Vol 50, No 4 (2024)

In this study took part 39 adult subjects, 28 children 12 years old, 21 children 8–9 years old, 26 children 5–6 years old and 19 newborns. In each age group, the coefficient of interindividual similarity (CIS) of the spatial organisation of the electroencephalogram (EEG) was calculated using Pearson's crosscorrelation algorithm. Results reveal high level of interindividual similarity of spatial structure of EEG distant connections. Both in adults and children CIS exceeded 0.80. In women, compared with men, a significantly higher level of interindividual similarity of the spatial organization of the EEG was revealed for all studied combinations of EEG connections. The obtained data shows that relative stability in ontogenesis of the spatial structure of dynamic activity of the cortex is apparently provided mainly through determined by a genotype distant intra- and interhemispheric interconnections that forming certain morfofunctional “skeleton” of neocortex. The functionally specific interactions realizable across more plastic “local chains” of near intercortical interrelations are carried out on basis of the dynamic activity of the brain hemispheres that ordered by means of such “global” interactions. Such system organization of intercortical interactions can provide both safety of individual properties of personality and the ability of the brain to effectively adapt to various influences of environment at phenotype formation in ontogenesis.

Twenty-eight people (30–70 years old, 12 men, 16 women, artists and non-artists) participated in a comparative neuroaesthetic study in the conditions of real-life visit to M. Vrubel mono-exhibition (Russian Museum, St. Petersburg). During the visit to the exhibition (usually lasted for around 60 min), EEG of participants was recorded. The subjects were looking at the paintings for 30 seconds to 3 min and evaluated the subjective aesthetic “attractiveness” of the paintings by a series of button presses (from 1 to 10). Were analyzed EEG spectral power in the α₁ (8–10 Hz)-, α₂ (10–13 Hz)-, β₁ (13–18 Hz)-, β₂ (13–30 Hz)-frequency bands during viewing the most famous Vrubel paintings (“Bogatyr”, “Swan Princess”, “Swan”, “Sitting Demon”, “Flying Demon”, “Pan”, etc.) and event-related EEG synchronization/desynchronization in relation to the subjective emotional and aesthetic evaluation of these paintings. Professional artists showed lower spectral power values in α₁ (leads F₃, C₃, T₄, Pz) and α₂ (F₃, Fz, F₄, C₃, Cz, C₄, P₃, Pz, P₄)-frequency bands in frontal, central, and parietal regions. The artists were also found to have lower power values in β_1,2-frequency bands in frontal (F₃, F₄, C₃) regions and higher power values in occipital (O₁, O₂ – β₁, β₂) and posterior temporal (β₂) cortical regions compared to the group of subjects with no special artistic education. Moreover, artists decision-making about the high emotional-aesthetic attractiveness of paintings was accompanied by an increase in event-related EEG synchronization for 11.5–27 Hz in frontal and central cortical areas over 580–360 ms before giving the response, compared to non-artists, whereas low emotional-aesthetic evaluation was characterized by 9–27 Hz EEG desynchronization, which started 60 ms before the giving the response and lasted up to 440 ms after it, in the posterior temporal and parietal regions. The differences in frontal cortical areas may indicate a higher engagement of the reward system during the perception of aesthetically pleasing paintings, and the differences in parietal and posterior temporal areas may indicate a continuing visual synthesis (more sustained visual attention) during the perception of subjectively less attractive paintings in artists compared to non-artists.

Postactivation effect (PAE, postactivation phenomenon) is a specific type of involuntary muscle tone (tonic automatism) which is generated in the “tonogenic” structures of the brain, presumably without the “sensory copy” and “motor command” mechanisms. In this regard, the electromyogram (EMG) signal of PAE may have a simpler temporal signal structure compared to PAE-inducing voluntary activity. The purpose of this work is to characterize the temporal structure and complexity of surface EMG (sEMG) of the human deltoid and biceps brachii muscles using fractal (D) and correlation dimensions (D_c). It was found that in deltoid muscles the value of D was 1.78–1.81 both during PAE and voluntary effort (p > 0.05). D_c (approximately 4.0–4.2) also did not differ between PAE and voluntary effort, although the average frequency of the sEMG spectrum during PAE was 15–16 Hz (p < 0.05) higher compared to voluntary effort. In biceps brachii muscles, the D value was 1.8 during PAE and 1.62 during voluntary effort (p < 0.05). D_c values did not differ between PAE and voluntary contraction (4–4.8). Thus, despite the supposed difference in the central organization of PAE and voluntary effort, the temporal structure of their sEMG did not differ, indicating that isometric voluntary effort and involuntary tone in the form of PAE share a common principle of sEMG signal generation. At the same time, the differences in the frequency of the sEMG spectrum indicate that the organization of sEMG signal during PAE is specific on the level of the motoneuron pool.

The changes in blood pressure (BP) and heart rate (HR) during exercise grow with the development of muscle fatigue due to activation of the ergoreflex (ER), which is commonly assessed by post-exercise blood flow occlusion. However, this approach does not reproduce ER functioning in natural conditions and is of little use for testing ER from receptors of lower limb muscles, which differ from upper limb muscles in metabolic characteristics, and are also subject to more pronounced changes as a result of physical inactivity in various diseases. The aim of this study was to compare changes in systemic hemodynamics during “natural” ER activation with the development of severe fatigue in a test with rhythmic static contractions of thigh or forearm muscles until failure to work. Nine young men performed rhythmic isometric contractions of the knee extensors or the wrist flexors while maintaining a given load level (40% of the maximum voluntary effort) in a 20 s contraction/20 relaxation mode until fatigue (work duration in both tests was about 30 min). During the tests, systemic BP (Finapres), stroke volume (SV, ModelFlow algorithm) and ECG were continuously recorded. Rhythmic contractions of both muscle groups were accompanied by an increase in BP and HR, while SV decreased. As fatigue developed, the changes in BP and SV during muscle contraction became more pronounced. Importantly, during contractions of the thigh muscles, fatigue potentiated an increase in BP because of an increase in total peripheral resistance, and during contractions of the forearm muscles, because of an increase in cardiac output. Thus, fatigue of various muscle groups is accompanied by activation of different components of the ER – vascular component during lower limb exercise and cardiac component during upper limb exercise. The results obtained must be considered when developing methods for assessing hemodynamic control in cardiovascular diseases, which are often associated with changes in both skeletal muscles and the functioning of the ergoreflex.

For successful exploration of near space, construction of planetary bases and exploration of the Solar System planets, it is necessary to fill the gaps in understanding the molecular mechanisms of the human body response to space flight (SF) conditions. Subsequently, this will make it possible to get closer to the discovery of potential molecular targets for protection against adverse processes occurring in the body under the influence of SF conditions. The aim of the work was to assess the effect of a 6-month space flight on the proteome of dried blood spots of cosmonauts. As a result of proteomic analysis, processes with highly and moderately enriched proteins were identified. Among them, processes with reliable dynamics were identified on the 7th day of SF, as well as on the 3rd and 6th months of flight: these are clusters of energy processes, presentation of molecules on the membrane, initiation of immune defense, proteostasis and metabolism. Biological processes were identified in which the representation of proteins decreased most significantly, which was reflected in a weakening of activity in the presentation of molecules on the membrane, the initiation of immune defense, as well as in the mechanisms of proteostasis in the acute period of adaptation to the factors of the initial stage of flight. It has been shown that there is a close interaction with proteins of the cytoskeleton organization that disappear or reappear in the dried blood spots proteome during flight, and that relate to processes whose activity significantly decreased during SF (immune system, proteostasis, metabolism).

The article discusses the physiological significance of the Na⁺/K⁺ ratio in blood serum as a criterion of a person’s functional state. Normally, in an adult, the ratio is 32.2 ± 0.5, it increases in a healthy person under the influence of extreme factors (space flight (cosmonauts, astronauts), long-term strict bedrest, etc.), with Covid-19 disease, and some orphan diseases in children. The issue of Na⁺/K⁺ in blood serum is being discussed, but not between the K⁺-rich cell and the Na⁺-dominated extracellular environment. The Na⁺/K⁺ ratio in blood serum is considered as an important parameter of a person’s physiological state and, depending on the numerical value, as an indicator of the functional state from normal to overload, severe complications to the prognosis of death.

The paper provides a historical review of the concepts of overtraining in sports since 1923 and summarizes the results of the study of the problem. The author’s concept of overtraining syndrome is considered from the perspective of the theory of stress and adaptation. The commonality of overtraining with the syndrome of relative energy deficiency in sports and disruption of adaptation of the circulatory apparatus is shown. Much attention in the article is paid to non-training stress, which under certain conditions can become the leading cause of overtraining syndrome.