Auditory Go/NoGo Task in the Dry Immersion Model of Microgravity

The effects of a ground-based model of microgravity on executive functions (namely, inhibition) were investigated in this study. Volunteers participated in so-called dry immersion (DI), during which they spent 21 days in a water-filled tub in the supine position. During this period, they performed an auditory Go/NoGo task while multichannel EEG activity was recorded. The Go/NoGo task was performed one time outside of the DI and two times during the stay in the DI. ERPs were computed on correct NoGo and Go trials. While no behavioral deterioration of the Go/NoGo task was found during their stay in the DI, a significant difference was found in amplitudes between NoGo N2 ERP peaks before DI and during DI. The N2 peak was smaller on the 17th day of DI, indicating a potentially lower level of inhibitory control during simulated microgravity conditions. The amplitudes of the N1 and P3 peaks did not change significantly. The dry immersion procedure reproduces some of the important physiological factors of real space flights (support withdrawal, bodily liquid redistribution), thus our results hint at possible brain and behavioral alterations in real space flight that have so far been unnoticed.