title: Decreased otolith-mediated vestibular response in 25 astronauts induced by long-duration spaceflight.
abstract: The information coming from the vestibular otolith organs is important for the brain when reflexively making appropriate visual and spinal corrections to maintain balance. Symptoms related to failed balance control and navigation are commonly observed in astronauts returning from space. To investigate the effect of microgravity exposure on the otoliths, we studied the otolith-mediated responses elicited by centrifugation in a group of 25 astronauts before and after 6 mo of spaceflight. Ocular counterrolling (OCR) is an otolith-driven reflex that is sensitive to head tilt with regard to gravity and tilts of the gravito-inertial acceleration vector during centrifugation. When comparing pre- and postflight OCR, we found a statistically significant decrease of the OCR response upon return. Nine days after return, the OCR was back at preflight level, indicating a full recovery. Our large study sample allows for more general physiological conclusions about the effect of prolonged microgravity on the otolith system. A deconditioned otolith system is thought to be the cause of several of the negative effects seen in returning astronauts, such as spatial disorientation and orthostatic intolerance. This knowledge should be taken into account for future long-term space missions.
authors.affiliation: AUREA, (Antwerp University Research center for Equilibrium and Aerospace), Biomedical Physics, University of Antwerp, Antwerp, Belgium;
authors.forename: Emma
authors.initials: E
authors.lastname: Hallgren
authors.affiliation: Institute of Biomedical Problems, Moscow, Russia;
authors.forename: Ludmila
authors.initials: L
authors.lastname: Kornilova
authors.affiliation: StatUa Center for Statistics, University of Antwerp, Antwerp, Belgium;
authors.forename: Erik
authors.initials: E
authors.lastname: Fransen
authors.affiliation: Institute of Biomedical Problems, Moscow, Russia;
authors.forename: Dmitrii
authors.initials: D
authors.lastname: Glukhikh
authors.affiliation: Mount Sinai School of Medicine Human Aerospace Laboratory, New York, New York;
authors.forename: Steven T
authors.initials: ST
authors.lastname: Moore
authors.affiliation: Lyon Neuroscience Research Center, University of Lyon, Lyon, France; and.
authors.forename: Gilles
authors.initials: G
authors.lastname: Clément
authors.affiliation: AUREA, (Antwerp University Research center for Equilibrium and Aerospace), Biomedical Physics, University of Antwerp, Antwerp, Belgium;
authors.forename: Angelique
authors.initials: A
authors.lastname: Van Ombergen
authors.affiliation: University of Sydney School of Psychology, Sydney, New South Wales, Australia.
authors.forename: Hamish
authors.initials: H
authors.lastname: MacDougall
authors.affiliation: Institute of Biomedical Problems, Moscow, Russia;
authors.forename: Ivan
authors.initials: I
authors.lastname: Naumov
authors.affiliation: AUREA, (Antwerp University Research center for Equilibrium and Aerospace), Biomedical Physics, University of Antwerp, Antwerp, Belgium; floris.wuyts@uantwerpen.be.
authors.forename: Floris L
authors.identifier: 0000-0002-4485-6412
authors.initials: FL
authors.lastname: Wuyts
mesh_terms: D000328:Adult; D018480:Astronauts; D016009:Chi-Square Distribution; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010037:Otolithic Membrane / Q000502:physiology*; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D012399:Rotation; D013026:Space Flight; D013997:Time Factors; D014893:Weightlessness
keywords: artificial gravity; centrifugation; ocular counterrolling; otolith function; spaceflight