HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 96/2/925    most recent 01250.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Aw, S. T. Articles by Halmagyi, G. M. Search for Related Content PubMed PubMed Citation Articles by Aw, S. T. Articles by Halmagyi, G. M.

REPORT

Latency and Initiation of the Human Vestibuloocular Reflex to Pulsed Galvanic Stimulation

Neurology Department, Royal Prince Alfred Hospital, Sydney, Australia

Submitted 30 November 2005; accepted in final form 27 March 2006

Cathodal galvanic currents activate primary vestibular afferents, whereas anodal currents inhibit them. Pulsed galvanic vestibular stimulation (GVS) was used to determine the latency and initiation of the human vestibuloocular reflex. Three-dimensional galvanic vestibuloocular reflex (g-VOR) was recorded with binocular dual-search coils in response to a bilateral bipolar 100-ms rectangular pulse of current at 0.9 (near-threshold), 2.5, 5.0, 7.5, and 10.0 mA in 11 normal subjects. The g-VOR consisted of three components: conjugate torsional eye rotation away from cathode toward anode; vertical divergence (skew deviation) with hypertropia of the eye on the cathodal and hypotropia of the eye on the anodal sides; and conjugate horizontal eye rotation away from cathode toward anode. The g-VOR was repeatable across all subjects, its magnitude a linear function of the current intensity, its latency about 9.0 ms with GVS of 2.5 mA, and was not suppressed by visual fixation. At 10-mA stimulation, the g-VOR [x, y, z] on the cathodal side was [0.77 ± 0.10, –0.05 ± 0.05, –0.18 ± 0.06°] (mean ± 95% confidence intervals) and on the anodal side was [0.79 ± 0.10, 0.16 ± 0.05, –0.19 ± 0.06°], with a vertical divergence of 0.20°. Although the horizontal g-VOR could have arisen from activation of the horizontal semicircular canal afferents, the vertical-torsional g-VOR resembled the vestibuloocular reflex in response to roll-plane head rotation about an Earth-horizontal axis and might be a result of both vertical semicircular canal and otolith afferent activations. Pulsed GVS is a promising technique to investigate latency and initiation of the human vestibuloocular reflex because it does not require a large mechanical apparatus nor does it pose problems of head inertia or slippage.

This article has been cited by other articles:

				S. T. Aw, M. J. Todd, G. E. Aw, K. P. Weber, and G. M. Halmagyi Gentamicin vestibulotoxicity impairs human electrically evoked vestibulo-ocular reflex Neurology, November 25, 2008; 71(22): 1776 - 1782. [Abstract] [Full Text] [PDF]

				G. M. L. Son, J.-S. Blouin, and J. T. Inglis Short-duration galvanic vestibular stimulation evokes prolonged balance responses J Appl Physiol, October 1, 2008; 105(4): 1210 - 1217. [Abstract] [Full Text] [PDF]