Validation of centrifugation as a countermeasure for otolith deconditioning during spaceflight: Preliminary data of the ESA SPIN study1

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.

Spaceflight-induced neuroplasticity in humans as measured by MRI: what do we know so far?

“…57,69 Previous spaceflight studies have already shown that inter-subject variability in space travelers is quite high, also for other physiological processes such as sensorimotor adaptation 75,76 and vestibular and otolith deconditioning. 77,78 High inter-subject variability is therefore a feature that should be kept in mind when analyzing and interpreting spaceflight studies, in particular with regards to studies on spaceflight-induced neuroplasticity. Earth-based studies have already shown that neuroplasticity is a process that is highly individually dependent and is related to several factors such as demographics (e.g.…”

EMT Transcription Factors Are Involved in the Altered Cell Adhesion under Simulated Microgravity Effect or Overloading by Regulation of E-cadherin

“…Most of them belong to glycoproteins and function through the formation of receptor-ligand binding. The expression of cell adhesion proteins directly reflects the degree of adhesion between cells, or between cells and extracellular matrix [8]. Integrin is a heterodimeric transmembrane receptor composed of two subunits, α and β.…”

Hypergravity Increases Blood–Brain Barrier Permeability to Fluorescent Dextran and Antisense Oligonucleotide in Mice

“…Likewise, centrifugation, close to 2× g, is also proposed as a countermeasure against the deleterious effects of microgravity seen in humans [33,34]. Therefore, before the exposure of humans to centrifugation, it is important to study its biological impacts.…”