Changes in Sensory Functions in Response to Living in an Extreme Underwater Saturation Environment

Abstract

The present challenges of long duration spaceflight and other missions in extreme environments include changes of sensory functions, including vision impairment and changes in taste perception. In order to monitor and improve astronaut health and performance during long duration spaceflight and future spaceflight missions we studied sensory functions in response to living in an extreme environment during the NASA Extreme Environment Mission Operation (NEEMO) 23. The Aquarius Reef Base is located at 20 m (66 ft) with 2.6 atm (air) pressure inside the habitat, while levels of CO2 are elevated similarly to the International Space Station.This study assessed the changes in visual acuity and taste perception in 6 NEEMO 23 subjects (2 males, 4 females) 1 day before the mission, during the mission at half time and 1 day post mission. Visual changes were assessed using the NIH Toolbox protocol, while changes in taste perception were measured using solutions containing concentrations of either salty, sweet and bitter flavors in three different concetrations on the side of the tongue and in full mouth.We observed a trend of decreased salty and bitter taste sensation in the habitat and post mission, compared to baseline, while the sweet taste sensation did not change. When testing the full mouth, the salty taste sensation significantly decreased post mission, compared to baseline at low or medium concentration. Bitter taste sensation significantly decreased at low concentration in habitat and post mission, compared to baseline. At medium concentration the bitter taste sensation significantly decreased post mission, compared to baseline and in‐habitat, while at high concentration it significantly decreased post mission, compared to baseline. There was a signifcant reduction in the Overall Raw and in Overall Uncorrected Vision Scores between baseline and post mission indicating a significant reduction in visual acuity during the 9 days mission that was not restored immediately after the mission.Living in a saturation environment decreases certain sensory modalities that may persist for an unknown length of time after the exposure. Diminished sensitivity to taste can alter nutritional status and chemosensory changes may also relate to space sickness, stress and psychological factors, while changes in vision may impair operational tasks. These data indicate that mitigation strategies need to be developed and tested in space analog environments.Support or Funding InformationKetone Technologies LLC provided partial funding for the study. SIFT provided partial salary for CA.