Changes in the autonomic reactivity pattern to psychological load under long-term microgravity--twelve men during 6-month spaceflights.

A complex psychophysiological test battery was applied to twelve subjects during long-term spaceflights. This experiment was designed to assess the psychophysiological reactivity to acute psychological stressors. A set of noninvasive physiological measurements (electrocardiogram, electromyogram, blood pressure, skin conductance, peripheral skin temperature) was used to describe the reactivity of the autonomic nervous system and the cardiovascular system to an induced series of changes between mental activity load and quiet relaxation. It could be shown that under space conditions the subjects react differently than on earth. On the basis of significantly lower heart rates we concluded that an extended parasympathetic cardial influence is present during later periods of long-term space flights. The peripheral skin conductance reactivity, however, indicated a tendency to higher peripheral sympathetic tonus under microgravity. Assuming individually different pathways of sympathetic-parasympathetic traffic under psychological stress, the whole set of data could be classified into autonomic outlet types (AOT) based on clinical reference data. Most of the subjects changed their AOT during flight. After flight the subjects eventually fell back into their pre-flight patterns, but seven of twelve subjects showed a significantly different autonomic system reactivity at least once after landing that was similar to that of hypertensive patients, indicating an extended sympathetic overshoot directly post-flight. In conclusion it is assumed that sympathetic effects in one measurement do not exclude less sympathetic or even parasympathetic effects in others during adaptation to extreme environments.

Differences in the autonomic reactivity pattern to psychological load in patients with hypertension and rheumatic diseases.

As a ground-based reference study to a space experiment, a complex psychophysiological test battery (heart rate, blood pressure, skin conductance, finger temperature, forearm electromyogram during psychological loading task solving) was developed and first applied on two cohorts of subjects with different blood pressure levels at rest (53 hypertensive patients, and 30 normal controls). The data describing autonomic reactivity could be differentiated by cluster analysis into four Autonomic Outlet Types (AOT). The method was subsequently applied to 20 patients with systemic Lupus erythematosus and 13 subjects with rheumatoid arthritis to work out a discriminant function for classifying and testing it's validity. The AOT classification of all subjects showed a significant correlation with the different types of diseases.

Voice stress monitoring in space--possibilities and limits.

An overview of experimental investigations into the use of the voice pitch mode (F0 m) as a distance tool for the monitoring of emotional stress reactions is given. Seven experiments are summarized describing the relations between voice reaction and psychological and physical load in laboratory and field applications. The reactivity of F0 m to mental load depends on psychological personality traits. F0 m is less related to physical load. The evaluation of F0 m as voice stress indicator requires an individual calibration. This calibration has to include the assessment of the individual Autonomic Outlet Type (AOT) because the physiological relevance of voice reactions depends on the individual AOT. The calibration is based on statistical reference data which have to be improved in the future. The calibration has to be done under comparable environmental circumstances. A 3-yr application of the method on board Mir station documents the applicability of the procedure.

Regulatory changes at high altitudes in comparison with post-space-flight reactions.

This report will compare results of applications of the psychophysiological method "Assessment of Autonomic Outlet Type" (AOT) in space as well as at high altitudes. The aim was to find out whether it is possible to differentiate a subject's reaction to different environments by this method (Johannes et.al. 1995). This assessment as described below was first applied to clinically well defined cohorts and to healthy subjects. By means of cluster analysis it could be demonstrated that different reaction patterns exist. These different patterns were correlated to two groups of normal controls ([I] = non-responder/voice-responder and [II] = heart-responder) and two groups of patients with different clinical diagnoses (rheumatic diseases ([III] = autonomic-responder) and [IV] = hypertensives). Based on these clinical reference data the method provides for each "new" experiment a common classification of the complex regulatory reaction pattern of the autonomic nervous system (ANS) and the Cardiovascular system (CVS) to psychological stressors by means of a discriminant function. Since August 1997 the experiment has been applied to all Russian cosmonauts continuously each month. (Johannes et.al. 1998). At the same time numerous terrestrial experiments have been running parallel for comparison with the results from space. This report will focus on a study at altitudes of 3600 m.

Psychophysiological reactivity under Mir-simulation and real micro-G.

A complex psychophysiological test battery (ECG, blood pressure, SCL, finger temperature e.t.c.) was applied on two subjects in space. It could be shown that the subjects react under space conditions differently than on earth. The data received could be classified into four types of regulation. The subjects changed this type of regulation during the flight and returned to their former pattern after the flight.