[Visual–manual tracking after long spaceflight]

This study presents the results of the pre- and postflight clinical and physiological examination (CPE) and scientific experiment “Sensory Adaptation-2” carried out in Yu.A. Gagarin Research & Test Cosmonaut Training Center. There were examined 14 Russian cosmonauts, crewmembers of long-term international spaceflights ISS-28/29 to ISS 36/37, who were in microgravity from 159 to 195 days. Age of the cosmonauts was 35–50 years. Studies were conducted twice before space flight (baseline), and on days R+1(2), R+4(5), and R+8(9) after landing. In the study of visual–manual tracking (VMT), eye movements were recorded by the electrooculography method (EOG), hand movements - by a joystick using biological visual feedback (on the screen represented the current angle/position of a joystick). Examinations were conducted using computerized stimulation programs, which were presented on the screen of the hardware-software complex "Sensomotor". Examinations of the VMT took place in the dialog mode and included the following sections: a) EOG-calibration; b) visual-manual tracking within ±10° on the screen with blank background (smooth linear and sinusoidal movement of a point target with a frequency of 0.16 Hz in the vertical and horizontal directions). There were evaluated time, amplitude, and velocity characteristics of visual and manual tracking (VT and MT), including the effectiveness (EC) and gain (GC) coefficients which were calculated respectively, as the ratio of amplitude and velocity of the visual stimulus (target). A study of the vestibular function (VF) was performed before and after space flight using videooculography. There were assessed static torsion otolith–cervical–ocular reflex, dynamic vestibular–cervical–ocular reactions, vestibular reactivity, spontaneous eye movements. Study of VF in the first postflight has shown a sharp decrease (up to its complete absence) of static vestibular excitability (otolith reflex) accompanied by the increased dynamic reactivity of the vestibular system. Study of VTM has shown a significant decrease of gain and effectiveness/amplitud of VT in the first days postflight, as well as correlation between the parameters of VF and MT, between the VF and VT, and no found correlation between parameters of VF and MT. It was found that the conditions of space flight (microgravity) have a greater impact on the accuracy of the VT than the accuracy of MT. Full return of characteristics of the VMT and VF to the baseline was observed on R+8(9) days after space flight.