M. O. Zhuravlev

Intermittency of intermittencies.

A phenomenon of intermittency of intermittencies is discovered in the temporal behavior of two coupled complex systems. We observe for the first time the coexistence of two types of intermittent behavior taking place simultaneously near the boundary of the synchronization regime of coupled chaotic oscillators. This phenomenon is found both in the numerical and physiological experiments. The laws for both the distribution and mean length of laminar phases versus the control parameter values are analytically deduced. A very good agreement between the theoretical results and simulation is shown.

Estimate of the degree of synchronization in the intermittent phase synchronization regime from a time series (model systems and neurophysiological data)

A method for determining the degree of synchronization of intermittent phase synchronization regime from a time series has been proposed on the basis of estimating the zero conditional Lyapunov exponent. The efficiency of the method has been tested on model systems near the boundary of the appearance of the synchronous regime. The method has been used to determine the degree of synchronization between various regions of the brain of rats of the WAG/Rij line having a genetic predisposition to epilepsy.

A discrete time model system with “intermittent” intermittency

A model system with discrete time is developed in which there are simultaneously two different types of intermittency: intermittency of type 1 and eyelet intermittency. Statistical characteristics for this type of behavior have been found. The calculation data are compared to the derived theoretical regularities. A good agreement between analytical and numerical results is obtained.

Theoretical and numerical investigation of “intermittent” intermittency in coupled chaotic systems

The behavior of a chaotic system is theoretically described that simultaneously exhibits type-I intermittency and ring intermittency. The theory, as applied to a system of two unidirectionally coupled chaotic Rössler oscillators, shows good agreement with the results of numerical simulations.

Studying the behavior of a nonautonomous Van der Pol oscillator in different time scales with the presence of noise near the synchronization boundary

A new level of organization of the temporal behavior of two coupled complex systems is revealed. We report for the first time the coexistence of two types of intermittent behavior that occurs simultaneously near the boundary of the synchronization regime of coupled chaotic oscillators. This intricate phenomenon was observed both experimentally in a physiological experiment and numerically. The laws for both the distribution and the mean length of the laminar phases versus the control parameter values are analytically deduced. Very good agreement between the theoretical results and the numerically calculated data is shown.

Method for separating laminar and turbulent intervals in intermittent time series of systems near the phase synchronization boundary

A new method is proposed for separating the intervals of synchronous (laminar) and asynchronous (turbulent) behavior in intermittent time series of coupled chaotic systems occurring near the boundary of the phase synchronization regime. Using this method, it is possible to determine the durations of turbulent and laminar intervals, which are necessary for an analysis of the statistical characteristics of a given dynamical system. The proposed approach directly employs the instantaneous phases of chaotic signals and provides exact values of the durations of turbulent and laminar intervals in the system behavior. The validity of the new method is verified by a comparison of the results to analogous data obtained previously, which shows their good agreement.

Recognition of neural brain activity patterns correlated with complex motor activity

In this paper, based on the apparatus of artificial neural networks, a technique for recognizing and classifying patterns corresponding to imaginary movements on electroencephalograms (EEGs) obtained from a group of untrained subjects was developed. The works on the selection of the optimal type, topology, training algorithms and neural network parameters were carried out from the point of view of the most accurate and fast recognition and classification of patterns on multi-channel EEGs associated with the imagination of movements. The influence of the number and choice of the analyzed channels of a multichannel EEG on the quality of recognition of imaginary movements was also studied, and optimal configurations of electrode arrangements were obtained. The effect of pre-processing of EEG signals is analyzed from the point of view of improving the accuracy of recognition of imaginary movements.

Analysis of psycho-physiological features of a subject in simple tests with the registration of electroencephalograms

In this paper we found a correlation between the characteristics of a person revealed in classical psychological testing on the basis of Schulte tables, and its neurophysiological features of the functioning of the brain obtained from the time-frequency analysis of EEG. The results obtained are interesting from the point of view of the choice of training strategies for a particular individual. We believe that the obtained results are of interest for fundamental science and applied works of psychological testing and diagnostics. The study of such forming strategies on EEG data can be automated and do not require the work of highly skilled psychologists.

The study of human higher mental functions as they relate to neurophysiological processes and personal characteristics

In this paper we study the correlation between the neurophysiological processes and personal characteristics arising in the processes of human higher mental functions. We find that the activity of the brain correlates with the results of psychological tests (according to the Cattell test). Experimental studies and math processing are described for operation design with the registration of human multi-channel EEG data in two phases (the processes of passive wakefulness (background) and special psychological testing (active phase)).

Synchronization of infra-slow oscillations of brain potentials with respiration

We study the synchronization of infra-slow oscillations in human scalp electroencephalogram signal with the respiratory signal. For the cases of paced respiration with a fixed frequency and linearly increasing frequency, we reveal the phase and frequency locking of infra-slow oscillations of brain potentials by respiration. It is shown that for different brain areas, the infra-slow oscillations and respiration can exhibit synchronous regimes of different orders.