Responsible Center: NASA JSC
Grant Monitor: Norsk, Peter
Solicitation / Funding Source: 2017-2018 HERO 80JSC017N0001-BPBA Topics in Biological, Physiological, and Behavioral Adaptations to Spaceflight. Appendix C
Grant/Contract No.: Internal Project
Project Type: FLIGHT
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|Human Research Program Gaps:
(1) SM-103:Effects of short and long-duration weightlessness, with and without deep-space radiation, on spatial orientation and motion sickness after G transitions. Performance impacts that effect critical mission tasks: G-transition motion sickness, diplopia, hand-eye coordination, autonomic dysfunction, vertigo (IRP Rev L)
|| Adaptation to the absence of Earth's gravitational environment during spaceflight causes neurological disturbances that are either directly or indirectly mediated by the vestibular system. These disturbances include space motion sickness, spatial disorientation, cognitive impairment, as well as changes in head-eye coordination, vestibulo-ocular reflex, and strategies for postural control and locomotion. After return to Earth, astronauts experience other vestibular-driven behavioral changes, including reentry motion sickness, motion illusions, gaze-induced nystagmus, poor balance, and potentiation of postural muscle reflexes.
It seems that the otolith-mediated reflexes gain adapts rapidly over time during flight and after landing. However, animal studies have shown that structural modifications of the vestibular sensory apparatus appear for long flight exposure. To date, no flight studies have directly investigated potential changes in the vestibular organs of astronauts. An examination of vestibular function in crewmembers is therefore necessary for establishing Human Research Program's risk and gaps associated with the sensorimotor system, and in particular gap Sensorimotor (SM) 26 "Determine if exposure to long-duration spaceflight leads to neural structural alterations and if this remodeling impacts cognitive and functional performance." We therefore propose to perform a systematic neuro-vestibular examination of crewmembers in orbit at regular intervals, as well as immediately after landing.
In orbit, the subject will be exposed to various maneuvers executed by the operator. Observations and recordings of eye, head, and body movements, as well as subjective perception of motion and verbal reports, will be used for evaluating the presence of abnormal eye movements, dysmetria, motion sickness symptoms, and illusions of motion during head or body movements. The whole examination will last less than 30 minutes. Tests will be performed both early in the mission and once every one or two months thereafter. The post-flight examination will be performed on R+0 and R+9. Measurements will be the same as in-flight. The operator will be a trained otologist. The post-flight investigation will leverage on the results of the posturography and sensorimotor standard measures also performed on R+0 and R+9. Preflight data collection will take place at L-90 using the same procedure/equipment as the post-flight examination.
Crewmembers from short-duration, six-month, and one-year missions are requested to investigate temporal changes, and to identify trends in adaptation to vestibular health and performance. The question is whether the vestibular organs and/or the central vestibular system undergo some structural changes during long exposure to microgravity, which would be responsible for vestibular disorders when transitioning to a new gravitational environment.
The tests proposed in this study are well established and validated protocols that are able to detect head-motion oscillospia and predict acute or chronic vestibular syndromes. If the observed physiological changes in the crewmembers are more deleterious after the year-long International Space Station (ISS) expeditions than those documented after standard-duration ISS expeditions, then relevant countermeasures will be required to enable longer duration missions. Depending on the etiology of the vestibular disorders revealed by our tests, countermeasures to these problems will be proposed based on vestibular rehabilitation therapy currently used in patients with vestibular disorders, such as habituation, gaze stabilization, and/or balance training exercises.