Coordination des Mouvements Oculaires dans l'Espace 3D chez l'Homme : substrat Cortical Étudié par TMS

Abstract : Any gaze shift in 3D space is divided in one conjugate component (equal direction for both eyes) and another disconjugate (opposed directions). This division reflects the activation of separate systems, which however interact. We assume that this interaction, traditionally localized in the brainstem, takes place at multiple levels from the cortex and is activated for all eye movements. With the method of transcranial magnetic stimulation (TMS), the interaction is examined in the initiation of eye movements combining saccades and divergence and in the binocular coordination of saccades. During combined movements, there is a mutual influence for the triggering of saccades and divergence. The TMS of posterior parietal cortex (PPC) delays the initiation of unpredictable movements but not of predictable ones: the same areas, parietal or frontal according to the predictability, coordinate the triggering of both components. Reading is based on automated sequences of saccades, during which coordination is optimized, at least in young adults with good binocular vision. The TMS of PPC disturbs the binocular coordination of isolated saccades and of entire reading sequences of saccades. For the first time, we show that binocular coordination is also cortical. The results suggest a permanent cortical interaction between the saccade and vergence systems. Regulation of coordination throughout life is based on plasticity and learning of this interaction. The thesis has clinical implication for the reeducation of people with coordination deficits.
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Submitted on : Tuesday, February 23, 2010 - 4:43:41 PM
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  • HAL Id : tel-00459341, version 1

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Marine Vernet. Coordination des Mouvements Oculaires dans l'Espace 3D chez l'Homme : substrat Cortical Étudié par TMS. Neurosciences [q-bio.NC]. Université Pierre et Marie Curie - Paris VI, 2009. Français. ⟨tel-00459341⟩

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