Psychophysiological responses of artificial gravity exposure to humans

The aim of this study was to determine psychophysiological responses and cognitive performance after a single bout of artificial gravity, in order to investigate its use as a potential holistic countermeasure for long-duration human space flight, considering mental health.

Sixteen male participants were exposed to two different hypergravity protocols in a randomized order, one providing a constant +2 Gz environment for 30 min, the other providing participants for five times with repeated 3-min intervals of +2 Gz and rest, respectively. EEG was recorded prior, during and after AG. In addition, self-reported mood and cognitive performance was assessed before and after AG exposure. EEG data were analyzed using standardized brain electromagnetic tomography (sLORETA).

Beta-1 EEG activity (12-18 Hz) was decreased in the left middle frontal gyrus after the continuous profile. Participants' motivation decreased after continuous artificial gravity, while perceived physical state was increased. The intermittent profile did not induce any changes in the observed parameters. Cognitive performance was not affected by either of both profiles.

The continuous profile induced neurophysiological changes, which are considered with negative affect and withdrawal related motivation, according to the model of frontal asymmetry. This notion was further confirmed by decreases in self-reported mood after continuous AG. Therefore, the continuous profile would not be appropriate for the human space flight program. Intermittent AG did not induce any psychophysiological changes and might therefore provide a more appropriate approach as a countermeasure for further investigations.