The force of gravity has remained constantly present over the course of animal evolution and forms our frame of reference with the environment, including spatial orientation, navigation, gaze and postural stability. Inertial head accelerations occur within this gravity frame of reference naturally during voluntary movements and perturbations. Execution of movements of aquatic, terrestrial and flight species widely differ, but the sensory systems detecting acceleration forces, including gravity, have remained remarkably conserved among vertebrates. The utricular organ senses the sum of inertial force due to head translation and head tilt relative to gravitational vertical. A sudden or persistent change in gravitational force would be expected to have profound and global effects on an organism. Physiological data collected immediately after orbital missions, after short and extended increases in gravity load via centrifugation, and after readaptation to normal gravity exist in the toadfish model. This review focuses on the otolith adaptive responses to changes in gravity in a number of model organisms and their potential impact on human space travel.

重力在动物进化过程中一直存在，并构成我们与环境的参照系，包括空间方向，航行，凝视和姿势稳定性。惯性运动和摄动期间，惯性头加速度自然会在此重力参考框架内发生。水生，陆地和飞行物种运动的执行方式大不相同，但是检测加速度（包括重力）的感觉系统在脊椎动物中仍然非常明显。眼球器官感测到由于头部平移和头部相对于重力垂直方向倾斜而产生的惯性力之和。引力的突然或持续变化将对生物产生深远而全面的影响。蟾蜍模型中存在在执行轨道任务后，通过离心使重力负荷短暂和长期增加以及重新适应正常重力之后立即收集的生理数据。这篇综述着重于耳石对许多模型生物重力变化的适应性反应及其对人类太空旅行的潜在影响。