IMAGING STUDIES OF LEARNING AND MEMORY

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The major goal of the proposed research is to employ modern functional neuroimaging in normal subjects to characterize brain areas related to specific aspects of explicit memory and skill learning. This proposal focuses on three specific areas of research including: 1) experiments designed to identify brain regions used during various encoding and retrieval tasks. Models of explicit (or declarative) memory often include processes related to selection of information to be stored, encoding of that information, information storage, and information retrieval. An extension of previous work on the functional anatomy of retrieval processes and a beginning exploration of brain regions related to encoding processes are proposed. 2. experiments designed to determine what task demands modulate blood flow in medial temporal lobe regions particularly in the hippocampus. Because damage to the medial temporal lobe, particularly the hippocampus and adjacent structures, produces specific deficits in explicit (or declarative) memory, much attention has been focused on the hippocampal contribution to memory. Experiments are proposed to explore the contribution the hippocampal regions might make to memory, focusing on ideas related to specific aspects of encoding. 3. experiments designed to explore the functional anatomy of skill learning. Skill learning appears to be intact in amnesic individuals. Skill learning also shows several properties that may be implemented by different neural systems. For example, evidence gathered from this and other laboratories supports the hypothesis that different brain regions are used in the performance of very similar tasks in skilled and unskilled versions. Experiments are proposed to assess the generality of these effects. Further experiments are proposed to explore other properties of skill learning, including passage through multiple stages of skill acquisition, chunking of simple skills Into more complex units, and hierarchical encoding of high-level motor programs. While this proposal focuses on memory and learning in normal subjects, the knowledge gained from such studies should be relevant across a wide range of health issues. Memory impairment is one of the most tragic consequences of degenerative illnesses, such as Alzheimer's disease and other dementias, as well as being a frequent complaint even in normal aging. An understanding of the normal human biology of memory can not help but to deepen our understanding of these health problems and lead to better approaches to their solution.