The contribution of semantic bias to false memory in healthy aging

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Project Summary/Abstract Memory concerns are prevalent in healthy cognitive aging and are associated with lower quality of life. False memory – remembering events differently than how they happened – increases across the lifespan. Older adults also show a shift toward semantic memory – memory for concepts – and away from episodic memory – memory for events within a spatiotemporal context. However, it is unclear how the shift toward semantic memory con- tributes to increased false memory in older adults. An improved understanding of the mechanisms that give rise to false memories across the lifespan will be the first step toward alleviating memory concerns in healthy aging. Using a combination of behavioral and neuroimaging approaches, this proposal aims to directly link semantic bias to false memory in older adults. Experimental paradigms traditionally used to investigate false memory capi- talize upon semantic overlap between study items to produce robust false memory effects; however, experiences can also temporally overlap, or occur close together in time. Temporal overlap may differentially impact false memory across the lifespan. Young adults can leverage temporal information to support true memories, and preliminary data suggests that young adults can also utilize temporal information to reject false memories. How- ever, older adults may have greater difficulty utilizing temporal information and thus be more susceptible to falsely remembering. Therefore, identifying the relative contributions of semantic and episodic processing will improve understanding of false memory increases in older adults. This proposal tests the hypothesis that older adults' bias toward semantic processing modulates encoding mechanisms to promote false memory. To determine the extent to which semantic versus episodic processing contribute to false memory, young and older adults will complete a behavioral task in which temporal and semantic overlap between study items is manipulated, and then com- plete a test of false memory. To establish a link between older adults' semantic bias and neural representations of true and false memories, semantic overlap will be manipulated between study items and functional magnetic resonance imaging (fMRI) will be used to measure neural pattern similarity for true and false memories in young and older adults. The proposed research is directly in line with the mission of the NIA, as the results of this pro- posal will provide insight into memory impairments in healthy aging and serve as a first step towards ameliorating memory concerns to improve quality of life in older adulthood. Because healthy aging is characterized by subtle cognitive changes, it can be difficult to distinguish between cognitive declines due to typical aging and those due to amnestic mild cognitive impairments or Alzheimer's Disease. Thus, a more thorough understanding of how the mechanisms that give rise to false memories change in healthy aging will also provide a foundation for further disambiguation of healthy aging from dementia.