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This work was carried out on the model of cognitive set to facial expression under conditions of high load on working memory by lengthening interval between the facial and triggering stimuli to 8 seconds. The aim of this work was to try to reveal, there is the phenomenon of correspondence between the dynamics of gamma- responses (21-60 Hz) to the facial-stimuli and the real "success" of the job (number of mistakes in performing a task): To do this, we used a different method of estimating the power compared to the wavelet transform, as if it is applied in a previous worksuch a dependending was not revealed. In this paper we analyzed the index of the average amplitude, built in a similar method specific variation to estimate the power of gamma responses (range: gamma1-21-40 and gamma2-41-60 -Hz), which revealed correspondence between patterns of gamma responses and the number of subjects admitted mistakes. The obtained results allow us to consider gamma2-responses to facial stimuli as electrographic correlate of states (the so-called their gamma code) corresponding to the adequacy of real actions of the subject at the test under the same conditions of 8-second interval between the facial and trigger stimuli.

Power EEG gamma-band (21-60 Hz) in the process of forming and testing the cognitive set on the face expression is seen in conditions of the model, which provides a higher load on working memory by lengthening the intervals between the target and trigger stimuli to 8 s. The results are compared with data from previous experiments with increased load in the form of additional cognitive tasks, when there was an increase of gamma responses by "success" of the job subjects. In this study, the responses to set-stimuli were observed significant lower (relative to prestimulus period) in all groups of subjects that were treated as inhibition of gamma activity. Significant differences in the levels of power gamma-band between the groups were identified by comparing the set up steps (forming and testing), and frequency-bands. The second important difference is the absence of differences in the dynamics of power patterns gamma2 (41-60 Hz) between groups of subjects depending on the "success" of the job. We present arguments to substantiate the "paradoxical" results in the conditions of use of the plant model.

In the context of understanding of the mechanisms of cognitive human accounting functional role in these processes of neocortical gamma activity, the science progress of the 21st century at least three new logically related directions are outstanding to: 1) combination with intracranial recordings by functional magnetic resonance imaging (fMRI) has indicated a closely correlation between the level of power of high gamma-band (90-150 Hz) at corresponding localization and the level of blood oxygenation (responses BOLD; blood oxygenation level dependent), which provides an estimate of the dynamics of power in aspect of metabolic resources; 2) results parallel evaluation of parameters gamma activity (frequency, bandwidth, amplitude) in combination with the size of BOLD responses and the GABA concentration as measured by magnetic resonance spectroscopy, formed the basis of hypothesis about the individual peculiarities (specific features) of the subject (trait); 3) new methods of measuring the phase synchrony of gamma frequencies has created the phenomenon of cross-frequency interaction (cross-frequency coupling, CFC) between phases of gamma oscillations with theta, alpha waves. This phenomenon is considered by some authors as the basis of interrelations of different separated networks, possibly providing approach to understanding of various aspects of defining the mechanisms of cognitive processes.

A review. Studies in the period of 2009-2011 are discussed, in which a new phenomenon in human EEG was found out, i.e., personal (individual) features ofneocortical gamma activity in parameters such as amplitude, frequency and width of the gamma band. This phenomenon was revealed in induced responses to visual stimuli in people under conditions of repeated research (after different time intervals - hours, weeks, months). The findings suggest the necessity of development of the metric system for assessment of this phenomenon and corresponding estimation of personal features of the gamma band and their stability (reliability), which would allow interindividual differences to be revealed.

A review. The problem of the functional significance of gamma-band EEG in different cognitive paradigms, including the aspect of the gamma-band heterogeneity (different origin and functional significance of "low gamma" and "high gamma").

The dynamics of power of short-term (0.8 s) induced responses to facial stimuli (wavelet transform in the 15-60 Hz band) were assessed in the study of the visual cognitive set under conditions of different loads on working memory in two groups of subjects. Subjects of the first group had to react only to facial stimuli (n = 29), whereas the second group solved an additional task loading the working memory (they had to find a target stimulus in a matrix of letters, n = 35). We estimated wavelet spectra in the occipital, temporal, central and frontal areas of both hemispheres. In both groups of subjects with the plastic form of set, the power level in the gamma2 band (41-60 Hz) was significantly higher than in subject with the rigid form. In group A at the set-testing stage, the largest increase in the gamma2 band was related to the central areas of the left hemisphere. In more complex situation (group ), the increase in power in the gamma2 and gamma1 (21-40 Hz) bands was observed in the occipital and temporal areas of both hemispheres. At the same time, the EEG power of the central areas in these gamma bands was significantly lower. In the frontal areas there were no significant differences in the dynamics of power between the subjects of both groups.

Power spectra of cortical potentials of baseline activity during interstimuli intervals (4 s; Fourier transform in the frequency band of 1-60 Hz) and short-term (0.8 s) induced responses to facial stimuli (wavelet transform in the 15-60 Hz band) were assessed in the study of the visual cognitive set to facial expression. Significant differences between groups of subjects with different set rigidity were observed only at the set-testing stage. Estimation of the short-term (0.8 s) induced responses of the wavelet spectra in the group with plastic set revealed an increase in the power (in comparison with the power of background activity) of the gamma2 band (41-60 Hz) in the left hemisphere of the temporal, central and occipital areas, whereas in the group with rigid set these power spectra decreased. At the same time the power in the gamma1 band (21-40 Hz) was significantly lower (at the same level with the rigid form), indicating a discrete nature and functional selectivity in the gamma frequency band.

Power spectra of cortical potentials at frequencies of 1-60 Hz were assessed in subjects in the state of resting with the eyes open, after listening to instructions, and during the prestimulus periods at the stages of forming and testing a cognitive set to a facial expression. Comparative assessment of power spectra in five frequency ranges (2-7, 8-13, 14-20, 21-40, and 41-60 Hz) showed significant decreases in the power of potentials in the 1-20 Hz frequency band in most subjects, along with a parallel increase in power in the 21-60 Hz band in all states, as compared with the resting state. Interregional differences in power were maximal in the 2-7 and 41-60 Hz bands and minimal in the 14-20 Hz band. In terms of power dynamics in the states being compared, intergroup differences were seen only at the test stage. Thus, a larger proportion of subjects with the plastic type of set had greater power in the gamma frequency range than was the case in subjects with the rigid type of set.

Interhemispheric relations of the EEG power in the 1-60 frequency band were studied at the stages of formation and testing of the cognitive set to facial expression. Different topographic asymmetry patterns were revealed in subjects with different set plasticity. In subjects without behavioral actualization (n = 11) of the set at the stage of set formation, EEG power in the gamma band (21-40 and 41-60 Hz) prevailed in the frontal areas of the right hemisphere, whereas the power of electrical oscillations in the bands of 2-7 and 8-13 Hz was higher also in the frontal areas but of the left hemisphere. At the stage of set testing, this basic topographical asymmetry pattern persisted. Formation of the set in subjects with pronounced actualization (n = 18) was characterized by another topographical asymmetry pattern: a significant excess of the power of gamma oscillations was observed in the posterotemporal and occipital areas of the left hemisphere, whereas the power of oscillations in the bands 2-7, 8-13, and 14-20 Hz was higher also in the posterior areas but of the right hemisphere. No asymmetry in the EEG power was observed in these subjects at the stage of set testing.

Power spectra of cortical potentials in the frequency band of 1-60 Hz were estimated in 29 healthy subjects in the states of rest with the open eyes, after listening to instruction, and in prestimulus periods at the stages of forming and testing of the visual cognitive set to facial expression. Comparative assessment of the power spectra in five frequency bands 2-7, 8-13, 14-20, 21-40 and 41-60 Hz revealed a significant decrease in the power for the frequencies of 1-20 Hz and its parallel increase in the band of 21-60 Hz in all the states under study as compared to the state of rest. At all the set stages, interregional differences in the EEG power were the highest in the bands of 1-20 and 41-60 Hz and the lowest in the band of 14-20 Hz. Significant differences between the "plastic" and "rigid" groups in the power dynamics were observed only at the set-testing stage. Thus, in subjects with the plastic set, the power of the gamma-frequency band was more frequently higher than in subjects with the rigid set.

The power spectra of baseline (prestimulus) EEG recordings from various parts of the cortex in the band 1-60 Hz were studied in adult subjects during the stage of formation of a cognitive set to facial expressions. Individual variability in the power spectra of the baseline EEG, particularly in the gamma range (41-60 Hz) made it impossible to average spectra from different subjects. This is the first study demonstrating that the EEG at 41-60 Hz was more informative during the prestimulus period than recordings at 1-20 Hz and 21-40 Hz. High levels of gamma-frequency power were found to be dominant in the frontal areas of the right hemisphere in groups of subjects with plastic sets; the group of subjects with a rigid set showed dominance of gamma-frequency power in the posterior temporal and occipital areas of the left hemisphere.

Prestimulus EEG power spectra from different cortical areas in frequency band 1-60 Hz were studied at a stage of formation of the cognitive set to facial expression. Diversity of individual power spectra of baseline EEGs, especially in gamma frequency band 41-60 Hz makes averaging individual spectra impossible. The authors pioneered in finding that, in prestimulus periods, EEG frequencies 41-60 Hz were of higher information value than frequencies 1-20 and 21-40 Hz. The highest power of the gamma frequencies was revealed in the frontal areas of the right hemisphere in subjects with a plastic set. In the group with a rigid set, gamma frequencies of high power prevailed in the posterotemporal and occipital areas of the left hemisphere.

A review. The article dedicated to the centenary of academician Mikhail Nikolaevich Livanov briefly outlines the history of development of his original concept of the functional significance of the brain potential's spatial synchronization phenomenon as a possible way of studying systemic organization of the brain electrical activity. The new parameter of "space" introduced into neurophysiology by M. N. Livanov made it possible to research the earlier unknown aspect of the brain activity. Livanov's ideas have been developed in many studies of the late decades of the XX century. In the review, much attention is given to specific functional significance of this phenomenon in a broad frequency band 1-250 Hz, especially, during instrumental learning. Energy (power spectra) and coherent-phase characteristics of cortical potentials in traditional (1-30 Hz), gamma-(30-80 Hz) and high-frequency (80-250 Hz) bands are compared. The problem of linear and nonlinear processes in the organization of the brain potentials is mentioned.

Power spectra of short-term (less than 1 sec) electrical responses to conditioned stimuli were studied over the frequency range 1-225 Hz in dogs during food-related operant conditioning. These spectra demonstrated regional characteristics in terms of energy levels and frequency composition. Responses were more marked in the visual and parietal areas of the left hemisphere. Power in responses to a differential stimulus were significantly lower than with responses to positive stimuli, mainly because of the high-frequency range (80-225 Hz); energy levels in these two situations were similar during prestimulus intervals. The frequency composition of responses was defined by a series of discrete frequencies in the gamma (30-80 Hz) and high-frequency ranges.

Power spectra over the frequency range 1-225 Hz in short-term (less than 1 sec) EEG reactions arising in different areas of the cerebral cortex in response to presentation of differential signals were investigated in dogs during operant feeding behavior in conditions of both adequate and erroneous responses. The energy levels of these reactions decreased several-fold as compared with responses to positive signals, mainly because of frequencies in the high-frequency range (90-225 Hz), where power was greater than not only the traditional range of 1-30 Hz, but also the gamma range of 30-80 Hz. The frequency composition of EEG reactions in adequate responses was determined by a series of discrete frequency subgroups belonging predominantly to the high-frequency band. In erroneous reactions, the discrete structure of the corresponding EEG reactions was lost.

Power spectra of short-term (less than 1 s) EEG-reactions (in the frequency band of 1-225 Hz) were studied in dogs in the course of instrumental food conditioning. These reactions were observed in different areas of the cortex in response to positive and differentiated conditioned stimuli. Regional features between the spectra were found both in the power level and frequency structure. The power of the reactions in the visual and parietal areas of the left hemisphere was higher than in the motor areas. Power spectra of reactions to differentiated stimuli were significantly lower than the spectra of reactions to positive stimuli mainly owing to the high-frequency components (80-225 Hz). In these both cases, prestimulus power spectra did not differ. The frequency structure of corresponding EEG-reactions consisted of individual spectral peaks, mainly both gamma (30-80 Hz) and higher-frequency (80-225 Hz) bands.

Experiments were performed to address the energy characteristics (power spectra) of short-term (less than 1 sec) EEG reactions arising in different areas of the neocortex in response to positive conditioned stimuli presented in conditions of selective attention. These EEG reactions directly preceded the motor reactions, which consisted of a strong blow with the paw on a feeder pedal to obtain reinforcement. The energy levels of EEG reactions were 1.5-3 times greater than pre-stimulus levels. The frequency structures of the corresponding EEG reactions were divided into discrete frequency subgroups, including the traditional (1-30 Hz) and the gamma ranges (30-80 Hz) as well as higher-frequency components (80-200 Hz). In some cases, the greater proportionate increases in power occurred in the high-frequency band.

Power spectral (in the broad frequency band of 1-225 Hz) of short-term (less than 1 s) EEG reactions were studied in dogs in the course of instrumental food conditioning. These reactions appeared in different cortical areas in response to differentiating signals under conditions of both adequate and erroneous responses. The EEG power of such reactions was several times lower as compared to responses to positive signals, mainly, at the expense of the frequencies in the band of 90-225 Hz (the power of which was higher than that of the traditional band of 1-30 Hz and the gamma band of 30-80 Hz). The frequency composition of EEG reactions accompanying adequate responses was defined, mainly, by discrete subgroups of high-frequency components. During erroneous responses, the discrete structure of the corresponding EEG reactions was broken.

The state of selective attention formed during operant food-related behavior was studied using the coherence-phase characteristics between potentials in several areas of the neocortex at frequencies of 1-220 Hz. Functional groups were identified among the areas compared, which appear to have priority for this state. The temporal relationships between potentials in these groups were established from values for coherence functions at a particular optimum level (0.7) mainly in the band 1-15 Hz and the high-frequency range 40-200 Hz. The phenomenon of synchronicity appeared at phase shifts close to zero, while at significant phase shifts the phenomenon of non-synchronous time relationships with defined spatial directions was seen in the high-frequency range.

Experiments were performed in dogs to study the state of selective attention formed during operant food-related training and apparent during interstimulus intervals as a state of tense expectation of the conditioned signal. Electrical activity in various parts of the neocortex, in both hemispheres, was analyzed in the frequency range 1-220 Hz (epidural electrodes) using Fourier transforms. The electrical activity of the motor area of the right hemisphere showed a predominance of high-frequency (40-200 Hz) components, as did the visual and parietal areas of the left hemisphere. The state of selective attention was associated with a different functional mosaic in the organization of neocortical electrical activity.

A review. Current views of the so-called binding problem, which considers hypothetical mechanisms of perception of sensory stimuli and formation of their corresponding Gestalts (internal images) are discussed. The mechanism of intensification of synchronized reactions of cortical electrical activity in the gamma band frequency (30-80 Hz) is the basis of the most popular point of view of "binding". The article considers the evidence for the functional significance of the high-frequency components exceeding the gamma-range (to 200 Hz) obtained by the author, the origin of these oscillations, and conditions of their focal derivation. The problem of "binding" and stages of instrumental conditioning (a stimulus, perception of the stimulus, and its transformation into a signal) as well as significance of the context in learning and formation of tonic states ensuring the realization of phasic reactions is discussed. Forms of "binding" at the final stage of conditioning (selective attention) are considered. The question is posed as to whether "binding" is exhausted only by the mechanisms of synchronization of activities of large neuronal populations and only in the frequencies of the gamma range.

Coherent-phase characteristics of cortical potentials (1-220 Hz) derived from different cortical point of both brain hemispheres of dogs were analyzed in the state of selective attention developed in the course of instrumental food conditioning. Among the compared cortical points, functional groups were found that were probably of priority for the state of selective attention. Values of coherence function between these derivations (an assessment of temporal relations) were at a certain optimal level (about 0.7), predominantly, in the frequency ranges of 1-15 and 40-200 Hz. Under such conditions, if the average phase shifts between the potentials were near zero, phenomenon of potential synchronism was formed. In case of significant phase shifts, phenomenon of asynchronous temporal relations with a certain spatial direction developed.

The state of selective attention was studied in dogs in the course of instrumental conditioning. During interstimuli intervals, this state was manifested in the state of strained waiting for conditioned stimuli. Electrical activity of different areas in both hemispheres was analyzed using the Fast Fourier Transformation. It was shown that in the process of development of selective attention, the high-frequency EEG components (40-200 Hz) in the motor area of the right hemisphere and the visual and parietal areas of the left hemisphere had a predominant significance over the traditional EEG frequencies of 1-30 Hz. The state of selective attention was characterized by another functional mosaic organization of the neocortical potentials.

The study was aimed to reveal the subbands of correlated changes in power spectral density of brain electrical activity (EA), including the low-voltage (up to 10 microV) high-frequency (HF) components (40-200 Hz) in dogs during instrumental conditioning by means of factor analysis. The values of the EA spectral density in interstimulus intervals calculated with a resolution of 1 Hz were used for subsequent factor analysis (the standard principle component technique with varimax rotation). Twenty factors could explain about 80% of total variance. The groups of frequencies which were presented by comparatively narrow peaks (2-3 points) of high loads (more than 0.6) of single factors ("stable" factors) were taken into consideration. In the process of conditioning the factor organization of the EA became substantially complicated, the number of the "stable" factors increased. It was originally shown that the high loads of these factors divided the HF band in comparatively narrow frequency subbands, which appear to reflect the functional mosaics in the neocortex.

Bursts of high-frequency (HF, 80-90 Hz, 70-80 microV) oscillations in the electrical activity (EA, 1-200 Hz) of the dog neocortex were studied during operant conditioning. These bursts of HF oscillations appeared in the EA of interstimulus intervals at the generalization stage on a background of dominant oscillations of lower frequency and amplitude (10-40 microV). Use of a new strategy for primary analysis of EA production (specifically, a coefficient of inhomogeneity) allowed amplitude-frequency inhomogeneity of the EA to be estimated, with isolation of bursts of HF oscillations. Use of an original nonharmonic analysis, consisting of expansion of EA waves into a system of half-waves which were used to construct distribution maps, revealed the regional properties of bursts of HF oscillations. The results of these investigations supplement previous data obtained using other methodological approaches (Fourier transformation and spectral density factor analysis). The properties of bursts of HF oscillations observed here provide evidence for the differential involvement of cortical areas (even close-lying areas separated by distances of 3-5 mm) in the spatial-temporal organization of potentials typical of this conditioning paradigm.

Inhomogeneity indexes were developed, and were found to be quite reliable indicators of the presence of short-term high-frequency bursts in the electrical activity of the dog brain, and were also sensitive discriminators of quasi-homogeneous fragments in terms of the level of "general activation." Studies demonstrated that the values of these coefficients reflect the individual features of animal brain electrical activity, as well as its dynamics during the development of conditioned operant feeding reflexes. At the same time, these indexes did not reveal any regional variations. Using the construction of an inhomogeneity spectrum as an example, an approach to identifying similar numerical characteristics, also based on traditional harmonic analysis (Fourier transformation), is discussed.

We studied the electroencephalographic (EEG) phenomenon of high-frequency (HF) bursts (within the limits of 60-170 cycle, 70-80 microV) in the electrical activity (EA) of the brain (1-200 Hz) of dogs in the process of alimentary instrumental conditioning. These bursts appeared at the stage of generalization in a number of neocortical areas in the interstimulus intervals at the background EA, which was at lower amplitudes (10-40 microV). Application of novel strategies developed by us to the primary analysis of EA realization (in particular, introduction of inhomogeneity factor and activation index) enabled estimation the amplitude-frequency inhomogeneity of EA, namely, HF bursts. The regional peculiarities of HF bursts were revealed by means of the technique, developed by us, that was based on expansion of the EA variations into a system of half-waves and construction of distribution maps on the basis of their parameters. The presented data verify our earlier findings obtained with the use of other techniques (fast Fourier transform analysis and factor analysis). These data testify to differential participation of cortical areas (even those that are within 3-5 mm of each other) in the spatiotemporal organization of potentials that is characteristic for a given learning paradigm.

The EEG phenomenon was studied of high-frequency bursts (60-70 Hz, 70-80 mcV) in electrical activity of dog's neocortex (EA, 1-200 Hz) in the process of instrumental conditioning. These bursts of high-frequency oscillations appeared at the generalization state of the conditioned reflex during interstimulus intervals at the background of dominant EA of the lower frequency and voltage (10-40 mcV). Application of the developed by us novel strategy of the primary analysis of EA realizations (in particular, inhomogeneity coefficient) enabled estimation of the amplitude-frequency EA inhomogeneity, namely, high-frequency bursts. The regional peculiarities of the high-frequency bursts were revealed by means of the original technique based on the expansion of EA oscillation into a system of half-waves and construction of distribution maps on the basis of their parameters. The presented data verified our earlier findings obtained using other techniques (FFT analysis and factor analysis). These data testify to differential participation of cortical areas (even those which are close to each other within a distance of 3-5 mm) in the spatio-temporal organization of potentials characteristic for a given learning paradigm.

This study was undertaken with the aim of identifying frequency bands with correlated changes in the spectral power amplitudes of brain electrical activity, including high-frequency components (the 1-200 Hz band) in four dogs, using one-dimensional analysis. Factor and cluster analysis of the spectral densities of various parts of the cortex and the olfactory bulb were carried out. The ratios of factors in different parts of the brain, both in terms of the proportions of the total dispersity and in terms of weightings, provided data on regional and individual differences in electrical activity. During learning (development of a motor habit consisting of pressing a feeder pedal), the factor organization of electrical activity became more, complex, particularly in the high-frequency part of the spectrum (40-170 Hz). The changes consisted of the appearance of narrower frequency sub-bands, each of which was present at high weighting (0.7-0.9) for one of the factors. The use of high-frequency components allowed functional mosaicism of the neocortex to be detected.

At present, the significance of high-frequency (HF) components in brain electrical activity (EA) is widely discussed in literature. In particular, the gamma range of human EEG is considered as one of the indices of cognitive activity. In the paper a review is presented of the author's own data concerning the functional estimation of low-voltage HF components of the neocortical EA recorded in the broad band (1-100, 1-256 Hz) in the course of instrumental conditioning in dogs. Three different techniques of EA analysis were used in the study: 1) fast Fourier transformation (FFT) of EA in a broad band, 2) developed by us alternative method of non-harmonic expansion of the EEG curves taking into account their shape, 3) factor analysis of the EA spectral densities. Combination of these techniques allowed us to obtain some novel evidence indicative of high informativity of the HF fluctuations. Spatial cortical localization of the HF components of the EA is much more expressed in comparison with the traditional 1-30 Hz range. Results of factor analysis suggest functional heterogeneity of the HF band. Obtained data open new ways for researches concerning the phenomena of the functional mosaics in the neocortex as one of fundamental mechanisms in brain activity organization.

The qualitative techniques are considered of mathematical description of curve inhomogeneity which adequately reveal non-stationary fragments in EEG samples with a pseudorandom process. The introduced inhomogeneity coefficient turned to be a sufficiently adequate indicator of the presence of short-term high-frequency bursts in the electrical activity of dog's brain and a sensitive index for discrimination of quasihomogeneous fragments by the level of "general activation". It is shown that the values of this coefficient reflect the individual features of the brain electrical activity of the animals and its dynamics in the process of alimentary motor conditioning. At the same time, this index is ineffective in revealing the regional differences. A novel approach is developed for signal inhomogeneity description which is based on the traditional harmonic analysis (Fourier transform).

The study was aimed to reveal frequency ranges of correlated changes of power spectral densities of the brain electrical activity (EA) including the high-frequency components (HFC) in dogs (4 animals) by means of factor analysis technique. Spectral densities of EA in different cortical areas and olfactory bulb were factored. Relationships between the structure of the selected factors both by the parts of the total variance determined by them and their frequency loads suggest the regional and individual EA differences. In the process of learning (elaboration of motor skill of pressing the food-dispenser pedal with a forepaw) the factor organization of the EA became substantially more complicated, mainly, in the HFC-range (40-170 Hz). This was manifested in formation of narrower frequency subbands of the HFC each of which being highly loaded (0.7-0.8) by one of the factors. The evidence obtained by means of the FA was completely verified using original version of cluster analysis.

The parameters of the electrical activity of various regions of the neocortex (NC) and the olfactory bulbs (OB) of dogs were studied by means of correlation-spectral analysis during the development of a food-dispenser paw pedal-pressing motor skill; a wide band of frequencies (1-100 Hz), which included both the traditional range (1-20 Hz) as well as high frequencies (HF), were used. Differences were demonstrated in the dynamics of the parameters in the NC and OB. The energy level of the potentials of the NC increased in the HF range (beta 3 and gamma), while in the OB it increased in the HF and alpha range. The coherence-phase characteristics of the NC potentials suggest that more stable (by comparison with resting wakefulness) temporal relationships between the oscillations not only within the limits of HF, but also in the alpha band, are formed in the presence of the developed skill. At the same time, greater phase shifts are characteristic for the interrelationships of the OB potentials and those of the NC, and the increase in coherence relates only to the HF range, whereas the oscillations of the traditional range are characterized by a decrease in coherence. The possible role of the alpha range (along with the HF) in the processing of information which supports appropriate behavior is stressed.

Dynamics of parameters of low-voltage high-frequency components (HFC; 40 Hz and higher) of electrical activity (EA) of the brain in a broad frequency range (1-256 Hz) was studied in dogs in the process of conditioning using correlation and spectral analysis. Motor skill of pressing the pedal of the food dispenser in response to presentation of sound stimuli was elaborated. Spectra of power, coherence and phase of EA were studied in interstimulus intervals (2-3 minutes) and intervals (1 sec) of EEG reaction to conditioned stimuli preceding the motor response. It follows from the distinctions between the parameters of EA at these states that underlying them mechanisms are different. It is assumed that the dynamics of HFC (40-170 Hz) in interstimulus intervals (intensification of HFC and dominance of small phase shifts) is an expression of cognitive activity (forming of the internal integral image of forthcoming activity). Characteristics of EEG reactions to the conditioned stimuli (increase of phase shifts between potentials) are regarded as a "motor program" which ensure direct realization of multicomponent motor reaction.

A new method has been developed for the coding of EEG tracings which is an alternative to the classical spectral correlation analysis. This method has made it possible to compensate to a considerable degree for limitations which are unavoidable with the Fourier transform, and to obtain additional information regarding the form of the tracing, which reflects the fluctuations of brain potentials. The new system that has been presented for coding the EEG is, in our view, the most adequate (of the methods known to us) for identifying the individual features of the EEG, in terms of evaluating both their regional differences and similarities. The data obtained convince us once again of the real existence of high-frequency low-power components of the EEG, and their enhancement during instrumental learning in dogs (motor alimentary conditioned reflexes). In addition, data have been obtained pointing to the intensification in some regions of a slow-wave constituent; this has not been observed previously in carrying out a Fourier transform.

The work was aimed to reveal the functional significance of separate narrow-frequency bands in the high-frequency range (40-200 Hz) of brain electrical activity of dogs in the process of lever-pressing instrumental conditioning. In order to divide this range into separate bands we applied one of the methods of multivariate statistics, factor analysis (FA) with varimax rotation. Values of function of spectral density in the wide range (1-200 Hz) were factorized. The structure of factors reflected both regional cortical characteristics of electrical activity and individual features. Conditioning induced changes in factor description of brain electrical activity mainly in the high-frequency part of the spectra. A number of new factors appeared which divided high-frequency band of the brain activity into narrower parts with definite functional significance.

Parameters of EEG recorded from some areas of the cortex and olfactory bulbs were studied during lever-pressing alimentary conditioning in dogs and analysed using FFT in a wide frequency range (1-100 Hz). Parameters of electrical activity in the cortex ans olfactory bulbs were shown to have different dynamics. Power level of cortical potentials increased in the high frequency band (40 Hz and upwards) and that of the olfactory bulbs increased in both high frequency and alpha bands. Coherent-phase characteristics of the cortical potentials give evidence that in the process of conditioning more stable relations establish between activities of different cortical areas in both high frequency and alpha bands than in the state of quiet wakefulness. At the same time relations between potentials in the cortex and in the bulbs were characterized by the larger phase shifts, increase of coherence attributed only to the high frequency but not traditional bands. Possible role of the alpha frequencies along with the high frequency band in the process of information processing is discussed.

EEG reactions to positive and differentiated signals were compared during lever-pressing alimentary conditioning in dogs by means of described by us earlier non-standard forms of EEG analysis in a wide frequency band (1-256 Hz). Findings concerning EEG reactions to positive stimuli, confirmed the earlier obtained data on a high representativeness of the high-frequency components of dog's EEG. EEG reactions to differentiated stimuli were also excitatory. Developed by us techniques allowed us to show some quantitative characteristics of these reactions. Diversity of expression of high-frequency components in different dogs, accompanied by similarity of their effector reactions (absence of movement), was considered as a reflection of individual features of their CNS.

A new method of EEG coding (alternative to classical FFT) was worked up. It allowed to compensate for limitations of FFT and to obtain new information on the shape of EEG curve reflecting peculiarities of oscillations of potentials. Proposed technique of EEG coding seems to be adequate for revealing individual and regional features of EEG and their estimation at different stages of instrumental conditioning. Data obtained using this method confirm the reality of high frequency EEG components of small power. In addition, by the method used the intensification of slow wave EEG components was demonstrated in some cortical regions which could not be revealed by FFT.

The background electrical activity of the neocortex in the interstimulus periods at the stage of generalization during the development of alimentary motor conditioned reflexes (CR) in dogs was the investigational object. It was characterized by the appearance of brief (0.1-0.3 sec) trains of high frequencies (HF), significantly exceeding the adjacent initial baseline in frequency and amplitude. The relative variance index which we had developed made it possible to distinguish this EEG phenomenon in the initial realizations of the background activity when they were inputted into a digital computer. It was not possible to evaluate the parameters of the HF chains by means of a spectral correlation analysis. Nonstandard techniques of computer analysis directed toward the decomposition of the EEG tracing into a system of oscillations and toward the obtaining of the corresponding amplitude-frequency distributions (maps) were developed by us for the purpose of accomplishing this objective. It was demonstrated that HF trains were localized in these maps in specific, quite compact regions.

Coherence-phase characteristics of cortical and bulbus olfactorius (BO) potentials were studied during the lever-pressing alimentary conditioning in dogs. These parameters were considered as the basic ones for forming the interareal functional relations in the process of conditioning. Variety of distributions of phase shifts between potentials in a wide frequency band (1-100, 1-256 Hz) at wakefulness permits to think about the spatial-successive processes participating in organization of the brain electrical activity. Values of phase shifts between cortical potentials were significantly less then those between the cortex and BO. At stable conditioned responses phase shifts between the cortical potentials diminished considerably due to intensification of the spatial synchronization processes while those between the cortex and BO increased to a higher degree.

Background electric activity was studied of different neocortex areas in interstimulus intervals at the stage of generalization during elaboration of motor alimentary conditioned reflexes in dogs. For this stage the appearance is typical of short-term (0.1-0.3 s) packs of high frequencies (above 40 osc./s) significantly exceeding the adjacent initial background by frequency and amplitude (along side with motor interstimulus reactions). The index of specific variation, elaborated by us, allowed to single out this EEG pattern in the initial realizations of the background activity during their input in the computer. With the purpose of further evaluation of the above phenomenon parameters non-standard approaches of computer analyses were used, directed to decomposition of the EEG curve into the system of oscillations and receipt of corresponding amplitudes frequencies distributions (maps). It was shown, the described high frequencies packs were localized on these maps in definite sufficiently compact places.

Electrical activity was studied of five different regions of dogs neocortex in inter-stimuli periods in the process of learning of motor habit of pressing the feeder pedal. Epidural electrodes were used. The processing was performed by means of correlation-spectral analysis in a wide band of 1-256 Hz. Values of cross-correlation coefficients, spectra of power, coherence and phase shifts were obtained. In the process of the habit consolidation the high frequencies power increased significantly (within the limits from 60 to 150-170 osc/sec), as well as the part of high coherence (over 0.75), falling on these limits, with low phase shifts. Relatively slow-wave oscillations (1-20 osc/sec) underwent changes of considerably lesser degree. A greater locality of high frequencies (in comparison with the traditional range of 1-20 Hz) was shown. The question of the nature of high frequency EEG components is discussed.

With the purpose of levelling the restrictions appearing at the EEG correlative-spectral analysis, particularly of short (1-2 sec) realizations, as a result of Fourier transform, a new algorithm is elaborated of decomposition and analysis of bioelectrical activity. The created algorithm of complete EEG reduction to the list of oscillations singled out has been tested by a corresponding program. It provides for the measurement of parameters of concrete characteristics of the curve, and the adequacy of decomposition is ascertained by the exact restoration from the list of oscillations of the initial EEG. The method shows good sensitivity to the revealing of transient EEG phenomena and also regional specificity of the cortical bioelectrical activity.

Phase-coherent characteristics of neocortex background electrical activity were studied in a wide frequency range (1-100 Hz) during interstimulus periods in the process of elaboration of motor alimentary conditioned reflexes in dogs. It was shown that the process of learning led to a considerable increase of the part of high (greater than 0.75) and significant (0.5-0.75) coherences, and also of small (0 +/- 15 degrees) and accounted (+/- 16 - +/- 30 degrees) phasic shifts as compared with the state of calm wakefulness. This increase lay mainly in the high-frequency range (40-100 Hz). The analysis of the interregional relations showed that they differed not only by values of phase-coherent characteristics, but also by distributions of the latter. The obtained data testify that the state of activation is manifested both in the rise of frequency of potentials oscillations and in the increase of their synchronization.

During elaboration of a stereotype system of defensive conditioned reflexes in dogs (Pavlov dynamic stereotype), a correlation spectral analysis was made of electrical activity in the neocortex. With a stable dynamic stereotype, substantial changes of background electrical activity were observed in the interstimuli periods, manifested in a significant growth of linear relations of cortical potentials at certain frequencies. This was expressed in separation from the wide-band random process (involving background activity before the formation of the dynamic stereotype) of definite, relatively narrow ranges of frequencies which formed the high coherence of the processes. No such changes of electrical activity were observed in conditioning without a stereotype; this points to special mechanisms of the dynamic stereotype, which differ from those of ordinary conditioned reflexes.

The responses of 288 neurons with background activity in the first auditory cortex were investigated using glass microelectrodes in chronic experiments on cats at rest (123 neurons) and during elaboration of a defensive conditioned reflex to sound stimulation (165 neurons). At rest 43% of recorded neurons did not respond to the sound stimulus. Pronounced inhibition of background activity prevailed among responding neurons (about 60%). The conditioning caused an increase (to 72%) in proportion of neurons responsive to the sound stimulus, appearance of tonic reactions, as well as an increase in frequency of bursts and in proportion of activation type responses. It is suggested that these changes indicate the enhancement of neurons excitability in the zone under study during conditioning.

Using glass microelectrodes, the impulse activity of auditory cortex neurons was studied in chronic experiments on cats. It was shown that an increase in frequency of the background activity occurring in many neurons during conditioning was often observed prior to the appearance of conditioned motor reactions. Comparison of mean frequencies of the background activity and corresponding evoked activity shows, on the one hand, the nonlinear dependence between them and, on the other hand, the prevalence of activation reactions as compared with inhibitory ones. Some levels of background activity were distinguished corresponding to mean evoked activity frequency ranges. Background activity analysis performed prior to the presentation of the conditioned stimulus and after its cessation (aftereffect) shows that at stable conditioned reflex mean frequencies in these periods are close to each other.