During the Long Way to Mars: Effects of 520 Days of Confinement (Mars500) on the Assessment of Affective Stimuli and Stage Alteration in Mood and Plasma Hormone Levels

For future interplanetary manned spaceflight, mental issues, as well as physiological problems, must inevitably be considered and solved. Mars500 is a high-fidelity ground simulation experiment that involved 520 days of confined isolation for six multinational crewmembers. This experiment provided a good opportunity to perform psycho-physiological and psycho-social researches on such missions. To investigate emotional responses and psychological adaptation over long-term confinement, the International Affective Pictures System (IAPS) was selected as the visual emotional stimuli in this study. Additional data collected and analyzed included the Profile of Mood States (POMS) questionnaire and the levels of four types of plasma hormones: cortisol, 5-hydroxy tryptamine, dopamine, and norepinephrine. The results demonstrated an obvious bias on valence rating for unpleasant stimuli with time (p<0.05), and the correlation between psychological and biochemical data was identified (p<0.05). Overall, we concluded that the confined crew tended to assign positive ratings to negative pictures with time, which might be driven by a defensive system. There was a stage-changing pattern of psychological adaptation of the Mars500 crew, which is similar to the third-quarter phenomenon.     

Hormonal regulation during a 60-day confinement (ESA-EXEMSI'92) in humans

EXEMSI'92 was a 60-day isolation and confinement experiment with an international crew. During this second experiment of the European Space Agency (the first one was a 28-day confinement with 6 men: ISEMSI'90), blood volume regulating hormones and water balance were studied. During ISEMSI'90, stress level was elevated as shown by specific markers and we observed some interesting results which have been already observed before, during bed-rest experiments. Thus, our conclusion was that some of the physiological effects observed during bed rest could be the consequence of the "confinement effect" and/or stress imposed to the subjects during such experiments. The aim of the present physiological study was: 1/to define the origin of the blood pressure increase seen during ISEMSI'90; 2/ to study the blood volume regulating hormones (ANP, renin, aldosterone) variations; 3/ to determine the dehydration level by measuring the total body water with the doubly labeled water (DLW) method and fluid balance in general.     

Relation between the parameters of lipid peroxidation and the constant potential of the rat brain

Studies were carried out of the relationship between the constant potential level (CPL) and the intensity of lipid peroxidation (LP) of the brain membranes in rats with different motor asymmetry. Strong correlation was found between CPL and the content of LP products (diene conjugates, hydroperoxides and Schiff bases) in the hemispheres of the brain (R = 0.7-0.8).     

Effects of the 520-day isolation on the functional state of the cardiovascular system

The purpose of the study was to estimate the cardiovascular effects of simulated factors in a 520-day crewed mission to Mars, and to validate the diagnostic value of the ultrasonic investigation of microcirculation and endothelium-dependent dilation of the right brachial artery in six male volunteers at the age of 28 to 39 years. It appears that a 520-day isolation affected intracardiac hemodynamics and endothelium function more dramatically compared with a 105-day isolation, increasing the risk of atherosclerosis. These findings add insight into the “cost of human adaptation” to very long isolation.     

Effects of the watch system of job management on central hemodynamic parameters and the constant potential of the brain

The effects of the watch system of job management on central hemodynamic parameters and the constant potential of the brain were studied in sailors during a long voyage. Twenty crew members were examined during a 120-day translatitudinal voyage. The studies were performed on days 4–6, 40–42, 73–75, and 107–109 of the voyage. It was found that the role of the peripheral regulatory loop in maintaining physiological functions increases during the second half of the voyage and that the functional activity before a watch determines the changes in the parameters by the end of the watch. For each stage of the study, the baseline value of the constant potential of the brain is an important element of functional activity. The system of ratios between parameters before and after a watch that is formed in the early period of the voyage breaks up during the second month, the general reactivity of the body after a watch being independent of the reactivity before the watch; the reactivity is stochastic and is mainly controlled by central mechanisms. In the second month of the voyage, the first signs of a strategy aimed at making the functioning more economical are observed in crew members. The second and third months of the voyage are characterized by a considerable strain of the mechanisms of adaptation, activity, and reactivity in sailors. During the third month of the voyage, overfatigue develops.Translated from Fiziologiya Cheloveka, Vol. 31, No. 2, 2005, pp. 58–68.Original Russian Text Copyright © 2005 by Myznikov, Shcherbina.     

Content and structure of crew’s communicative behavior and gonadal hormone excretion during long-term chamber isolation of all-male international crew

The characteristics of psychophysiological adaptation to the simulation of the extended autonomous manned mission to Mars with limited resources and external communication were studied. The behavioral (communication with the external world) and physiological correlates of 105-day life and work in a pressurized compartment of the crew of six male subjects representing Russian and European space agencies under the conditions of sensory deprivation, confinement, monotony, and high autonomy were studied. Psychological, physiological, and biochemical (urinary cortisol and gonadal hormones) testing together with content analysis of the crew??s communication with the external world were made in parallel. The results confirmed, to a considerable extent, the preliminary hypothesis about the serious impact of stressful factors, including conflict, the significant decrease of the variety and scope of communication with the outer world, and social pressure on the verbal behavior and hormone levels in the future Martian crew. The correlation between the metabolism of the gonadal hormones and the volume, content, and creativity of the verbal human behavior during various stages of adaptation to the extended isolation in pressurized compartments has been discovered.     

Nutritional Status in the Experiment with 105-Day Isolation as the First Phase of the Mars-500 Project

In a 105-day experiment simulating crew life in a interplanetary spaceship, shifts in the nutritional status were assessed in six volunteersthat differed in the body weight index, basal metabolic rate, attitude to the proposed diet, physical exercise, and workload. The results of the investigation showed that hard physical work under the conditions of the experiment led to the formation of the nutritional status against the background of more intensive basal metabolism, elevated metabolism of carbohydrates and lipids, and their increased mobilization from fat depot. Food ration, though it was sufficient to sustain health and fairly high calorie, did not fully meet individual taste preferences of some crewmembers and energy needs for physical activities. Under these conditions, heavy workloads required mobilization of lipids from fat depot and reducedthe hepatic detoxification and metabolic capacities. Self-limitation of eating protein-rich desserts led to a relative deficiency of protein intake. These changes in the diet were the reason why four out of six test subjects reduced their basal metabolism and lost body mass. The recovery of metabolism and slowdown of the body weight loss were achieved under these conditions by supplementing meals with digestible proteincontaining products.     

Psychological selection and optimization of interpersonal relationships in an experiment with 105-days isolation

New approaches to optimization of interpersonal relationships in an isolated small group proposed in this paper can be applied to a manned mission to Mars. Some of these approaches have been tested in the course of preparation and implementation of an experiment with a 105-day isolation (the MARS-105 project) simulating the initial period of a manned mission to Mars. A variety of methods, such as evaluating the efficiency of interpersonal interaction (a Homeostat device), value orientations, self-perception, and interpersonal relationships within the crew (the PSPA test, classic sociometry) have been used. In the middle of the isolation period (the second 35-day cycle), a decrease in cohesion of the crew was observed; in the same time, tension appeared, which enabled the phenomenon of pairing; i.e., the crew split into stable pairs opting for inner communication. Closer relations between some crew members and clashes between the others modulated interpersonal perception. The set of methods provided efficient evaluation of the group behavior, diagnosis of interpersonal problems, and the grounds for improving psychological selection for participation in future manned interplanetary missions.     

Neuroendocrine interactions in thyroid pathology

Neuroendocrine interactions in thyroid pathology were studied by means of recording and analysis of the constant potential level (CPL) of the brain. The topography of changes in cerebral metabolism upon changes in the thyroid status was determined. A twofold CPL decrease in the central and left temporal areas was shown in hypothyroidism as compared with euthyroidism; in hyperthyroidism, there was a threefold CPL increase in the occipital area and a twofold CPL increase in the frontal and temporal areas as compared to euthyroidism. These variations were associated with corresponding changes in the metabolism of the brain’s energy. The constant potential value averaged over all derivations was approximated by the linear dependence on the logarithms of concentrations of the thyrotropic hormone (TTH), r = ?0.70, (p < 0, 001), n = 82. Drawing the dependences of the CPL value in derivation sites on the TTH concentration on a semilogarithmic scale, yielded approximation equations with negative correlation coefficients of ?0.53 to ?0.7. The method allows for the monitoring of the state of patients and assessment of the efficiency of treatment for thyroid pathology by the change in the CPL in different regions of the brain.     

Human immunity system under conditions of 105-day isolation and confinement in an artificial environment

The study of the adaptive immunity system of six test subjects volunteered for a 105-day isolation and confinement in an artificial environment showed activation of the immune system and overstrain and depletion of its functional reserve. Significant differences in the adaptability of the immune system of the test subjects indicate individual susceptibility to disorders in immunological reactivity.     

Wireless Monitoring of Changes in Crew Relations during Long-Duration Mission Simulation

Group structure and cohesion along with their changes over time play an important role in the success of missions where crew members spend prolonged periods of time under conditions of isolation and confinement. Therefore, an objective system for unobtrusive monitoring of crew cohesion and possible individual stress reactions is of high interest. For this purpose, an experimental wireless group structure (WLGS) monitoring system integrated into a mobile psychophysiological system was developed. In the presented study the WLGS module was evaluated separately in six male subjects (27–38 years old) participating in a 520-day simulated mission to Mars. Two days per week, each crew member wore a small sensor that registered the presence and distance of the sensors either worn by the other subjects or strategically placed throughout the isolation facility. The registration between two sensors was on average 91.0% in accordance. A correspondence of 95.7% with the survey video on day 475 confirmed external reliability. An integrated score of the “crew relation time index” was calculated and analyzed over time. Correlation analyses of a sociometric questionnaire (r = .35-.55, p< .05) and an ethological group approach (r = .45-.66, p < 05) provided initial evidence of the method''s validity as a measure of cohesion when taking behavioral and activity patterns into account (e.g. only including activity phases in the afternoon). This confirms our assumption that the registered amount of time spent together during free time is associated with the intensity of personal relationships.     

Night sleep structural alteration as a function of individual strategy of adapting to 520-day isolation

The purpose of the study was to establish a relationship between trends in sleep alteration and individual adaptation to stress factors in the 520-day isolation study. Psychological evaluations using a battery of motivation tests, Sobchik’s modification of the Luscher personality test, and Mirror coordinograph made it possible to differentiate groups responding to the stress according to the pattern “control” (G-1) or “search” (G-2) manifested in individual styles of behavior and operator’s activity. The two groups exhibited different dynamics of the night sleep structure. Difficulties with falling asleep in G-1 arose on the eve of “landing onto Mars” and end of the experiment, whereas in G-2 they were evident prior to the end only. In addition, the micro- and segmental sleep structures were more stable in G-1, suggesting the integrity of somnogenic mechanisms despite difficult sleep initiation.     

Muscle volume, MRI relaxation times (T2), and body composition after spaceflight.

Postflight changes in muscle volume, calf muscle transverse relaxation time, and total body composition were measured in 4 crewmembers after a 17-day mission and in 14-16 crewmembers in multiple shuttle/Mir missions of 16- to 28-wk duration. During the 17-day mission, all muscle regions except the hamstrings significantly decreased 3-10% compared with baseline. During the shuttle/Mir missions, there were significant decreases in muscle volume (5-17%) in all muscle groups except the neck. These changes, which reached a new steady state by 4 mo of flight or less, were reversed within 30-60 days after landing. Postflight swelling and elevation of calf muscle transverse relaxation time persisted for several weeks after flight, which suggests possible muscle damage. In contrast to the 17-day flight, in which loss in fat, but not lean body mass, was found (25), losses in bone mineral content and lean body mass, but not fat, were seen after the longer shuttle/Mir missions. The percent losses in total body lean body mass and bone mineral content were similar at approximately 3.4-3.5%, whereas the pelvis demonstrated the largest regional bone loss at 13%.     

Characteristics of the interhemispheric EEG relationships in assessing the functional state of the human brain

In healthy subjects (11 right-handed men) reorganization was studied of intra- and interhemispheric correlation of the electrical brain activity at transition from the state of alertness to drowsiness. At the lowering of alertness level, the coherence of hemispheres symmetrical points changed not abruptly, with a tendency towards an increase at differently directed character of changes of combinations of separate physiological rhythms ranges. Comparison of the EEG coherence changes within the right and left hemispheres revealed a greater reactivity of the left (dominant) hemisphere. The reduction of the predominance (observed in the dominant hemisphere in alertness) of the degree of EEG conjunction, at transition to drowsiness, leads to smoothing of interhemispheric asymmetry in the organization of electrical brain processes.     

Changes of neurochemical and electrophysiological indices of rat brain under ethanol intoxication

It was found that acute ethanol intoxication caused an imbalance of the neurotransmitters in the CNS: accumulation of GABA and serotonin and depletion of catecholamines. Alcohol depression was characterized by suppression of the evoked potentials of the various rat brain structures. Under chronic ethanol intoxication of animals, relative stabilization of the electrophysiological indices of the rat brain activity was observed. This reflects the CNS adaptation to the constant ethanol presence in the blood. This state was also characterized by the relative stabilization of the serotonin system and by the increase of the catecholamine level. Withdrawal of ethanol after prolonged consumption caused accumulation of catecholamines in rat brain, depletion of serotonin and GABA, and increased excitability of the nervous structures. The changes of activity of the GABA- and monoaminergic systems are coupled to manifestation of symptoms of alcohol depression and convulsive reactions during ethanol withdrawal.     

Photoinduced resonance phenomena in the human electroencephalogram as a function of frequency, intensity, and duration of stimulation

The features of resonance phenomena in high-resolution EEG structure were analyzed for two intensities and three values of duration of exposure to 20 constant frequencies of intermittent photic stimulation in a range of 1-20 Hz with 1 Hz steps. It was shown that with a 6 s step duration, an irregular activation of multiple spectral EEG components for both light intensities occurs. With longer durations (12 and 18 s) of fixed-frequency stimulation, the EEG reactions are of resonance nature. Low-intensity flashes cause only the resonance activation of the intrinsic oscillator in the range of dominant alpha-EEG frequency. During a more intensive stimulation, the resonance EEG phenomena are observed for the whole range of stimulation frequencies. The interval of 6-12 s is supposed to be the relaxation period for a system of brain electrical activity generation. After this time, the low-intensity stimuli cause the adaptation of the system to light, whereas more intensive flashes cause more pronounced resonance EEG phenomena and physiological effects.     

Rotational stimulation-related changes of the motor asymmetry in the goldfish

We studied changes in the motor asymmetry of the goldfish induced by single-session long-lasting vestibular stimulations (clockwise and counter clockwise rotations around the rostro-caudal body axis) and repetitive everyday short sessions of such stimulation (training); the latter mode led to the development of adaptation (resistance to fatigue). Rotational stimulation of different durations and directions elicited effects of different patterns and intensities. Such stimulation enhanced or, vice versa, smoothed the motor asymmetry in “dextral” and “ sinistral” fishes, up to full symmetry or even a change of the preferred turning direction. Adaptation to unilateral rotational stimulation allows an experimenter to selectively and gradually induce the resistivity of the left-or right-ward asymmetry to fatigue effects. Earlier, we found that the motor asymmetry in the goldfish, which is determined by the functional asymmetry of the brain, correlates with the morphological asymmetry of Mauthner neurons localized in the medulla in a mirror manner and playing a crucial role in the control of turnings in the course of locomotion (swimming). Experimental rotational stimulation-induced gradual modification of the motor asymmetry in the goldfish can serve as a physiological model for more detailed studies of the structural base of the functional brain asymmetry and some mechanisms of adaptation on the level of single neurons. Neirofiziologiya/Neurophysiology, Vol. 37, Nos. 5/6, pp. 432–442, September–December, 2005.     

Decrease in dopamine and norepinephrine concentration in different brain regions of mice during progression of Sarcoma 180 tumour

The distribution and concentration of dopamine (DA) and norepinephrine (NE), the catecholamine neurotransmitters, were studied in discrete brain areas of Sarcoma 180 tumour bearing mice. With the progression of tumour, marked depletion of DA and NE concentration was observed in some brain areas richly innervated with dopaminergic and noradrenergic neurons suggesting an inverse relationship between brain CA and tumour growth. Since brain CA influence different important physiological activities like hormonal and immunological functions, it's alteration in brain areas during malignant growth suggests the possibility that the hormonal and immunological alterations during tumour growth is at the level of brain CA.     

The significance of interhemispheric asymmetry in the development of compensatory processes in the human brain

For more precise definition of the role of hemispheric interconnections in mechanisms of human CNS compensation the intercentral relations of the electrical activity of the left and right cerebral hemispheres were studied on physiological model of focal interhemispheric asymmetry. Spectral-coherent EEG characteristics of 36 patients with tumoral damage of one hemisphere were studied in condition of chronic (prior to operation) and acute (early terms of postoperative period) brain decompensation. In was shown that the reorganization of the structure of the EEG intercentral relations correlated with definite stages of CNS compensatory processes and that the character of hemispheric interconnections depended on the lateralization of the damage focus. The primary role was revealed of the degree of the left (dominant) hemisphere preservation in restoration of normal pattern of the interhemispheric asymmetry of the coherence of human brain electrical processes.     

Unconscious components of the psychophysiological reactions of the participants of the experiment with 520-day isolation

Six participants of Mars-500 were examined to obtain information about intrapersonal conflicts and life spheres with high emotional tension associated with them by participation in an experiment with prolonged group isolation. The investigation was performed using operational analogy-based neurosemantic psychodiagnostics, with the subconscious regarded as a semantic filter with unstructured semantic information at the input and information structured by the inner world content at the output. The results shed light on the semantic structure of the subjective experience and functioning of protective mechanisms, as well as organizational levels and modality of emotional experience. Before and after a 520-day isolation, all the participants were shown to have intrapersonal conflicts and high emotional tension in the socio-professional sphere, caused by the family/sexual and interpersonal relations and self-assessment, and concerns about life and health. On completion of the isolation, the psychoemotional tension was reduced in interpersonal relations and increased in family/sexual ones.