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Vestibulo-Cervico-Ocular Responses and Tracking Eye Movements after Prolonged Exposure to MicrogravityThe vestibular function and tracking eye movements were investigated in 12 Russian crew members of ISS missions on days 1(2), 4(5-6), and 8(9-10) after prolonged exposure to microgravity (126 to 195 days). The spontaneous oculomotor activity, static torsional otolith-cervico-ocular reflex, dynamic vestibulo-cervico-ocular responses, vestibular reactivity, tracking eye movements, and gaze-holding were studied using videooculography (VOG) and electrooculography (EOG) for parallel eye movement recording. On post-flight days 1-2 (R+1-2) some cosmonauts demonstrated: - an increased spontaneous oculomotor activity (floating eye movements, spontaneous nystagmus of the typical and atypical form, square wave jerks, gaze nystagmus) with the head held in the vertical position; - suppressed otolith function (absent or reduced by one half amplitude of torsional compensatory eye counter-rolling) with the head inclined statically right- or leftward by 300; - increased vestibular reactivity (lowered threshold and increased intensity of the vestibular nystagmus) during head turns around the longitudinal body axis at 0.125 Hz; - a significant change in the accuracy, velocity, and temporal characteristics of the eye tracking. The pattern, depth, dynamics, and velocity of the vestibular function and tracking eye movements recovery varied with individual participants in the investigation. However, there were also regular responses during readaptation to the normal gravity: - suppression of the otolith function was typically accompanied by an exaggerated vestibular reactivity; - the structure of visual tracking (the accuracy of fixational eye rotations, smooth tracking, and gaze-holding) was disturbed (the appearance of correcting saccades, the transition of smooth tracking to saccadic tracking) only in those cosmonauts who, in parallel to an increased reactivity of the vestibular input, also had central changes in the oculomotor system (spontaneous nystagmus, gaze nystagmus).
Document ID
20070021565
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Kornilova, L. N.
(Academy of Sciences (USSR) Russian Federation)
Naumov, I. A.
(Academy of Sciences (USSR) Russian Federation)
Azarov, K. A.
(Academy of Sciences (USSR) Russian Federation)
Sagalovitch, S. V.
(Academy of Sciences (USSR) Russian Federation)
Reschke, Millard F.
(NASA Johnson Space Center Houston, TX, United States)
Kozlovskaya, I. B.
(Academy of Sciences (USSR) Russian Federation)
Date Acquired
August 23, 2013
Publication Date
January 1, 2007
Subject Category
Aerospace Medicine
Meeting Information
Meeting: 16th IAA Humans in Space Symposium
Location: Beijing
Country: China
Start Date: May 20, 2007
End Date: May 24, 2007
Sponsors: International Academy of Astronautics
Distribution Limits
Public
Copyright
Other

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