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theses

Declarative memories are paramount for the survival of an individual and their species. Declarative memories are those which are formed and reinforced through the personal history and experiences of an individual. The mammalian hippocampus plays an irreplaceable role in the formation of declarative and spatial memory. The hippocampus is vital in forming and storing a new memory, yet not completely necessary for the recall of a previously established memory.
Teleost fish possess the capacity to form declarative memories, however, the homologue to the mammalian hippocampus in the teleost brain is not clearly defined. Due to differences in embryonic development of the prosencephalon (invagination vs eversion), topological comparisons of the mammalian and teleost brain cannot directly identify corresponding regions.
To locate the areas in the teleost brain equivalent to the hippocampus, we devised an experiment that focuses on cell activity during memory formation. The telencephalon regions most active in the teleost brain during spatial memory formation are located and compared to the same areas during memory recall. The regional differences in activity between forming a memory and recalling a memory in a teleost may identify the equivalent to the hippocampus. The study focuses on three regions of the dorsal pallium of the teleost forebrain selected as probable regions of interest based on previous studies and literature. The study uses cytochrome oxidase activity as a measure of the most recent cellular activity in the investigated regions.
A naïve group was used as a control. An experimental group was trained to learn a spatial oriented task. A recall group, taught the same task as the experimental group, but left inactive for 2 weeks, was forced to recall the same task. After the forced recall, their forebrains activity was immediately studied.
The experimental group displayed a significant increase in activity in Dm compared to the recall group. The difference in activity between experimental and recall groups show activation of Dm during learning the spatial tasks, not during recall of the learned tasks. Dm appears to be part of the telencephalon used for encoding and storing memories, not the recall of the same learned task.

ETD_9180

M.S.

Includes bibliographical references

by John Rapacz

doi:10.7282/T3GQ72BN

ETD graduate

The author owns the copyright to this work.