Crane B T, Viirre E S, Demer J L
Department of Ophthalmology, University of California, Los Angeles 90095-7002, USA.
Exp Brain Res. 1997 Apr;114(2):304-20. doi: 10.1007/pl00005639.
We employed binocular magnetic search coils to study the vestibulo-ocular reflex (VOR) and visually enhanced vestibulo-ocular reflex (VVOR) of 15 human subjects undergoing passive, whole-body rotations about a vertical (yaw) axis delivered as a series of pseudorandom transients and sinusoidal oscillations at frequencies from 0.8 to 2.0 Hz. Rotations were about a series of five axes ranging from 20 cm posterior to the eyes to 10 cm anterior to the eyes. Subjects were asked to regard visible or remembered targets 10 cm, 25 cm, and 600 cm distant from the right eye. During sinusoidal rotations, the gain and phase of the VOR and VVOR were found to be highly dependent on target distance and eccentricity of the rotational axis. For axes midway between or anterior to the eyes, sinusoidal gain decreased progressively with increasing target proximity, while, for axes posterior to the otolith organs, gain increased progressively with target proximity. These effects were large and highly significant. When targets were remote, rotational axis eccentricity nevertheless had a small but significant effect on sinusoidal gain. For sinusoidal rotational axes midway between or anterior to the eyes, a phase lead was present that increased with rotational frequency, while for axes posterior to the otolith organs phase lag increased with rotational frequency. Transient trials were analyzed during the first 25 ms and from 25 to 80 ms after the onset of the head rotation. During the initial 25 ms of transient head rotations, VOR and VVOR gains were not significantly influenced by rotational eccentricity or target distance. Later in the transient responses, 25-80 ms from movement onset, both target distance and eccentricity significantly influenced gain in a manner similar to the behavior during sinusoidal rotation. Vergence angle generally remained near the theoretically ideal value during illuminated test conditions (VVOR), while in darkness vergence often varied modestly from the ideal value. Regression analysis of instantaneous VOR gain as a function of vergence demonstrated only a weak correlation, indicating that instantaneous gain is not likely to be directly dependent on vergence. A model was proposed in which linear acceleration as sensed by the otoliths is scaled by target distance and summed with angular acceleration as sensed by the semicircular canals to control eye movements. The model was fit to the sinusoidal VOR data collected in darkness and was found to describe the major trends observed in the data. The results of the model suggest that a linear interaction exists between the canal and otolithic inputs to the VOR.
我们使用双眼磁性搜索线圈来研究15名人类受试者的前庭眼反射（VOR）和视觉增强前庭眼反射（VVOR）。这些受试者进行围绕垂直（偏航）轴的被动全身旋转，旋转以一系列伪随机瞬态和频率在0.8至2.0赫兹的正弦振荡形式进行。旋转围绕一系列五个轴进行，范围从眼睛后方20厘米到眼睛前方10厘米。受试者被要求注视距离右眼10厘米、25厘米和600厘米的可见或记忆中的目标。在正弦旋转期间，发现VOR和VVOR的增益和相位高度依赖于目标距离和旋转轴的偏心度。对于眼睛之间或眼睛前方的轴，正弦增益随着目标距离的增加而逐渐降低，而对于耳石器官后方的轴，增益随着目标距离的增加而逐渐增加。这些效应很大且非常显著。当目标较远时，旋转轴偏心度对正弦增益仍有微小但显著的影响。对于眼睛之间或眼睛前方的正弦旋转轴，存在一个随旋转频率增加的相位超前，而对于耳石器官后方的轴，相位滞后随旋转频率增加。在头部旋转开始后的前25毫秒以及25至80毫秒期间对瞬态试验进行了分析。在瞬态头部旋转的最初25毫秒内，VOR和VVOR增益不受旋转偏心度或目标距离的显著影响。在瞬态反应的后期，即运动开始后的25 - 80毫秒，目标距离和偏心度都以与正弦旋转期间的行为类似的方式显著影响增益。在光照测试条件下（VVOR），聚散角通常保持在理论理想值附近，而在黑暗中聚散角常常与理想值有适度差异。对瞬时VOR增益作为聚散函数的回归分析仅显示出微弱的相关性，表明瞬时增益不太可能直接依赖于聚散。提出了一个模型，其中耳石所感知的线性加速度按目标距离进行缩放，并与半规管所感知的角加速度相加，以控制眼球运动。该模型与在黑暗中收集的正弦VOR数据拟合，发现能够描述数据中观察到的主要趋势。模型结果表明，VOR的半规管输入和耳石输入之间存在线性相互作用。
