We studied hand movement during imitation of cello bowing while the rectilinear movement of the right bowing arm should occur in parallel with the bow orientation along the arm trajectory. Musically untrained individuals moved the bow across the bar that imitated the cello. Motion analysis was used to investigate the influence of a variety of experimental conditions: (1) bow motion on the bar surface, (2) on the left hand lying on the bar, and (3) in the air without touching the bar. It was found that the trajectory of the marker on the index finger at the bow frog differed significantly from the marker trajectory at the bow tip. In all conditions the marker on the index finger moved along a trajectory close to a straight line with an orientation slightly deviating from perpendicular to the bar. The marker trajectory at the bow tip deviated more from the perpendicular direction. Differences in the trajectories of markers at the bow frog and the bow tip depended on the condition of bow movement. The smallest differences were observed when the bow was moved on the left hand. It is suggested that sensation from the contralateral hand was used to create the internal representation of the relative position of the bow and the bar.

The notions on neuromuscular tone are discussed up from the time of N.A.Bernstein, who regarded it as level A, Rubro-Spinal Level of Paleokinetic Regulations in his book On the Construction of Movements (1947). In 1963, an article on Tonus (Tone) written by N.A. Bernstein together with Y.M. Kots appeared in the second edition of the Big Medical Encyclopedia. It extended the notion of neuromuscular tone with the use of new experimental data obtained by that time by R. Granit and P.B.C. Matthews. Parts of the interview of the author with A.G. Feldman, the author of the Equilibrium-Point Hypotheses are also presented, where the specificity of scientific research and achievements of the “Moscow motor control school” are discussed. Different methods of experimental measurement and ways of influencing the human neuromuscular tone are presented in this paper.

The authors have presented an unpublished manuscript by Nikolai Aleksandrovich Bernstein written in the form of a diary in 1949. Bernstein focused on the concept of time as a coordinate in four-dimensional space and discussed a variety of issues, including the definition of time, its measurement, time travel, asymmetry of the past and future, and even linguistics. In particular, he offered a definition of life tightly linked to the concept of time. Overall, this manuscript offers a glimpse into Bernstein’s thinking, his sense of humor, and his sarcasm, intimately coupled with the very serious attitude to scientific discourse.

In this paper, we analyze Nikolai Bernstein's notion of the activity of living organisms, which he introduced at the end of his career. Bernstein did not leave a systematic description of his last thoughts, but many remarks in his writing, especially in his last book [Bernstein, 1966], show that he thought deeply about the biological significance of the ideas that he developed while studying motor control. He accepted that negentropy (the tendency towards probabilistic determinacy, orderliness, free energy expenditure) is a hallmark of all life processes but wrote extensively about the insufficiency of this property and searched for a more complete definition of living organisms. This definition would include the goal-directedness of development, anticipation, persistence, tendency toward autonomy, initiative, and more. Thus, this paper is an attempt to present the definition of the activity of living organisms from Bernstein's later work to English-speaking readers.

New, earlier unknown manuscript by Nikolai Aleksandrovich Bernstein written in the August-September of 1949 is presented. Here Bernstein discusses the concept of time as a coordinate in the four-dimensional space and its essential difference from space coordinates, analyses the specificity of time expression in Russian language, offers a definition of life and also analyses the subjectivity of sensation in humans.

The authors have presented an unpublished manuscript by Nikolai Aleksandrovich Bernstein written in the form of a diary in 1949. Bernstein focused on the concept of time as a coordinate in four-dimensional space and discussed a variety of issues, including the definition of time, its measurement, time travel, asymmetry of the past and future, and even linguistics. In particular, he offered a definition of life tightly linked to the concept of time. Overall, this manuscript offers a glimpse into Bernstein's thinking, his sense of humor, and his sarcasm, intimately coupled with the very serious attitude to scientific discourse.

Body sway has usually been studied during symmetrical standing while lower limbs equally contributed in upright posture. The present study aimed to examine the dynamics of body sway while turning during standing with symmetrical and asymmetrical weight distribution between the legs. Subjects performed a body turn of 30° to the right and left during quiet standing and standing with the right or left foot loaded with 70% of body weight. We found that body turn in the symmetrical posture induced weight increase on the foot contralateral to the turning direction and the common center of pressure (COP) velocity increase. Body turn in the asymmetrical posture induced further loading of the foot that was initially overloaded; also turning in the direction of the unloaded foot affects weight distribution more than turning in the direction of the overloaded foot. The posture transition from symmetrical to asymmetrical induced the common COP velocity increase and forward protraction of the unloaded foot COP. Turning in the asymmetrical posture produced further increase of the common COP velocity and further forward protraction of the unloaded foot COP. Moreover, when the left leg was unloaded this resulted not only in left leg's COP forward, but also in left leg's COP lateral protraction, and left leg's COP frontal velocity increase. These findings reveal that body position and weight distribution between the feet interact to stabilize upright posture and show the effect of footedness during turning in asymmetrical standing.

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.

Experiment was carried out to study the proprioception accuracy of elderly (61-83 years old) and young (22-36 years old) subjects during contralateral elbow matching in sagittal plane. The subjects performed the task under ordinary condition and under experimental condition (matching forearm attached to the rocking cylindrical platform of low (LS), or high (HS) height, so that the elbow flexion was associated with tilting movement of the support and with backward movement of the upper arm). Control matching of young and elderly subjects does not differ significantly in terms of constant and absolute error. First block of LS and HS induced absolute error increase and matching arm velocity decrease in both groups, but in the second block of matching on rocking supports both arms velocity of elderly subject decreased and absolute error of elderly subjects toward the second block of rocking condition appeared lower than those of young subjects. Aftereffect of the restricted matching could be observed in elderly as a significant increase of matching arm velocity and corresponding constant error increase. It could be concluded that under unusual mechanical constraints elderly subjects tended to use "conservative" strategy followed by significant aftereffect toward the final ordinary support condition.

We analyzed kinematics of stair ascent and descent in autistic children and adolescents in comparison with age-matched healthy children and adolescents. Eight healthy adolescents, 6 autistic adolescents, 7 healthy children and 6 autistic children participated in the study. We found that autistic subjects of both groups showed significantly more fluctuations of hip joint angular velocity than age-matched control subjects while preparing for stair ascent. During preparation for stair descent these velocity fluctuations appeared mainly in autistic adolescents, moreover, autistic children exhibited less velocity fluctuations than children in control group while preparing for stair descent. The kinematics of the movement itself demonstrated significantly less hip abduction in both autistic children and adolescents than in age-matched controls during stair ascent, and less ankle joint plantar extension in autistic adolescents than in healthy adolescents during stair descent. We suppose that age-related changes in kinematics of leg motion during stair ascent and descent in autistic patients indicate aggravated motor coordination in autistic adolescents as compared with both healthy adolescents and autistic children.

Nikolai Alexandrovich Bernstein (1896-1966) is well known today primarily for formulating the problem of redundant degrees of freedom and their elimination in motor control, as well as his hierarchical theory of movement coordination. This paper aims to uncover new pages in the biography of N.A. Bernstein, based on materials from the archive of his nephew Alexander Sergeevich Bernstein, as well as recent interviews with the former pupils of N.A. Bernstein. Concentrated around several interdisciplinary seminars, they grew into a young generation of physiologists in the late sixties and made remarkable contributions inspired by Bernstein's new principles of neuroscience. These include the discovery of the spinal automatism of stepping in the cat, the "equilibrium point" hypothesis, the hindlimb wiping reflex of the frog as an example of a targeted trajectory organized at the spinal level, and the probabilistic prognosis in human activity.

Knowledge of the effects of Functional Electrical Stimulation (FES) of different intensity on postural stability during walking in healthy subjects is necessary before these relationships in patients with postural disorders can be assessed and understood. We examined healthy subjects in Control group walking on a treadmill for 40 min and in FES group - provided with 30 min of stimulation, which intensity increased every 10 min. The main difference between Control and FES group was the progressive increase of trunk oscillations in sagittal, frontal and horizontal planes and an increase of relative stance duration in parallel with FES intensity increase. Both Control and FES groups exhibited shank elevation angle increase as an after-effect. It is concluded, that high intensity FES significantly changes the postural component of locomotor activity, but the fatigue signs afterwards were not FES specific.

Motor evoked potentials (MEPs) in the right first dorsal interosseous (FDI) muscle elicited by transcranial magnetic stimulation of left motor cortex were assessed in ten healthy subjects during maintenance of a fixed FDI contraction level. Subjects maintained an integrated EMG (IEMG) level with visual feedback and reproduced this level by memory afterwards in the following tasks: stationary FDI muscle contraction at the level of 40 ± 5 % of its maximum voluntary contraction (MVC; 40 % task), at the level of 20 ± 5 % MVC (20 % task), and also when 20 % MVC was preceded by either no contraction (0–20 task), by stronger muscle contraction (40–20 task) or by no contraction with a previous strong contraction (40–0–20 task). The results show that the IEMG level was within the prescribed limits when 20 and 40 % stationary tasks were executed with and without visual feedback. In 0–20, 40–20, and 40–0–20 tasks, 20 % IEMG level was precisely controlled in the presence of visual feedback, but without visual feedback the IEMG and force during 20 % IEMG maintenance were significantly higher in the 40–0–20 task than those in 0–20 and 40–20 tasks. That is, without visual feedback, there were significant variations in muscle activity due to different prehistory of contraction. In stationary tasks, MEP amplitudes in 40 % task were higher than in 20 % task. MEPs did not differ significantly during maintenance of the 20 % level in tasks with different prehistory of muscle contraction with and without visual feedback. Thus, in spite of variations in muscle background activity due to different prehistory of contraction MEPs did not vary significantly. This dissociation suggests that the voluntary maintenance of IEMG level is determined not only by cortical mechanisms, as reflected by corticospinal excitability, but also by lower levels of CNS, where afferent signals and influences from other brain structures and spinal cord are convergent.

The vertical posture of patients with impaired sensorimotor integration was compared with that in healthy subjects before and after 30 sec of involuntary cervical muscle contraction. Studies were performed on seven patients with impaired sensorimotor integration. The movement trajectories of the center of mass were recorded for 30 sec in the standing position with the eyes open and closed and on foam rubber with the eyes open before and after involuntary contraction of the cervical muscles. The areas of oscillation of patients standing with the eyes open and on foam rubber were greater than those in healthy subjects, while the mean positions of the center of mass standing with the eyes open and closed were closer to the axis of the talocrural joints. Closing of the eyes had a smaller destabilizing effect on patients than on healthy subjects. Contraction of the cervical muscles for 30 sec in healthy subjects led to a backward displacement of the center of pressure toward the axis of the talocrural joints, especially on standing with the eyes open, along with a decrease in the length of the center of pressure curve, especially its frontal components, on standing on foam rubber. In patients, the aftereffects of involuntary cervical muscle contraction consisted of a reduction in the area of oscillations on foam rubber and a relative increase in frontal oscillations while standing with the eyes closed. These results lead to the conclusion that standing in patients with impaired sensorimotor integration was more sensitive to changes in proprioceptive than visual afferentation, while 30-sec involuntary cervical muscle contraction brought measures of vertical stability in patients closer to age-normal values.

We studied voluntary control of integrated electromyogram (IEMG) in the range of 20 +/- 5% and 40 +/- 5% of the IEMG of m. abductor pollicis brevis during its maximum voluntary contraction with and without visual feedback. Healthy subjects performed IEMG control with visual feedback in 5 trials; IEMG control with visual feedback in 5 trials for 5 days, and the reproduction of memorized IEMG value without visual feedback after 5 trials of IEMG under the visual control. The accuracy of IEMG control was estimated by the following parameters: time of IEMG being out of the required 10% range (ERROR); IEMG variability (VARIABILITY), and the bias of IEMG mean level (BIAS) during 30-sec trials. The IEMG control in the range of 20 +/- 5% with visual feedback improved in all subjects over the course of 5 trials. Within 5-day training, ERROR and VARIABILITY reduced on the first day only; during the last 4 days there was no accuracy increase. ERROR increased more than twice when the 20% IEMG level was reproduced without vision. The IEMG control in the range of 40 +/- 5% improved neither during 5 trials, nor during 5 days of training with visual feedback. ERROR increased for about 1.5 times when the 40% IEMG level was reproduced without vision. It was concluded that the motor system, particularly the motor cortex, could control the given level of muscle activity using the visual feedback.

We compared the upright standing in 7 patients with sensory-motor disorders and 7 healthy subjects (control) before and after 30-s involuntary neck muscle contraction. A trajectory of the center of pressure was recorded during 30-s standing with the eyes open, eyes closed and standing on a foam-rubber with the eyes open. As compared to healthy subjects, patients exhibited an increased body sway area during standing with the eyes open on both the firm surface and foam-rubber and a backward shift of the center of pressure during standing with the eyes both open and closed. Closing the eyes affected the upright standing of patients to a lesser extent than standing of healthy subjects. Involuntary neck muscle contraction within 30 s elicited a backward shift of the center of pressure in healthy subjects, especially during standing with the eyes closed, and a decrease in the length of the center-of-pressure trajectory, especially of its frontal component during standing on the foam-rubber. In patients, a post-effect of the neck muscle contraction manifested itself as a decrease in the body sway area during standing on the foam-rubber and relative increase in the frontal component of the center-of-pressure trajectory during standing with the eyes closed. The results suggest that the upright standing of patients with sensory-motor disorders is more sensitive to somatosensory than visual input, and 30-s neck muscle contraction approach their postural stability to the age-matched control.