The overarching goal of the proposed project is to study how episodic memory changes with frontal-lobe (FL) and medial-temporal lobe (MTL) functioning during normal adult aging. Towards this end, we will apply three complimentary approaches involving (1) a neuropsychological battery designed to be sensitive to FL and MTL functioning, (2) event-related potential (ERP) measures, and (3) cognitive-process modeling, including a) hierarchical models of memory (with single- and dual-process accounts as special cases), and b) Ratcliff's diffusion model (1978). Young and older adult participants will complete a neuropsychological battery and two recognition memory tasks (an associative memory and a remember-know task). The battery will be used to characterize the FL and MTL functioning (high or low for each) of both young and older adult participants, behavioral measures (accuracy, response time, and confidence ratings) will be obtained for each participant in both memory tasks, and ERPs will be recorded during both the encoding and retrieval phases of the remember-know task. The ERPs will be used to examine the electrophysiological signatures of different retrieval processes (familiarity-based, recollection-based, overall old/new judgment) and the encoding that leads to these retrieval differences in all participant groups (young or older adults with high or low FL/MTL function). The hierarchical and diffusion models will be fit t the behavioral data to characterize the effects of age and FL/MTL function on associative and item recognition, as well as on recollection- and familiarity-based judgments.
The specific aims of the proposed research are to (1) disentangle effects of the different aging trajectories on episodic memory from age-independent effects of high vs. low FL and MTL functioning, (2) examine the influence of FL and MTL functioning and age on ERP indices of old-new memory effects, as well as recognition judgments based on recollection and familiarity, during encoding and retrieval, (3) examine encoding and retrieval phase ERP indices of recollection and familiarity while controlling for mnemonic strength, (4) develop and apply hierarchical process models to study effects of age and FL/MTL function in episodic memory for associative and item information and for recollection- and familiarity-based processes, and (5) apply the diffusion model to characterize the nature of age- and FL/MTL-related impairments in episodic memory for associative and item information and for recollection and familiarity. In summary, the proposed project will provide a rich dataset to test hypotheses concerning the relationship between FL/MTL functioning and episodic memory in younger and older adults. It also contains a number of innovations involving multiple methodological approaches. The results will contribute to a deeper and more integrated understanding of age-related changes and individual differences in episodic memory.
Lapses in memory are one of the most prevalent and noticeable changes associated with aging. The proposed research will employ behavioral, neuropsychological, electrophysiological, and formal computational approaches to study how episodic memory changes with adult aging and frontal-lobe and medial-temporal lobe functioning. By contributing towards a deeper and more integrated understanding of these changes, the results should help address a pervasive and debilitating problem of cognitive aging.
