Department of Aeronautics and Astronautics, MIT, Cambridge, MA 02139-4307, USA.
J Vestib Res. 2010;20(1):45-51. doi: 10.3233/VES-2010-0350.
Subjective body position, as influenced by 21-day 6 degrees -head-down bed rest and intermittent supine centrifugation, was investigated in two experimental groups. Treatment subjects were exposed to a daily dose of 1-hour of horizontal centrifugation, whereas control subjects were also put on the centrifuge, but were not spun. During the centrifuge runs subjects were exposed to a constant gradient with 1-G(z) at the heart and 2.5-G(z) at the feet. Subjects reported their subjective postural position (SPP) before, during and after each 1-hour centrifuge exposure. We find that subjects shift their frame of reference over the first week of bed rest and perceive the 6 degrees -head-down position as horizontal. Spinning shifts the SPP by about 30 degrees towards an upright position, consistent with the angle of the gravito-inertial vector positioned close to the vestibular system. The SPP estimates for the upper and lower body failed to reflect the massive gravity gradient between head and feet, and subjects generally reported a single tilt for the whole body.
在为期 21 天的 6 度头低位卧床和间歇性仰卧位离心作用下，研究了两组实验对象的主观体位。实验组每天接受 1 小时的水平离心作用，而对照组也被放在离心机上，但没有旋转。在离心机运行期间，实验对象会受到 1-G（z）在心脏和 2.5-G（z）在脚部的恒定梯度的影响。在每次 1 小时的离心作用暴露之前、期间和之后，实验对象都会报告他们的主观体位（SPP）。我们发现，在卧床休息的第一周，实验对象会改变他们的参考系，将 6 度头低位视为水平位。旋转会使 SPP 向垂直位置移动约 30 度，这与位于前庭系统附近的重引力惯性向量的角度一致。上下半身的 SPP 估计值未能反映头部和脚部之间巨大的重力梯度，实验对象通常报告整个身体只有一个倾斜。
