The Journal of Neurophysiology Vol. 87 No. 3 March 2002, pp. 1635-1640
Copyright ©2002 by the American Physiological Society

RAPID COMMUNICATION

Inactivation of Semicircular Canals Causes Adaptive Increases in Otolith-Driven Tilt Responses

 ¹Department of Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110;  ²Department of Otolaryngology, University of Texas Medical Branch, Galveston, Texas 77550; and  ³Department of Research, Central Institute for the Deaf, St. Louis, Missouri 63110

Angelaki, Dora E., Shawn D. Newlands, and J. David Dickman. Inactivation of Semicircular Canals Causes Adaptive Increases in Otolith-Driven Tilt Responses. J. Neurophysiol. 87: 1635-1640, 2002. Growing experimental and theoretical evidence suggests a functional synergy in the processing of otolith and semicircular canal signals for the generation of the vestibulo-ocular reflexes (VORs). In this study we have further tested this functional interaction by quantifying the adaptive changes in the otolith-ocular system during both rotational and translational movements after surgical inactivation of the semicircular canals. For 0.1-0.5 Hz (stimuli for which there is no recovery of responses from the plugged canals), pitch and roll VOR gains recovered during earth-horizontal (but not earth-vertical) axis rotations. Corresponding changes were also observed in eye movements elicited by translational motion (0.1-5 Hz). Specifically, torsional eye movements increased during lateral motion, whereas vertical eye movements increased during fore-aft motion. The findings indicate that otolith signals can be adapted according to a compromised strategy that leads to improved gaze stabilization during motion. Because canal-plugged animals permanently lose the ability to discriminate gravitoinertial accelerations, adapted animals can use the presence of gravity through otolith-driven tilt responses to assist gaze stabilization during earth-horizontal axis rotations.