title: Characteristics of secondary phase post-rotatory nystagmus following off-vertical axis rotation in humans.
abstract: The nystagmus following yaw earth-vertical axis rotation often reverses direction, a phenomenon known as the "secondary phase". The purpose of this study was to examine the existence and the spatial and temporal properties of the secondary phase of post-rotatory nystagmus following off-vertical axis rotation (OVAR). Eleven normal human subjects were rotated at 120 or 180 degrees/s about an off-vertical axis and stopped in the left ear down or right ear down lateral position. Horizontal and vertical eye positions were recorded with a scleral search coil, and horizontal and vertical slow component eye velocities were computed. Our results indicate that (a) there is a robust secondary phase nystagmus following OVAR, and (b) the direction of the secondary phase nystagmus tends to align with earth-horizontal. These results can be explained by a minor modification of an existing VOR model that has been shown to produce secondary phase responses.
authors.affiliation: Department of Otolaryngology, University of Pittsburgh, PA 15213, USA. furman@pitt.edu
authors.forename: J M
authors.initials: JM
authors.lastname: Furman
authors.forename: I
authors.initials: I
authors.lastname: Koizuka
authors.forename: R H
authors.initials: RH
authors.lastname: Schor
mesh_terms: D000328:Adult; D005260:Female; D018475:Head-Down Tilt; D006801:Humans; D008297:Male; D009759:Nystagmus, Pathologic / Q000503:physiopathology*; D012399:Rotation; D013997:Time Factors