Context Compensation in the Vestibuloocular Reflex During Active Head Rotations

• Published in: Journal of neurophysiology 2000-12, Vol.84 (6), p.2904-2917
• Main Authors: Medendorp, W. P, Van Gisbergen, J.A.M, Van Pelt, S, Gielen, C.C.A.M
• Format: Article
• Language: English
• Subjects: Adult; Biomechanical Phenomena; Distance Perception - physiology; Eye Movements - physiology; Feedback - physiology; Fixation, Ocular - physiology; Head Movements - physiology; Humans; Linear Models; Male; Middle Aged; Photic Stimulation; Reflex, Vestibulo-Ocular - physiology; Reproducibility of Results; Retina - physiology; Rotation; sensory integration; Space life sciences; Vision, Binocular - physiology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.2000.84.6.2904

Department of Medical Physics and Biophysics, University of Nijmegen, NL 6525 EZ Nijmegen, The Netherlands Medendorp, W. P., J.A.M. Van Gisbergen, S. Van Pelt, and C.C.A.M. Gielen. Context Compensation in the Vestibuloocular Reflex During Active Head Rotations. J. Neurophysiol. 84: 2904-2917, 2000. The vestibuloocular reflex (VOR) needs to modulate its gain depending on target distance to prevent retinal slip during head movements. We investigated gain modulation (context compensation) for binocular gaze stabilization in human subjects during voluntary yaw and pitch head rotations. Movements of each eye were recorded, both when attempting to maintain gaze on a small visual target at straight-ahead in a darkened room and after its disappearance (remembered target). In the analysis, we relied on a binocular coordinate system yielding a version and a vergence component. We examined how frequency and target distance, approached here by using vergence angle, affected the gain and phase of the version component of the VOR and compared the results to the requirements for ideal performance. Linear regression analysis on the version gain-vergence relationship yielded a slope representing the influence of target proximity and an intercept corresponding to the response at zero vergence ("default gain"). The slope of the fitted relationship, divided by the geometrically required slope, provided a measure for the quality of version context compensation ("context gain"). In both yaw and pitch experiments, we found default version gains close to one even for the remembered target condition, indicating that the active VOR for far targets is already close to ideal without visual support. In near target experiments, the presence of visual feedback yielded near unity context gains, indicating close to optimal performance (retinal slip