Neuroscience Laboratories, NASA Johnson Space Center, Houston, TX, USA.
Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
J Vestib Res. 2023;33(5):313-324. doi: 10.3233/VES-220127.
Coordination of motor activity is adapted to Earth's gravity (1 g). However, during space flight the gravity level changes from Earth gravity to hypergravity during launch, and to microgravity (0 g) in orbit. This transition between gravity levels may alter the coordination between eye and head movements in gaze performance.
We explored how weightlessness during space flight altered the astronauts' eye-head coordination (EHC) with respect to flight day and target eccentricity.
Thirty-four astronauts of 20 Space Shuttle missions had to acquire visual targets with angular offsets of 20°, 30°, and 49°.
Measurements of eye, head, and gaze positions collected before and during flight days 1 to 15 indicated changes during target acquisition that varied as a function of flight days and target eccentricity.
The in-flight alterations in EHC were presumably the result of a combination of several factors, including a transfer from allocentric to egocentric reference for spatial orientation in absence of a gravitational reference, the generation of slower head movements to attenuate motion sickness, and a decrease in smooth pursuit and vestibulo-ocular reflex performance. These results confirm that humans have several strategies for gaze behavior, between which they switch depending on the environmental conditions.
运动活动的协调性适应地球重力（1g）。然而，在太空飞行期间，重力水平在发射期间从地球重力变为超重（1g），在轨道上变为微重力（0g）。这种重力水平之间的转换可能会改变注视性能中眼睛和头部运动之间的协调性。
我们探讨了在太空飞行期间失重如何改变宇航员的眼头协调（EHC）与飞行天数和目标偏心度的关系。
20 次航天飞机任务中的 34 名宇航员必须用 20°、30°和 49°的角度偏移获取视觉目标。
在飞行前和飞行第 1 天至第 15 天期间收集的眼、头和注视位置测量结果表明，在目标获取期间会发生变化，这些变化随飞行天数和目标偏心度而变化。
EHC 在飞行中的改变可能是多种因素的综合结果，包括在没有重力参考的情况下，从向心参考到自我中心参考的空间定向的转移、产生较慢的头部运动以减轻晕动病、以及平滑追踪和前庭眼反射性能的下降。这些结果证实，人类有几种注视行为策略，他们根据环境条件进行切换。
