PREFRONTAL CONTRIBUTIONS TO MEMORY IN THE YOUNG AND OLD

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The goal of the proposed project is to more precisely characterize, cognitively and neurally, processes involved in short-term, or working memory (WM; Baddeley, 1986), and memory for events, or episodic memory (Tulving, 1972). Although WM and episodic memory are typically discussed separately, there is a growing consensus among researchers that common cognitive processes, referred to as executive functions, contribute to both WM and episodic memory performance. Unfortunately, although researchers have proposed several models to specify what these executive functions might be and how they are involved in WM and episodic memory, identification of the cortical networks subserving these functions has lagged behind. Available evidence indicates that regions of prefrontal cortex (PFC) are particularly involved in these functions. For example, neuroimaging studies of WM suggest that whereas ventral regions of PFC are involved in keeping representations "on-line" in consciousness (active maintenance), dorsal regions are more involved in performing operations upon these active representations (manipulation). Although these finding have emerged from studies of WM, it is possible that the same mechanisms also contribute to the encoding and retrieval of specific perceptual details of events that are useful for determining the source of an episodic memory (e.g., determining when, where, and how an event took place, differentiating perceived events from thoughts and mental images). Thus, encoding and retrieval of this source-specifying information may require executive functions that contribute to both WM and episodic memory.