Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Long-term potentiation (LTP) is an electrophysiological phenomenon of neuroplasticity, whereby synaptic transmission of specific brain pathways become enhanced, or potentiated, after the delivery of a series of brief, high-frequency electrical trains. The increase in synaptic efficacy is of substantial duration, and therefore LTP has been likened to the theoretical reverberatory circuit that lead to permanent memory traces, as originally hypothesized by Hebb (1949). To further examine the direct relations between LTP and learning this thesis focused on the paradigm of complex environments, which have been shown to enhance learning, neocortical thickness, and hippocampal evoked potentials. It was decided to examine the effects of this manipulation upon a wide variety of behavioral, electrophysiological, and neuroanatomical measures, which prior to this thesis had not been examined on such a broad scale, nor within the same preparation. Additionally, the effects of complex environments upon LTP induction were studied, an experiment, which surprisingly had not yet been performed.;Results from the complex environment studies indicated that rats housed in complex environments differed from their individually housed littermates in many ways, including learning, LTP, and cortical thickness, with rats that had been housed in the complex environments outperforming their individually housed littermates on all aspects. However, when the inter-relatedness of LTP, learning and neocortical thickness were examined it was found that both learning and LTP independently had relations to neocortical thickness at separate locations, but that LTP and learning did not relate to each other directly. Thus overall, this thesis provided mixed support for the link between LTP and learning, but in doing so, may have clarified a number of issues, and indicated some valuable directions for future research. Finally, this thesis stands out as the most comprehensive examination of the effects of complex environments completed to date.



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