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Title: Thalamocortical interactions in recognition memory
Author: Cross, Laura Rachael
ISNI:       0000 0004 2736 8550
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2012
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The mediodorsal thalamus (MD) is implicated in recognition memory however its exact role is unclear. The aims of this study were to provide a detailed analysis of the role of MD in recognition memory in the rat using variants of the spontaneous object recognition task to assess item (object or odour) recognition, recency recognition or associative recognition memory separately. In the first series of experiments, bilateral lesions in MD or mPFC impaired both recency and associative recognition, but spared item recognition and object location performance. The second series of experiments used disconnection techniques to investigate whether an interaction between the MD and mPFC is necessary during these recognition memory processes. Unilateral lesions in MD and mPFC in contralateral hemispheres produced deficits in recency and object-in-place associative recognition but spared item recognition, and object-in-context memory. The final series of experiments investigated the neurochemical basis of object-in-place associative recognition memory. Intra-MD Infusions of either NBQX, a glutamatergic antagonist, or muscimol, a GABAergic agonist produced selective deficits in retrieval, but not in acquisition of object-in-place associative memory. In contract, intra-mPFC infusions of NBQX impaired both acquisition and retrieval, while muscimol had no effect. Interestingly, crossed infusions into both the MD and mPFC disrupted retrieval but not acquisition. These findings indicate that MD plays a selective role in recognition memory when associative or recency, but not single item, discriminations are made. Secondly these data show that to make these discriminations, MD must functionally interact with the mPFC. Finally, it was shown that during object-in- place associative recognition memory, MD and the interaction between MD and mPFC appears critical during the retrieval phase only. Thus together these results show for the first time that MD plays a selective role in the recognition memory via a thalamocortical interaction with mPFC, and that for associative recognition memory this interaction is required for the retrieval phase only.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available