Engineering topics

B. T. Peters

Publications and source records attributed to B. T. Peters.

3 records

NASA NTRSDate not supplied

Sensorimotor Predictors: Examining the Relationship Between Measures of Post-Landing Sensorimotor Functional Task Performance

Spaceflight drives adaptive changes in healthy individuals appropriate for sensorimotor function in a microgravity environment. These changes are maladaptive for return to Earth's gravity. The inter-individual variability of sensorimotor decrements is striking, although poorly understood. The goal of this study is to identify a set of behavioral, neuroimaging and genetic measures that can be used to predict early post-flight performance on sensorimotor functional tasks. To date, we have recruited fifteen astronauts who returned from the International Space Station on Soyuz and participated in sensorimotor field tests and/or posturography within one day following long-duration spaceflight. We are specifically utilizing a combination of three quantitative post-flight functional task outcomes(relative to pre-flight baselines): tandem walk, recovery from fall and dynamic posturography, along with a subjective self-rating of post-flight decrements and recovery. The recovery from fall is performed with eyes open on a stable support, allowing the use of vestibular, visual and proprioceptive feedback for task performance. In contrast, the dynamic posturography measures are performed with eyes closed on asway-referenced unstable support, requiring reliance on vestibular feedback for task performance. Tandem walk is performed on a stable surface with eyes open and eyes closed. Fourteen of the 15 subjects performed the field tests. These were nominally performed during three timepoints on the first postflight day, while posturography was performed only once during the third time point after direct return to JSC. More than 20% were unable to complete the initial field testing in the medical tent, while all participants completed testing during the third time point at JSC. As expected, there was considerable variability among all performance outcome measures, with more variability post-flight relative to preflight. Given the variability in all post-flight outcomes, we have been examining the relationships in performance across tasks. While there is a strong association within tests obtained at different landing daytime points, our preliminary findings suggest that by R+24 hrs performance on one post-flight test does not necessarily correlate with performance on other post-flight tests. This underscores the importance of a comprehensive post-flight test battery including different types of tasks with varying sensory feedback. We expect that further examining specific behavioral, neuroimaging and genetic sensorimotor biomarkers with post-flight functional task performance will improve both our understanding of the individual variability and our strategy to optimize sensorimotor countermeasures.

S J Wood↗

NASA NTRSDate not supplied

DEVELOPING AN EARTH-FIXED VISUAL REFERENCE TO AID STABILITY, READAPTATION, AND EGRESS AFTER A WATER LANDING

Water landings present the worst possible sensory conditions for crews trying to orient and stabilize themselves immediately after long-duration spaceflight. Of the three sensory feedback systems involved in maintaining stability (i.e., proprioceptive, vestibular, and visual), none will provide reliable orientation information under the current water landing scenarios. Although the visual system is likely not affected by the disuse and adaptation to microgravity that affect the proprioceptive and vestibular systems, the visual environment within an enclosed space that is subject to wave-induced rocking will prevent the crewmember from using vision to determine which direction is up. This is true whether enclosed in the capsule or in a room on the recovery ship. The result is an increased risk of fall-related injury. In a prior study, 70% (21 of 30) of nonimpaired subjects reported that the presence of an Earth-fixed horizontal line helped them stabilize when their visually enclosed environment was exposed to wave motion. In addition to aiding stability, an Earth-fixed visual reference also can assist in the readaptation process. Sensory re-adaptation occurs when the three sensory systems are synchronized with one another and aligned with Earth’s gravity. The earlier an Earth-fixed visual reference can be introduced the sooner the readaptation process can begin. The goal of this project is to identify the optimal features of a device that visually presents gravitational reference cues to support egress, stability and readaptation. **Remainder of abstract in document preview or downloadable version

B. T. Peters↗

NASA NTRSDate not supplied

Development of a Sensorimotor Ground Analog from Astronaut Postflight Experience

Exploration class missions including Artemis, Gateway, and beyond will require a new level of autonomy around periods of gravitational transition, where sensorimotor disturbances are great. Because of this, there is a need to define sensorimotor assessment thresholds that indicate when performance in operational tasks might be impacted or unsafe. To define these thresholds, a Sensorimotor Adaptation Analog (SAA) was proposed that could induce varying levels of sensorimotor disorientation through combined vestibular, visual, and proprioceptive disruptions. The purpose of this study was to gather subjective feedback on the SAA from previously flown astronauts that would mimic their post-flight experience and functional performance immediately after landing (R+0-4hrs; high level) and post-landing (R+24-48hrs; low level). The SAA consisted of galvanic vestibular stimulation (GVS), visual disorientation goggles, and a weighted suit to alter proprioceptive feedback and replicate subjective heaviness. A random sum-of-sines profile between 0-1Hz was used for the GVS with peak amplitudes ranging from 1-4mA. The GVS was applied first at the low (2mA) and high (3mA) levels, followed by the weighted suit alone, then combined with the GVS at the low (20% body weight) and high levels (40% body weight). Last, the disorientation goggles were applied alongside both the GVS and weighted suit at the low (0.07-0.10+ blood alcohol content (BAC)) and high (0.12-0.15+ BAC) levels. Each element of the SAA could be increased or decreased depending on crew feedback to find the disorientation levels that best matched their experience. Five USOS astronauts (1 male, 4 female) who had previously flown (average time since flight: 377 days) participated. Crewmembers reported that GVS alone replicated ~80-90% of their post-flight performance with the weighted suit fine-tuning the experience to replicate an additional 5-10% of their experience. Crewmembers did not believe the disorientation goggles represented either the visual disruptions or illusory sensations that they experienced, nor did they impact performance in post-flight tasks similarly. The final SAA, resulting from crewmember feedback, includes the GVS at the levels described above and the weighted suit at 15% and 30% body weight. The disorientation goggles were removed from SAA. These results provided a more realistic SAA that can be used to define the sensorimotor assessment thresholds through ground subjects and potentially expanded for use in countermeasure testing and as a pre-flight training tool.

S. C. Moudy↗