Latency of cross-axis vestibulo-ocular reflex induced by pursuit training in monkeys

To examine the latency of smooth pursuit induced, short-term modifications of the vestibule-ocular reflex (VOR), Japanese monkeys were rewarded for tr acking a vertically moving target spot synchronized with horizontal whole b ody rotation. Eye movements induced by equivalent rotation in complete dark ness were examined before and after training. Before training, the horizont al trapezoidal rotation (peak acceleration similar to 780 degrees/s(2)) res ulted in a collinear VOR with a mean latency of 15.3 ms, and no orthogonal component in any of the three monkeys tested. After training, the collinear VOR remained unchanged but an orthogonal, cross-axis VOR developed. It had a mean latency of 42.4 ms with gain (eye/chair) of 0.19, followed by a dec aying phase that had a mean time constant of 80 ms. These results suggest t hat the cross-axis VOR induced by pursuit-vestibular interaction is differe nt from previously reported cross-axis VOR induced by optokinetic-vestibula r interaction. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.