Aging and components of cognitive control in associative memory

Georgia Institute Of Technology, Atlanta GA

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Abstract

? DESCRIPTION (provided by applicant): Healthy aging, even in the absence of dementia, is associated with memory decline, particularly for details associated with previously encountered events. Age-related impairments in this associative type of memory are pervasive and dysfunction in prefrontal cortical (PFC) mediated cognitive control functions like comparative reasoning is a major contributor to these impairments. Existing theories of cognitive aging propose unitary, non-specific PFC changes. We contend that such theories oversimplify the role of the PFC in age-related memory impairments. We propose a new control of associative memory in aging model with clear testable predictions that will provide knowledge of the precise control functions and related neural networks affected by aging. Our model predicts that the effects of age are greater for high order than lower order control operations during associative memory encoding and retrieval. We make concrete predictions about both regionally specific and distributed patterns of activity as well as the time course of control functions. Consequently, we will employ a novel multipronged approach utilizing complementary behavioral, univariate and multivariate functional magnetic resonance imaging (fMRI) techniques, and event-related potential (ERP) to address the following specific aims: (1) We predict that dysfunction in rostral PFC high order processes that support integration of multiple relationships during encoding contributes to age-related associative memory impairments. We predict minimal dysfunction in left caudal PFC supported 1st order item selection and 2nd order inter-item relational encoding processes. We predict that multivariate fMRI analyses will show that reduced functional connectivity within an encoding network containing the rostral PFC contributes t0 poor associative memory performance. (2) We predict that dysfunction in rostral PFC high order processes that support integration of multiple retrieved associations during retrieval contributes to age-related associative memory impairments. We predict minimal dysfunction in right caudal PFC supported post-retrieval monitoring processes. We predict that multivariate fMRI analyses will show that reduced functional connectivity within a retrieval network containing the rostral PFC contributes t0 poor associative memory performance. We predict that ERPs indexing these control functions will be engaged after memory recovery. Post-retrieval ERPs indexing rostral PFC but not caudal PFC functions will be attenuated by aging. The combination of univariate measures of regional activation alongside multivariate measures of functional connectivity and ERPs will provide a more complete understanding of precisely how aging affects PFC function and memory. These results will be essential in developing interventions to improve associative memory functioning by targeting specific cognitive control functions in aging.