Episodic memory declines substantially and, relative to other forms of memory, disproportionately, with age. Understanding the cognitive and neural bases of age-related episodic decline in healthy subjects is important because even the modest impairment (by clinical standards) typical of healthy individuals entering their 70?s is sufficient to have a detrimental impact on quality of life. Identifying the specific cognitive processes, and their neural substrates, which are most responsible for age-related memory decline is a crucial precursor to the development of potential rehabilitative interventions. Equally important, a full understanding of the much more severe memory impairments characteristic of age-related neurodegenerative diseases like Alzheimer?s Disease will be difficult to achieve without knowledge of how memory and its neural substrates vary over the course of the healthy lifespan.
The aim of the present research program is to investigate the possible role in age-related memory decline of the recently identified process of ?retrieval gating?, a process that controls the content of recollection in light of the retrieval goal. The program takes as its starting point findings from three experiments employing fMRI that converge to indicate that healthy young adults are able to ?gate? or ?suppress? recollection of goal-irrelevant features of a prior episode, along with preliminary findings indicating that, as a group, healthy older adults do not engage retrieval gating under the same conditions. Two experiments are proposed. In the first, which will employ groups of young and older adults, the effects on retrieval gating of varying the strength of goal-irrelevant memories will be examined. The experiment will examine the hypothesis that older adults require a greater incentive (more intrusive goal-irrelevant memories) than young subjects to adopt a retrieval gating strategy, but that they are capable of doing so when sufficiently incentivized. The second experiment will employ young subjects only and will utilize a divided attention manipulation to examine the hypothesis that retrieval gating is a resource-limited process, and hence is increasingly vulnerable to disruption with age.
Decline in episodic memory ? memory for unique events ? is typical of healthy aging and, in a much more exaggerated fashion, of age-related neurodegenerative disorders such as Alzheimer?s Disease. The proposed research will contribute to the understanding of age-related differences in cognitive abilities, and the brain systems supporting them, that accompany age-related differences in episodic memory. An important aim of the research is to help pave the way for the development of interventions that will ameliorate memory decline by enhancing the memory processes that are most affected by aging.
