Title
Velocity storage activity is affected after sustained centrifugation: a relationship with spatial disorientation
Author
TNO Defensie en Veiligheid
Nooij, S.A.E.
Bos, J.E.
Groen, E.L.
Publication year
2008
Abstract
Prolonged exposure to hypergravity in a human centrifuge can lead to post-rotary spatial disorientation and motion sickness. These symptoms are mainly provoked by tilting head movements and resemble the Space Adaptation Syndrome. We hypothesized that the occurrence of these post-rotary effects might be related to changes in the velocity storage (VS) mechanism, which is suggested to play an important role in spatial orientation. In particular, we investigated whether the re-orientation of the eye velocity vector (EVV) towards gravity during off-vertical optokinetic stimulation was affected by centrifugation. Twelve human subjects were exposed to a hypergravity load of 3G (G-load directed along the naso-occipetal axis) for a duration of 90 min. Before and after centrifugation we recorded optokinetic nystagmus (OKN) elicited by a stimulus pattern moving about the subjects yaw axis, with the head erect and tilted 45 to both sides. During OKN with the head erect, we observed a pitch-down component, reorienting the EVV on average 4.5 (SD 3.6, pretest values) away from the stimulus axis. Head tilt induced an additional shift of the EVV towards the spatial vertical of 6.4 on average (SD 3.2). This head-tilt induced reorientation was significantly decreased after centrifugation to 4.7 (SD 2.9), suggesting a reduction of VS-activity. By means of a vector model we estimated the reduction in VSactivity at 31%. Such a decrease in VS-activity light reflect a deterioration of the ability to integrate sensory signals to obtain an estimate of gravity during tilting head movements, resulting in motion sickness in susceptible subjects.
Subject
Hypergravity
Optokinetic nystagmus
Vestibular adaptation
Human
Motion sickness
Gravity
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http://resolver.tudelft.nl/uuid:ac71bd44-aef2-4137-8cc7-8be9bbb9baef
DOI
https://doi.org/10.1007/s00221-008-1460-3
TNO identifier
22072
Source
Experimental brain research, 190 (190), 165-177
Document type
article