processes through which future experiences are envisioned and planned, and 2) how age-related differences in memory function and the stress response interact to impact such flexible thought. The proposed study will characterize the neural mechanisms of planning in aging and study how these mechanisms are impacted by stress. It will utilize cutting-edge neuroimaging and virtual reality techniques, and an experimental manipulation of stress. The study will combine individual differences measures with sophisticated brain activation decoding techniques that provide neural measures of when people plan and what they are bringing to mind from memory. Aim 1 will be to examine how psychological stress affects aged individuals? flexible use of memory, decreasing their ability to envision future routes during planning and increasing their reliance on inflexible, habitual navigation. Independent of stress, aging is associated with an increase in the degree to which people rely on inflexible navigational strategies based on habitual behaviors. Aim 2 will be to test how stress and age-related differences in inherent navigational strategies interact. For older adults who exhibit a stronger inherent bias towards habitual behavior, the degree to which stress limits memory retrieval, and consequently efficient route planning, may be profound. The proposed research will yield critical insight into the neural and cognitive bases of age-related decline in memory and navigation, and how stress interacts with this decline to profoundly impact goal-directed, flexible behavior. Ultimately, the insights from this study will lay groundwork for developing interventions that ameliorate age-related cognitive decline, promote improved quality of life, and encourage cognitive and neural resiliency in aging.