[Violation of Assessing the Salience of Information in Schizophrenia].

The history of study of schizophrenia has more than 100 years. During all this period there was collected a lot of data on clinical picture of the disease, psychological peculiarities of patients, biochemical and electrophysiological phenomena. In this respect it becomes actual nowadays to look for a concept that could combine different levels of schizophrenia research (clinical, biochemical, social, etc.) and explain relationships with various symptoms of the disease. In this article we analyze experimental psychological data on thinking of patients, instrumental studies (ERP fMRI, rhythmic patterns of thinking, dopamine theory) and their relationship with clinical implications. It is shown that all these data complement each other and allow us to tell about a basic violation in schizophrenia--the difficulty of patients to differentiate between more and less salient information. We can observe the violation on different levels of schizophrenia investigation and explain different symptoms of the disease as manifestations of that basic violation.

[High Variability of Rhythmic EEG Patterns, Intrinsic for Different Type of Thinking in Schizophrenia Patients].

It has been shown in the previously performed experiments that it is possible to "recognize" by the EEG data the type of thinking and to know what kind of task (spatial or verbal-logical) is solving currently. This article describes the application of this technology to the study of schizophrenia patients..We obtained data about the essential difficulty of such recognition in schizophrenia patients, correlation of these difficulties with the severity of negative symptoms. It is shown that the'difficulty of recognition is associated with higher variability of rhythmic EEG patterns, intrinsic for particular type of thinking.

[Cognitive brain­Computer interface and probable aspects of its practical application].

A new type of brain-computer interface was elaborated. It considers a variety of brain activity parameters to determine the type of mental operation being performed at the moment. The corresponding algorithm previously developed in the lab was modified for real-time application. The possibility of interface application for cognitive skills training was investigated. In the proposed paradigm, as soon as the EEG spectral pattern was adequate for the current task, some clue to the solution was presented. As we supposed, such positive biofeedback should facilitate memorization of the current brain state. After just one learning session, the differences in EEG spectra, corresponding two types of tasks, were concentrated in more narrow frequency ranges. It indicates the decrease of mental effort. Moreover, the majority of subjects succeeded to solve the tasks faster, that's an evidence of efficiency increased. The developed interface could be used for the new type of training, based on objective features of brain activity.

[Central EEG rhythm associated with movement and EEG rhythm associated with spatial reasoning: are they homologous?].

EEG rhythmical picture of subject's movement suppression and spatial-figurative task solving was examined and analyzed. Rhythms appearing during spatial reasoning and suppressed movements with the frequency of about 11 Hz were isolated. It was hypothesized that a functional link exists between these rhythms in the considered behavioral tests. To test the hypothesis and to reveal this connection, experiments were developed and carried out. Then the analysis of recorded EEG signals was conducted by applying Fourier transform, independent component analysis (ICA) and equivalent dipole source localization. Unexpected conclusion about the existence of a general mechanism of movement suppression was drawn.

Correlation of brain rhythms between frontal and left temporal (Wernicke's) cortical areas during verbal thinking.

The aim of this study was to investigate an interaction between frontal and left temporo-parietal cortices in tasks requiring word association. A new method was used to examine averaged event-related potentials in different frequency bands by calculating correlation coefficients between wavelet curves in distant cortical areas. This method was applied to previous event-related potentials recordings which found successive activation of frontal and left posterior areas [1]. Correlated activity at 17 Hz was observed between frontal and left temporal (Wernicke's) areas prior to full activation of Wernicke's area.

Cortical connectivity during word association search.

Cortical connectivity was studied in tasks of generating the use of words in comparison with reading aloud the same words. These tasks were used earlier in PET and high density ERP recordings studies (Posner and Raichle, 1997; Abdullaev and Posner, 1998), in which both the functional anatomy and the time course of cortical areas involved in word processing were described. The wavelet transforms of ERP records and the calculation of correlations between wavelet curves were used to reveal connections between cortical areas. Three stages of intracortical communications while task performance were found. These were: (1) the connections between right and left frontal and central areas which preceded stimulus delivery and persisted up to 180 ms after it; (2) the network connecting right and left frontal with left posterior temporal-parietal junction at 280-450 ms; and (3) communications between left and right temporal zones in 550-800 ms. The data are in good agreement with results of previous PET and ERP studies and supply the earlier findings with circuitry of cortical information transfer.