Adaptive changes in smooth pursuit eye movements induced by cross-axis pursuit-vestibular interaction training in monkeys

• Published in: Experimental brain research 2001-08, Vol.139 (4), p.473-481
• Main Authors: FUKUSHIMA, Kikuro, WELLS, Stephen G, YAMANOBE, Takanobu, TAKEICHI, Norihito, SHINMEI, Yasuhiro, FUKUSHIMA, Junko
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological - physiology; Animals; Biological and medical sciences; Eye; Eye movements; Feedback; Fundamental and applied biological sciences. Psychology; Latency; Macaca; Male; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Motor Skills - physiology; Movement - physiology; Photic Stimulation; Pursuit, Smooth - physiology; Rotation; Smooth pursuit eye movements; Velocity; Vertebrates: nervous system and sense organs; Vestibular system; Vestibule, Labyrinth - physiology; Vestibulo-ocular reflex; Visual perception
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s002210100792

The smooth pursuit system interacts with the vestibular system to maintain the accuracy of eye movements in space. To understand neural mechanisms of short-term modifications of the vestibulo-ocular reflex (VOR) induced by pursuit-vestibular interactions, we used a cross-axis procedure in trained monkeys. We showed earlier that pursuit training in the plane orthogonal to the rotation plane induces adaptive cross-axis VOR in complete darkness. To further study the properties of adaptive responses, we examined here the initial eye movements during tracking of a target while being rotated with a trapezoidal waveform (peak velocity 30 or 40 degrees/s). Subjects were head-stabilized Japanese monkeys that were rewarded for accurate pursuit. Whole body rotation was applied either in the yaw or pitch plane while presenting a target moving in-phase with the chair with the same trajectory but in the orthogonal plane. Eye movements induced by equivalent chair rotation with or without the target were examined before and after training. Before training, chair rotation alone resulted only in the collinear VOR, and smooth eye movement-tracking of orthogonal target motion during rotation had a normal smooth pursuit latency (ca 100 ms). With training, the latency of orthogonal smooth tracking eye movements shortened, and the mean latency after 1 h of training was 42 ms with a mean gain, at 100 ms after stimulus onset, of 0.4. The cross-axis VOR induced by chair rotation in complete darkness had identical latencies with the orthogonal smooth tracking eye movements, but its gains were