Vol 73, No 4 (2023)

The paper reviews data on changes of various indices calculated from multi-channel EEG, MRI, fMRI, and DTI data obtained from post-stroke patients during motor function recovery. The indices are most frequently discussed in literature on the topic of both motor rehabilitation in general and using BCI-based procedures in particular. The dynamics of the indices considered reflects the changes in interhemispheric imbalance during movement, the contribution of different areas and their interaction during motor execution as well as structural reorganization. The role of damaged and intact hemispheres and particular areas in motor recovery is discussed.

This research is aimed at studying the dynamics of the parietal-occipital alpha rhythm in its connection with the process of stimuli duration comparison. EEG study was conducted in which participants (n = 48) were asked to compare pairs of visual stimuli of different durations ranging from 3.2 to 6.4 s. The time-frequency analysis of the EEG was carried out in the range of 8–12 Hz. The power of alpha rhythm increases from the stimulus onset to the middle of its presentation, but then its dynamic depends on the stimulus duration: it further increases for short durations (3.2, 3.6, 4.0 s), stays the same for middle durations (4.4, 4.8, 5.2 s) and decreases for long durations (5.6, 6.0, 6.4 s). The relative decrease of alpha power for long stimuli in relation to the short ones was related to subjective perception of time. The results are discussed from the point of view of the “dual klepsydra” model: it is assumed that alpha rhythm acts as an electrophysiological correlate of the functioning of “neural accumulators” associated with the subjective passage of time.

A brain-spine neurointerface based on the kinesthetic imagination of foot dorsiflexion with additional activation of foot movement by Biokin robotic device (mechanotherapy), and transcutaneous electrical spinal cord stimulation (TESCS) has been developed. Accuracy of classification of EEG-signals during the neurointerface control was on average 68% and significantly increases with the addition of mechanotherapy and TESCS by 9%. The EMG activity of the tibialis anterior (TA) – the muscle, which performs dorsiflexion of the foot, significantly increased during the instruction to imagine movement compared to that during the instruction to be at rest. The addition of mechanotherapy and TESCS during the neurointerface control has a greater effect not on the increase in TA activity when imagining the movement of the ipsilateral foot, but on the decrease in TA activity at rest. The revealed effects are apparently important for the formation of adequate coordination patterns of control signals from the CNS and of muscle activity during the implementation of movements and can be used in the clinical rehabilitation of motor activity using the cortico-spinal neurointerface.

Modern experimental data show that interictal discharges consist of a short spike and a slow wave, which is regarded as a prolonged hyperpolarization. On the model of interictal discharges synchronization, a study of reciprocal inhibitory connections was carried out. In rats in light narcotic sleep, after application of GABA A-receptor blockers to the cortex, interictal discharges occurred in neighboring cortical areas independently of each other, and then synchronization occurred. In the experiments in which the interictal discharges occurred simultaneously, the durations of the slow wave (inhibitory phase) were the same. During the registration in these and other experiments, there was an increase in the time delay between the moments of interictal discharges generation. Under conditions of increased synchronization, the duration of the slow wave (inhibitory phase) of interictal discharges increased. Interictal discharges, which occurred first, had a longer duration of inhibition compared to the duration in the neighboring point, because the inhibition from the neighboring networks via feedback inhibitory connections is added to its own inhibition in the neuronal network. When excitation occurred, it was followed by inhibition via feedback, which limited the period of excitation, and thus created a temporary integration window, and this also happened in the neighboring neural networks of the cortex.

We have studied the effects of acute normobaric hypoxia in the early postnatal period of the development (the 2nd postnatal day) on learning and memory abilities and the expression of GABA_B receptors in the neocortex (medial prefrontal cortex) in adolescent rats (the 55–60th postnatal day), as well as the possibility of correction of the revealed impairments by GABA derivative salifen. It was shown that perinatal hypoxia disrupts task acquisition and consolidation in the novel object recognition test, impairs passive avoidance performance, and also reduces spatial learning abilities in the Morris water maze. Western blotting analysis revealed increased levels of GABA_B receptor protein in the medial prefrontal cortex of the rats following the exposure to perinatal hypoxia. Post-hypoxic daily salifen injections over 14 days at a dose of 15 mg/kg improved cognitive abilities in rats, and also normalized GABA_B receptor content in the rat medial prefrontal cortex. The results of the present research are of considerable significance for solution of applied problem of neonatology – the search for effective drug candidates for the pharmacological correction of the impacts of perinatal hypoxia.

In this work, we propose a method for training rats electrical self-stimulation in response to rearing head in a telemetric system that records the level of extracellular dopamine. Initially, in the experiments of J. Olds, it was shown that in response to electrical stimulation of zones of positive reinforcement, rats exhibit natural exploratory behavior aimed at finding the source of the reward. It has been suggested that a natural behavioral act, in particular rearing head, can accelerate the development and stabilization of the self-stimulation reaction. A change in the position of the head can serve as an internal proprioceptive conditioned signal. The experiments were carried out in an annular chamber, where the ventral tegmental area (VTA) was stimulated using a telemetric system when the rat’s head was raised by 38°. The self-stimulation response to rearing head was developed and stabilized during the first day of training. With pedal self-stimulation, distinct repetitive reactions were observed only on the 3rd day of training after the procedures of “pushing” on the pedal on the 1st day of training and “repulsing” from the pedal on the 2nd day of training, stabilization of the reaction was observed only by the 4th day training. After stabilization of the self-stimulation response in rats, the level of extracellular dopamine in the nucleus accumbens was recorded by fast-scan cyclic voltammetry in response to the imposed stimulation of the VTA before and after each of the three series of self-stimulation lasting 10 minutes. After each series of self-stimulation, the level of extracellular dopamine decreased, which reflects the depletion of the intracellular pool of the neurotransmitter during prolonged self-stimulation of the VTA. The conclusion is made about the prospects of using the method of training rats to electrical self-stimulation in response to rearing head to study the mechanisms of reinforcement.