Patterns of hippocampal amnesia and population activity in rats: Implications for categorical and single-process models of long-term memory organization

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Lee, Justin Quinn
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta.: Univeristy of Lethbridge Dept. of Neuroscience
Contemporary views on the organization of long-term memory (LTM) suggest the hippocampus is involved in a unique category of LTM. Recent experiments illustrate that hippocampal damage before and after a learning episode result in different patterns of amnesia, and many types of memory are affected by damage after the learning episode. These results challenge contemporary views of LTM organization, and motivate the present thesis. We describe a concept, termed heterarchic reinstatement (HR) to account for the pattern of amnesia following hippocampal damage. We observed a pattern of results, in both hippocampal activity and amnesia following damage that support the HR view. However, an experiment using temporary inactivation reveals limitations of the HR view. Thus, we provide a new predictive model of hippocampus and memory, termed the Memory Manifold Theory (MMT), that incorporates the HR concept and our observations along with the broader research literature.
Hippocampus , Rat , Memory