Vertical optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN) studied in 4 subjects during parabolic flights were compared with data obtained on 2 subjects before, during, and after a 7-day space shuttle flight. In parabolic flight, the vertical OKAN following upgoing optokinetic stimulation increased during the 0 g phase, and decreased during the 1.8 g phase. In spaceflight, the vertical OKN gain asymmetry showed a reversal during early exposure to microgravity. This asymmetry reversal is likely the same effect seen in parabolic flight and could be a direct response to the change in otolithic output. However, if asymmetry changes were due only to the otolithic sensory input, we would also expect large changes upon return to normal gravity. Instead, there were large OKN and OKAN changes at the beginning of the flight, but the deviation from the original vertical OKN gain asymmetry constantly decreased throughout the flight and continued post-flight until pre-flight asymmetry value was restored. This suggests one adaptive goal which reinstates the original pre-flight gain and asymmetry value regardless of changing inputs. This adaptation resembles mechanisms seen in posture experiments where the motor programs on Earth are reinstated in microgravity after a period of adjustment.


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    Titel :

    Up-down asymmetry of vertical optokinetic nystagmus and after-nystagmus elicited in microgravity


    Beteiligte:

    Kongress:

    IAF, International Astronautical Congress ; 1993 ; Graz, Austria


    Erscheinungsdatum :

    1993-10-01


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Keine Angabe


    Sprache :

    Englisch


    Schlagwörter :


    Nystagmus (A Bibliography with Abstracts)

    E. A. Harrison | NTIS | 1979


    Nystagmus (A Bibliography with Abstracts)

    E. A. Harrison | NTIS | 1975


    Nystagmus (A Bibliography with Abstracts)

    E. A. Harrison | NTIS | 1977


    Nystagmus (A Bibliography with Abstracts)

    E. A. Harrison | NTIS | 1976


    Nystagmus (A Bibliography with Abstracts)

    E. A. Harrison | NTIS | 1978