AGING & VISUAL-SPECIFICITY OF EXPLICIT & IMPLICIT MEMORY

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A key feature of normal aging is that memory becomes less rich in perceptual and conceptual details. This property has been proposed to primarily reflect a tendency of elderly to retrieve events in a less specific and so more generic manner than young people and to a lesser extent encoding that is less perceptually and conceptually distinct. Proposed research investigates changes with age in neural systems supporting memory for perceptual details. To do so, the visual-specificity of brain areas supporting explicit and implicit memory for particular perceptual properties (view size) of objects and faces are assessed using 2 complementary techniques. 1. Neuropsychological studies use Parkinson's disease as a model for frontal-basal ganglionic dysfunction and mild Alzheimer's dementia as a model for MTL and posterior extrastriate dysfunction to assess the contributions of these brain systems to changes in normal aging age-related disorders. 2. Combined event-related functional magnetic resonance imaging (fMRI) and simultaneous magnetoencephalogram (MEG) and event-related potential (ERP) recordings in the same young and old normal people define differences in the functional dynamics of young and aged brains that may impair perceptual memory. Experiments use implicit memory tests, and explicit memory is assessed using recognition (not recall) tests to reveal the extent to which implicit and explicit perceptual representations are encoded and potentially available for retrieval using frontal lobe strategic search processes that are impaired with age. Findings will also contribute to the functional characterization of these brain systems, and by defining brain areas underlying age-related memory disturbances, the work addresses a clinical goal of specifying which regions should be targeted by treatments.