Dynamics of cognitive and neurophysiological functions of a person in the simulation of weightlessness in terrestrial conditions

Abstract

Introduction. The authors have conducted a study of the influence of the conditions of 21-day antiorthostatic hypokinesia (AOSH) on the dynamics of neurophysiological reactions and cognitive functions of a person on the basis of Institute of Biomedical Problems, RAS, with the participation of six healthy male volunteers aged 24 to 40 years (30.7±5.4) who were in bed with hypokinesia in an antiorthostatic position with an angle of inclination –6° relative to the horizon.
 The study aims to determine the dynamics of neurophysiological reactions and cognitive functions of a person during a 21–day AOSH (–6°).
 Materials and methods. The researchers analyzed the dynamics of cognitive functions based on the results of performing complex dynamic tasks with elements of uncertainty from the CleverBalls software test block. The authors determined the dynamics of neurophysiological reactions by the relative dynamics index (RDI) of the relative power value (RPV) of all the studied ranges of the EEG spectrum. The experts carried out measurements of all indicators before the start of the study (Background), on the 3rd (1st session), 10th (2nd session), 17th (3rd session) and 21st (4th session) days, as well as 3 days after the end of the experiment — aftereffect (After).
 Results. Scientists have found an increase in inhibitory processes in the brain as a result of solving complex dynamic tasks with elements of uncertainty in the acute period (3 days) and in the aftereffect. After the acute period and before the end of the experiment, they observed the restoration of brain functions to the background level. An increase in the performance of complex dynamic tasks with elements of uncertainty (according to the indicators "Percentage of correct choice" and "Average harmonic click time") was observed from ten days to the aftereffect inclusive, which indicated, at least, the absence of a decrease in cognitive functions during the 21-day AOSH.
 Conclusion. At the end of the experiment, the authors noted a less pronounced increase in Delta and Theta activity than in the acute period, with a simultaneous decrease in Alpha and Beta activity, but at the same time, they did not observe a decrease in the success of cognitive tests.
 Ethics. The program of the experiment was approved at the section of the Scientific Council and approved by the Commission on Biomedical Ethics at the Institute of Biomedical Problems, RAS (Protocol No. 599 of 06.10.2021).