Citation

Fitzpatrick RC, Watson SR. J. Physiol. 2015; 593(10): 2389-2398.

Affiliation

Neuroscience Research Australia and University of New South Wales, Sydney, Australia.

Copyright

(Copyright © 2015, The Physiological Society, Publisher John Wiley and Sons)

DOI

10.1113/JP270334

PMID

25809702

Abstract

With the hypothesis that vestibular sensitivity is regulated to deal with a range of environmental motion conditions, we explored the effects of passive whole-body motion on vestibular perceptual and balance responses. In ten subjects, vestibular responses were measured before and after a period of imposed passive motion. Vestibulospinal balance reflexes during standing evoked by galvanic vestibular stimulation (GVS) were measured as shear reaction forces. Perceptual tests measured thresholds for detecting angular motion, perceptions of suprathreshold rotation, and perceptions of GVS-evoked illusory rotation. The imposed conditioning motion was 10-minutes of stochastic yaw rotation (0.5-2.5 Hz ≤ 300 deg.s(-2) ) with subjects seated. This conditioning markedly reduced reflexive and perceptual responses. The medium-latency galvanic reflex (300-350 ms) was halved in amplitude (48%; P  =  0.011) but the short-latency response was unaffected. Thresholds for detecting imposed rotation more than doubled (248%; P < 0.001) and remained elevated after 30 minutes. Over-estimation of whole-body rotation (30-180°/5 s) before conditioning was significantly reduced (41.1% to 21.5%; P  =  0.033). Conditioning reduced illusory vestibular sensations of rotation evoked by GVS (mean 113º for 10 s @ 1 mA) by 44% (P <0.01) and the effect persisted for at least one hour (24% reduced; P < 0.05). We conclude that a system of vestibular sensory autoregulation exists and that this most likely involves central and peripheral mechanisms, possibly through vestibular efferent regulation. We propose that failure of these regulatory mechanisms at different levels could lead to disorders of movement perception and balance control during standing. This article is protected by copyright. All rights reserved.

Language: en