Changes in the Horizontal Angular Vestibulo-ocular Reflex of

Vestibulo-Ocular Reflex (VOR) data was recorded in 4 astronauts (3m, if; age 36-51) before, during, and after a 14 day space shuttle mission (November, 1993). 129 days before launch subjects were tested in parabolic flight. Subjects were then tested pre-flight, 122/110/88/18 days before launch; in-flight, 4/10 days after launch; post-flight, 0/1/2/6/9/11 days after landing. Horizontal eye position (bi-temporal EOG) was sampled by computer. Subjects were blindfolded eyes open and instructed to keep head erect, and to gaze straight ahead. Alertness was maintained with conversation. To study "head erect " yaw axis dynamics, subjects were accelerated to a angular velocity of 120 deg/sec within 0.5 seconds with their heads erect. After 1 minute, the chair stopped within 0.5 seconds, and the subjects continued to keep their heads erect. Post-rotatory recording of the VOR continued for 1 minute. This procedure was repeated in the opposite direction. To study "dumping " yaw axis dynamics, the same procedure was used, except that after chair stop, subject