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Investigating the Role of Hippocampal States in Episodic-like Memory Consolidation
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- Author / Creator
- Meghji, Zemina
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Acquisition and storage of episodic-like information fundamentally contributes to quality of life. It is the type of information that allows us to remember meaningful events such as our graduation and our heartaches. The memory of these events allows us to adapt our behaviours to facilitate more of the good (graduation) and less of the bad (heartache). Though this form of mental time travel plays an important role in daily life, much of the way in which this type of information is stabilized is still under question. An avenue unto which we can investigate the stabilization of episodic-like information, a function that has been shown to rely on the hippocampus, is by looking at the one-to-one relationships previously established between brain and behaviour since generating episodes in our life often requires some sort of action/movement/presence of us. Specifically, researchers have demonstrated theta activity while a rat engages in active behaviours such as running, walking, swimming, and rearing. Large irregular amplitude (LIA) in addition to sharp-wave ripples (SPW-R) activity appears when a rat is grooming, drinking, or immobile. And finally, we observe slow oscillatory (SO) activity in a rat while in sleep behaviour, specifically during slow wave sleep (SWS). Here in this study, we wanted to determine how these behaviourally-associated hippocampal states contributed, if at all, to the solidification of episodic-like memory retrieval. To do this, we used a delayed matched to sample paradigm in the circular water maze. We provided rats four training trials inter-leaved with one-minute breaks. External cues were placed within the maze room to facilitate the learning of the platform location on that day. The four training trials were then followed by a one-hour delay during which specific behavioural conditions were encouraged. To test whether a difference in behavioural condition would affect the consolidation of episodic-like information, we then administered a probe trial. During this trial , the platform was not available. Therefore, rats were required to remember the location of the platform based on an allocentric map. An aggregation of our results demonstrated that when rats spent at least 40% of their time sleeping during the inter-leaved one-hour delay, their performance, measured in terms of latency, was improved as compared to when they engaged in exploratory or grooming behaviours. In fact, performance appeared to be hindered when rats spent most of their time exploring. Thus, we have demonstrated differentiated affects on episodic-like memory recollection as a function of hippocampal state suggesting that hippocampal state may also need to be taken into consideration when investigating information solidification processes with respect to episodic-like memory.
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- Graduation date
- Fall 2019
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.