The Journal of Neurophysiology Vol. 86 No. 4 October 2001, pp. 2118-2122
Copyright ©2001 by the American Physiological Society

RAPID COMMUNICATION

Neural Readaptation to Earth's Gravity Following Return From Space

 ¹National Aeronautics and Space Administration, Ames Research Center, Moffett Field, California 94035;  ²Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri 63110;  ³Department of Physiology, University of Tsukuba, Tsukuba 305-8575;  ⁴Toyohashi University of Technology, Toyohashi 441-8580, Japan;  ⁵Department of Otolaryngology/Head-Neck Surgery, Oregon Health Sciences University, Portland, Oregon 97201; and  ⁶Department of Biological Sciences, Florida Institute of Technology, Melbourne, Florida 32901

Boyle, Richard, Allen F. Mensinger, Kaoru Yoshida, Shiro Usui, Anthony Intravaia, Timothy Tricas, and Stephen M. Highstein. Neural Readaptation to Earth's Gravity Following Return From Space. J. Neurophysiol. 86: 2118-2122, 2001. The consequence of exposure to microgravity on the otolith organs was studied by recording the responses of vestibular nerve afferents supplying the utricular otolith organ to inertial accelerations in four toadfish, Opsanus tau, sequentially for 5 days following two National Aeronautics and Space Administration shuttle orbital flights. Within the first day postflight, the magnitude of response to an applied translation was on average three times greater than for controls. The reduced gravitational acceleration in orbit apparently resulted in an upregulation of the sensitivity of utricular afferents. By 30 h postflight, responses were statistically similar to control. The time course of return to normal afferent sensitivity parallels the reported decrease in vestibular disorientation in astronauts following return from space.