Affiliations: [a] Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA, 15213, USA | [b] Department of Otolaryngology, St. Marianna University School of Medicine, Kanagawa, Japan
Note: [*] Correspondence to: Joseph M. Furman, MD, PhD, Department of Otolaryngology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213 USA. Tel.: +1 412 647 2117;
Fax: +1 412 647 2080; E-mail: furman@pitt.edu
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∘/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.
Keywords: human otolith vestibulo-ocular reflex, velocity storage
