[Abstract Title]. - Society for Neuroscience

especially if a correction was made for any vertical drift due to divergence (p =0.003, paired ttest).
Since gaze shifts from near-to-far are common during locomotion, we postulate that the
enhancement of OFR during divergence movements serves to stabilize the visual field when the
eyes arrive at the new fixation point.
Disclosures: A.C. Joshi, None; M.J. Thurtell, None; M.F. Walker, None; A. Serra, None; R.
Leigh , None.
Poster
264. Eye Movements: Smooth Pursuit
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 264.16/DD33
Topic: D.06.c. Eye and head control
Support: Department of Veterans Affairs
Evenor Armington Fund
NIH R01-EY06717
Title: Vertical saccadic and smooth pursuit eye movements violate Listing‟s law in normal
humans
Authors: M. J. THURTELL 1 , *M. F. WALKER 1 , A. C. JOSHI 2 , R. J. LEIGH 1 ;
1 Neurol, 2 Biomed. Engin., Case Western Reserve Univ., Cleveland, OH
Abstract: For Listing‟s law to be obeyed during eye movements, the „half-angle rule‟ must be
satisfied, such that the eye velocity axis must tilt by exactly half the angle of eye eccentricity
from primary position. In the present study, we aimed to determine how closely the half-angle
rule is obeyed during vertical compared with horizontal saccadic and smooth pursuit eye
movements. Using the magnetic search coil technique, three-dimensional eye and head rotation
data were acquired from normal humans. With the head fixed, saccades were recorded in
response to 40 deg jumps in laser target position. Horizontal saccades were recorded at five
elevations (20 deg up, 10 deg up, 0 deg, 10 deg down, and 20 deg down), while vertical saccades
were recorded at five azimuths (20 deg left, 10 deg left, 0 deg, 10 deg right, and 20 deg right). In
the pursuit paradigm, subjects followed a laser target moving at 20 deg/s with a peak-to-peak
amplitude of 40 deg. Horizontal pursuit was recorded at the same elevations as for horizontal
saccades, while vertical pursuit was recorded at the same azimuths as for vertical saccades. Data
were rotated into Listing‟s coordinates and the pursuit data were desaccaded. Eye velocity axis