INTRODUCTION: Following a transition from microgravity to a gravity-rich environment (e.g., Earth, Moon, or Mars), astronauts experience sensorimotor impairment, primarily from a reinterpretation of vestibular cues, which can impact their ability to perform mission-critical tasks. To enable future exploration-class missions, the development of lightweight, space-conscious assessments for astronauts transitioning between gravity environments without expert assistance is needed. METHODS: We examined differences in performance during a two-dimensional (2D) hand–eye multidirectional tapping task, implemented in augmented reality in subjects (N = 20) with and without the presence of a vestibular-dominated sensorimotor impairment paradigm: the binaural bipolar application of a pseudorandom galvanic vestibular stimulation (GVS) signal. Metrics associated with both the impairment paradigm and task performance were assessed. RESULTS: Medial-lateral sway during balance on an anterior-posterior sway-referenced platform with eyes closed was most affected by GVS (effect size: 1.2), in addition to anterior-posterior sway (effect size: 0.63) and the vestibular index (effect size: 0.65). During the augmented reality task, an increase in time to completion (effect size: 0.63), number of misses (effect size: 0.52), and head linear accelerations (effect size: 0.30) were found in the presence of the selected GVS waveform. DISCUSSION: Findings indicate that this multidirectional tapping task may detect emergent vestibular-dominated impairment (near landing day performance) in astronauts. Decrements in speed and accuracy indicate this impairment may hinder crews’ ability to acquire known target locations while in a static standing posture. The ability to track these decrements can support mission operations decisions. Allred AR, Weiss H, Clark TK, Stirling L. An augmented reality hand–eye sensorimotor impairment assessment for spaceflight operations. Aerosp Med Hum Perform. 2024; 95(2):69–78.
Galvanic vestibular stimulation (GVS) modifies the afferent signals innervating the vestibular organs, which is in turn centrally processed in determining a central state estimate of position in space.
A) SOT 1 and SOT 5 configurations are presented. Both SOT 1 and SOT 5 were conducted with and without Galvanic vestibular stimulation (GVS). B) An example subject’s inferred center-of-gravity sway trace in an Earth-horizontal plane is depicted both with and without GVS during SOT 5. C) The 2D hand–eye multidirectional tapping task protocol. Each block consisted of five trials. On the right, an AR view from the subjects’ perspective is displayed. The GVS electrodes remained on the subjects during all four blocks but was only turned on for the GVS block. D) The 2D hand–eye multidirectional tapping task pattern. Not all paths are shown. All 16 targets are acquired for each sequence.
Two performance clusters found during the training block. Clusters were determined using density-based spatial clustering of applications with noise. The proficient cluster (N = 16; blue) is normally distributed (the fitted normal distribution is shown with the matching blue curve). The nonproficient cluster (N = 4) is shown in red.
A) Peak-to-peak A-P sway compared across our 20 subjects, shown individually. Median scores across the three SOT 5 trials with and without galvanic vestibular stimulation (GVS) are shown (95% CI shown with blue bars). Shuttle-era R + 0 astronauts (N = 34)23 are compared as a population preflight and postflight (95% CI shown with red bars). B) Peak-to-peak M-L sway (95% CI shown with blue bars). C) Vestibular index with and without GVS (95% CI shown with blue bars). Asterisks denote significance level. Individual subject markers are consistent throughout this figure and Fig. 5, and horizontal jitter was applied to individuals.
A) Average times to press between the blocks with no Galvanic vestibular stimulation (no-GVS) and with GVS. The four subjects excluded from the statistical analysis (transparent blue bars) are highlighted in red and have been made transparent. B) The average distance pressed from the center of the target for successful presses, compared between the no-GVS and GVS blocks. C) Number of misses between the no-GVS and GVS blocks. D) The variation in index finger velocity between the no-GVS and GVS blocks. E) The total path length between the no-GVS and GVS blocks. F) The root mean square (RMS) of XY-plane acceleration compared between the no-GVS and GVS blocks. Population mean 95% confidence intervals are displayed with transparent blue bars.
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