Hess Bernhard J M, Angelaki Dora E
Department of Neurology, University Hospital Zurich, CH-8091 Zurich, Switzerland.
J Neurophysiol. 2003 Sep;90(3):1996-2004. doi: 10.1152/jn.00302.2003. Epub 2003 May 28.
The accuracy with which the vestibular system anticipates and compensates for the visual consequences of translation during forward and backward movements was investigated with transient motion profiles in rhesus monkeys trained to fixate targets on an isovergence screen. Early during motion when visuomotor reflexes remain relatively ineffective and vestibular-driven mechanisms have an important role for controlling the movement of the eyes, a large asymmetry was observed for forward and backward heading directions. During forward motion, ocular velocity gains increased steeply and reached near unity gains as early as 40-50 ms after motion onset. In addition, instantaneous directional errors also remained <10 degrees for forward headings. In contrast, backward motion was characterized by smaller vestibular gains and larger directional errors during the first 70 ms of the movement. To evaluate the accumulated retinal slip and vergence errors during the early epochs of motion when vestibular-driven mechanisms dominate gaze stability, the movement of a virtual fixation point defined by the intersection of the two gaze lines was quantitatively compared with the respective movement of the extinguished target in head coordinates. Both conjugate retinal slip and vergence errors were <0.2 degrees during the first 70 ms of the movement, with forward motion conjugate errors typically being smaller as compared with backward motion directions. Thus vestibularly driven gaze stabilization mechanisms can effectively minimize conjugate retinal slip errors as well as keep binocular disparity errors low during the open loop interval of head movement.
通过在恒河猴身上训练其在等辐辏屏幕上注视目标时使用瞬态运动轮廓，研究了前庭系统预测和补偿向前和向后运动过程中平移视觉后果的准确性。在运动早期，当视觉运动反射仍然相对无效且前庭驱动机制在控制眼球运动中起重要作用时，观察到向前和向后的航向方向存在很大的不对称性。在向前运动期间，眼速度增益急剧增加，早在运动开始后40 - 50毫秒就达到接近单位增益。此外，对于向前的航向，瞬时方向误差也保持在<10度。相比之下，向后运动的特点是在前70毫秒的运动中前庭增益较小且方向误差较大。为了评估在前庭驱动机制主导注视稳定性的运动早期阶段累积的视网膜滑动和辐辏误差，将由两条注视线交点定义的虚拟注视点的运动与头部坐标系中熄灭目标的相应运动进行了定量比较。在运动的前70毫秒内，共轭视网膜滑动和辐辏误差均<0.2度，与向后运动方向相比，向前运动的共轭误差通常较小。因此，在前庭驱动的注视稳定机制可以在头部运动的开环间隔期间有效地最小化共轭视网膜滑动误差，并保持双眼视差误差较低。
