Effects of rectilinear acceleration, caloric and optokinetic stimulation of human subjects in the Spacelab D-1 mission.
A set of vestibular experiments was performed during the course of the German Spacelab D-1 mission from 30 October to 6 November 1985 by a consortium of experimenters from various european countries. Similar to the Spacelab SL-1 mission all of the scientific crew members were theoretically and practically trained for the experiments. Baseline measurements for all tests were collected 113, 86, 44, 30 and 18 days prior to the mission and compared with data taken inflight, on the landing day and the consecutive 7 to 14 days. The hardware comprised mainly a motordriven accelerating platform, the SPACE SLED, and the vestibular helmet, a multi-purpose instrument in support of a variety of vestibular experiments including air-calorisation of the ears, optokinetic stimulation pattern presentation and optical and nystagmographic recording of eye movements. Measurements of the threshold for the perception of detection of whole body movement did not reveal any dramatic changes in the 2 measured axes inflight when compared to preflight values. Early postflight values show a significantly elevated threshold for all axes in 3 out of 4 subjects. The caloric nystagmus, already found during the SL-1 mission, was confirmed on all three tested subjects during the D-1 mission. It's amplitude and in some instances it's direction were influenced by horizontal acceleration on the SLED. The amplitude of optokinetic nystagmus increased when subjects were allowed to free-float over that seen when subjects were fixed. Stimulation of the neck receptors by roll movements of the body against the fixated head resulted in illusory object motion to the contralateral side. Torsional movements of the eyes during such neck receptor stimulation was present inflight and postflight, while it had not been observed preflight. Most results point to a reduction of otolithic effects in favour of visual and proprioceptive influences for spatial orientation.
Wetzig
J
J
Department of Physiology, Johannes-Gutenberg-University, Mainz, FRG.
von Baumgarten
R
R
D000054:Acceleration; D000337:Aerospace Medicine; D002150:Caloric Tests; D005133:Eye Movements; D006260:Head Protective Devices; D006801:Humans; D009039:Motion Perception / Q000502:physiology; D009333:Neck / Q000502:physiology; D017120:Nystagmus, Optokinetic / Q000502:physiology*; D009949:Orientation / Q000502:physiology; D010037:Otolithic Membrane / Q000502:physiology; D011434:Proprioception / Q000502:physiology*; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology; D013026:Space Flight / Q000295:instrumentation*; D018489:Space Motion Sickness / Q000209:etiology* / Q000503:physiopathology; D014724:Vestibular Function Tests; D014893:Weightlessness / Q000009:adverse effects*