| 1. |
- Bergquist, Filip, 1970, et al.
(författare)
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Role of the commissural inhibitory system in vestibular compensation in the rat.
- 2008
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Ingår i: The Journal of physiology. - : Wiley. - 1469-7793 .- 0022-3751. ; 586:Pt 18, s. 4441-52
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the role of the vestibular commissural inhibitory system in vestibular compensation (VC, the behavioural recovery that follows unilateral vestibular loss), using in vivo microdialysis to measure GABA levels in the bilateral medial vestibular nucleus (MVN) at various times after unilateral labyrinthectomy (UL). Immediately after UL, in close correlation with the appearance of the characteristic oculomotor and postural symptoms, there is a marked increase in GABA release in the ipsi-lesional MVN. This is not prevented by bilateral flocculectomy, indicating that it is due to hyperactivity of vestibular commissural inhibitory neurones. Over the following 96 h, as VC occurs and the behavioural symptoms ameliorate, the ipsi-lesional GABA levels return to near-normal. Contra-lesional GABA levels do not change significantly in the initial stages of VC, but decrease at late stages so that when static symptoms have abated there remains a significant difference between the MVNs of the two sides. We also investigated the role of the commissural inhibition in Bechterew's phenomenon, by reversibly inactivating the intact contra-lesional labyrinth in compensating animals through superfusion of local anaesthetic on the round window. Transient inactivation of the intact labyrinth elicited the lateralized behaviour described by Bechterew, but did not alter the GABA levels in either MVN, suggesting the involvement of distinct cellular mechanisms. These findings indicate that an imbalanced commissural inhibitory system is a root cause of the severe oculomotor and postural symptoms of unilateral vestibular loss, and that re-balancing of commissural inhibition occurs in parallel with the subsequent behavioural recovery during VC.
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| 2. |
- Olabi, Bayanne, et al.
(författare)
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Rebalancing the commissural system: mechanisms of vestibular compensation.
- 2009
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Ingår i: Journal of vestibular research : equilibrium & orientation. - 1878-6464. ; 19:5-6, s. 201-7
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Forskningsöversikt (refereegranskat)abstract
- Vestibular compensation after unilateral vestibular loss is a complex, multi-factored process involving synaptic and neuronal plasticity in many areas of the brain, and it is a challenge to identify the key sites of plasticity that determine the rate and extent of behavioural recovery. Experimental evidence strongly implicates the vestibular commissural inhibitory system which links the brainstem vestibular nuclei of the two sides, both in causing the initial severe oculomotor and postural symptoms of vestibular deafferentation, and in the subsequent recovery that takes place in the early stages of compensation. Of particular interest are changes in GABAergic neurotransmission within the commissural system, and the possibility that histaminergic drugs as well as stress steroids and neurosteroids that can modulate compensation, may do so at least in part by their effects on commissural inhibition. A fuller understanding of the role of the commissural system in compensation and the effects of GABAergic neuromodulators is likely to reveal the mechanisms of action of histamine in the vestibular system and the interactions between stress, anxiety and vestibular dysfunction.
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| 3. |
- Samoudi, Ghazaleh, et al.
(författare)
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Noisy galvanic vestibular stimulation promotes GABA release in the substantia nigra and improves locomotion in hemiparkinsonian rats.
- 2012
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The vestibular system is connected to spinal, cerebellar and cerebral motor control structures and can be selectively activated with external electrodes. The resulting sensation of disturbed balance can be avoided by using stochastic stimulation patterns. Adding noise to the nervous system sometimes improves function. Small clinical trials suggest that stochastic vestibular stimulation (SVS) may improve symptoms in Parkinson's disease. We have investigated this claim and possible mechanisms using the 6-hydroxydopamine (6-OHDA) hemilesion model of Parkinson's disease.
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