Implicit Relational Memory in Aging

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DESCRIPTION (provided by applicant): A well-established finding in cognitive aging is that older adults do not perform as well as young adults on tests of episodic memory. Episodic memories are contextually-specific, such as events that occurred at a particular place and time. Indeed, memory deficits have been found to be nearly twice as large for contextual details than for content items. The exact mechanism underlying this memory deficit remains unclear. One explanation for older adults' relatively poor performance is an impairment in the process of both creating and retrieving links, or relationships, among the separate contextual features of a to-be remembered episode. An alternative viewpoint posits that the impairment evident in episodic memory is part of a more general age-related decline in strategic, controlled processes. Such processes include the intentional manipulation, organization, or evaluation of features or contextual attributes and, especially, the conscious retrieval of contextual or relational information. According to this view, automatic or unintentional processes remain relatively unimpaired in aging. A way to differentiate between these alternative viewpoints is to examine implicit relational memory. Implicit memory refers to non-conscious, unintentional influences of memory - when some aspect of a previous experience influences or facilitates behavior in a new, seemingly unrelated situation. If a deficit in binding mechanisms at encoding can explain later episodic memory impairment, then such a deficit should be evident using both tests of both implicit and explicit retrieval. Alternatively, if older adults are impaired in strategic, controlled processing of relational information, then an age-related deficit should not occur with implicit testing. The current project proposes three studies aimed at determining: 1) whether the typical finding of age-related impairment in relational processing can be generalized to implicit memory, using two complementary paradigms, and 2) whether older and younger adults exhibit similar medial temporal lobe (MTL) activations during encoding and implicit relational retrieval, using functional magnetic resonance imaging (fMRI). Critically, the proposed experiments are aimed at resolving two competing viewpoints; thus, results in either direction are intended to be informative for the greater theoretical context. The focus of this project is aligned with the broader goal of conducting clinically applicable research related to the cognitive neuroscience of aging. Understanding the nature of this deficit in relational processing is not only of theoretical importance, but also has critical implications for older adults' day-to-day memory function. The ability to bind elements together into a rich, contextual representation is what allows for successful and coherent memories of everyday events.