fMRI Studies of Age-related Changes in Executive Processing

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DESCRIPTION (provided by applicant): Normal aging is accompanied by reduced cognitive functioning that can have a broad impact on older adults' lives, including work, social interactions, and managing daily tasks such as finances. Perhaps one of the most common subjective complaints is problems with working memory and long term memory. A major factor contributing to such age-related decline is impaired functioning of the executive processes by which information is maintained and manipulated during higher-order cognitive activities such as comprehension, memory, decision-making and problem-solving. There is accumulating evidence converging on the critical role of prefrontal cortex (PFC) in the executive processes involved in such cognitive activities, and there is increasing evidence that PFC shows functional organization with respect to the processes engaged. There is also evidence that a primary role of PFC is to modulate activity in other brain regions, including those involved in initial perception and the encoding of enduring representations of experienced events. Aging disproportionately affects the PFC, compared to other brain regions, and structural, functional, and metabolic changes have been associated with cognitive dysfunction. There are a growing number of reports of positive correlations between older adults' cognitive performance and scores on cognitive tasks sensitive to executive function, and fMRI studies showing age-related differences in PFC and posterior area activity during cognitive tasks, including tasks assessing executive function. A common goal of investigators working on executive function is to characterize the functional organization of PFC with respect to individual processes, groups of related functions, and/or an area's role in modulating other areas during tasks requiring control. Yet, in spite of increasing interest in these topics, there is still little agreement on a single workable taxonomy of executive functions, how specific regions of frontal cortex map onto specific executive processes, or the dynamic networks that support them. One possible reason is that many of the laboratory tasks traditionally used to tap executive functions are complex---involving multiple component executive processes and subject to potential strategy differences across groups. The proposed project will thus use simple tasks to advance four broad aims: (1) To further specify the component cognitive processes involved in executive function; (2) To identify their neural bases, including functional networks between brain regions; (3) To assess how component processes and underlying neural activity are affected by aging; (4) To examine how individual differences in performance on measures of executive function relate to differences in patterns of brain activity (and connectivity) related to component executive processes.