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Title: Cellular mechanisms of vestibular compensation : an in vitro study
Author: Cameron, Susan A.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1999
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This thesis examines the cellular mechanisms which may underlie vestibular compensation, a process of behavioural recovery which follows damage to one vestibular labyrinth or nerve. Using in vitro slices of the medial vestibular nucleus (MVN) prepared from animals which had received a unilateral labyrinthectomy at various time points previously, extracellular recording techniques were used to examine changes which occurred in the intrinsic excitability of MVN neurones. When the MVN is isolated in vitro, removed from the influence of the inhibitory commissural system which links the two nuclei in vivo, MVN cells in the rostral region of the ipsilateral nucleus developed a sustained increase in their intrinsic excitability between 2-4h after unilateral labyrinthectomy, which remained significantly higher up to 1 week after surgery. To test the hypothesis that a functional down-regulation of GABA receptors on these MVN cells occurred as a response to the sustained increase in commissural inhibition to which these cells are subject to in vivo, the responsiveness of MVN cells recorded from slices in which animals had received a unilateral labyrinthectomy 4 hours previously, were tested with the GABAA agonist muscimol and the GABAB agonist baclofen. These results showed that there are marked changes in the functional efficacy of GABAergic inhibition in both the ipsilateral and contralateral MVN during the early stages of vestibular compensation. In the second part of this thesis experiments were conducted to determine the role which the stress axis may play in vestibular compensation. The results demonstrate for the first time, that changes in the cellular properties of MVN neurones occur rapidly after unilateral labyrinthectomy and suggest that at least two mechanisms are important in inducing the process of vestibular compensation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available