Perceptual responses to linear acceleration following spaceflight:
human neurovestibular studies on sls-2.
Merfeld, Daniel M., Karla A. Polutchko, and Karl Schultz.
Dept. of Neuro-otology, R.S. Dow Neurological Sciences Institute,
Legacy Good Samaritan Hospital, Portland, OR, Man-Vehicle Laboratory,
Massachusetts Institute of Technology, Cambridge, MA
APStracts 2:0248A, 1995.
Perceptual responses of four astronauts were measured before and after
a fourteen day spacelab mission during inter-aural (Y-axis) and
rostro-caudal (Z-axis) linear acceleration to measure adaptive
changes in perceptual responses to inertial cues. In one test,
subjects used a joystick to null a pseudo-random velocity
disturbance. Postflight, two of three subjects showed a significantly
enhanced ability to null linear self-motion in the Y-axis and Z-axis
orientations. In another test, the subjects used a joystick to
indicate their direction of motion during a series of low
-acceleration steps. The postflight responses of three of the four
subjects showed a significant increase in the response latency for
both Y-axis and Z-axis orientations. In a third test, subjects were
asked to track a stationary but unseen target with their eyes while
they translated linearly in the dark. No significant changes were
observed in the postflight responses. The observed changes, when
present, may be due to a reinterpretation of inertial cues that is
functionally adaptive for the microgravity environment but is not
optimal for responses on Earth.
Received 23 December 1994; accepted in final form 8 May 1995.
APS Manuscript Number A1320-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.