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This Article Full Text Full Text (PDF) All Versions of this Article: 582/1/153    most recent jphysiol.2007.132092v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Day, B. L. Articles by Guerraz, M. Search for Related Content PubMed PubMed Citation Articles by Day, B. L. Articles by Guerraz, M. Related Collections Neuroscience

¹ MRC Human Movement Group, Sobell Department for Motor Neuroscience and Movement Disorders, Institute of Neurology, UCL, Queen Square, London WC1N 3BG, UK
² Laboratoire de Psychologie et Neurocognition CNRS UMR 5105 Université de Savoie, 73376 Le Bourget du lac, France

Visual information modulates the balance response evoked by a pure vestibular perturbation (galvanic vestibular stimulation, GVS). Here we investigate two competing hypotheses underlying this visual–vestibular interaction. One hypothesis assumes vision acts in a feedforward manner by altering the weight of the vestibular channel of balance control. The other assumes vision acts in a feedback manner through shifts in the retinal image produced by the primary response. In the first experiment we demonstrate a phenomenon that is predicted by both hypotheses: the GVS-evoked balance response becomes progressively smaller as the amount of visual self-motion information is increased. In the second experiment we independently vary the pre-stimulus and post-stimulus visual environments. The rationale is that feedback effects would depend only upon the post-stimulus visual environment. Although the post-stimulus visual environment did affect later parts of the response (after 400 ms), the pre-stimulus visual environment had a strong influence on the size of the early part of the response. We conclude that both feedforward and feedback mechanisms act in concert to modulate the GVS-evoked response. We suggest this dual interaction that we observe between visual and vestibular channels is likely to apply to all sensory channels that contribute to balance control.

(Received 9 March 2007; accepted after revision 18 April 2007; first published online 19 April 2007)
Corresponding author B. L. Day: MRC Human Movement Group, Sobell Department for Motor Neuroscience and Movement Disorders, Institute of Neurology, UCL, Queen Square, London WC1N 3BG, UK. Email: b.day{at}ion.ucl.ac.uk