Vol 45, No 4 (2019)

We studied the influence of the rotational speed and eccentricity of the ring image on the severity of the stereokinetic effect (SE) in a group of 36 children aged 8 to 16 years with partial optic atrophy and in the control group of 44 age-matched children with a normal fundus. Four variants of the ring image with the eccentricity of 0.2, 0.4, 0.6 or 0.8 were used as a test image. The rotational speed of the ring image was 2, 10, 30, 60 or 90 rpm. It was found that the stereokinetic effect was absent in the majority of children (63.9%) with optic atrophy at a combination of eccentricity of 0.2 and a rotational speed of 2 rpm, in contrast to the control group, where the stereokinetic effect was only absent in 9.1% of children under the same conditions of stimulus presentation. The stereokinetic effect was observed with all eccentricities when the speed of rotation of the test image was 30–90 rpm in children with optic atrophy and 10–90 rpm in children from the control group. The number of children with alternate perception of the virtual cone and the virtual funnel was significantly higher in the control group than in the group of children with optic atrophy at all the test image eccentricities and rotational speeds used. The binocular figure size estimates were equal to the monocular estimates in the group of children with optic atrophy for all the image eccentricities and rotation speeds in contrast to the control group with a general tendency for the virtual cone size estimate to increase under the monocular conditions of observation. An increase in the test image rotation speed from 2 to 60 rpm was accompanied by an increase in the size of a virtual figure and a significant decrease in the duration of alternate dominance of virtual cone and virtual funnel perception in both groups of subjects with all the eccentricities used. The difference between the results obtained in the group of children with POA and in the control group may be explained by reduction of afferent visual information flow. These differences are partially offset by increased speed and increased eccentricity of the test image.

In psychophysical studies, we compared the Wundt–Hering illusion (or fan’s illusion) with distortions in perception of the orientation of lines and in estimation of lengths of the inclined lines projections. Four experiments were carried out: the curvature of the lines crossing the divergent lines (fan) was determined; the curvature of the mentally drawn lines through points located on the fan was evaluated; the tilt illusion that appeared due to contact of the inclined line with the test one was studied; and the length of the projections of the inclined lines was estimated. It was shown that the curvature of the lines is evaluated identically for the continuous lines and for the lines interpolated through the points of intersection with the fan. The length of projections of the inclined lined is overestimated by some observers and underestimated by others. A test line seems to be inclined to an additional line for small difference in orientations, but it seems tilted in the opposite direction with increasing differences. The hypotheses of the genesis of the Wundt–Hering illusion and the tilt illusion, as well as the connection between the obtained distortions of visual perception are discussed.

We studied the vertical posture in subjects in the standing position with different turns of the body and different distributions of the load between the legs. We recorded the motion of the projection of the common center of pressure (CCP) and of the center of pressure (CP) for the left and right legs. The predominant direction of CP movement was determined from a stabilogram, and then changes of this direction were analyzed during body turns and with different load distributions between the legs. Body turn led to the shift of the predominant direction of CCP movement towards the turn side. This change in the direction of CCP movement was observed with any load distribution between the legs. At the same time, weight transfer to one leg also led to the direction shift of CCP movement towards the loaded leg. The direction of CP movement of the loaded leg did not change, but the direction of CP movement of the unloaded leg shifted clockwise upon unloading both right and left legs. We assume that the changes in the mechanisms of maintaining the vertical position with asymmetric distribution of the leg load may be associated not only with the change in the force interaction with the supporting surface, but also with asymmetry of axial muscle tone.

Testing of sensory-motor performance and motor rehabilitation training in post-stroke patients are often executed in lying position. At the same time, influence of the body position on proprioceptive perception is poorly studied. In this study, we have investigated proprioceptive perception of single-joint arm movements in 10 healthy subjects and 17 post-stroke patients with unilateral arm paresis in the sitting and lying positions using the method we developed. Movements of flexion–extension in shoulder, elbow and wrist joints and abduction–adduction in shoulder and wrist joints were tested. The subjects were made to perform a series of the passive single-joint movements with the eyes closed and had to copy these movements simultaneously by active movements of another arm. We recorded the angles at the tested joint and the homonymous joint of the other arm, and the status of proprioceptive sensitivity was evaluated basing on the degree of similarity of these “passive” and “active” movements. Qualitative and quantitative indicators were used to assess the similarity. It was found that healthy subjects reproduce the passive movements without rough qualitative errors in both the sitting and lying positions. The movement reproduction was less accurate in the lying position by values of some quantitative indicators, however only 3% of trails did not match the conventional criterion for proprioceptive sensitivity intactness. On the contrary, the movement reproduction in almost half of tests in the group of post-stroke patients was performed with qualitative and quantitative errors and did not match the requirements of the conventional criterion. A deficit of proprioception was observed in 1 to 5 different test-movements in 88% of patients in the sitting position and 71% of patients in the lying position. Most frequent and rough errors in the movement reproduction were observed in distal segments of the paretic arm. It was found that the body position could have different effects on the proprioceptive perception of the same test-movement in patients: the proprioceptive perception was evaluated as intact in the sitting position and as distorted in the lying position in 14% of all test trials and vice versa it was evaluated as distorted in sitting position and as intact in lying positions in 17% of trials. Such individual differences must be considered when choosing conditions for motor rehabilitation procedures in patients with paresis of the arm.

The short- and long-term postural effects on the forced expiratory tracheal noise time were studied in a sample of 12 subjects. In contrast to the spirometric parameters, the tracheal forced expiratory noise time does not respond to a short-term change in the body posture from sitting and standing positions to the lying position, as well as to 14-day-long orthostatic hypokinesia in a lying position with a body angle of +9.6°. However, significant multidirectional individual dynamics of the tracheal forced expiratory noise time was observed in all subjects during long-term orthostatic hypokinesia, whereas the spirometric parameters had a dominant growth response. It is assumed that the estimation of the forced expiratory tracheal noise time during long-term orthostatic hypokinesia in lunar gravity simulation may provide useful data in addition to spirometry when assessing the individual lung function dynamics. The dynamics of acoustic parameters, as well as spirometric parameters, during long-term postural effects can be considered as adaptive changes.

Anatomical and physiological features of sympathetic innervation provide a basis for developing methods to treat sympathetic dysfunction. Preganglionic neurons (PNs) that project to the upper limbs are in the spinal segments T₂–T₉ (mainly at the level of the T₂–T₆ segments); the respective postganglionic neurons are in the sympathetic trunk from the ganglion stellatum to the ganglion T₆. Sympathetic control is provided by the coordination of adrenergic and cholinergic receptors, mediators, co-transmitters, and the involvement in complex interconnections with other regulatory systems.

The growth hormone (GH) is prohibited for use by athletes, while its anabolic effect on muscle tissue is still debated. The review provides a systematic evaluation of the GH effects on the body composition and strength parameters in well-trained healthy young subjects. A meta-analysis of published data from randomized controlled trials (RCTs) was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Pooled results of 11 RCTs showed that GH administration significantly increases the lean body mass (2.72, 95% CI: 2.02; 3.38, p < 0.01), total water content (1.10, 95% CI: 0.54; 1.66, p < 0.01), and extracellular water (1.78, 95% CI: 1.04; 2.52, p < 0.01) and reduces the fat mass (–0.67, 95% CI: –0.93; –0.40, p < 0.01) without changing the muscle protein synthesis rate (0.00, 95% CI: –0.01; 0.02, p = 0.70) and muscle strength (–0.02, 95% CI: –0.05; 0.02, p = 0.36) as compared with placebo. A conclusion was made that GH administration can improve the body composition in healthy young subject by exerting a significant lipolytic effect without causing hypertrophy of muscle fibers. The increase in lean body mass is due to an accumulation of extracellular water.