Grigorova V K, Kornilova L N
Laboratory of Motor Control, Institute of Physiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
Aviat Space Environ Med. 1996 Oct;67(10):947-54.
We studied whether microgravity influences horizontal and vertical vestibulo-ocular reflex (VOR), and what the otolith contributes to VOR in the absence of gravity, in six cosmonauts during and after space missions.
VOR was elicited by active yaw and roll head movement at a frequency of about 0.2 Hz.
The various individual quantitative changes (increase, decrease, and left-right asymmetry) found in the horizontal VOR evoked by yaw head movements during the adaptation period to microgravity suggested central reprogramming of mechanisms controlling VOR; i.e., a non-specific effect of microgravity on VOR. At the same time, horizontal and vertical VOR's were recorded during roll head movements, which were not obvious before flight. In the consmonaut who participated in a long-term flight, the increased activity of vertical canals turned to unidirectional (downward) eye movements, independent of the head movement direction, lasting during the whole mission. These VOR changes probably resulted from the absent adequate otolith stimulation and reduced otolith influence upon semicircular canal function.
Thus, a specific effect of microgravity on VOR was observed during roll head movements, when the interaction between semicircular canals and otoliths should be more pronounced, mainly in the vertical plane. The stability of the "space" pattern of interactions in the readaptation period depended on the time spent in microgravity. We suggest that in visual-vestibular interactions revealed in VOR evoked by head movements with open eyes, vision dominates when a conflict arises between "space" and "terrestrial" patterns of sensory interactions.
我们研究了微重力是否会影响水平和垂直前庭眼反射（VOR），以及在失重状态下耳石对VOR有何作用，研究对象为六名宇航员在太空任务期间及之后的情况。
通过以约0.2赫兹的频率主动进行偏航和横滚头部运动来诱发VOR。
在适应微重力的过程中，偏航头部运动诱发的水平VOR出现了各种个体定量变化（增加、减少和左右不对称），这表明控制VOR的机制发生了中枢重新编程；即微重力对VOR有非特异性影响。同时，在横滚头部运动期间记录到了水平和垂直VOR，这在飞行前并不明显。在参与长期飞行的宇航员中，垂直半规管的活动增加转变为单向（向下）眼球运动，与头部运动方向无关，在整个任务期间持续存在。这些VOR变化可能是由于缺乏足够的耳石刺激以及耳石对半规管功能的影响减弱所致。
因此，在横滚头部运动期间观察到了微重力对VOR的特异性影响，此时半规管和耳石之间的相互作用应该更加明显，主要在垂直平面内。重新适应期内“空间”相互作用模式的稳定性取决于在微重力环境中度过的时间。我们认为，在睁眼头部运动诱发的VOR所揭示的视觉-前庭相互作用中，当“空间”和“地面”感觉相互作用模式之间出现冲突时，视觉起主导作用。
