Large gaze shift generation whilst standing up - the role of the vestibular system

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Title: Large gaze shift generation whilst standing up - the role of the vestibular system
Authors: Anastasopoulos, D
Ziavra, N
Bronstein, A
Item Type: Journal Article
Abstract: The functional significance of vestibular information for the generation of gaze shifts is controversial and less well established than the vestibular contribution to gaze stability. Here, we asked seven bilaterally avestibular patients to execute voluntary, whole-body pivot turns to visual targets up to 180° whilst standing. In these conditions not only the demands imposed on gaze transfer mechanisms are more challenging but also neck-proprioceptive input represents an inadequate source of head-in-space motion information. Patients' body segments motion was slower and jerky. In the absence of visual feedback, gaze advanced in small steps, closely resembling normal multiple-step gaze shift patterns but, as a consequence of the slow head motion, target acquisition was delayed. In approximately 25% of trials, however, patients moved faster but the velocity of prematurely emerging slow-phase compensatory eye movements remained lower than head-in-space velocity due to vestibulo-ocular failure. During these trials, therefore, gaze advanced towards the target without interruption but taking again longer than when normal controls use single-step gaze transfers. That is, even when patients attempted faster gaze shifts, exposing themselves to gaze instability they acquired distant targets significantly later than controls. Thus, whilst upright, loss of vestibular information not only disrupts gaze stability but also gaze transfers. The slow and ataxic head and trunk movements introduce significant foveation delays. These deficits explain patients' symptoms during upright activities and show, for the first time, the clinical significance of losing the so called "anti-compensatory" (gaze shifting) function of the vestibulo-ocular reflex.
Issue Date: 1-Nov-2019
Date of Acceptance: 4-Sep-2019
DOI: 10.1152/jn.00343.2019
ISSN: 0022-3077
Publisher: American Physiological Society
Start Page: 1928
End Page: 1936
Journal / Book Title: Journal of Neurophysiology
Volume: 122
Issue: 5
Copyright Statement: © the American Physiological Society. Licensed under Creative Commons Attribution CC-BY 4.0:
Sponsor/Funder: Medical Research Council (MRC)
Imperial College Healthcare NHS Trust- BRC Funding
Funder's Grant Number: MR/J004685/1
RDC04 79560
Keywords: anticompensatory
bilateral vestibular loss
Neurology & Neurosurgery
11 Medical and Health Sciences
17 Psychology and Cognitive Sciences
Publication Status: Published
Online Publication Date: 2019-09-04
Appears in Collections:Faculty of Medicine

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