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Theses

Propriétés électrophysiologiques intrinsèques des neurones vestibulaires centraux en conditions physiologiques et physiopathologiques

Abstract : The rationale of this thesis is to investigate both the resting and the dynamical properties of central vestibular neurons. A principal objective of this work is to determine the functional properties of different populations of neurons within a particular nucleus. In particular, two neuronal groups in the medial vestibular nucleus (MVN), type A and type B, having different action potential profiles, were investigated to evaluate their resting and dynamical properties. In order to address these issues, we compared different central vestibular neurons recorded under several experimental conditions. Namely, we studied (1) the behaviour of normal MVN neurons, (2) the plasticity of the intrinsic properties of MVN neurons after lesions, (3) the properties of vestibular neurons located in the lateral nucleus, and finally (4) the characterictics of vestibular neurons in another species, the frog. For (1) and (2), long term studies of the plasticity of MVN neurons intrinsic properties following unilateral labyrinthectomy showed that the lesion differentially affects ipsi and contralesional neurons. Ipsilesional MVN neurons developed more tonic discharge properties while contralesional MVN neurons evolved towards more phasic discharge properties. From a functional point of view, some of these neural modifications might help to restore the deficits triggered by the lesion, whereas others will indefinitly impaire the behaviour. On (3), a comparison of the normal electrophysiological intrinsic properties of MVN neurons and of the giant Deiters' neurons located in the lateral vestibular nuclei recorded in control conditions was performed. This shows that a particular function of neurons appears to be directly correlated with its electrophysiological intrinsic properties. Finally in (4), the properties of guinea-pig and frog central vestibular neurons were compared. Central vestibular pathways are organized in complementary, frequency tuned channels. The neuronal populations constituting those overlapping channels were involved in common motor tasks. These studies suggest that in both frog and guinea-pig, the central vestibular system consists of essentially linear tonic neurons and more nonlinear phasic neurons. Thus it would appear that the basic organization of the vestibular system is conserved throughout Vertebrates. These results are interpreted within the framework of a coadaptation between the intrinsic electrophysiological properties and the synaptic inputs for particular neurons.
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Theses
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https://tel.archives-ouvertes.fr/tel-00007257
Contributor : Mathieu Beraneck <>
Submitted on : Friday, October 29, 2004 - 11:50:26 AM
Last modification on : Tuesday, December 8, 2020 - 3:42:51 AM
Long-term archiving on: : Thursday, September 13, 2012 - 12:35:08 PM

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  • HAL Id : tel-00007257, version 1

Citation

Mathieu Beraneck. Propriétés électrophysiologiques intrinsèques des neurones vestibulaires centraux en conditions physiologiques et physiopathologiques. Neurosciences [q-bio.NC]. Université Pierre et Marie Curie - Paris VI, 2004. Français. ⟨tel-00007257⟩

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