Neuroscience 2003 Abstract
| Presentation Number: | 391.15 |
|---|---|
| Abstract Title: | Pulley shifts explain vertical disconjugacy of horizontal angular vestibulo-ocular reflex (AVOR) during convergence and vertical gaze. |
| Authors: |
Tian, J.*1
; Demer, J. L.1,2
1Ophthalmol, David Geffen Med. Sch. at UCLA, Los Angeles, CA 2Neurol., David Geffen Med. Sch. at UCLA, Los Angeles, CA |
| Primary Theme and Topics |
Motor Systems - Oculomotor -- Physiology |
| Secondary Theme and Topics | Motor Systems<br />- Oculomotor<br />-- Anatomy |
| Session: |
391. Anatomy & Physiology Poster |
| Presentation Time: | Monday, November 10, 2003 10:00 AM-11:00 AM |
| Location: | Morial Convention Center - Hall F-I, Board # I6 |
| Keywords: | EYE MOVEMENT, KINEMATICS, OCULOMOTOR, VESTIBULAR |
If rectus extraocular muscle pulleys provide predominantly mechanical determinants of ocular kinematics, then pulley locations should predict behavior. We tested predictions of vertical disconjugacy of the horizontal aVOR in situations where magnetic resonance imaging (MRI) demonstrates horizontal rectus pulley misalignment (Demer et al. JNP 89:2072, 2003). Binocular eye movements were recorded using search coils in humans undergoing transient, whole-body yaw rotation (2,800°/s2 peak) in darkness while fixating straight ahead, as well as ± 20° vertically, at distances of 500 and 15 cm. Four subjects achieved large, uninterrupted horizontal slow phases. During unconverged viewing, MRI shows that the lateral rectus pulley shifts inferiorly relative to medial rectus in up gaze, but superiorly in down gaze. During 500 cm viewing, the eyes rotated 31° horizontally by 275 ms. The adducting eye moved up relative to the abducting eye by 1.39 ± 0.19° (SEM) in up gaze, but 0.71 ± 0.38° downward in down gaze (P < 0.02), consistent with pulley shift. During convergence, MRI shows extorsion of pulleys to increase in down and reverse in up gaze. With the 15 cm target, the eyes rotated 22° horizontally by 200 ms. In convergence gazing down, the adducting eye moved upward relative to the abducting eye 1.51±0.71°, but as predicted moved downward 1.13±0.44° in up gaze (P < 0.02). Confirmations of predicted vertical aVOR disconjugacy and its reversal in convergence support the idea that shifts of rectus pulleys influence kinematics for all eye movements.
Supported by EY08313, DC005224, & RPB
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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