On the role of otoliths and semicircular canals in spatial orientation: Dynamics of the visually perceived eye level during gondola centrifugation.
The visually perceived eye level (VPEL) was measured during gondola centrifugation. Subjects (N = 11) were seated upright, facing motion in a swing-out gondola The head was adjusted so that Reid's baseline was tilted 10 degrees anterior end up. The subjects were requested to adjust the position of a small luminous dot so that it was perceived as gravitationally at eye level. In the 1-g environment, the VPEL was a few degrees below the true gravitational eye level (M = -1.75 degrees, SD = 1.90 degrees). After rapid acceleration of the centrifuge to 2 G (vectorial sum of the earth gravity force and the centrifugal force), there was an exponentially increasing depression of the VPEL. The initial value was -6.4 degrees +/- 5.2 degrees. During 10 min at 2 G, the VPEL approached an asymptotic value of -24.8 degrees +/- 5.4 degrees. The time constant showed a large interindividual variability, ranging from 59 to 1,000 sec (M = 261 sec, median = 147 sec). The findings are discussed, taking into consideration otolith-semicircular-canal interaction, as well as memory functions of the vestibular system.
Tribukait
Arne
A
Karolinska Institute and Swedish Defense Research Agency, Stockholm, Sweden. arne.tribukait@foi.se
Eiken
Ola
O
D000328:Adult; D002498:Centrifugation; D005260:Female; D006801:Humans; D008297:Male; D010037:Otolithic Membrane / Q000502:physiology*; D011434:Proprioception; D012665:Semicircular Canals / Q000502:physiology*; D013028:Space Perception; D013037:Spatial Behavior; D014722:Vestibule, Labyrinth / Q000502:physiology; D014796:Visual Perception