Listing's plane and the 3D-VOR in microgravity - The role of the otolith afferences
Listing's plane and the 3D-VOR in microgravity - The role of the otolith afferences
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DOI：
10.3233/ves-130476
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发表时间：
2013-01-01
影响因子：
2.3
通讯作者：
Schoenfeld, U.
中科院分区：
文献类型：
--
作者：
Clarke, Andrew H.;Just, K.;Schoenfeld, U.
这项研究解决的问题，在何种程度上耳石介导的重力矢量保持稳定的前庭眼反射和眼系统的坐标框架，由上市的平面。在正常的1G条件下，猴的Listing平面（LP）和三维前庭眼反射（3D-VOR）接近共线[10]。在本研究中，在1g重力条件下和长时间微重力期间测量了眼反射系统和三维前庭眼反射（3D-VOR）系统的坐标系，国际空间站（ISS）上。为此，我们用Listing坐标描述了眼动系统的坐标系，用最小增益矢量描述了3D-VOR系统的坐标系，结果表明，在地球上，1g条件下，人体的两个坐标系相差约20度。在没有重力矢量的情况下，耳石介导的对动态VOR的贡献中的自由基损失导致扭转VOR分量的减少，进而导致由最小增益矢量描述的眼坐标系的向前倾斜。与此相反，在水平和垂直扫视的LP的扭转分量被发现增加，导致在一个向后倾斜的LP。观测到LP的聚散度随着LP的后倾发生了微小但一致的变化，LP的厚度在没有重力的情况下似乎没有变化。在零重力状态下的六个月期间，坐标框架方向的变化持续存在。飞行后的测量结果表明，重新适应飞行前的值进行了几天到weeks。研究结果表明，重力矢量代表了一个共同的参考前庭和眼反应。他们还支持重力矢量为整个感觉运动复合体提供了中心参考的观点。
The study addresses the question as to what extent the otolith-mediated gravity vector maintains the stability of the coordinate frames of the vestibulo-ocular reflex and the oculomotor system, described by Listing's Plane. Under normal 1 G conditions it has been demonstrated in the monkey that Listing's Plane (LP) and the 3D vestibulo-ocular response (3D-VOR) are close to collinear [10].In the present study the coordinate frames of the oculomotor system and the three-dimensional vestibulo-ocular reflex (3D-VOR) system were measured under one-g gravity conditions and during a period of prolonged microgravity, on-board the International Space Station (ISS). To this end, the coordinate frame of the oculomotor system is described in Listing's coordinates and that of the 3D-VOR system by the minimal gain vector.The findings demonstrate that under Earthbound, one-g conditions the two coordinate frames diverge by approximately 20 degrees in the human. In the absence of the gravity vector the radical loss in the otolith-mediated contribution to the dynamic VOR leads to a reduction of the torsional VOR component and in turn to a forward tilt of the oculomotor coordinate frame, described by the minimal gain vector. In contrast, the torsional component of LP during horizontal and vertical saccades was found to increase, resulting in a backward tilt of LP. Together with the backward tilt of LP a small but consistent change in LP vergence was observed.The thickness of LP did not appear to change in the absence of gravity. The changes in coordinate frame orientation persisted over the six-month periods spent in zero gravity. The postflight measurements demonstrate that re-adaptation to preflight values proceeds over several days to weeks.The findings demonstrate that the gravity vector represents a common reference for vestibular and oculomotor responses. They also support the idea that the gravity vector provides a central reference for the entire sensorimotor complex.