Clément G, Andre-Deshays C, Lathan C E
Laboratoire de Physiologie Neurosensorielle du CNRS, Paris, France.
Aviat Space Environ Med. 1989 Dec;60(12):1194-8.
Recordings of horizontal and vertical eye movement were obtained on eight subjects exposed to repeated patterns of vertical and horizontal optokinetic stimulation, visual fixation with a fixed or unseen target, and voluntary head oscillation in the high force and free-fall periods of parabolic flight. The downward shift of the beating field of vertical optokinetic nystagmus (OKN) observed in previous experiments was confirmed in the present study. The same directional shift was also noticed during optokinetic after-nystagmus (OKAN). Vertical direction of gaze clearly shifted downward during the decreased gravitoinertial force level when subjects were exposed to horizontal optokinetic stimulation, or when they attempted to track an unseen target in the dark with the head stationary or actively moved up and down. A vertical nystagmus with slow phases directed upward was observed during transition from high force level to free-fall when subjects were fixating their gaze on a stationary target. These findings are in agreement with those showing a general downward drive of the eyes on the first exposure to microgravity during orbital flight and an upward drive on the first day of return. Although this drive could be a consequence of a disorientation experienced by subjects undergoing parabolic flight or by astronauts, the phenomenon also supports the hypothesis of a tonic influence exerted by the otoliths on the postural and extra-ocular musculature in order to compensate for the downward pull by the gravitoinertial forces.
对八名受试者进行了水平和垂直眼动记录，这些受试者暴露于垂直和水平视动刺激的重复模式、用固定或不可见目标进行视觉注视以及抛物线飞行的高重力和自由落体阶段的自主头部摆动中。在本研究中证实了先前实验中观察到的垂直视动性眼震（OKN）摆动场的向下偏移。在视动性后眼震（OKAN）期间也注意到了相同的方向偏移。当受试者受到水平视动刺激时，或者当他们试图在黑暗中用头部静止或上下主动移动来跟踪不可见目标时，在重力惯性力水平降低期间，垂直注视方向明显向下偏移。当受试者将目光固定在静止目标上时，在从高重力水平过渡到自由落体期间观察到了慢相向上的垂直眼震。这些发现与那些表明在轨道飞行首次暴露于微重力时眼睛普遍向下驱动以及返回第一天向上驱动的研究结果一致。尽管这种驱动可能是进行抛物线飞行的受试者或宇航员所经历的定向障碍的结果，但该现象也支持了耳石对姿势和眼外肌肉组织施加紧张性影响以补偿重力惯性力向下拉力的假设。
