2008 — 2009 |
Dew, Ilana T. Z. |
F31Activity Code Description: To provide predoctoral individuals with supervised research training in specified health and health-related areas leading toward the research degree (e.g., Ph.D.). |
Implicit Relational Memory in Aging @ University of North Carolina Chapel Hill
[unreadable] 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. [unreadable] [unreadable] [unreadable]
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0.928 |
2010 — 2012 |
Dew, Ilana T. Z. |
F32Activity Code Description: To provide postdoctoral research training to individuals to broaden their scientific background and extend their potential for research in specified health-related areas. |
Effects of Aging On Recollection, Familiarity, and Conceptual Priming
DESCRIPTION (provided by applicant): A major goal in cognitive neuroscience of aging is to identify the neural bases of cognitive abilities that are impaired vs. spared by aging. Recollection is the form of memory most impaired by healthy aging and Alzheimer's Disease. Recollection refers to vividly remembering a past event including its associated contextual details, and it differs from familiarity, which refers to the vague feeling that the event occurred in the past even though details cannot be retrieved. Behavioral studies have provided strong evidence that older adults are impaired in recollection but largely unimpaired in familiarity (for a review, see Yonelinas, 2002). Very little is known about the neural bases of this dissociation. In young adults, recollection has been shown to be more dependent on the hippocampus and prefrontal cortex (PFC), while familiarity is more dependent on the rhinal cortex. However, it is unclear whether age-related declines in recollection are primarily mediated by hippocampal or PFC dysfunction. Furthermore, it is uncertain whether the sparing of familiarity is related to the preservation of conceptual priming, a form of implicit memory in which memory performance is facilitated by previous exposure to semantically-related information. The proposed study integrates three methodological approaches to investigate the scope and limits of impaired and preserved episodic memory processes in older adults. First, functional magnetic resonance imaging (fMRI) is used to determine whether older and younger adults use similar or different brain regions during recollection, familiarity, and conceptual priming. Second, diffusion tensor imaging (DTI) is used to quantify white matter integrity in pathways linking regions of interest. Finally, a test battery is used to assess individual differences in neuropsychological status (NS) and determine whether varying levels of executive and memory function can account for differences in task performance and in associated brain activity. These three approaches will be used together to investigate each question of interest. The proposed project is significant for several reasons. Although PFC dysfunction is assumed to play a major role in cognitive aging, the contribution of this region to memory deficits in older adults is still uncertain. In addition, the rhinal cortex is one of the first sites of Alzheimer's Disease neuropathology;thus, understanding its precise role in memory is an important step in distinguishing healthy aging from pathological aging. Moreover, if we can show that the reengagement of conceptual information during measures of familiarity is used to influence and improve memory judgments, then this offers a potential avenue for cognitive training and rehabilitation. Thus, investigating these questions is important at both basic and applied levels. PUBLIC HEALTH RELEVANCE: The rhinal cortex is one of the first sites of Alzheimer's Disease neuropathology;thus, understanding its precise role in memory is an important step in distinguishing healthy aging from pathological aging. Moreover, if we can show that the reengagement of conceptual information during measures of familiarity is used to influence and improve memory judgments, then this offers a potential avenue for cognitive training and rehabilitation. Thus, investigating these questions is important at both basic and applied levels.
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0.958 |