Vestibular Perception and Action Employ Qualitatively Different Mechanisms. II. VOR and Perceptual Responses During CombinedTilt&Translation

• DOI: 10.1152/jn.00905.2004
• Publication Date: 2005-02-24T01:30:45Z
• Authors: Daniel M. Merfeld; Sukyung Park; Claire Gianna-Poulin; F. Owen Black; Scott Wood
• Keywords: Adult; Male; 0301 basic medicine; Eye Movements; Rotation; Acceleration; Motion Perception; Reflex, Vestibulo-Ocular; Middle Aged; 410; 03 medical and health sciences; 0302 clinical medicine; Psychophysics; Humans; Female; Gravity Sensing

II. VOR and perceptual responses during combined Tilt&Translation. To compare and contrast the neural mechanisms that contribute to vestibular perception and action, we measured vestibuloocular reflexes (VOR) and perceptions of tilt and translation. We took advantage of the well-known ambiguity that the otolith organs respond to both linear acceleration and tilt with respect to gravity and investigated the mechanisms by which this ambiguity is resolved. A new motion paradigm that combined roll tilt with inter-aural translation (“ Tilt&Translation”) was used; subjects were sinusoidally (0.8 Hz) roll tilted but with their ears above or below the rotation axis. This paradigm provided sinusoidal roll canal cues that were the same across trials while providing otolith cues that varied linearly with ear position relative to the earth-horizontal rotation axis. We found that perceived tilt and translation depended on canal cues, with substantial roll tilt and inter-aural translation perceptions reported even when the otolith organs measured no inter-aural force. These findings match internal model predictions that rotational cues from the canals influence the neural processing of otolith cues. We also found horizontal translational VORs that varied linearly with radius; a minimal response was measured when the otolith organs transduced little or no inter-aural force. Hence, the horizontal translational VOR was dependent on otolith cues but independent of canal cues. These findings match predictions that translational VORs are elicited by simple filtering of otolith signals. We conclude that internal models govern human perception of tilt and translation at 0.8 Hz and that high-pass filtering governs the human translational VOR at this same frequency.