[Classification of EEG Patterns of Imagined Rhythmic Movements of the Fingers of One Hand].

The article presents the results of classification of EEG patterns registered during imagined rhytmic movements of the fingers of the right hand (little, thumb, index, middle fingers) in 8 healthy subjects. The subjects imagined finger movements in a given rhythm; no external stimuli were used. A two-level committee of classifiers was developed for decoding: the first level included support vector machines and artificial neural networks; the second level included artificial neural network used for generalizing. As the key parameters for classification, we used the area of zone under the envelope of EEG signal and the length of the envelope calculated in sliding time window for leads F3, C3 and Cz in system 10-20 were chosen as the key features for signals of sensorimotor and adjoining frontal area cortex contralateral to movements. The accuracy of classification of single trials for 4 movements averaged for all subjects for the pair of leads F3-C3 was 50 ± 7% [SD] (maximal - 58%); for the pair of leads C3-Cz, 46 ± 11% [SD] (maximal - 62%); theoretical guessing level is 25%.

[Age-Related Features of EEG Coherence in Children and Adolescents Living in the European North of Russia].

The paper presents data on the formation of spatial synchronization of brain potentials in 91 children aged 7-18 years living in European North of Russia. We estimated coherence values for 19 derivations (pair 171) in five EEG frequency bands (delta, theta, alpha-1, alpha-2 and beta). We described age-related changes, gender differences and topical specific features of the formation of coherence in the left and right hemispheres, and in inter- and intrahemispheric synchronization. We carried out computer assessment of the differences in EEG coherence between three age groups of children in order to determine criteria for identification of children with retarded formation of spatial organization of local EEG processes. Age-related changes in the structure of EEG patterns observed in the study reflect the processes of morphofunctional brain development in children and adolescents at different stages of postnatal ontogenesis under severe conditions of northern climate.

[General Features of the Formation of EEG Wave Structure in Children and Adolescents Living in Northern European Russia].

The article presents the results of the analysis of EEG wave structure formation in children and adolescents aged 7-18 years living under severe conditions of the North. The approaches developed in discrete mathematics (the graph theory, the theory of network flows) were used to assess the time-frequency transformations of EEG patterns. We evaluated conditional probabilities of reciprocal transitions between the components of six frequency bands of E EG (delta, theta, alpha-1, alpha-2, beta-1, beta-2). We described age- and sex-related features as well as regional specificities of the EEG wave structure. We defined the age periods of reorganization of diffuse EEG activities into the main EEG rhythms; the role of distinct rhythms in the maintenance of the EEG wave structure and its dynamic rearrangements was also discussed. The age-related changes of the structure of EEG patterns form some general picture of the morphofunctional development of brain in children and adolescents at different stages of postnatal ontogenesis under severe climate and socio-economic conditions of the North.

Error detection mechanisms of the brain: background and prospects.

Historical background of error detection (ED) studies is restored here from the first suggestion of such a mechanism published (Rabbit, 1966) and the first related anatomo-physiological correlates observed [Bechtereva, N.P., Gretchin, V.B., 1968. Physiological foundations of mental activity. Int. Rev. Neurobiol., vol. 11. Academic Press, N.Y., pp. 239-246; Bechtereva, N.P., 1971. Neurophysiological Aspects of Human Mental Activity. Meditzina, Moskow. 120 pp., (in Russian); Bechtereva, N.P., 1974. Neurophysiological Aspects of Human Mental Activity, second edition, revied and complete Meditzina, Moskow. 151 pp., (in Russian)]. Data from evoked potentials together with new opportunities offered by the technological revolution of the 1980s-1990s provided a large body of knowledge on the ED. The overwhelming majority of the papers stress the spatial relation of ED to Anterior Cingulate Cortex. ED was revealed in a number of other zones to whose role should be specially discussed. The other point of interest is the late appearance of ED after the brain signs of correction which seems particularly important considering the supposed functional role of ED. Data of direct observations of ECoG dynamics in left and right human ACC on correct and erroneous test performance are presented. Research on ED resulted in the development of new ways in treatment of the obsessive-compulsive syndrome. Further psychophysiological research into the ED phenomena is considered as one of the priorities of fundamental and applied investigations for the elucidation of human brain functions. Opinion that ED plays an extremely important role in mechanisms of cognition and creativity is further argumented. Investigations in the field can contribute a lot to clinical neurophysiology as well.

Longitudinal study of EEG frequency maturation and power changes in children on the Russian North.

The aim of the study was to reveal longitudinal changes in electroencephalogram spectral power and frequency (percentage frequency composition of EEG and alpha peak frequency) patterns in normal children from northern Russia. Fifteen children (9 girls and 6 boys) participated in the study. The resting state (eyes closed) EEGs were recorded yearly (2005-2013) from age 8 to age 16-17 for each child. EEG frequency patterns were estimated as the percentages of waves with a 1 Hz step revealed by measuring the interval durations between points crossing zero (isoline) by a curve. EEG spectral power changes were analyzed for delta (1.5-4 Hz), theta (4-7.5 Hz), alpha-1 (7.5-9.5 Hz), alpha-2 (9.5-12.5 Hz), beta-1 (12.5-18 Hz) and beta-2 (18-30 Hz) bands. According to the frequency composition of the EEG signals fast synchronous, polymorphous synchronous, polymorphous desynchronous and slow synchronous types of children EEG were revealed. These EEG types were relatively stable during adolescence. In these EEG types, the frequency patterns and spectral power dynamics with age had several common and specific features. Slow wave percentage and spectral power in the delta band remarkably decreased with age in all groups. Starting from the theta band the EEG types were characterized by different EEG spectral power changes with age. In fast synchronous EEG type, the theta and alpha-1 EEG power decreased, and the alpha-2 power increased in the occipital and parietal areas. The polymorphous synchronous type was characterized by increased both the alpha-1 and alpha-2 power with regional peculiarities. In the polymorphous desynchronous type spectral power in all bands decreased with age, and in the slow synchronous type, the alpha-1 power massively increased with age. Obtained results suggest predictive strength of the spatial-frequency patterns in EEG for its following maturation through the years.