Early components of the human vestibulo-ocular response to head rotation: latency and gain
Early components of the human vestibulo-ocular response to head rotation: latency and gain
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DOI：
10.1152/jn.2000.84.1.376
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发表时间：
2000-07-01
影响因子：
2.5
通讯作者：
Smeets, JBJ
中科院分区：
文献类型：
--
作者：
Collewijn, H;Smeets, JBJ
为了表征在其他系统贡献最小的时间窗口内前庭-眼反射的特性，分析了正常人在扭矩头盔施加的瞬时角加速度(类似于1000度/S(2))开始后50-100ms内的眼球运动。用磁性搜索线圈记录头部和双眼的方位(分辨率，类似于1min弧度；1000个样本/S)。通常，对头部扰动的第一反应是反补偿性眼动，潜伏期为零，峰值速度为每秒几度，峰值漂移为十分之几度。这被解释为对眼球偏心旋转引起的眼眶组织线性加速的被动机械反应。响应被模拟为轨道内容物的衰减振荡(类似于13赫兹)，对于持续的线性加速，接近恒定的视线偏差。随后的补偿性眼球运动(就像头部运动一样)显示出速度的线性增加，这使得通过线性回归来估计潜伏期和增益。在适当考虑了前面的被动眼球运动后，平均VOR潜伏期(针对集中的眼睛、方向和受试者)被计算为8.6ms。两只眼睛之间的配对比较显示，与头部旋转方向相反的眼睛的潜伏期平均比同侧眼睛短1.3ms。这种高度显著的平均眼间差异归因于同侧眼通路中额外的核间外展神经元数。在最初的40-50毫秒内，平均加速度增益(眼球斜率与头部速度之比)类似于1.1。瞬时速度增益，计算为Vye(T)/Vhead(t潜伏期)，显示出逐渐向单位收敛的累积(通常在轻微超调之后)。瞬时加速度增益也趋于一致，但表现出更陡峭的积聚和更大的振荡。这种加速度和速度增益的行为可以通过将眼球运动建模为对线加速度的被动反应和主动旋转VOR的总和来解释。由于潜伏期和反代偿成分，凝视稳定从未完成。视觉目标的影响是有限的。最初的VOR与远处的目标(连续可见或中断)完全相同，处于完全黑暗中。近视目标导致VOR增益上升到一个更高的水平，但在此之后，远目标和近目标之间的差异出现的时间因个体而异。
To characterize vestibulo-ocular reflex (VOR) properties in the time window in which contributions by other systems are minimal, eye movements during the first 50-100 ms after the start of transient angular head accelerations (similar to 1000 degrees/s(2)) imposed by a torque helmet were analyzed in normal human subjects. Orientations of the head and both eyes were recorded with magnetic search coils (resolution, similar to 1 min arc; 1000 samples/s). Typically, the first response to a head perturbation was an anti-compensatory eye movement with zero latency, peak-velocity of several degrees per second, and peak excursion of several tenths of a degree. This was interpreted as a passive mechanical response to linear acceleration of the orbital tissues caused by eccentric rotation of the eye. The response was modeled as a damped oscillation (similar to 13 Hz) of the orbital contents, approaching a constant eye deviation for a sustained linear acceleration. The subsequent compensatory eye movements showed (like the head movements) a linear increase in velocity, which allowed estimates of latency and gain with linear regressions. After appropriate accounting for the preceding passive eye movements, average VOR latency (for pooled eyes, directions, and subjects) was calculated as 8.6 ms. Paired comparisons between the two eyes revealed that the latency for the eye contralateral to the direction of head rotation was, on average, 1.3 ms shorter than for the ipsilateral eye. This highly significant average inter-ocular difference was attributed to the additional internuclear abducens neuron in the pathway to the ipsilateral eye. Average acceleration gain (ratio between slopes of eye and head velocities) over the first 40-50 ms was similar to 1.1. Instantaneous velocity gain, calculated as Veye(t)/Vhead(t-latency), showed a gradual build-up converging toward unity (often after a slight overshoot). Instantaneous acceleration gain also converged toward unity but showed a much steeper build-up and larger oscillations. This behavior of acceleration and velocity gain could be accounted for by modeling the eye movements as the sum of the passive response to the linear acceleration and the active rotational VOR. Due to the latency and the anticompensatory component, gaze stabilization was never complete. The influence of visual targets was limited. The initial VOR was identical with a distant target (continuously visible or interrupted) and in complete darkness. A near visual target caused VOR gain to rise to a higher level, but the time after which the difference between far and near targets emerged varied between individuals.