Eye-position Dependence of Torsional Velocity During Step-ramp Pursuit and Transient Yaw Rotation in Humans.
From: Department of Neurology, The Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Pathology 2-210, Baltimore, MD, 21287, USA.
Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale
- Publish Date: May 2006
- ISSN: 0014-4819
- Volume: 171
- Issue: 2
- Pages: 225-30
- Medium: Print
- Language: English
- Citation (JAMA): Tian Jing, Zee David S, Walker Mark F, et al. Eye-position Dependence of Torsional Velocity During Step-ramp Pursuit and Transient Yaw Rotation in Humans.. May 2006;171:225-30
Abstract
The time course of eye-position-dependent torsion during transient horizontal pursuit and yaw rotation was examined in seven normal human subjects. The stimuli consisted of step-ramp target motion (25, 40 degrees /s) and brief chair rotation (approximately 200 degrees /s(2) accelerated to 40 degrees /s) at three different vertical positions (center 0 degrees , up or down 15 degrees ). Three-dimensional eye movements were recorded with dual search coils. The kinematics of pursuit and the rotational vestibulo-ocular reflex (rVOR) were assessed by determining the tilt-angle slope, a measure of the variation of the axis of eye-velocity with vertical eye position. We found that the tilt-angle slope during pursuit was initially 0.4+/-0.07 (mean+/-95% confidence interval) and then gradually rose to 0.64+/-0.04, at about the time that the steady-state eye-velocity was reached. The rVOR began with a nearly head-fixed axis (0.08+/-0.04), appropriate for full retinal image stabilization, followed by a gradual increase of the tilt-angle slope to 0.31+/-0.02. Thus, differences between pursuit and the rVOR with respect to Listing’s law can be seen from the onset of transient responses, although in both cases eye-position-dependent torsion increases with time. This temporal evolution of the axis of eye-velocity may involve the velocity-storage mechanism.
Mesh Headings (Keywords): Adult, Analysis of Variance, Biomechanics, Eye, Humans, Middle Aged, Pursuit, Smooth, Reflex, Vestibulo-Ocular, Rotation, Time Factors, Torsion Abnormality
Check for Full Text / PubMed Unique Identifier (PMID): 16307248
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