Nancy A. Dennis, PhD - US grants

Historically, memory declines have been cited as the foremost cognitive deficit affecting older adults (second only to physical ailments, when considering age-related problems in general). However, while the vast majority of research in this domain focuses on the subjective experience of forgetting, false memories - memories for events that never happened - are also a significant contributing factor to age-related memory impairment. With funding from the National Science Foundation, Nancy Dennis, Ph.D., of Pennsylvania State University, University Park, is carrying out research using functional magnetic resonance imaging (fMRI) to characterize the neural mechanisms mediating true and false memories in both young and older adults. Previous research suggests that both forgetting and false memories are the consequence of the same underlying shift in cognitive processing in aging, that is, an overreliance on familiarity or gist memory (i.e., memory for general features of an episodic event or memory) at the expense of item-specific processing (i.e., memory for specific details of the event or memory). This research project is examining the neural substrates mediating item-specific and gist processing as they relate to semantic, perceptual and conceptual episodic memories. The research is characterizing age-related changes in item-specific and gist processing, and developing a unified understanding of the common and unique neural mechanisms that support true and false memories in younger and older adults.

The research will also provide valuable insight into the ways in which the brain processes true memories. In this way, the research will clarify overall processing shifts in aging and the direct impact of these age-related changes on memory functioning. Furthermore, by increasing the understanding of how older adults encode, process, and retrieve information, the research is contributing to the enhancement of study and testing techniques designed to optimize memory processing across the lifespan. To facilitate this translational process, the research is being disseminated to others at both national conferences and community-attended lectures. Presentations are part of an extensive series aimed at educating seniors in the community about advances in cognition, nutrition, exercise, and other research on aging. This research project also offers educational opportunities for both graduate and undergraduate students in the field of memory and the cognitive neuroscience of aging. Students are trained in both behavioral methods and advanced neuroimaging methodologies and analyses. Students learn the importance of integrating psychological theory with neuroimaging methods in order to gain insight into the neural processes mediating cognitive behavior across the lifespan. Experience with experimental design and multiple behavioral and fMRI analyses techniques lays a foundation for students' development as independent researchers.

The proposed project seeks to examine and understand individual differences underlying the occurrence of false memories, which is defined as remembering an event incorrectly or differently than how it originally occurred. The investigation of individual differences underlying both cognitive and neural variability in memory performance will be a critical factor in understanding the sources of false memories across the lifespan. By understanding the mechanisms that lead to these memory errors, we can better understand how to avoid these errors. The project will examine the benefits of a cognitive training strategy aimed at reducing false memories in older individuals. The research will use both behavioral and neuroimaging (fMRI) methods to understand the basis of false memories. Neuroimaging analyses will include univariate, functional connectivity, and multivariate analyses to uncover the neural mechanism underlying both true and false memories. This will expand understanding of factors that contribute to false memories across the lifespan. The research will train undergraduate and graduate students on cognitive neuroscience of memory and cognitive aging and will educate the public about memory and cognitive processes that change with age.

Memory research typically aims to identify how memories are represented in the brain. Aging research typically aims to identify sources of age-related deficits in memory. The current proposal combines these goals to reveal the cognitive and neural processes underlying a significant source of error in cognitive aging, that of false memories. The long-term goal is to identify domain-general and domain-specific sources of variance associated with false memories across the lifespan and identify effective, evidence-based strategies for reducing memory errors. This project aims to identify the cognitive and neural markers of such variance as well as individual differences factors that contribute to false memories. The research will also examine the effects of cognitive training in older adults to successfully reduce the incidence of false memories. To do so, the work will utilize behavioral methods examining individual differences in false memories in older adults, as well as advanced neuroimaging methods to investigate how neural information is processed, and represented, throughout the brain. By understanding both common and unique influences associated with the susceptibility to false memories across difference sources, the project can identify strategies for effectively reducing false memories, thereby ameliorating age-related memory decline.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Abstract. By 2050, roughly 83.7 million individuals in the U.S. alone will be over the age of 65. Within this population, memory declines are at the forefront of age-related cognitive complaints. Associative memory, or the ability to link together multiple pieces of information, is especially vulnerable to aging. Associative memory is central to everyday memory function, supporting everything from our ability to remember face-name associations to links between medicines and their daily dosages. As such, there is an urgent need to identify methods that can improve associative memory in older adults. Our long-term goal is to identify effective, theory-driven, evidence-based approaches for enhancing associative memory in older adults. The objective of this application is to elucidate the mechanism underlying the cognitive and neural benefits of unitization on associative memory. The overarching hypothesis is that unitization operates by creating representations of object pairs that mirror how single items are encoded in memory, and does not require conscious, strategic implementation [nor is it dependent on semantic relatedness]. Instead we posit that unitization can be effectively induced through the way in which information is presented to a person. We expect that unitization will result in shifts from hippocampal-based associative processing to cortical-based item processing, with similar shifts observed throughout the memory network, whereby patterns of unitization-related activity are more similar to item-level processing than to associative processing. Additionally, if unitization operates by forming an integrated representation of item pairs, then the unitized ensemble should be both encoded and subsequently retrieved as a single ensemble, with retrieval processes mirroring that of item retrieval. This hypothesis is based on a) findings that unitized information is processed by item-processing regions in young adults and b) the ability of Gestalt principles to transform the representations of individual items into a holistic representation. Finally, we posit that unitization is not limited to binding amongst co-occurring statically presented items, but can occur across temporally presented visual and auditory information as well. The approach is innovative because it directly applies a well-established theory of perception to ameliorate the burden of binding in associative memory processing, with the goal of enhancing associative memory in aging. The approach employs cutting-edge multivariate and network connectivity analyses to test the neurocognitive mechanism underlying the application of unitization to associative memory at all stages of memory. The proposed research is significant because it tests a method for enhancing memory in aging that can be employed across a range of applications absent of subject-generated strategy deployment. In doing so, the work is a critical step in elucidating the flexibility of neural processing across the lifespan to the betterment of memory function. By identifying ways to improve memory function in young and older adults, this work has the potential to 1) enhance other cognitive processes, 2) improve the quality of life in aging, and 3) help dissociate normal aging from early signs of dementia.