[EEG Beta and Gamma Powers When Comparing Certain Psychophysiological States with Normal and Weakened Electromyogram of Facial Muscles.]

The aim of the present study was to investigate EMG contamination on high-frequency scalp electroencephalogram (EEG) during comparisons of certain cognitive tasks performance. 19 healthy women who performed similar test tasks before and after cosmetic injections of Dysport in various face regions for reduction of facial muscles activity took part in the study. The test tasks were focused on induction of emotional states with different valences, on memory storing and extraction of verbal information. Default state of rest was uncluded too. During performance of the tasks, parallel registrations of EEG from a scalp surface(19 channels) and EMG from several facial muscles (6 channels) were carried out. Changes of spectral power in ß2 and low γ frequency ranges (18-40 Hz) in EEG- and EMG-derivations after Dysport injections were analyzed. Changes of spectral power in the same derivations during comparisons of the different test tasks were analyzed before and after Dysport injections separately. It was demonstrated that Dysport injections lead to reduction of EMG power in regions of injections and to reduction of EEG power in frontal and temporal derivations. However, the EEG-correlates revealed when comparing different test tasks remain qualitatively invariable both after, and before Disports injections. These facts confirmed that EMG makes a noticeable contribution to the electric activity registered from a scalp in the frequency ranges more than 18-Hz. At the same time, it was shown that in certain experimental situations influence of EMG not necessarily interferes with identification of EEG-correlates of mental activity during EEG registration from a head surface in ß2 and low γ frequency ranges.

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.

Current methodology and methods in psychophysiological studies of creative thinking.

Important points on methodology and detailed description of methods used in polymodal psychophysiological studies of human verbal creative thinking are presented. The psychophysiological studies were conducted with healthy volunteers during implementations of specially developed and adapted psychological tests aimed to bring the subjects into states of verbal creative thinking. Four different task sets ("story composition", "associative chains", "original definitions", "proverb sense flipping") were developed and applied. Positron emission tomography of regional cerebral blood flow (rCBF) and state-related quantitative electroencephalography (power and coherence evaluated) were used. The effectiveness of the methods is illustrated with figures.