[Changes in the late components of evoked cortical potentials during the human solving of a visual-spatial task]. / Izmeneniia pozdnykh komponentov vyzvannykh korkovykh potentsialov pri reshenii chelovekom zritel'no-prostranstvennoi zadachi.

The ability of mental construction of easily verbalized geometric figures was studied in 20 healthy subjects by means of recording of the evoked potentials of the cerebral cortex. Fragments of geometric figures were presented with the intervals of 80 and 500 ms. To one half of the subjects the stimuli were presented unilaterally (both fragments to one and the same visual field, to the left or to the right one) and to the second half of the subjects--bilaterally (the first fragment--to one visual field and the second one--to the other). It was established that the latency of the wave P300 was shorter and the amplitude--greater at correct decisions of the visual-spatial task than at false ones, both at unilateral and bilateral fragments presentation. At a great interval (500 ms), when the effects of masking became significantly weaker, a predominant activation of the left hemisphere was observed: the latency of the late components was shorter and the amplitude--greater, when the information came "directly" to the left hemisphere. The obtained results testify once more to a great variability, dynamic interhemispheric relations, impossibility of connecting the realization of some functions with one of the hemispheres.

[The dependence of the dynamics of the extinction of a temporary connection on the recognizability of a reinforcing stimulus]. / Zavisimost' dinamiki ugashcheniia vremennoi sviazi ot osoznavaemosti podkrepliaiushchego stimula.

Dynamics was studied of the extinction of temporary connection, elaborated by means of motivationally significant word, in patients with chronic alcoholism. Two series of studies were conducted. In the first one the reinforcing stimulus was not recognized by the subject and was perceived as a dull light flash on the screen. In the second one the word was easily read, i.e. it was recognized. It was found that conditioned changes of P300 wave at the elaboration of temporary connection depend on the recognition of the reinforcing stimulus. Temporary connections, elaborated by non-recognized motivationally significant stimulus are considerably stronger that the connections, elaborated by means of recognized reinforcement.

[Lateralization of visuo-spatial function during masking in healthy subjects and in patients with chronic alcoholism]. / O lateralizatsii zritel'no-prostranstvennoi funktsii v usloviiakh maskirovki u zdorovykh lits i bol'nykh khronicheskim alkogolozmom.

In healthy subjects and patients with chronic alcoholism, the ability to construct in mind geometric figures in conditions of masking was studied by means of recording the number of correct decisions, the reaction time and evoked cortical electrical activity. It has been found that solution of visual-spatial task of mentally constructing geometric figures is accomplished better if a figure-standard can be formed from the presented fragments. During solution of the visual-spatial task in norm the reaction time is shorter if the information comes "directly" to the right hemisphere. Such interhemispheric differences are not observed at chronic alcoholic intoxication. In patients with chronic alcoholism the late components of EPs N200 and P300 developed with a longer latency and lesser amplitude than in healthy subjects. The greatest depression of cortical activity is observed in the right hemisphere.

[Dynamics of cortical evoked activity during human learning to discriminate microintervals of time using feedback]. / Dinamika korkovoi vyzvannoi aktivnosti v protsesse obucheniia cheloveka razlicheniiu mikrointervalov vremeni s pomoshch'iu obratnoi sviazi.

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.

[Effect of verbal reinforcement on evoked cortical activity]. / Vliianie slovesnogo podkrepleniia na vyzvannuiu korkovuiu aktivnost.

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.

[Lateralization of perception of short time intervals and cortical evoked activity in man]. / Lateralizatsiia vospriiatiia korotkikh intervalov vremeni i korkovaia vyzvannaia aktivnost' u cheloveka.

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.

[Elaboration of a conditioned reflex in chronic alcoholics using an unrecognizable motivationally significant word]. / Vyrabotka uslovnoi sviazi u bol'nykh khronicheskim alkogolizmom s pomoshch'iu neosoznavaemogo motivatsionno-znachimogo slova.

20 patients suffering from chronic alcoholism and 10 healthy, righthanded persons with normal sight were examined. Alcoholics were trained to elaborate a temporary connection by means of unrecognized significant word "vodka" related to their dominant motivation. The amplitude of the late positive response P300 was greater and its latency was shorter comparing with responses to neutral words. The latency of P300 potential to a conditioned stimulus combined with the word "vodka" is reduced in all recorded areas, especially in the left occipital zone. Healthy persons did not manifest this facilitation. The amplitude of the potential considerably decreased in all recorded areas (occipital, parieto-temporo-occipital and central) especially in the left hemisphere. Conditioned changes of the P300 wave during conditioning by means of the unrecognized stimulus are stable and do not extinct despite multiple signal presentations without pairing with the significant word. The formation of conditioned connections by means of unrecognized stimulus in patients suffering from chronic alcoholism suggests that a certain role in psychical dependence upon alcohol may be played by unrecognized stimuli.

[Effect of alcohol on interhemispheric functional relations]. / Vliianie alkogolia na mezhpolusharnye funktsional 'nye otnosheniia.

By means of backward masking, the time of perception of letter stimuli presented to the left and right visual fields, was determined in practically healthy persons who were given different doses of alcohol, and in patients with chronic alcoholism. Evoked electrical activity to the same stimuli was recorded in identical conditions. A small dose of alcohol (0.41 g/kg) increases in healthy subjects the time of perception of visual signals only if they are presented in the left visual field: a medium dose (0.82 g/kg) increases the time of stimuli perception in both halves of the visual field, but obviously more so in the left one, in patients with chronic alcoholism the time of perception is substantially longer in the left visual field. A small dose of alcohol does not affect evoked electrical cortical activity in healthy persons. Distinct regional differences are exhibited in the action of the medium dose of alcohol on the cerebral cortex of healthy persons. Evoked potential in the central area is depressed to a greater extent than in the visual and associative (Brodman field 37) zones. With chronic alcohol intoxication, evoked activity in the right hemisphere is depressed considerably more than in the left one.

[Interhemispheric interrelationships in oligophrenic patients]. / Osobennosti mezhpolusharnykh vzaimootnoshenii u bol'nykh oligofreniei.

The author registered evoked electrical activity from the right and left occipatal area in oligophrenic patients to letters and nonverba stimula presented unilateraly to different halves of the field of vision. For control purposes a group of normals was studied according to the same method. A hemispheric asymmetry seen in the group of normals was not detected in oligophrenic patients. It is assumed that this is one of the nervous mechanisms of declined intellectual activity.

[Asymmetry of visual perception]. / Asimmetriia zritel'nogo vospriiatiia.

In healthy adult subjects recognition was studied of geometrical figures presented unilaterally, and of separate letters presented unilaterally and dichoptically to the right and left visual fields. At near-threshold exposition, separate letters are better recognized in the right visual field, than in the left one, regardless of the method of presentation. There is no asymmetry in recognition of geometrical figures. In conditions of backward masking asymmetry of perception of separate letters is likewise observed, but they are better recognized in the left visual field. This suggests that the perception time of separate letters is shorter when they are addressed "directly" to the right hemisphere.

[Hemispheric asymetry of the evoked electrical activity of the cerebral cortex to letter and non-verbal stimuli]. / Polushernaia asimmetriia vyzvannoi élektricheskoi aktivnosti kory golovnogo mozga na bukvennye i neverbal'nye stimuly

Average evoked potentials (AEP) were recorded in practically healthy subjects to "meaningless" figures and letters, presented to different halves of the visual field. Analysis of the amplitudes of AEP late components to verbal and non-verbal stimuli reveals hemispheric asymmetry. A higher amplitude of the late positive evoked response (P300) to a "direct" stimulation both by verbal and non-verbal stimuli (in the contralateral field of vision) is recorded in the left hemisphere than in the right one. Similar stimulation of the right hemisphere does not reveal sucha difference. In the left hemisphere the P300 wave is of a clearly greater amplitude to a "direct" stimulation (contralateral visual field) than to an "indirect" one (ipsilateral visual field), regardless of the nature of the stimulus. No such difference is observed in the right hemisphere. The magnitude of the late negative wave (component N200) to non-verbal stimuli is greater in the right hemisphere both in response to "direct" and "indirect" stimulations. No intrahemispheric difference has been found in the amplitude of late evoked responses of the cerebral cortex to verbal and non-verbal stimuli.

[Hemispheric interaction in man during perception of visual stimuli]. / Mezhpolusharnoe vzaimodeistvie u cheloveka pri vospriiatii zritel'nykh stimulov

Averaged evoked potentials (AEP) to verbal (letters) and nonverbal (random shapes) stimuli exposed in the left and right visual fields were registered in healthy subjects with normal vision. Analysis of the later AEP latencies pointed to asymmetry in the temporal parameters of the interhemispheric interaction. The late AEP latency is shorter in the right hemisphere than in the left hemisphere. The difference is more pronounced in responses to nonverbal stimuli. The earlier development of the evoked potential in the right hemisphere (or the later one in the left hemisphere) accounts for the interhemispheric difference in the temporal parameters of the late AEP components. Comparison of the latency of the component P300 to verbal and nonverbal stimuli presented in the ipsilateral or the contralateral visual fields reveals a transfer of the results of the cortical processing of visual information in the course of interhemispheric interaction.