Vestibular-visual interactions in balance and orientation
Multiple Paper Presentation

Richard Fitzpatrick
Prince of Wales Medical Research Institute

Daina Sturnieks
Prince of Wales Medical Research Institute

Rebecca St George
Prince of Wales Medical Research Institute

Daniel Wardman

     Abstract ID Number: 127
     Last modified: June 4, 2007
     Presentation date: 07/07/2007 2:00 PM in Quad General Lecture Theatre
     (View Schedule)

Abstract
We have argued that galvanic vestibular stimulation (GVS) delivers a pure vestibular perturbation without affecting other sensory channels. Two experiments reveal GVS vestibular-visual interactions important for postural control and orientation. The first study shows that GVS evokes visual as well as vestibular balance responses. When GVS was delivered to standing subjects with the eyes, but not the head, turned to the side, the normal GVS sway response was turned towards the gaze direction, but only with the eyes open. The same was seen for GVS with prism glasses that turned the visual field. As GVS produces ocular torsion though the VOR, it also provides a visual signal that produces secondary postural corrections. Unlike the visual signal, the semicircular canal signal has no absolute reference to external space. The second study shows that the orientation response to GVS is calibrated to prior visual signals. During an initial walk with eyes shut, GVS caused subjects to turn. On opening the eyes, they walked straight ahead despite GVS. On shutting the eyes again, the GVS caused only a slight turn but a large turn when the polarity was reversed, indicating that the vestibular signal was calibrated to straight ahead during the eyes-open period.

To be Presented at the Following Symposium:
Multisensory mechanisms of posture control
Other papers in this Symposium:

• Brian Day
  MRC Human Movement Group, Sobell Department for Motor Neuroscience and Movement Disorders, Institute of Neurology, UCL, London
  Michel Guerraz
  Laboratoire de Psychologie et Neurocognition CNRS UMR 5105 Université de Savoie, France.
  Feedforward versus feedback modulation of human vestibular-evoked balance responses by visual self-motion information
• Stephen Lord
  Prince of Wales Medical Research Institute
  Annie Butler
  Richard Fitzpatrick
  PROPRIOCEPTION, STRENGTH AND STANDING
• Rebecca St George
  Prince of Wales Medical Research Institute
  Richard Fitzpatrick
  Prince of Wales Medical Research Institute
  Perceptions of orientation after vestibular, visual and proprioceptive conditioning
• Ian Curthoys
  Psychology, University of Sydney
  Hamish MacDougall
  Psychology, University of Sydney
  Dena Attalla
  Psychology, University of Sydney
  Fabienne MBongo
  LNRS, Universite Paris
  Pierre-Paul Vidal
  LNRS, Universite Paris
  Catherine de Waele
  LNRS, Universite Paris
  Human head and body stability after unilateral vestibular loss