The Impact of Emotional Salience and Aging on Selective Sleep-Based Memory Consolidation

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DESCRIPTION (provided by applicant): Sleep preferentially preserves aspects of memory that are most salient and valuable to remember over less relevant details, but the majority of these provocative studies were conducted on young adults. Little is known about which aspects of sleep are crucially involved in selective consolidation and how these sleep phenomena vary with age. The objective of the proposed studies is to detect potential mechanisms, and the age- and salience-related influences, underlying sleep-based selectivity in memory. Based on preliminary data, the central hypothesis is that selective consolidation of salient parts of memory will occur during sleep rich in slow waves and spindles, with emotional salience overriding other salience cues, and that these effects will decrease with age. The rationale for this project is tha an understanding of nuanced sleep-based consolidation and the role of emotion beyond the restricted cohort of young adults will foster the ability to determine the underlying age-related changes in the phenomenon. This research training program includes coursework, mentoring, and training designed to enable the candidate to examine mechanisms of, and age-effects on, selective memory consolidation in sleep. A novel dual nap paradigm will be used to control for time-of-day effects and to capitalize on the tendency of early and late naps to naturally differ with respect to sleep stage composition. Subjects 18-39 years (young) and 45-64 years (middle age) will be recruited to participate. Study 1 (n=90) will aim to identify sleep physiology correlates of selective consolidation of emotional components of memory. Subjects will be shown complex scenes of negative or neutral foreground objects on neutral backgrounds and then nap or remain awake. Memory for individual scene components (objects, backgrounds) will be assessed both before and after the sleep/wake retention period. Study 2 (n=90) will assess the relative importance of emotional salience in selective sleep-based consolidation by examining the interaction of emotional salience with another task-related salience cue (remember/forget). Negative and neutral stimuli will be presented, each followed by a cue to remember or forget the item, before a nap/wake retention period. Recognition memory for stimuli will be tested to directly assess how emotional salience influences the ability to remember important and forget irrelevant information. [An exploratory pilot study (n=15) using functional MRI will follow the general methods of Study 1 to investigate the feasibility of examining the neural mechanisms behind altered sleep-based selective consolidation of emotional memory with age.] EEG recordings will be analyzed to determine sleep staging, spectral frequency power, and sleep spindle density to correlate with age and memory performance data in all studies. The results will move the field forward by clarifying the interaction between aging, emotion, and sleep in nuanced memory consolidation in a healthy population, positioning the candidate to take a crucial step to- ward determining the underlying neural mechanisms, and modeling normal and abnormal processing for potential clinical applications.