We analyzed event-related changes in the electroencephalogram (EEG) spectrum while listening to nouns in 23 typically developing children and 23 children with sensory alalia aged 4 to 10 years. In the EEG θ-frequency range of healthy children, synchronization was detected in the frontal, central, and temporal leads, and desynchronization was found in most leads in children with sensory alalia. Intergroup differences in the reactivity of the EEG θ-range reached the level of statistical significance in the C4 lead. In the α-range, EEG desynchronization was observed in typically developing children, and synchronization was observed in children with sensory alalia. Differences in the α-activity power reached the level of statistical significance in C3, F3, P3, and O1 leads. An EEG θ-band synchronization decrease while listening to words in children with sensory alalia may reflect an impairment of retrieving words from memory and less emotional involvement in the speech perception process, while the absence of α-activity desynchronization in the central leads is an impairment of the functioning of sensorimotor neural networks, involved in speech perception and generation. The revealed features of EEG reactivity are important for understanding the central speech perception mechanisms in normal children, as well as in children with disorders such as sensory alalia.

The analysis of electroencephalography (EEG) event related spectrum perturbations in 23 normally developing and 23 sensory alalia children of age between 4 and 10 years old during listening to nouns is conducted. In EEG θ-frequency range of healthy children, synchronization was detected in the frontal, central, and temporal leads, and desynchronization was found in most leads in children with sensory alalia. Intergroup differences in the reactivity of the EEG θ-range reached the level of statistical significance in C4 lead. In the α‑range, EEG desynchronization was observed in typically developing children, and synchronization was observed in children with sensory alalia. Differences in the α-activity power reached the level of statistical significance in leads C3, F3, P3, O1. An EEG θ-band synchronization decrease during words listening in children with sensory alalia may reflect an impairment of retrieving words from memory and less emotional involvement in the speech perception process, while the absence of α-activity desynchronization in the central leads is a impairment of the functioning of sensorimotor neural networks, involved in the speech perception and generation. The revealed features of EEG reactivity are important for understanding the central speech perception mechanisms in normal children, as well as in children with disorders such as sensory alalia.

An analysis was made of event-related changes in the electroencephalogram (EEG) spectrum during the auditory perception of nouns in 83 typically developing children aged 4 to 10 years, including 50 children of preschool age and 33 children of primary school age. Following intergroup differences were revealed: in preschool children, neuronal systems are more involved in word processing, the activity of which is reflected in extensive desynchronization of alpha and synchronization of theta activity in the frontal zones of the left hemisphere. The EEG reactivity of primary school children is characterized by bilateral and more pronounced theta synchronization, which indicates an increased intensity of lexico-semantic operations, as well as a decrease in the background and an increase in the evoked theta activity. In children of this group, EEG synchronization in the beta range was also observed, represented by separate flashes and most pronounced in the frontal leads, which is typical for more mature speech processing mechanisms. The study results are important for clarifying the mechanisms of speech understanding in typically developing preschool and primary school age children.

Use of the sLORETA method in 62 adult subjects with different intelligence levels located sources generating rhythms in the frequency band 8–12 Hz during observation, performance, and imitation of circular movements with a computer mouse by the experimenter. A relationship between the level of intelligence and differences in the spatial patterns of cerebral cortex activation during performance and imitation of movements was seen. More marked and localized activation of neocortical structures was seen in adult subjects with high levels of general intelligence. Differences in the activation of cortical areas in groups with different general intelligence levels were largely mediated by structures in the right hemisphere, which is involved in processes of visuomotor coordination and the discrimination of own from others’ actions. The greater involvement of the precentral, cingulate, and postcentral gyri of the left hemisphere in the process of imitating the experimenter’s movements in the group with high intelligence may point to a higher level of activation of the mirror system of the brain.

Neuronal synchronization, reflected in the EEG pattern, is the mechanism by which the brain integrates different types of information contained in a speech message and presented in different areas of the brain (for example, phonological, spelling, semantic and syntactic information). The process of understanding a sentence consists of two groups of interrelated cognitive operations: it begins with searching in memory for phonological, syntactic and semantic properties of words, which is followed by integrating information into a general idea of the sentence meaning. The stage of searching for words in adults results in an increase in the theta rhythm power. The stage of integrating words into a sentence results in the growth of theta, beta, and gamma rhythms. At the same time, the growth of theta rhythm is more typical for children than for adults. Higher rhythms reactivity during speech perception indicates better developed speech skills in children. Under conditions of relative relaxation, the EEG of children with a high level of speech development is characterized by a moderate power level of theta and beta rhythms and a high level of alpha and mu rhythms.It is assumed that a key role in the process of understanding speech is played by the so-called «action perception circuits», surrounding the Sylvian sulcus of the left hemisphere. The «action perception circuits» are composed of nerve cells capable of providing the speech signals perception and generation. The most important subgroup of neurons included in the «action perception circuits» are mirror neurons that are activated when performing and observing actions. The desynchronization of the EEG mu rhythm is considered as mirror neurons activation marker.In several studies, it revealed that the level of mirror neurons activation and the level of speech understanding in children are connected. It is a topic of great interest to research the mu rhythm alpha and beta components reactivity both during the production of speech and during the perception of another person speech. At present, it is becoming obvious that analyzing the EEG rhythms power changes during the speech understanding in different scenarios could be used to identify the mechanisms of the brain language network and speech disorders. The revealed patterns make it possible to propose ways of correcting the children speech development using EEG biological feedback methods.

Kurs neyroreabilitatsii s primeneniyem kompleksa «Ekzokist'-2» (neinvazivnyy interfeys mozg–komp'yuter i ekzoskelet kisti) v sochetanii s traditsionnym kurortnym lecheniyem privodit u detey s DTSP k znachimomu uluchsheniyu pokazateley dvizheniy, odnako kharakteristiki EEG ne byli proanalizirovany. Tsel'yu raboty bylo opredelit' osobennosti reaktivnosti EEG patsiyentov v chastotnom diapazone a-ritma pri prokhozhdenii kursa iz 10 seansov robotizirovannoy terapii. EEG registrirovali v 21 otvedenii v usloviyakh pokoya i kinesteticheskogo voobrazheniya dvizheniy razgibaniya pal'tsev ruk u 32 detey oboyego pola v vozraste 10–18 let, imeyushchikh diagnoz «levo- i pravostoronniy gemiparez». Vo vremya pervogo seansa patterny reaktivnosti a-ritma pri voobrazhenii dvizheniy u grupp detey s levo- i pravostoronnim gemiparezom razlichalis', prichem razlichiya dostigali statisticheskoy znachimosti v otvedenii R2 pri voobrazhenii dvizheniy levoy kisti (F1, 30 = 5,10; p < 0,05). Pattern reaktivnosti a-ritma vo vremya desyatogo seansa otlichalsya zameshcheniyem reaktsiy sinkhronizatsii v ryade otvedeniy na desinkhronizatsiyu, chto svidetel'stvuyet ob uvelichenii aktivatsii neokorteksa. Naiboleye vyrazhennymi byli izmeneniya EEG u detey s levostoronnim gemiparezom (F20, 300 =1,84; p < 0,05). Po zavershenii kursa stepen' razlichiya pokazateley EEG u patsiyentov s levo- i pravostoronnim gemiparezom umen'shilas'. Vyyavlennyye perestroyki patterna EEG v chastotnoy polose a-ritma mozhno rassmatrivat' kak proyavleniye protsessov blagopriyatnoy reorganizatsii neyronnykh tsepey, kontroliruyushchikh planirovaniye i vypolneniye slozhnykh dvizheniy ruk.

A total of 67 adult subjects took part in studies of the amplitude of the lower (α1) and upper (α2) frequency components of EEG α activity, using individually defined ranges, during execution of circular movements of a computer mouse and during observation of another person carrying out this movement. Topographic specificity was demonstrated for the α2 rhythm, and this rhythm was found to have greater amplitude reactivity than the low-frequency component on execution of movements. The sources of rhythms were identified by low-resolution brain electromagnetic tomography (sLORETA). Both execution and observation of the execution of movements produced similar activation of a number of structures presumptively belonging to the so-called “mirror” system of the brain (precuneus and cingulate gyrus, for the α1 rhythm; inferior parietal lobe, supramarginal and angular gyri, superior and middle temporal gyri, and insular cortex for the α2 rhythm). A significantly greater number of activated voxels was seen in some structures of the right hemisphere than in the left. In the case of executed movements, this phenomenon could be explained in terms of increased needs for subjects’ visuomotor coordination (holding the computer mouse cursor within a specified area of the screen). On observation of movements executed by others, additional activation of the right hemisphere could be due to the social context of the task being performed, supposing attribution of the observed actions to another person. These data can be evaluated as additional evidence supporting the hypothesis of the functional significance of the mirror system of the brain and its involvement in the process of perceiving the movements of another person. The study results also evidence the potential of using a standard computer mouse as an object for operant movement in studies of the neurophysiological mechanisms of motor activity and observations thereof.

The EEG alpha rhythm (8-12 Hz) sources have been localized by means of the sLORETA method in 62 adult subjects having different IQ levels (average, higher than average and high) when they were observing, executing and imitating circular right hand movements with a computer mouse. Subjects with different IQ levels also differed significantly in their cortex activation patterns when executing and imitating movements. A more pronounced and focused activation of neocortex structures was registered in the high IQ adult subjects. The cortex activation differences were mostly found in the right hemisphere brain regions assumingly associated with the processes of visual-motor coordination and action attribution. A larger involvement of the left hemisphere precentral, girdle and postcentral gyri when executing the task of the real-time imitation of hand movements in the high IQ subjects may be an indicator of a greater activation of their mirror neuron system.

It was demonstrated previously that neurorehabilitation with the BCI-controlled robotic device Exohand-2 combined with conventional therapeutic modalities resulted in significant motor improvement in children with cerebral palsy. However, EEG records were not analyzed in the previous study. The aim of this paper was to describe the reactivity patterns of the EEG α-rhythm during a series of 10 BCI-based neurorehabilitation sessions. The study was carried out in 32 boys and girls aged 10 to 18 years with right- or left-side hemiparesis. EEG was recorded from 21 electrodes at rest and during kinesthetic imagery of finger extension. During the first session, patterns of α-rhythm reactivity during motor imagery differed between patients with left- and right-side hemiparesis. The differences were statistically significant at Р2 during left hand movement rehearsal (F1, 30 = 5.10; p < 0.05). During the final session, the pattern of α-rhythm reactivity was different: synchronization was taken over by desynchronization at some electrode sites, suggesting increased activity of the neocortex. The most conspicuous EEG changes were observed in children with left-side hemiparesis (F20, 300 = 1.84; p < 0.05). By the end of the rehabilitation course, the differences between patients with left-and right-side hemiparesis became much less pronounced. Rearrangements in the EEG patterns in the α-frequency band can be regarded as signs of beneficial reorganization of neural circuits responsible for planning and executing complex hand movements.

The EEG amplitude reactivity of the individually defined upper and low alpha frequency ranges was measured in 67 adults when they performed circular hand movements with a computer mouse and observed similar movements produced by another person. The upper alpha rhythm was topographically more specific and had higher amplitude reactivity under condition of self-paced movements in comparison with the low alpha rhythm. The sources for the alpha subranges were identified by means of the low-resolution brain electromagnetic tomography method (sLORETA). Comparable activation patterns for the brain structures associated with the so-called brain “mirror” system (precuneus, cingulate gyrus for the alpha1-rhythm; inferior parietal lobule, supramarginal and angular gyri, upper and middle temporal gyri, insular cortex for alpha2-rhythm) were found for the conditions of performance and observation of movements. During both conditions, there was found a significantly higher number of activated voxels in structures belonging to the right hemisphere relative to the left one. Under the condition of performing self-paced movements, this phenomenon can be the result of heightened demands to the process of visual-motor coordination (keeping the computer mouse cursor within a given screen area). Increased right hemisphere activation having a place when observing movements performed by another person can be interpreted as reflecting the social context of the task given the aspect of attributing observed movements to another person. Such results can be taken in favor of the hypothesis of the mirror neuron system and its involvement into the perception of actions performed by others. The obtained data also testify to the possibility of using a standard computer mouse as an object for instrumental movements when studying neurophysiological mechanisms underlying both movement performance and observation.