The general goals of this project are to illuminate the nature and functions of memory, and to examine how memory is used to create mental simulations of possible future and past experiences. Recent evidence indicates that the same brain network is involved in both remembering past personal experiences (episodic memory), and imagining or simulating hypothetical experiences that might occur in the future or might have occurred in the past (episodic simulation). The proposed experiments take a cognitive neuroscience approach that links together cognitive and neural processes to understand episodic memory and episodic simulation. One set of experiments will explore how episodic memories are modified or restructured as a consequence of retrieving them from alternative perspectives: either a field perspective (through one's own eyes) or an observer perspective (an external vantage point). These experiments will also examine the hypothesis that restructuring of episodic memories and constructions of episodic simulations rely on common underlying processes, applying a technique that analyzes repetition-related reductions in brain activity. A second set of experiments will use an episodic specificity induction: brief training in recollecting specific details of recent experiences that selectively increases the number of episodic details (e.g., what happened, where it happened) that participants provide on later tasks which require recalling episodic memories of actual past events or constructing episodic simulations of possible future events, while having no effect on retrieval of semantic details (e.g., related facts or reflections) and no effect on a task that requires describing a picture. Ths the specificity induction represents a promising means of selectively targeting episodic retrieval processes. Proposed experiments will test hypotheses concerning a specific brain subsystem that may be affected by the induction and whether the induction affects primarily the initial construction or subsequent elaboration of remembered or simulated events. The final set of studies will test hypotheses concerning a region that has been consistently linked with episodic memory and simulation, the ventromedial prefrontal cortex, but whose role in these processes remains poorly understood. These experiments will explore the idea that this region facilitates access to prior affective knowledge so that individuals can simulate what it might feel like to experience a future episode. For example, one study will test the hypothesis that greater activation in ventromedial prefrontal cortex is observed with greater familiarity of the people and places that comprise episodic simulations, and that this activity also increases with greater anticipated pleasantness of the simulated episode. Another study will explore how this region contributes to the affective quality of a simulated episode. Overall, these experiments should both enhance understanding of basic processes involved in episodic memory and episodic simulation, and could also provide insights relevant to clinical conditions in which episodic memory and simulation are impaired.
Memory is fundamentally important to numerous aspects of our everyday lives, and memory impairments that interfere with everyday functions are commonly observed in such conditions as amnesic syndromes, Alzheimer's disease, and normal aging as well as in psychopathological conditions such as depression, anxiety, and schizophrenia. Further, mental simulations of possible future events play a key role in influencing psychological well-being. Impaired abilities for mental simulation are closely related to memory impairments and have been documented in the same populations that are characterized by memory problems.
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