Journal of Applied Physiology, Vol 81, Issue 1 50-57, Copyright © 1996 by American Physiological Society
Effect of spaceflight on ability to sense and control roll tilt: human neurovestibular studies on SLS-2
D. M. Merfeld
Man-Vehicle Laboratory, Massachusetts Institute of Technology, Cambridge 02139, USA. dmm@nsi.lhs.org
To measure adaptive changes in the ability to sense tilt after spaceflight,
we measured the ability of four astronauts to control roll tilt in the
presence of a pseudorandom motion disturbance before and after a 14-day
Spacelab mission. The subjects were tested 1) in the dark, 2) with an
independent sum-of-sines visual display, and 3) by using a control
condition in which the visual cues confirmed the motion cues
(counterrotating). The two subjects tested on the landing day exhibited
significant decrements (P < 0.05) in their ability to control roll tilt
in the dark, whereas no significant performance decrements were observed in
the control condition. The absence of changes in the control condition
suggests that changes in the neuromuscular component of the task and
postflight fatigue were not major factors contributing to the observed
performance decrement in the dark. These findings indicate an adaptive
change in the way the nervous system interprets tilt cues. Readaptation of
all responses appeared to be rapid, with a return to preflight values
within 1-2 days after landing.
