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The model of cognitive set to emotionally negative facial expression was used in the study (35 young healthy subjects) of EEG events in a 8-second interval between the target and triggering stimuli. Coherence of brain potentials recorded from different cortical areas of the right and left brain hemispheres in the alpha and theta bands was analyzed in time segments within pre- and poststimulus intervals. A certain dynamics in the spatial synchronization in the alpha-band was revealed, which might reflect modulation of selective attention in time periods of the cognitive process providing its plasticity and set shift in response to a change in the situation. It is suggested that the source of attention modulation is the inner representation of the intervals between significant stimuli formed in the prefrontal cortex as a result of learning. Analysis of changes in the spatial synchronization in the theta band at individual stages of the set to angry face suggests that the corticohippocampal system is not directly involved in the time interval estimation but is linked to the emotional memory.

We used the experimental model of cognitive visual set, designed by D.N. Uznadze, to study the influence of previous experience on emotional face expression recognition in pre-school (6.1 +/- 0.3 years) and elementary school (10.5 +/- 0.1 years) children. Our results suggest that the ability to form a cognitive set to an angry face expression develops in ontogenesis in strong concordance with functional maturation of prefrontal cortex that takes place at the age of approximately 10 years. At this age children display almost the same level of set plasticity and a similar kind of erroneous perceptions during set actualization as grown-ups. Children of younger age (6.1 +/- 0.3 years) display more perceverative erroneous perceptions, or assimilative illusions (probably of a priming origin), than the above mentioned groups. We consider this to be a result of a more strong influence of previous experience in their case.

Coherence functions in cortical electrical potentials in the theta (4-7 Hz) and alpha ranges (8-13 Hz) recorded during the formation and testing stages of a visual set to facial images bearing an emotional expression (an angry face) were studied in healthy adult subjects (n = 35). Differences in the spatial synchronization between theta and alpha potentials were seen, especially in rigid forms of the set, in which cases of erroneous perception of facial expressions were seen with contrast and assimilative illusions. This group of subjects (n = 23) showed increases in theta potentials between the dorsolateral areas of the frontal cortex (the orbitofrontal cortex) and the temporal area in the right hemisphere. A mechanism is proposed for the development of visual illusions. Analysis of the coherence functions of cortical potentials in the theta and alpha ranges generates a "window" which can be used to study the operation of the two functional systems integrating brain activity, i.e., the corticohippocampal and frontothalamic, in the perception of a facial expression. The frontothalamic system is associated with more diffuse types of cortical activation, especially in its anterior areas. The theta rhythm system evidently facilitates integration of the frontal cortex with the temporal area in the right hemisphere and the connections of the latter with the parietal and central zones in both hemispheres.

EEG coherence in the alpha and theta bands during set formation and testing was studied in healthy adult subjects (n = 35). The set was formed to pictures of faces with a negative emotional expression (an angry face). Different patterns of the EEG spatial synchronization were revealed for the theta and alpha bands, especially, in subjects who formed the rigid set (erroneous perception of the facial expression in the form of contrast and assimilative illusions). An increase in coherence in the theta band was observed in subjects of this group (n = 23) between the dorsolateral frontal and temporal regions of the right hemisphere. A neural mechanism underlying the visual illusions was suggested. Analysis of the EEG coherence in the theta and alpha bands makes it possible to obtain the "windows" for the insight into operation of the cortico-hippocampal and fronto-thalamic functional systems of the integrative brain activity and involvement of these systems in perception of facial expression. The fronto-thalamic system is involved in a more generalized activation of the brain cortex, especially of its frontal regions. The theta rhythm system seems to facilitate the integration of the frontal and temporal cortices of the right hemisphere and association of the right temporal region with the parietal and central regions of both hemispheres.

Effect of previous experience on the function of recognition of emotional facial expression was studied with the model of an unconscious visual set. It was found that repeated perception of pictures of face with angry expression caused a substantial effect on subsequent recognition of emotional facial expression. Recognition could be distorted, and expression of the face with "neutral" expression could be erroneously perceived as emotionally negative. Both contrast and assimilative illusions were observed. Evidence is presented that the described effect is the result of the set formation to emotional facial expression. The involvement of the prefrontal cortex into the structural-functional system of facial expression recognition is discussed. Kettel's test revealed significant correlations between the factor of rigidity of the set to emotional facial expression and the scores of personality traits such as social boldness--shyness on the H Scale, on the one hand, and the level of anxiety on the other.

Evoked cortical potentials in response to conditioned visual stimuli were recorded in excitable psychopathic personalities in the course of formation and reproduction of temporary relations with a realized or non-realized emotional word. Diazepam (10 mg intramuscularly) suppresses cortical reaction worked out previously with the aid of a realized emotional word and fails to produce and action if that word was non-realized. The fact of the lack of the diazepam effect on conditioned emotional reactions formed at the non-realized level should be taken into consideration in the treatment of patients with disturbances in the emotional sphere.

A number of experiments shows that the character of human cortical response to a conditioned stimulus is to a considerable degree determined by properties and significance of the second stimulus in the combined pair. In a combination of two stimuli differently expressed depression of cortical response to the first stimulus takes place. If the "reinforcing" stimulus is emotionally significant and is recognized then the changes of evoked cortical activity in response to conditioned stimulus are complex and of different signs; they result from simultaneous action on cortical structures of both inhibitory and activating "nonspecific" influences. In this case the facilitation of the cortical response is revealed by comparison with the tests of indifferent stimulus before pairing or with tests where association between two indifferent stimuli is formed. A considerable increase of evoked response after elimination of the "reinforcing" emotional stimulus testifies that this facilitation is merely relative, and along with activating influence via feedback has an inhibitory action on cortical structures which perceive the conditioned stimulus.

The influence of seduxen (diazepam) on cortical potentials P300 evoked by neutral and emotional words was studied in adult subjects having life conflicts. The therapeutic dose of seduxen (10 mg) had no significant effect on the amplitude of the late positive cortical response P300 to neutral words. Seduxen depresses the emotional activation of the cerebral cortex; that is manifested in selective elimination of those changes in latency and amplitude of P300 wave which are observed in response to emotionally significant words. Under the action of seduxen, the interhemispheric difference in the latency of cortical response disappears due to latency increase in the right hemisphere.

The P300 component of the evoked potential was recorded over both hemispheres in order to study interhemispheric differences in the process of perception of subliminal verbal stimuli. The stimuli--subliminal words, neutral and emotional--were presented at random to the left or right visual fields. In response to an unrecognized emotional word, the amplitude of P300 wave increased diffusely over both hemispheres as compared to that to a neutral word, with no changes in interhemispheric differences. The interhemispheric difference changed considerably in the presence of an 'unaccountable' emotion caused by a subliminal word. This suggests a unilateral activation of the right hemisphere and a predominant role of this hemisphere in the cortical organization of the unconscious function 'unaccountable' emotion.

The study was made on adult humans in a conflict situation. A combination of a non-verbal visual stimulus with an unrecognized emotional word substantially changes interhemispheric functional relations. The latency of the P300 potential in response to the first stimulus becomes reduced in the left occipital area. The potential amplitude considerably diminishes in all the recorded cortical areas (occipital, associative and central), but the reductions more pronounced in the left hemisphere. The nature of the P300 wave changes in response to the conditional stimulus is determined by psychophysiological properties of the "reinforcing" stimulus, in particular by its being non-recognized. Conditioned changes of the P300 wave in tests, where the "reinforcing" stimulus is not recognized, are very stable, and are not extinguished, despite repetitive presentation of the signal without combining it with the emotional word.

11 right-handed subjects with normal vision were examined. The analysis of latencies and amplitudes of the late AEP components elicited by verbal stimuli, presented in different halves of the visual field, revealed that the late positive evoked potential P300 to a single word with neutral meaning develops in the right occipital area with a shorter latency and a greater amplitude, than in the left one. Interhemispheric differences are not observed in "the associative" zone (presumably at the junction of the temporal, parietal and occipital areas). In the process of perception of an emotional word interhemispheric relations are considerably changed: in the left occipital area the P300 wave latency is considerably shorter, than in the right one; no differences in the amplitude of P300 are visible. The changes in P300 wave latencies reflect a local nonspecific activation of the cortex, directly connected with the analysis of the emotional verbal signal. The obliteration of interhemispheric differences in P300 wave amplitude is largely due to background emotional excitation.

The wave P300 was recorded in both hemispheres in order to study interhemispheric differences in the process of perception of unrecognized verbal stimuli. The stimuli--unrecognized words, neutral and emotional--were alternately presented at random in the left and right visual fields. In response to an unrecognized emotional word, the amplitude of the P300 wave increases diffusely in both hemispheres, as compared to the response to a neutral word, with no changes in interhemispheric differences. They change considerably in the process of an "unaccountable" emotion, caused by an unrecognized word, due to unilateral activation of the right hemisphere. The conclusion is made on the predominant role of the right hemisphere in the cortical organization of such unconscious function as "unaccountable" emotion.

Recordings of the P300 waves in left and right hemispheres in response to neutral and emotionally significant words corroborate the rightfulness of the principle stating that any psychic function, for instance emotion, is organized and controlled by means of a close and complementary collaboration of both hemispheres. A predominance of a hemisphere manifests itself in organizing a certain stage of the integral emotional function.

Function of time microintervals estimation was studied in emotionally excitable subjects (23 persons) as well as learning of this function by means of positive and negative reinforcements--words "good" and "error"--and interhemispheric relations. In excitable subjects, discerning is disturbed of short pauses between the visual stimuli, especially of 10 ms pause, presented in the right visual field. Deficit of learning of the intervals discerning is noted by reaction time parameter. There is no advantage of the left hemisphere in discerning the 10 ms pause from 60 ms, which is observed in healthy people.