The role of prior knowledge and event segmentation in age- and Alzheimer's-related changes in event memory

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PROJECT SUMMARY The hallmark symptom of Alzheimer's disease (AD) and most common complaint among cognitively healthy older adults is memory loss, especially for everyday events such as conversations with a loved one, a meal with friends, a trip to the grocery store. However, there is a critical difference between remembering these types of events and those that are often measured in the laboratory or in neuropsychological batteries, which often lack real-world contextual meaning. This project will investigate failures in memory for everyday activities by using dynamic real-world stimuli in which episodic memory is formed during a continuous stream of experience. We will test the extent to which older adults use semantic knowledge to create stable mental representations during the continuous stream of everyday experiences, and whether this ability changes in the early stages of AD. Such knowledge-related improvements could benefit older adults' ability to remember day-to-day information, make effective decisions in everyday life (e.g., decisions about healthcare and estate planning), and interact with new technology––all of which will improve their quality of life. This goal is highly relevant to the NIH core mission “to seek fundamental knowledge about the nature and behavior of living systems and the application of that knowledge to enhance health, lengthen life, and reduce illness and disability.” Aim 1 of this project will determine whether deficits in event memory are explained by age-related differences in maintaining stable mental representations during an experience. Aim 2 will determine whether older adults can effectively integrate new event information into existing knowledge structures. Aim 3 will determine whether cueing prior knowledge improves event memory in early-stage AD. The project will use an innovative combination of behavioral and neurophysiological measures of event encoding to address these aims. It will also use dynamic activities that are often encountered in daily life—the kind that older adults report having difficulties remembering. We predict that mPFC-mediated prior knowledge will facilitate the integration of new event information with prior knowledge resulting in better segmentation and event memory for older adults. However, when no prior knowledge is available, the extent to which people can effectively segment an activity (supported by mPFC-hippocampal coupling) will predict memory performance. Further, we predict that cueing relevant knowledge will scaffold the learning of new schema-consistent event information in cognitively healthy older adults and those with early AD. Our goal of improving older adults' ability to encode and retrieve everyday activities is aligned with the NIA's vision for older adults to “enjoy robust health and independence, remain physically and mentally active, and continue to make positive contributions to their families and communities.”