Amnesia impairs episodic memory in humans, and can occur following damage to the medial diencephalon. This thesis examines the importance of the anterior thalamic nuclei, a diencephalic structure, for different elements (what, when, where) of episodic memory (or episodic-like memory) in rats. The overall goal was to understand why this region is so critical for normal memory in humans. An initial series of experiments investigated the ability of rats with anterior thalamic lesions to recognise objects and odours with a variety of delays. These experiments found that anterior thalamic lesions spare item recognition (what). This same ability was further explored with the use of the immediate early gene zif268, and the results again indicated that this thalamic nucleus does not have a direct role in recognition. A related series of studies explored the effects of anterior thalamic lesions on temporal order judgments (when) for objects. Two different discrimination procedures were tested, between-block recency and within-block recency. Lesions to the anterior thalamic nuclei selectively impaired performance on within-block recency but spared between-block recency. The ability of rats with anterior thalamic damage to discriminate between two locations (where) in both complex and simple environments was also tested. Anterior thalamic lesions significantly impaired place learning compared with control animals, despite the finding that rats with anterior thalamic lesions could sometimes discriminate between the two locations (i.e., could perform significantly above chance). In addition, the effects of anterior thalamic damage on biconditional learning (what-where conjunction) were examined. The rats were trained on both item-place and item-context associations. Lesions to the anterior thalamic nuclei disrupted acquisition of the former, but not the latter. The results suggest that the contributions of the rodent anterior thalamic nuclei to episodic memory, as part of the extended-hippocampal system, primarily reflect the involvement of these nuclei in allocentric spatial learning.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:567448 |
| Date | January 2012 |
| Creators | Dumont, Julie R. |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/41978/ |
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