Huebner W P, Leigh R J, Seidman S H, Billian C
Department of Neurology, Case Western Reserve University, University Hospitals, Cleveland, OH.
J Neurol Sci. 1993 Jun;116(2):152-64. doi: 10.1016/0022-510x(93)90320-x.
We investigated the interaction of smooth ocular pursuit (SP) and the vestibulo-ocular reflex (VOR) during horizontal, combined eye-head tracking (CEHT) in patients with abnormalities of either the VOR or SP movements. Our strategy was to apply transient stimuli that capitalized on the different latencies to onset of SP and the VOR. During CEHT of a target moving at 15 deg/sec, normal subjects and patients with VOR deficits all tracked the target with a gain close to 1.0. When the heads of normal subjects were suddenly and unexpectedly braked to a halt during CEHT, the eye promptly began to move in the orbit to track the target, but eye-in-orbit velocity transiently fell to about 60-70% of target velocity. In patients with deficient labyrinthine function, following the onset of the head brake, eye movements to track the target were absent, and SP movements were not generated until about 100 msec later. In patients with deficient SP, CEHT was superior to SP tracking with the head stationary; after the onset of the head brake, tracking eye movements were initiated promptly, but eye velocity was less than 50% of target velocity and increased only slightly thereafter. These results indicate that at least two mechanisms operate to overcome the VOR and allow gaze to track the target during CEHT: (1) the SP system provides a signal to cancel a normally-operating VOR (this cancellation signal is not needed by labyrinthine-deficient patients who have no VOR to cancel), and (2) a reduction of the gain of the VOR is achieved, an ability that is preserved even in patients with cerebral lesions that impair SP.
我们研究了前庭眼反射（VOR）或平稳视跟踪（SP）运动异常患者在水平方向联合眼头跟踪（CEHT）过程中，平稳视跟踪（SP）与前庭眼反射（VOR）之间的相互作用。我们的策略是应用短暂刺激，利用SP和VOR起始的不同潜伏期。在目标以15度/秒移动的CEHT过程中，正常受试者和VOR缺陷患者均患者均以接近1.0的增益跟踪目标。当正常受试者的头部在CEHT过程中突然意外制动停止时，眼睛立即开始在眼眶内移动以跟踪目标，但眼眶内眼速度暂时降至目标速度的约60 - 70%。在内耳功能不足的患者中，头部制动开始后，跟踪目标的眼动消失，直到约100毫秒后才产生SP运动。在SP不足的患者中，CEHT优于头部固定时的SP跟踪；头部制动开始后，跟踪眼动迅速启动，但眼速度小于目标速度的50%，此后仅略有增加。这些结果表明，在CEHT过程中至少有两种机制起作用以克服VOR并使注视跟踪目标：（1）SP系统提供信号以抵消正常运作的VOR（对于没有VOR需要抵消的内耳功能不足患者，此抵消信号不需要），以及（2）实现VOR增益的降低，即使在损害SP的脑部病变患者中这种能力也得以保留。
