Dependence of Brain-Computer Interface Control Training on Personality Traits.

Personality traits (PTs) are predictors of the success of control of brain-computer interfaces (BCIs); however, it is unknown how the PTs that are optimal for BCI control changes during training. The paper for the first time analyzes the correlations between PTs and the accuracy of the classification (AC) of brain states in imagining the movements of the hands, feet, and locomotion during 10-day training of ten volunteers in BCI control. In the first 3 days of training, the AC is higher for more stressed and anxious volunteers; in the last days, for calmer ones. In the middle of the training period, AC is higher in low-demonstrativeness persons, it is more pronounced when imagining foot movements. Correlations of low demonstrativeness, as well as of foresight and self-control with AC when imagining foot movements are revealed significantly more often than when imagining hand movements and locomotions. During almost the entire period of training, AC with locomotion imagination is higher in individualists. The results make it possible to propose individually-oriented recommendations for the use of BCI based on the imagination of movements for the rehabilitation of patients with motor disorders.

Interhemispheric Asymmetry and Personality Traits of Brain-Computer Interface Users in Hand Movement Imagination.

Personality traits of users can affect the success in controlling brain-computer interfaces (BCIs), and the activity of right and left brain structures may differ depending on personality traits. Earlier, it was not known, how the success of BCI control with different personality traits is associated with interhemispheric asymmetry. In this work, the dependence of the success of imagination of movements, estimated by the success of recognition of EEG signals during imagination of hand movements compared to rest state, on the user's personal characteristics was studied. It is shown that in single control of BCI by naive subjects, recognition success in imagining right-hand (RH) movements was higher in expressive sensitive extroverts, and in imagining left-hand movements (LH) it was higher in practical, reserved, skeptical, and not very sociable persons. It is suggested that this phenomenon may be based on interhemispheric differences in dopamine level and in the way of encoding movement information.

Mechanisms of Blood Flow Regulation in the Skin during Stimulation of the Spinal Cord in Humans.

Changes in the blood flow in the shin skin were observed by laser Doppler flowmetry after transcutaneous electrical spinal cord stimulation (TSCS) by subthreshold bipolar pulses with a frequency of 30 Hz in 12 healthy subjects. It was found that TSCS in the area of the T11 and L1 vertebrae led to a significant increase in skin blood flow. The microcirculation rate increased by more than 85% relative to the baseline at a stimulus intensity of 90% of the motor threshold. Cutaneous blood flow activization by TSCS is implemented mainly through the antidromic stimulation of sensory nerve fibers. Nitric oxide (NO) is an important mediator that contributes to vasodilation and increase in cutaneous blood flow upon TSCS. NO is predominantly of endothelial origin.

[Noninvasive spinal cord electrical stimulation in the complex rehabilitation of patients with spinal cord injury]. / Neinvazivnaia élektricheskaia stimuliatsiia spinnogo mozga v kompleksnoi reabilitatsii bol'nykh so spinnomozgovoi travmoi.

BACKGROUND: Spinal cord injury causes significant impairments of both motor and pelvic organ functions. Latest studies have shown impressive potentials for using transcutaneous spinal cord electrical stimulation (TcSCES) in the late period of injury to restore motor functions. All results were obtained in a limited number of patients in the specific conditions of a physiological experiment. It remains unclear how effective a TcSCES cycle is in restoring motor activity in patients after spinal cord injury in real clinical conditions. AIM: The main objective of this investigation was to study the effectiveness of TcSCES in combination with the standard rehabilitation of patients after a spinal cord injury. An additional objective was to evaluate the effect of TcSCES to excretory functions in patients with spinal cord injury. SUBJECTS AND METHODS: The studies were conducted at Saint Petersburg City Hospital Forty, which included 15 patients with thoracic spinal injury at 2.4±2.06 years after injury; the severity of the latter was American Spinal Injury Association (ASIA) Grades B and C. All the patients underwent a 2-week standard cycle of rehabilitation treatment; of them 7 patients (a study group) received additionally TcSCES. Standard scales were used to assess neurological status and muscle strength and sensitivity. The patients filled out a urinary diary; residual urine volume was monitored using bladder catheterization or ultrasound. RESULTS: An increase in muscle strength was recorded in 6 patients of the study group and in 1 patient of the control one. The end of the treatment cycle was marked by a 1-score spasticity increase in 1 patient of the study group and in 2 patients in the control one. In the study group, the level of anesthesia decreased per segment in 1 patient; an improvement in deep and proprioceptive sensitivity was recorded in 2 patients; no change in sensitivity was observed in the control group. In the study group, 2 patients showed a reduction in the severity of injury from ASIA Grade B to ASIA Grade C. In three patients of the study group, the residual urine volume decreased and control and a sensation of urgency to urinate appeared; in the control group, these parameters remained unchanged after the treatment cycle. DISCUSSION: The main result of the study is evidence for the efficiency of using TcSCES in the complex therapy of motor neurorehabilitation. The performed cycle of TcSCES in patients was noted to result in better motor and excretory functions. CONCLUSION: The use of a short-term TcSCES cycle in the motor rehabilitation program for patients with spinal cord injury contributes to recovery of severe motor disorders and is accompanied by an improvement in urinary functions.

Differences in the Postural Responses to Approaching and Receding Sound Images in Subjects with Different Perceptual Styles.

A hypothesis on the universal character of perceptual style for analyzing the surrounding space during sensory interactions has been tested. The indices of postural responses to moving and stationary auditory images in the groups of field-dependent and field-independent subjects, i.e., those who perceive spatial information about the object considering or ignoring the background, respectively, have been investigated. The differences in the sway parameters in both groups were revealed only in the case of moving auditory images. Body sway was more prominent in the group of field-independent subjects, whereas in the subjects from the field-dependent group, backward body displacement was observed during listening to approaching auditory images. Therefore, the perceptual style is reflected in the vertical postural responses to auditory information about the motion in the acoustic space.

[The influence of non-invasive electrical stimulation of the spinal cord on the locomotor function of patients presenting with movement disorders of central genesis]. / Vliianie neinvazivnoi élektricheskoi stimuliatsii spinnogo mozga na lokomotornye funktsii patsientov s dvigatel'nymi narusheniiami tsentral'nogo geneza.

AIM: The objective of the present study was to evaluate the influence of non-invasive (transcutaneous) electrical spinal cord stimulation on the locomotor function of the patients suffering from movement disorders. PATIENTS AND METHODS: The study involved 10 patients of both sexes at the age from 32 to 70 years (including 40% of men and 60% of women) presenting with the compromised locomotor function of varying severity associated with the disturbances of cerebral blood circulation caused either by an injury to the brain and spinal cord or by stroke. The transcutaneous electrical spinal cord stimulation was applied using different frequency regimes with the placement of the electrodes in the projection onto the region of TXI-TXII vertebrae. The active factors were bipolar electrical stimuli 0.5 ms in duration; the current strength was chosen for each patient on an individual basis taking into consideration its threshold level. Electromyograms and evoked motor responses of selected muscles, viz. m. rectus femoris, m.biceps femoris, m. tibialis anterior, and m.gastrocnemius were recorded with the use of the 'Neuro-MVP-8 eight-channel electromyography' ('Neurosoft', Russia). RESULTS: The data obtained give evidence that the stimulation of the spinal cord with a frequency of 1 Hz induces reflectory responses with monosynaptic and polysynaptic components in the muscles of the lower extremities, with the thresholds of these responses being significantly higher in the patients presenting with serious neurological problems. Stimulation with the frequencies of 5 and 30 Hz caused in the patients with paresis the involuntary movement of the legs the characteristics of which were similar to those of the locomotor movements. CONCLUSION: It has been demonstrated that the application of transcutaneous electrical spinal cord stimulation leads to increased excitability of the lumbar spinal neural structures of the patients. The study has shown the possibility of regulation of the locomotor functions in the patients presenting with movement disorders of central genesis by means of non-invasive electrical stimulation of the spinal cord.

Effect of Combination of Non-Invasive Spinal Cord Electrical Stimulation and Serotonin Receptor Activation in Patients with Chronic Spinal Cord Lesion.

We analyzed the efficiency of percutaneous electrical stimulation of the spinal cord and serotonin receptor activation in rehabilitation of paralyzed patients. Four-week course of spinal cord electrical stimulation combined with mechanotherapy produced positive shifts in the status of chronically paralyzed patients. Serotonin receptor activation potentiated the effect of spinal cord stimulation and can be regarded as an additional neurorehabilitation option.

[Non-Invasive Methods for the Control of Human Spinal Locomotory Systems].

We studied the interrelations between the activation of the receptors of musculoskeletal system and the spinal cord stimulation in the regulation of locomotor behavior in healthy subjects. We observed the effect of afferent stimulation on the patterns of stepping movements caused by percutaneous stimulation of spinal cord. It was found that the combination of percutaneous spinal cord stimulation and vibrostimulation increases the amplitude of leg movements. It was shown that the vibrostimulation of limb muscles at a frequency of less than 30 Hz may be used for comtrolling involuntary movements, caused by non-invasive stimulation of the spinal cord.

[Effects of locomotor training and functional electrical stimulation on postural function in children with severe cerebral palsy].

Cerebral palsy (CP) considerably impairs the ability to maintain upright stance. In the present study the effects of locomotor training and functional electrical stimulation (FES) on postural control have been determined in children (n = 27) aged 6­12 years with severe CP. The severity level of the CP clinical manifestations was determined as 3 according to the Gross Motor Function Classification System (GMFCS) classification. All patients participated in 15 half-hour sessions of mechanic therapy using robot-assisted passive stepping. In 12 out of 27 children, the locomotion therapy was accompanied with FES. Stabilometry and plantography tests were performed before and after the course of interventions. In addition, similar posturographics tests were performed in 23 healthy children same age. Postural control in children with CP was characterized by a forward shift of the center of pressure (COP) projection; higher values of the COP trajectory area and length, as weel as by mean amplitude of the COP oscillations, and the absence of COP response to the eyes closed condition. After treatment, the posturographic characteristics had a tendency to normalization in relation to the values obtained in neurologically intact children. The improvement was observed in 43% of children without FES and in 75% of children which used FES. Analysis of plantograms revealed normalization of footprints in children received FES. Thus, it was demonstrated that FES combined with locomotor training resulted in the improvement in vertical posture control in children with severe CP.

[The regulation of balance in the children presenting with severe cerebral palsy following the treatment with the use of the locomotor training in combination with the electrical stimulation of leg muscles and spinal cord]. / Regulyatsiya balansa u detei s tyazhelymi formami detskogo tserebral'nogo paralicha posle lokomotornykh trenirovok v kombinatsii s elektrostimulyatsiei myshts i spinnogo mozga.

One of the cerebral palsy (CP) symptoms is the impairment of the ability to maintain upright standing. The objective of the present study was to investigate the effect of the locomotor training combined with electrical transcutaneous spinal cord stimulation (TSCS) and functional electrical stimulation (FES) of the muscles to facilitate the restoration of the vertical posture function in the children presenting with cerebral palsy. PATIENTS AND METHODS: This article is designed to present the results of the study that included 19 patients at the age from 6 to 12 years. The severity of the CP clinical manifestations was estimated to be around 3 in accordance with The Gross Motor Function Classification System (GMFCS). All the patients underwent 15 half-hour daily sessions of robotic mechanotherapy with the use of a locomotor training device. In 8 patients from the main group, each locomotor training session was accompanied by the TSCS and FES procedures. The patients of the control group underwent the locomotor training alone. RESULTS: The dynamics of regaining the standing posture regulation was evaluated by stabilometry that has revealed a significant increase of postural stability in the children of the main group in comparison with those in the control group. It was apparent as a statistically significant (p<0.05) reduction of the length and the area of the center of pressure (COP) projection with open eyes (the 167 mm and 112 mm2 decrease of the median, respectively). In addition, the tendency toward the normalization of the COP projection in the sagittal plane was documented. CONCLUSION: The present study has demonstrated the normalization of the impaired balance control system in the children presenting with the severe form of cerebral palsy under the influence of the combined treatment with the use of transcutaneous spinal cord stimulation and functional electrical stimulation of legs muscles supplemented by the locomotor training.

[Neurorehabilitation of Patients with Cerebral Palsy].

Cerebral palsy is one of the common diseases that cause significant motor impairments. This review deals with new methods of motor rehabilitation of children with cerebral palsy in terms of modern physiology, as well as with summarized and analyzed results of experimental studies on the effectiveness of these methods.

Effects of spinal cord electrical stimulation in patients with vertebrospinal pathology.

Until now, no scientific neurophysiologic methods of diagnostics and treatment of vertebrospinal pathologies were developed. Previous study showed that electrical stimulation of lumbar segments of the spinal cord in animals with complete spinal cord transection induced a well-coordinated weight-bearing locomotion. The present comparative study of motor activity triggered by electrical epidural stimulation of one or two segments of the spinal cord in spinal patients showed that stimulation of lumbar (L2-L4) or sacral (S2) segments facilitated generation of motor patterns of muscle activity. Combination of electrical stimulation with locomotor training resulted in the appearance of stepping patterns characteristic of normal walking and tonic activity of the muscles needed for body balance maintenance.

The role of cutaneous afferents in controlling locomotion evoked by epidural stimulation of the spinal cord in decerebrate cats.

The effects of the cutaneous input on the formation of the locomotor pattern in conditions of epidural stimulation of the spinal cord in decerebrate cats were studied. Locomotor activity was induced by rhythmic stimulation of the dorsal surface of spinal cord segments L4-L5 at a frequency of 3-5 Hz. Electromyograms (EMG) recorded from the antagonist muscles quadriceps, semitendinosus, tibialis anterior, and gastrocnemius lateralis were recorded, along with the kinematics of stepping movements during locomotion on a moving treadmill and reflex responses to single stimuli. Changes in the pattern of reactions observed before and after exclusion of cutaneous receptors (infiltration of lidocaine solution at the base of the paw or irrigation of the paw pads with chlorothane solution) were assessed. This treatment led to impairment of the locomotor cycle: the paw was placed with the rear surface downward and was dragged along in the swing phase, and the duration of the stance phase decreased. Exclusion of cutaneous afferents suppressed the polysynaptic activity of the extensor muscles and the distal flexor muscle of the ipsilateral hindlimb during locomotion evoked by epidural stimulation of the spinal cord. The effects of exclusion of cutaneous afferents on the monosynaptic component of the EMG response were insignificant.

Morphofunctional characteristics of the lumbar enlargement of the spinal cord in rats.

The topography of the lumbar enlargement of the spinal cord in rats was studied; an immunohistochemical method was used to determine the distribution of synaptophysin--a membrane protein of synaptic vesicles. Synaptophysin-immunoreactive structures were detected in the gray matter of all Rexed laminae, around most neurons and in the neuropil. Previously undescribed subpial synaptic contacts were detected immunohistochemically in the white matter and confirmed by electron microscopy. A non-myelinated component of the corticospinal tract, including axonal varicosities and synaptic contacts, was observed in the dorsal part of the white matter of the lumbar enlargement of the spinal cord.

Significance of peripheral feedback in the generation of stepping movements during epidural stimulation of the spinal cord.

Acute experiments on decerebrate and spinal cats were performed to study the role of the peripheral afferent input from hindlimb receptors in forming the locomotor pattern during epidural stimulation of the spinal cord. Evoked electromyographic activity in the muscles of the hindlimbs was analyzed, along with the kinematic parameters of stepping movements. Epidural stimulation (20-100 microA, 5 Hz) of segments L4-5 of the spinal cord was found to elicit well coordinated walking in the hindlimbs on a moving treadmill band. When the support conditions were changed (non-moving treadmill, unsupported position), epidural stimulation initiated walking with an unstable rhythm. This was associated with a change in the overall nature of the locomotor pattern and the internal structure of the stepping cycle. Alteration of the direction of movement of the treadmill band led to the appearance of backward walking. An increase in the speed of movement of the treadmill band increased the stepping frequency, mainly due to decreases in the extensor phase. Epidural stimulation applied 2-4 h after complete transection of the spinal cord at the T8-T9 level could elicit stepping movements, but only when the treadmill was moving. The role of peripheral feedback in generating the locomotor pattern in conditions of complete disconnection from supraspinal control increased significantly. These data show that peripheral feedback during epidural stimulation of the spinal cord can define the properties of the motor output.

[VESTIBULAR PROSTHETICS: CONCEPT, APPROACHES, RESULTS].

Unlike prosthetic hearing, which develops technology for more than 30 years, the problem of the vestibular prosthesis developed a little more than one and half decades. Meanwhile, the involvement of the vestibular system in ensuring the normal functioning of the visual, motor and other systems of the body determines its decisive contribution to the spatial orientation of humans and animals. In case of damage of the vestibular apparatus (the labyrinth), there are serious violations of posture control, stabilization of sight, spatial orientation, psychological status, that is, in the aggregate quality of human life deteriorates. At present, on the animals developed technology of prosthetic semicircular canals, sensing angular acceleration, and control eye movements in dynamic situations. New approaches based on the replacement of the lost natural vestibular afferent impulses by electrical stimulation through multichannel vestibular prosthesis, are successfully introducing into the clinic.

Hindlimb stepping movements in complete spinal rats induced by epidural spinal cord stimulation.

The locomotor ability of the spinal cord of adult rats deprived of brain control was tested by epidural spinal cord stimulation. The studies were performed on six rats that had a complete spinal cord transection (T7-T9) and epidural electrode implantations 2-3 weeks before testing was initiated. The stimulating epidural electrodes were implanted at the T12-L6 spinal segments. Epidural electrical stimulation of the dorsal surface of the spinal cord at frequencies between 1 and 50 Hz and intensities between 1 and 10 V without any pharmacological facilitation was used. Stimulation at each of the lumbar spinal cord segments elicited some rhythmic activity in the hindlimbs. However, stimulation at most segmental levels usually evoked activity in only one leg and was maintained for short periods of time (< 10s). Bilateral hindlimb locomotor activity was evoked most often with epidural stimulation at 40-50 Hz applied at the L2 segment. A necessary condition for initiation of locomotor activity was providing a specific amount (at least 5%) of body weight support. Therefore, the rat spinal cord isolated from brain control is capable of producing bilateral stepping patterns induced most readily by epidural stimulation applied at the L2 spinal segment. Furthermore, the induced stepping patterns were dependent on sensory feedback associated with weight bearing.

Formation of locomotor patterns in decerebrate cats in conditions of epidural stimulation of the spinal cord.

Acute experiments on decerebrate cats were performed to study the mechanism of formation of the locomotor pattern in conditions of epidural stimulation of the spinal cord. These studies showed that only segments L3-L5 contributed to generating the stepping pattern in the hindlimbs. At the optimum frequency (5-10 Hz) of stimulation of these segments, formation of electromyographic burst activity in the flexor muscles was mainly due to polysynaptic reflex responses with latencies of 80-110 msec. In the extensor muscles, this process involved the interaction of a monosynaptic reflex and polysynaptic activity. In epidural stimulation, the stepping pattern was specified by spinal structures, while peripheral feedback had modulatory influences.

[Mathematical model of the hindlimbs control during cat locomotion with balance].

The musculoskeletal model of cat's hind limbs, capable to step while maintaining balance, was developed using the MatLab. The skeletal part of the model (spine, pelvis, hips, shanks, foots) was created at SimMechanics. The joint in the spine attachment to the support and hip joint have three degrees of freedom. Knee and ankle joints have one degree of freedom. The pelvis is rigidly connected to the spine. The control of the skeleton's segments is done by six groups of muscles (flexors and extensors of hips, knees and ankles), modeled using the package VirtualMuscle. The generalized lateral force exerted on the spine was introduced to compensate insecure lateral deviations. Experimental verification of the model realness have shown that its locomotor characteristics (e. g., muscles activation patterns, oscillation period of pelvis, correlation between step length and maximal lateral shift of pelvis) do not significantly differ from the locomotion of decerebrate cats. The simulation confirms the key role of lateral force evolved by paravertebral and abductor-adductor muscles in the control of lateral stability during locomotion.

Control of locomotor activity in humans and animals in the absence of supraspinal influences.

Electrical epidural stimulation of the dorsal surface of the spinal cord at the level of the second lumbar segment induced step-like movements accompanied by the corresponding electromyographic activity in the leg muscles in patients lacking supraspinal influences as a result of vertebral trauma. Triggering of stepping movements was shown to occur with particular stimulation parameters. The results provide evidence that in humans, as in other mammals, the spinal cord contains a network of interneurons acting as generators of stepping movements and producing coordinated patterns of movement activity. Experiments on chronic spinal cats demonstrated the leading role of the propriospinal system of the spinal cord inactivating the spinal generators of stepping in response to epidural stimuli.