Inactivation of semicircular canals causes adaptive increases in otolith-driven tilt responses.
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.
Angelaki
Dora E
DE
Department of Neurobiology, Washington University School of Medicine, 600 S. Euclid Ave., St. Louis, MO 63110, USA. angelaki@pcg.wustl.edu
Newlands
Shawn D
SD
Dickman
J David
JD
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D005133:Eye Movements / Q000502:physiology; D018466:Gravity Sensing / Q000502:physiology; D008253:Macaca mulatta; D010037:Otolithic Membrane / Q000502:physiology*; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology; D012399:Rotation; D012665:Semicircular Canals / Q000502:physiology*; D013028:Space Perception / Q000502:physiology; D014102:Torsion Abnormality