Johnston J L, Sharpe J A
Neuroophthalmology Unit, Toronto Hospital Neurological Centre, University of Toronto, Ontario, Canada.
Exp Brain Res. 1994;99(2):302-8. doi: 10.1007/BF00239596.
The gain (ratio of eye velocity to head velocity) of the initial horizontal vestibulo-ocular reflex (VOR) was calculated in 12 normal subjects over 350 ms during impulsive, unpredictable whole body rotation under three conditions: (1) darkness; (2) visual enhancement of the VOR, while the subjects fixated a stationary target; and (3) visual cancellation of the reflex, while subjects fixated a target that rotated with the head. The gain of the initial 80 ms of compensatory eye movement increased significantly during visual fixation in 5 subjects and decreased during attempted VOR cancellation in 3 subjects, when compared with VOR gain in darkness. Compensatory vestibular smooth eye movements were slowed, becoming curved at the onset of VOR cancellation, at mean latencies ranging from 78 to 149 ms in individual subjects (group mean 128 ms). At about 190 ms, quick phases moved the eyes in the same direction as head and target motion. The subsequent vestibular eye movements were about 50% slower than the initial smooth eye movements, indicating more effective cancellation. Visual enhancement of the VOR can occur prior to the onset of pursuit, providing evidence that fixation and smooth pursuit are distinct ocular motor systems. Visual cancellation of the VOR also begins prior to smooth pursuit initiation and becomes more effective after the latency of smooth pursuit.
在三种条件下，对12名正常受试者在350毫秒内进行冲动性、不可预测的全身旋转时的初始水平前庭眼反射（VOR）增益（眼速度与头速度之比）进行了计算：（1）黑暗环境；（2）VOR的视觉增强，此时受试者注视一个静止目标；（3）反射的视觉抵消，此时受试者注视一个随头部旋转的目标。与黑暗环境中的VOR增益相比，5名受试者在视觉注视期间，最初80毫秒的代偿性眼球运动增益显著增加，3名受试者在试图进行VOR抵消时增益降低。代偿性前庭平稳眼球运动减慢，在VOR抵消开始时变得弯曲，个体受试者的平均潜伏期为78至149毫秒（组平均128毫秒）。在大约190毫秒时，快相使眼球向与头部和目标运动相同的方向移动。随后的前庭眼球运动比最初的平稳眼球运动慢约50%，表明抵消更有效。VOR的视觉增强可在追踪开始之前发生，这证明注视和平稳追踪是不同的眼球运动系统。VOR的视觉抵消也在平稳追踪开始之前开始，并在平稳追踪潜伏期之后变得更有效。
