Vol 45, No 1 (2019)

We analyzed the accuracy and reaction time (RT) of basic and superordinate image categorization under forward masking conditions in 41 healthy subjects. Images of man-made objects and animals were used as target stimuli, while images of man-made objects, animals, faces, and buildings were used as masks. The comparison of the psychometric characteristics of the basic and superordinate categorization showed the influence of mask and stimulus semantic similarity on the forward masking effectiveness, which depended on the type of experimental task performed by the subject (the level of categorization of the target stimulus). The masking effect at the basic-level categorization was more pronounced at a greater semantic similarity between the mask and the target stimulus. In contrast, a greater masking effect at the superordinate-level categorization was observed when the mask and the stimulus belonged to different categories. The images of faces and buildings had a less pronounced masking effect compared to the images of animals and man-made objects, regardless of the type of task. For basic-level categorization, the increase in RT under semantically related conditions was caused by distributional skewing. In contrast, for superordinate categorization, semantically unrelated conditions led to distributional shifting towards greater values. The results of this study suggest a hypothesis of temporal and spatial division of cognitive processes of the basic and superordinate categorization.

In order to reveal changes in the spatial organization of brain activity after a course of combined antidepressive therapy, including antidepressants and high-frequency (20 Hz) rhythmic transcranial magnetic stimulation (TMS) of the dorsolateral prefrontal cortex (DLPFC) of the left hemisphere, a multidisciplinary clinical psycho-neurophysiological study was performed on two groups of patients suffering from depression that were receiving a purely medication (control group), or combined (TMS group) therapy. It was shown that after the course of therapy an improvement of the clinical state occured in both groups, although the psychological state and general condition were better in the ТМS group. After the course of therapy, small changes in the spatial organization of brain activity were found in both groups, as reflected in the values of the EEG coherence (Coh), rather than of the spectral power of the EEG. The main changes of Coh in the control group were observed in the α₂ (9–11 Hz), α₃ (11–13 Hz), and θ₁ (4–6 Hz) EEG subbands, while in the ТМS group the changes were seen in the β₂ (20–30 Hz) subband, including the area of direct ТМS action. The results suggest that the therapeutic effect of the combined antidepressive therapy, including high frequency ТМS of the DLPFC of the left hemisphere, was manifested as a more pronounced improvement of psychological and cognitive conditions in the patients of the TMS group, which resulted from activation of not only this cortical area itself as a zone of direct influence of ТМS, but also of other areas of the cortex and subcortical regions that are closely connected with it. The increase of the Coh in lower-frequency EEG bands (α and θ) in other cortical areas may be based on strengthening of inhibitory influences from the prefrontal and orbito-frontal cortices.

Using nonlinear dynamics methods (wavelet and recurrence analysis) of electroencephalographic (EEG) patterns we have examined the photic driving reaction for patients with atrial fibrillation of the constant and paroxysmal forms. As quantitative parameters of this reaction we consider the coefficients of photic driving and holding, the times of remembering an external rhythm, and the values of wavelet coherence, as well as the average lengths of diagonal lines in joint recurrence plots of the light stimulus and EEG pattern. This study demonstrates the ability of the applied methods to quantitatively estimate the lability of the human brain to reproduce suggested rhythms for different patients.

We studied the pressor response to isometric handgrip (IHG) in relation to the level of habitual physical activity (PA) in men and women. The study involved 116 volunteers (69 women and 47 men) aged 20 to 59 years without a history of hypertension. The IHG test of 30% of maximal voluntary contraction of the right hand was performed for two minutes. Blood pressure (BP) was measured before IHG, at the end of the test and 5 minutes after. The International Physical Activity Questionnaire (IPAQ) was used to assess PA. It was found that the level of PA had a significant effect on the muscle and fat content of the body composition and diastolic blood pressure (DBP). In the subjects with a high level of PA, the percentage of muscle tissue was greater, of fat less, and DBP was lower than in the groups with moderate and low PA (p < 0.05). In women (but not in men) with a high level of PA, systolic BP (SBP) at rest was significantly lower than in women with low PA (p = 0.014). The SBP and DBP values during IHG were higher in men (p = 0.000); the factor of habitual physical activity did not affect them significantly. The SBP response to the IHG also depended on sex (p = 0.007 for absolute values and p = 0.027 for percentage of the baseline level) and did not depend on physical activity: the SBP increase during IHG was higher in men than in women. The DBP and heart rate response to the IHG did not depend significantly on either sex or physical activity. Thus, the level of PA is inversely related to the blood pressure at rest but does not affect the blood pressure reactivity in response to isometric handgrip in individuals without cardiovascular disorders.

Spaceflight (SF) conditions have a significant impact on the functioning of the human cardiovascular system. The endothelium plays an important role in the process of adaptation to SF factors. Therefore, the detection of biomarkers of endothelial dysfunction is necessary for understanding the molecular mechanisms involved in changes caused by SFs. For this purpose, the blood plasma proteins of 18 Russian cosmonauts were used for quantitative analysis by liquid chromatography with a UPLC 1290 Infinity chromatograph coupled to an Agilent 6490 triple quadrupole mass spectrometer. It was found that a decrease in the circulating plasma volume during the flight followed by the activation of fluid retention at the final stage of flight contributed to the changes in plasma protein concentrations on the first day after landing. We observed a significant increase in the concentration of the S100A9 protein that plays an important role in endothelium functioning and angiogenesis and can serve as a marker of inflammatory reactions. On the first day after landing, the complement system and acute-phase protein concentrations tended to increase, which can adversely affect the functioning of the endothelium.

The molecules of intercellular adhesion are the surface cellular glycoproteins responsible for interaction between cells of different types with one another and with the components of intercellular matrix. They play the primary role in the formation of tissue structure and participate in a number of physiological processes, such as morphogenesis, embryogenesis, organogenesis, wound healing, and inflammation. Together with the other free receptors and their ligands, free intercellular adhesion molecules are formed mainly through shedding, resulting from the proteolytic cleavage of the transmembrane region under physiological conditions or cell destruction. There are almost no literature data on the influence of free intercellular adhesion molecules on the functional activity of T and B lymphocytes and the contents of immunoglobulins, cytokines, and circulating immune complexes. Therefore, the purpose of this study was to identify the interrelationship between the content of free and membrane-bound intercellular adhesion molecules and the level of immunocompetent cell activity in the residents of the Arctic settlement of Revda (Murmansk oblast), who form one of special populations of residents living in the Arctic region of the Russian Federation. It has been found that the contents of sCD54, sCD62L, and sCD324 free intercellular adhesion molecules vary widely, which results from an increase in the concentration of cells with the corresponding membrane forms. An increase in the levels of sCD54 and sCD62 is accompanied by the activation of migration processes with increasing concentrations of circulating neutrophils and total lymphocyte count. The formation of a pool of membrane-bound and free adhesion molecules occurs together with an increase in the content of activated T cells of the HLADRII and CD8 + phenotypes. An increase in the serum levels of sCD54 and L-selectin (sCD62L) adhesion molecules is accompanied by a decrease in the level of immunocompetent cell activity and a twofold increase in the serum level of a natural immunosuppressant IL-10. Low activity of the sCD54 and sCD62L is associated with an increase in the IgE concentration and in immune responses caused by the basophil and eosinophil activation.

It is believed that real movements and those performed mentally (imaginary movements) are functionally similar. This hypothesis is based on the use of the imaginary movement approach for the investigation of the neurophysiological mechanisms of real movements of a person, as well as for rehabilitation and optimization of motor functions. A large body of evidence in favor of this hypothesis has been obtained for upper limb movements, whereas data on lower limb movements are quite scarce. The aim of this review is to generalize the published data that demonstrate the similarity of the mechanisms and brain structures involved in the organization of imaginary and real locomotion.