Affiliations: [a] Antwerp University Research Centre for Equilibrium and Aerospace (AUREA), Department of Biomedical Physics, University of Antwerp, Antwerp, Belgium | [b] Department of Psychology, University of Sydney, Sydney, Australia | [c] Signal and Image Centre, Electrical Engineering Department, Royal Military Academy, Brussels, Belgium | [d] Mount Sinai School of Medicine, New York, NY, USA
Correspondence:
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Corresponding author: F.L. Wuyts, Antwerp University Research Center for Equilibrium and Aerospace, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Tel.: +32 3 265 34 29; Fax: +32 3 825 05 36; E-mail: Floris.Wuyts@ua.ac.be
Note: [1] This article was presented at the 8th Symposium on the Role of the Vestibular Organs in Space Exploration April 8–10, 2011, Houston, TX, USA
Abstract: In the framework of further space exploration, countermeasures to combat the drawbacks of human space flights are essential. The present study focuses on the influence of microgravity on the otolith-ocular reflex and aims to test the hypothesis of artificial gravity being an adequate countermeasure for the deconditioning of the aforementioned reflex. The so-called SPIN study, commissioned by the European Space Agency, can be considered as a control experiment in the broad sense for the Neurolab mission (STS-90) during which 4 crewmembers of the space shuttle were subjected to in-flight centrifugation on the visual and vestibular investigation system (VVIS). After their nearly 16-day mission, they did not suffer from orthostatic intolerance and spatial disorientation. In addition, the relevant parameters of the otolith-ocular interaction remained unaffected. For this study cosmonauts from a long duration stay in the International Space Station that were not centrifuged in-flight were tested on the VVIS (1 g centripetal interaural acceleration) on 6 different days. Three measurements were taken about 1.5–2 months prior to launch and 3 were taken at 1, 4 and 9 days after return from space. Ocular counter-rolling was measured before, during and after rotation on the VVIS using infrared video goggles and compared pair wise using Friedman tests. The perception of verticality was monitored using an ultrasound system for perceptual evaluation. The preliminary results of 4 cosmonauts showed a surprisingly large inter-individual variability of the measurements. Although OCR and perception of verticality appeared to be influenced overall by the exposure to microgravity, the wide variability among the cosmonauts obscured any statistical significance, in particular due to one cosmonauts being inconsistent with the other 3. Despite the specificity of the tests under normal conditions, the diverse response to spaceflight of our subjects exposes the complexity of the peripheral and central neural adaptive processes.
Keywords: Otolith-ocular interaction, artificial gravity, VVIS, space motion sickness
