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T N Vazhnova

Publications and source records attributed to T N Vazhnova.

16 recordsLinked to original sources
PubMed1994

[The psychophysiological criteria for assessing the excitable type of psychopathy].

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.

Adult↗
PubMed1991

[Relation between cognitive activity of excitable psychopathic personalities and the pattern of reinforcement].

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.

Adult↗
PubMed1980

[Reflection of disorders in the choice process reaction in cortical evoked activity of oligophrenic patients].

Evoked cortical potentials (the late positive component P 300) were registered in situations of differentiating visual stimula and deciding on selecting motor reactions in oligophrenic patients (12 cases) and normals (17 cases). The patients demonstrated disturbances in the process of selecting the reaction, which may be expressed in evoked cortical electrical activity: the amplitude of the component P 300 in the vertex to a stimula, related to selecting reactions, is not increased. An assumption is made that oligophrenic patients show no focal cortical activation in the anterior cortical areas in situations, requiring selection of motor reactions.

Adolescent↗
PubMedDate not supplied

[Reflection of the decision making process in evoked cortical electrical activity in man].

Averaged evoked potentials to visual stimuli of different significance were recorded in healthy adult subjects. The magnitude of the late positive potential (component P300), recorded in response to visual stimulus, greatly increases at the vertex, if the stimulus is given a significance for decision making (the choice of reaction). No such changes are recorded in the occipital area. In the case of decision making, the magnitude of the component P300 is clearly greater at the vertex as compared with the occipital area. No correlation has been found between the latency of the P300 and the reaction time, hence one should not refer to any coincidence between the temporal parameters of the potential and the process of decision making. The authors believe that the component P300 reflects not the very process of decision making, but a local cortical "non-specific" activation which is an indispensable element of the neural mechanism of decision making.

Adolescent↗
PubMedDate not supplied

[Hemispheric lateralization of the visual-spatial function in chronic alcoholic intoxication in humans].

A series of behavioural and electrophysiological parameters was recorded in subjects with chronic alcohol intoxication during solving of visual-spatial nonverbalized task. It is shown that in comparison with the healthy subjects, their reaction time (RT) of correct decisions was increased; it was more expressed when stimuli were presented in the left visual field, i.e., directly to the right hemisphere, and the number of correct reactions decreased at stimuli presentation directly to the left hemisphere. During repeated tests there were no changes in the number of correct reactions and RT value in the group with chronic alcohol intoxication. It is found that long-term taking of alcohol produces an increase of latency and decrease of the amplitude of the late positive wave P300, more pronounced in the right cerebral hemisphere.

Adult↗
PubMedDate not supplied

[The discrimination of time microintervals by emotionally excitable personalities].

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.

Adult↗
PubMedDate not supplied

[Hemispheric lateralization of visuo-spatial function in man].

Two parts of a geometrical figure are consecutively presented to healthy adult subjects in the left and right visual fields; the subjects have to compare them mentally and to decide whether these parts form a standard figure or not. Correctness of the reaction is controlled by a computer which lights up on the screen the words "good" or "error". The number of correct decisions of this visual-spatial task does not depend on the hemisphere to which information is addressed. The reaction time is substantially shorter if the information comes "directly" to the right hemisphere. Due to better training in the left hemisphere interhemispheric difference in reaction time gradually disappears in repeated tests. Training to mental "constructing" takes place only in the tests following positive feedback stimulus. Analysis of amplitude-temporal parameters of P300 wave shows that at correct decision of the visual-spatial task the level of activation in the right hemisphere is higher than in the left one.

Adult↗
PubMedDate not supplied

[Lateralization of perception of short time intervals and cortical evoked activity in man].

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.

Adult↗
PubMedDate not supplied

[Effect of verbal reinforcement on evoked cortical activity].

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.

Adult↗
PubMedDate not supplied

[Psychophysiological criteria for assessing psychopathy].

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.

Adult↗