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Vestibulo-spinal response modification as determined with the H-reflex during the Spacelab-1 flight.
Exp Brain Res 1986; 64(2):367-79EB

Abstract

Our laboratory at the Johnson Space Center has employed the H-reflex recorded from the soleus muscle as a method of monosynaptic reflex testing in conjunction with vertical linear acceleration to assess modification of utriculo-saccular function induced through prolonged exposure to microgravity. It was hypothesized that exposure to free fall would reduce the necessity for postural reflexes in the major leg muscles, and that postural modification would reflect a change, not in the peripheral vestibular organs, but more centrally. This postural adjustment would reflect a sensory motor rearrangement where otolith receptor input was reinterpreted to provide an environmentally appropriate response. In addition to the H-reflex (which was the only inflight measurement), vestibulo-spinal EMG from the gastrocnemius, and self-motion reports were obtained in response to a sudden earth vertical fall. Preflight, inflight and postflight motion sickness reports were also recorded, and related to the H-reflex data. The results indicated that early inflight H-reflex amplitude was similar to that recorded preflight, but that measurements obtained later in the flight (day seven) did not show a change in potentiation as a function of the different drop to shock intervals. Immediate postflight H-reflex response in three of the four astronauts tested showed a rebound effect. Postflight gastrocnemius EMG in response to the sudden fall did not show a significant change from preflight values. However, one crewman who was tested early postflight did show an increase in EMG activity in response to the sudden fall. This immediate postflight effect returned to baseline rapidly. Self-motion perception obtained inflight suggested that the early inflight drops were perceived like those preflight. Drops later inflight were described as sudden, fast, hard and translational in nature. Immediately postflight the drops were perceived like those late inflight, and the astronauts said that they did not feel as though they were falling, rather the floor came up to meet them. Post hoc peak H-reflex amplitude, both preflight and postflight was related to inflight space motion sickness.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

3492388

Citation

Reschke, M F., et al. "Vestibulo-spinal Response Modification as Determined With the H-reflex During the Spacelab-1 Flight." Experimental Brain Research, vol. 64, no. 2, 1986, pp. 367-79.
Reschke MF, Anderson DJ, Homick JL. Vestibulo-spinal response modification as determined with the H-reflex during the Spacelab-1 flight. Exp Brain Res. 1986;64(2):367-79.
Reschke, M. F., Anderson, D. J., & Homick, J. L. (1986). Vestibulo-spinal response modification as determined with the H-reflex during the Spacelab-1 flight. Experimental Brain Research, 64(2), pp. 367-79.
Reschke MF, Anderson DJ, Homick JL. Vestibulo-spinal Response Modification as Determined With the H-reflex During the Spacelab-1 Flight. Exp Brain Res. 1986;64(2):367-79. PubMed PMID: 3492388.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Vestibulo-spinal response modification as determined with the H-reflex during the Spacelab-1 flight. AU - Reschke,M F, AU - Anderson,D J, AU - Homick,J L, PY - 1986/1/1/pubmed PY - 1986/1/1/medline PY - 1986/1/1/entrez SP - 367 EP - 79 JF - Experimental brain research JO - Exp Brain Res VL - 64 IS - 2 N2 - Our laboratory at the Johnson Space Center has employed the H-reflex recorded from the soleus muscle as a method of monosynaptic reflex testing in conjunction with vertical linear acceleration to assess modification of utriculo-saccular function induced through prolonged exposure to microgravity. It was hypothesized that exposure to free fall would reduce the necessity for postural reflexes in the major leg muscles, and that postural modification would reflect a change, not in the peripheral vestibular organs, but more centrally. This postural adjustment would reflect a sensory motor rearrangement where otolith receptor input was reinterpreted to provide an environmentally appropriate response. In addition to the H-reflex (which was the only inflight measurement), vestibulo-spinal EMG from the gastrocnemius, and self-motion reports were obtained in response to a sudden earth vertical fall. Preflight, inflight and postflight motion sickness reports were also recorded, and related to the H-reflex data. The results indicated that early inflight H-reflex amplitude was similar to that recorded preflight, but that measurements obtained later in the flight (day seven) did not show a change in potentiation as a function of the different drop to shock intervals. Immediate postflight H-reflex response in three of the four astronauts tested showed a rebound effect. Postflight gastrocnemius EMG in response to the sudden fall did not show a significant change from preflight values. However, one crewman who was tested early postflight did show an increase in EMG activity in response to the sudden fall. This immediate postflight effect returned to baseline rapidly. Self-motion perception obtained inflight suggested that the early inflight drops were perceived like those preflight. Drops later inflight were described as sudden, fast, hard and translational in nature. Immediately postflight the drops were perceived like those late inflight, and the astronauts said that they did not feel as though they were falling, rather the floor came up to meet them. Post hoc peak H-reflex amplitude, both preflight and postflight was related to inflight space motion sickness. SN - 0014-4819 UR - https://www.unboundmedicine.com/medline/citation/3492388/Vestibulo_spinal_response_modification_as_determined_with_the_H_reflex_during_the_Spacelab_1_flight_ L2 - http://hdl.handle.net/2027.42/46555 DB - PRIME DP - Unbound Medicine ER -