The hippocampus and non-hippocampal long-term memory systems each have the capacity
to learn and express contextual fear memory. How these systems interact during learning
and remembering revolves around hippocampal mediated interference, where the hippocampus
dominates for both the acquisition and expression of long-term memory. Hippocampal
interference during learning can be overcome by modifying learning parameters
such that learning is distributed across multiple independent sessions. The standard view of
the role of the hippocampus in long-term memory retrieval is that it is temporally limited,
where recently acquired memory is dependent on hippocampal function though as a memory
ages, dependency is transferred to other memory systems by a process called systems
consolidation. Distributed training demonstrates that learning parameters create a memory
that is resistant to hippocampal damage. We find little evidence to support temporally based
systems consolidation, and present data that supports the view that if the hippocampus is
initially involved in learning a memory, it will always be necessary for accurate retrieval
of that memory. A critical assessment of the rat literature revealed that initial memory
strength, and/or lesion techniques might be responsible for the few studies that report temporally
graded retrograde amnesia using contextual fear conditioning. Our experiments
designed to directly test these possibilities resulted in flat gradients, providing further evidence
that the hippocampus plays a permanent role in long-term memory retrieval. We
propose and assess alternatives to the standard model and conclude that a dual store model
is most parsimonious within the presented experiments and related literature. Interactions
of the hippocampus and non-hippocampal systems take place at the time of learning and
remembering, and are persistent over time. / xvi, 161 leaves : ill. (some col.) ; 29 cm
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:ALU.w.uleth.ca/dspace#10133/3116 |
| Date | January 2012 |
| Creators | Sparks, Fraser T |
| Contributors | Sutherland, Robert J |
| Publisher | Lethbridge, Alta. : University of Lethbridge, Dept. of Neuroscience, c2012, Arts and Science, Department of Neuroscience |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
| Relation | Thesis (University of Lethbridge. Faculty of Arts and Science) |
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