Pilot Studies in Adaptation in Parabolic Flight

描述(由申请人提供)：这项研究致力于适应抛物线飞行的独特环境。实验将在NASA的一架飞机上进行，该飞机以抛物线轨迹飞行，大约每25秒在0克和1.8克之间转换一次。这种不同寻常的运动环境，g水平的变化是正常情况下没有的，对身体的适应过程提出了显著的挑战。事实上，许多首次飞行的人都会经历定向障碍和晕动病。然而，适应过程占上风，在第二次和随后的飞行中，体验要愉快得多，这表明在非常短的时间内和在非常短暂的暴露之后(每次飞行大约一小时的抛物线动作)，发生了重大的适应。我们建议研究在这种情况下发生的适应过程。在飞行中的两种不同重力水平下，将进行一系列前庭和眼球运动功能测试。这些测试跨越了从低级反射到高级认知的一系列神经过程，尤其针对耳石信息(因为这些前庭器官感觉到线性加速，包括重力)和视觉(因为在许多情况下，视觉信息可以取代关于自我定向的前庭信息)。测试包括：1)眼球反转(OCR)，即眼球在重力场中相对于头部倾斜的反射性扭转运动，由耳石器官感知；2)平移VOR(TVOR)，响应于头部平移而进行的补偿性眼球运动，也依赖于耳石信号的处理；3)俯仰角VOR，涉及耳石和耳石信号的会聚；4)垂直眼球对齐，受重力水平的影响；5)主观视觉垂直，基于方向线索的多感觉整合；6)滚动向量，解决视觉和耳石信号的相互作用。将比较新飞行员和有经验的飞行员的反应，并将随着适应的发展评估连续飞行的反应进展。这些测试解决了两个相互矛盾的假设，即如何实现对抛物线飞行的适应：1)存在对每个单独重力水平的适应(特定于上下文)；2)适应更普遍地适用于整体飞行体验(意味着感官权重的非特定于g的变化)。从这项适应研究中获得的信息可能有助于我们更好地了解可能的适应机制的范围，并可能帮助我们确定哪些机制作用最快和最有效(就像抛物线飞行中那样)，作为前庭患者康复的候选机制。

DESCRIPTION (provided by applicant): This study addresses adaptation to the unique environment of parabolic flight. Experiments will take place in a NASA aircraft that flies parabolic trajectories which make transitions between 0 g and 1.8 g approximately every 25 sec. This unusual motion environment, with changes in g level not normally experienced, presents a remarkable challenge to the body's adaptive processes. Indeed, many first-time flyers experience disorientation and motion sickness. Nevertheless, adaptive processes prevail and on the second and subsequent flights the experience is much more pleasant, indicating that significant adaptation has occurred in a very short time and after a very brief exposure (approximately one hour of parabolic maneuvers per flight). We propose to study the adaptive processes that take place in this situation. A battery of tests of vestibular and oculomotor function will be performed during the two different gravity levels in flight. The tests span a range of neural processes from low-level reflexive through higher-level cognitive, and are aimed in particular at otolith information (since these vestibular organs sense linear accelerations, including gravity) and vision (since visual information can in many cases substitute for vestibular information about self-orientation). The tests are: 1) ocular counterrolling (OCR), a reflexive torsional movement of the eyes in relation to head tilt in a gravity field as sensed by the otolith organs; 2) translational VOR (TVOR), a compensatory eye movement made in response to head translations that also depends on processing of otolith signals; 3) pitch angular VOR, which involves convergence of otolith and canal signals; 4) vertical ocular alignment, which is affected by gravity level; 5) subjective visual vertical, based on multi-sensory integration of orientation cues; 6) roll vection, which addresses the interaction of visual and otolith cues. Responses from new and from experienced flyers will be compared, and the progression of responses over consecutive flights will be assessed as adaptation develops. The tests address two competing hypotheses of how adaptation to parabolic flight is achieved: 1) there is adaptation to each separate gravity level (context-specific); 2) adaptation is more generalized to the overall flight experience (implying a non-g-specific change in sensory weighting). The information to be gained from this study of adaptation may lead to better understanding of the range of possible adaptive mechanisms, and might help us to determine those mechanisms which act most rapidly and effectively (as they do in parabolic flight) as candidates for use in rehabilitation of vestibular patients.