NASA Neurolab: Chronic Recording of Otolith Nerves in Microgravity

所有脊椎动物的重力接收主要是由内耳前庭系统中称为耳石器官的结构完成的。这些器官是包含称为耳石的致密钙化物质的囊;重力对这些物质的作用，覆盖专门的机械感觉细胞，提供了确定正常地球垂直方向的信号。 这些耳石器官的神经活动表现出兴奋性和抑制性放电模式的组合，在某些情况下，大脑通过称为传出神经的神经纤维发送某种调制，影响传入的放电模式。 关于重力器官的长期活动的信息不多。 Neurolab的飞行提供了一个独特的机会来测试对远小于正常地球重力的力的重力反应，从而大大扩展了测试关于重力信号神经编码假设的研究范围。 该项目使用一种新的电生理记录技术，在自由移动的鱼比较地球和空间为基础的重力在广泛的力量的反应。 这项工作的结果将提供关于这种感觉系统的基本重要信息，并将对前庭神经科学以外的感觉科学产生影响，并且可能对人类航天的应用方面很重要。 对这一项目的贡献是国家科学基金会生物科学理事会参与美国航天局/机构间神经实验室在航天飞机轨道飞行器上的活动，而这又是大脑十年活动的一部分。

Gravity reception in all vertebrate animals is done largely by structures called otolith organs in the vestibular system of the inner ear. These organs are pouches that contain dense calcified masses called otoliths; the action of gravity on these masses, overlying specialized mechanosensory cells, provides a signal for determining the normal earth-vertical direction. Nerve activity from these otolith organs show combinations of excitatory and inhibitory firing patterns, and under some conditions the brain sends some kinds of modulation by nerve fibers called efferents, which affect the incoming firing patterns. Not much information is available about long-term activity of gravistatic organs. The flight of Neurolab provides a unique opportunity to test gravitational responses to forces far less than normal earth gravity, and so greatly extend the study range for testing hypotheses about neural encoding of gravity signals. This project uses a novel electrophysiological recording technology in freely-moving fish to compare earth-based with space-based responses to gravity over a wide range of forces. Results from this work will provide fundamentally important information on this sensory system, and will have an impact beyond vestibular neuroscience to sensory science in general, and is likely to be important to applied aspects of human spaceflight. Contribution to this project represents the NSF Biological Sciences Directorate's participation in the NASA/Interagency Neurolab activity on the space shuttle orbiter, which in turn is part of Decade of the Brain activities.