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Evoked cortical activity in response to acoustic stimuli (oddball paradigm) was studied in patients with different paranoid disorders. The analysis covered the N150 negative wave and positive complex P300. In patients with paranoid schizophrenia and paranoid form of involutional psychosis cortical responses to the stimuli and cortex effects were not recorded. Such cognitive deficiency is believed to be typical for schizophrenia.

The interstimulus intervals (10, 60 and 180 ms) discrimination were studied in psychopaths and subjects with psychopathic features (accentuated individualities after Leonard). Event related potentials to visual stimuli (successively presented strips with above mentioned intervals) were recorded. Essential intergroup differences were found in the cognitive performance and its dynamics. The deterioration of cognitive processes, learning deficiency and P300 decrease manifested by psychopaths allow to propose the existence of inherent or acquired pathology of the limbic brain, a key structure of the motivational and emotional behaviour.

In the excitable psychopaths and persons with some psychopathic traits (Leonard's "accentuated personality") the study was made of a cognitive function of discriminating microintervals and event-related potentials to visual stimuli. A qualitative difference in the accomplishment of the cognitive task between the two groups was found. Disturbances of the cognitive function, learning deficiency and reduction of the P300 wave provide grounds for referring this ""antisocial personality disorder" to pathology of the limbic system of the brain.

Two groups of schizophrenics with negative and positive syndromes were studied by registering cortical evoked potentials in response to acoustic stimuli of different meaning (odd-ball paradigm). Disfunction of selective attention is related to the impaired ability to differentiate relevant and irrelevant information. Disturbances of information selection were more pronounced in the patients with paranoid schizophrenia.

The formation of late evoked cortical responses, N150 and P300, correlates with some factors determining cognitive activity (selective attention, different types of memory, decision making process). Influence of different significance stimuli in a particular situation results in creation of an integral "psychonervous image" reflecting a context of these stimuli, whole complex of cognitive tasks to be solved. It influences significantly on the magnitude of cortical evoked reactions to different stimuli that allows to make a correspondence with the "psychological set" phenomenon and its role in the evaluation of the perceived stimuli.

Excitable psychopathic personalities manifest qualitative and quantitative disorders of cognitive activity directly unrelated to emotional reactions. If the result of the activity is estimated by some other person with the aid of positive and negative reinforcement stimuli, deficit of the training is marked to a much greater degree than in cases where the excitable personality itself draws, on the basis of information available in the feedback stimulus, the conclusion whether its decision was right or erroneous.

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.

Music as a factor of creating a certain emotional state, may be used for studying neurophysiological bases of human positive emotions. Investigations of conservatory students and people without special musical education have shown that music exerts complex influences on the CNS, manifested in changes of a number of neurophysiological reactions attesting changes in the flow of excitations in the cortico-thalamic and cortico-limbic circles. Listening to music is accompanied with a partial replacement of the dominating alpha-rhythm by activity in the frequency range of beta-, theta- and delta-waves and with a change of some vegetative reactions. It was possible to define some qualitative differences in the action of music on the CNS depending on the interpretation of the composition as well as the presence or absence of musical education of the listeners.

In elderly people, in comparison with the young ones, the latency of wave P300 is increased in response to all applied acoustic signals, the amplitude of P300 is lower only in response to significant stimuli. No age changes of the wave N150 parameters are noticed. P300 (or N150) wave amplitude depends on signal significance of the sound; it is the lowest in response to significant stimuli and the highest to the ignored ones. Possible reasons of this paradoxical phenomenon are discussed. Preferential participation of different stages of cortical information processing is determined by the difficulty of perceptive task solution. Cortical electrical reaction to separate stimuli is significantly determined by the context of the information perceived in the given period, creating psychological state of the personality.

An experimental study of individuals with late sequelae of closed cerebrocranial trauma, demonstrated that diverse signs of CNS activity to a different extent may be under the influence of small doses of alcohol. For instance, the sensorial process does not change significantly, which may indicate a relative independence of specific sensorial pathways (including the cortical area) from small doses of alcohol. Changes in cortical electro-activity and the threshold of the orientation reflex, the mechanisms of which are connected with the function of the brain stem reticular formation, points to an inhibitory action of alcohol on it. Against the background of alcoholic influence the socially significant emotionally negative stimula intensify emotional stress, the action of which is related to the activity of the limbic system structures and a weakening of the function of associative cortical fields. The results of this study permit to assume that different functional-structural mechanisms may lie at the basis of an emotional background (mood) and emotional stress.

Reaction time was recorded in adult healthy people at pauses of 80, 110, 150, 200, 300, 500 and 800 ms between the warning and the triggering stimuli. The warning signal determined the choice of reaction. The stimuli were presented to different halves of the visual field at random. 200 ms pause between the warning and the triggering stimuli is critical for the reaction time. Beginning with this interval, the reaction time was considerably reduced. When information from the triggering stimulus reached "directly" the hemisphere which was "to produce" the motor response, reaction time was considerably shorter, than at non-coincidence of these two factors. The influence of their combination on reaction time is particularly pronounced at 150-500 ms pauses between the warning and the triggering stimuli. The data obtained suggest that the decision making results in a lateralized activation of the hemisphere, which is "to produce" the motor reaction. As a rule, reaction time is not influenced by spatial location of the warning signal. The results of the work should be taken into account when organizing activity of an operator.

Recognition of short time intervals (10, 60, and 180 ms) between visual stimuli presented to the left or right hemisphere was studied in adult healthy people. The interval of 180 ms is recognized better than that of 10 or 60 ms. Learning with repeated tests with 180 ms intervals proceeds better than that with short intervals. The predominance of the left hemisphere has been revealed only for perception of 10 ms interval. The other time intervals asymmetry is not observed. It is suggested that the left hemisphere is predominant in estimation of short (less than 60 ms) time intervals. In formation of time nervous model a significant role is played by local activation of the cortical zone where the standard stimulus is addressed.

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.

Adult healthy subjects did not manifest any difference in latency and amplitude of the wave P300 elicited by a positive ("good") and negative ("error") reinforcing stimuli. After the negative reinforcement, the P300 wave amplitude decreases in response to the standard stimulus (light bars) and increases to a lesser degree in response to test stimuli (the same bars but presented with different pauses). In the processes of learning to assess time microintervals in comparison with the standard, the latency of wave P300 to the test stimuli shortens. It is suggested that formation and consolidation of feedback connection elaborated with the participation of a reinforcing verbal stimulus constitute the physiological basis for learning of comparative assessment of time microintervals.

Influence of music on motor reaction time (RT) was studied. Warning and triggering stimuli were presented either in the left or in the right visual fields. RT was recorded when playing classical or variety music; control sessions were not accompanied by music. Music shortened RT, and its stimulating effect was the stronger the longer were the initial RTs without music. The influence of variety music was more effective than of the classic one. RT was shortened more when the triggering stimulus was presented in the left visual field. This phenomenon is considered to be an evidence of predominant influence of music on the right cerebral hemisphere due to greater activation from emotional structures.

The study was made on healthy adult subjects. The reaction time of the hand (RT) was measured under two conditions: 1) the choice of reaction (right or left hand) is determined by the nature of the warning stimulus; 2) decision on the choice is taken, depending on the second, trigger stimulus. Stimuli are presented at random sequences to different visual fields. The reaction time to the visual signal presented to the visual field ipsilateral to the hand is significantly shorter (by 15 to 26 msec) than to the stimulus in the contralateral visual field. In a simple motor reaction, when no discrimination of trigger stimulus and the decision on the choice of reaction is required, a hemispheric asymmetry of reaction time is manifested: the left hemisphere only responds differently to direct visual stimulation and to that mediated through the contralateral hemisphere.

The dynamics of the cortical evoked activity in the process of learning of time microintervals (10, 60 and 180 ms) discrimination was studied in healthy adults. Feedback stimulus visually informing of the real correlations of the differentiated pauses facilitates the discrimination. The factor of the visual field does not affect the estimation of brief time intervals. At correct identifications, the P300 wave is recorded with a higher amplitude, than at errors. In the trial following the "nonconfirming" feedback stimulus, the standard and test stimuli evoke in the left hemisphere a greater P300 wave, than in the trial after the "confirming" stimulus. Feedback influence is retained in the long-term memory.

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.