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Biomedical subjects

A M Ivanitskiĭ

Publications and source records attributed to A M Ivanitskiĭ.

At least 19 recordsLinked to original sources
PubMed1997

[Use of artificial neural networks in recognition of types of thinking by EEG].

Reflection in EEG parameters of the process of solving two types of mental tasks, i.e. spatial-imaginary and verbal-logical, was investigated in nine test-subjects. Mental efforts were found to specify EEG spatiofrequency patterns depending on the task type and subject's identity. These patterns were unique and reproducible enough to enable identification of this or the other type of mental task within several seconds of EEG record. Recognition was executed with the use of an artificial neural network algorithm in order to simultaneously weigh a wealth of signs of a specific EEG pattern. Recognition precision was 85% on the average.

Adult↗
PubMed1984

[Effect of vasopressin on long-term memory (psychophysiological and clinical aspects)].

In chronic alcoholic patients with reduced ability for memorizing, lysin-vasopressin (LVP) exerts an obvious positive effect upon the involuntary long-term memory. The effect is more obvious in tests demanding a semantic processing of information rather than the automatic memorizing. Under the LVP effect, an enhancement of the alpha-rhythm synchronization occurs in the EEG. The maximal "inhibitory" effect of the LVP occurs against background of desynchronization with an initial increased level of unspecific ascending influences. The LVP rises the upper limit of the response in the form of the EEG rhythms rearrangement, i. e. it increases the lability of cerebral structures. In conditioning therapy of chronic alcoholism the LVP increases the negative reflex to ethanol formed on the basis of apomorphine. The data obtained reveal an essential acceleration and increased durability of conditioning to ethanol as the result of the LVP use.

Adult↗
PubMed1982

[Evoked negative cortical wave as a reflection of selective attention].

The study is devoted to the negative wave which sets in the cerebral cortex in response to a significant stimulus. Such negativity may be detected by way of subtracting from the amplitude of the EP to the significant stimulus of the amplitude of the EP to a less significant one. It was found that the negativity consists of two components: the first one, with a peak latency of 140 ms, is most pronounced in the analyser projection zone; it may be recorded during both voluntary and involuntary attention and is apparently due to selective activation of the cortex by the ascending thalamocortical system. The second peak, with a latency of 200 ms, is diffusely spread over the cortex and is recorded only during voluntary attention; it may be caused by activation of the cortex by the mesencephalic reticular formation.

Attention↗
PubMed1976

[Mechanisms of disorders in the assessment of external signals in psychopathies].

The author discusses some results of studies in evoked brain potentials of excitative and inhibitive psychopathic personalities. The evoked brain potentials to signal significant stimula in psychopaties are changed these changes being different in the groups of excitative and inhibitive psychopaths. In psychopathic personalities the amplitude changes to a significant stimula, not so much of the late but of the early components of response. The changes of early waves in the excitative and inhibited groups are differently directed. It can be supposed that these changes reflect the disturbances in the informational brain processes in psychopathic personalities which can be most distinctly seen in emotionally significant situation.

Antisocial Personality Disorder↗
PubMedDate not supplied

[Brain physiology and origin of the human subjective experience].

The modern approaches to the problem of the brain basis of subjective experience are reviewed in the paper. The main hypothesis proposes that the events of subjective experience emerge as a result of information comparison and synthesis in crucial for this mental function cortical areas. This synthesis is provided by the special organization of brain processes which includes circulation of nerve impulses in the brain structures. Memory traces are retrieved during this process, and then the appropriate centers of motivations and emotions are activated. Afterwards, the excitation returns to the sites of initial projections, where the synthesis of new information and that retrieved from memory is performed. The hypothesis has been proposed by the author more than twenty years ago and is based on the experimental study of the brain mechanisms of sensation and thinking. It is also shown that the frontal cortex and, particularly, the verbal centers are involved in recognition and decision making. The last part of the paper deals with the problem of the functional significance of subjective events. The possible double bottom-up and top-down determination of brain and mental events is considered and the importance of the search for experimental approaches to these problems is argued.

Brain↗
PubMedDate not supplied

[The cortical interactions in short time intervals during the search for verbal associations].

Cortical connectivity was studied in tasks of generating the use of words in comparison with reading aloud the same words. These tasks were used earlier in PET and high-density ERP recording studies, which described both the functional anatomy and time course of involvement of cortical areas in word processing. We developed a new method for studying the synchrony of EEG spectral components within the short time intervals compatible with the duration of particular cognitive operations. The wavelet transform of the ERP records and calculation of correlations between the wavelet curves were used to reveal connections between cortical areas. Three stages of intracortical communications developing over the course of task performance were discovered: between the right and left frontal areas (0-200 ms after the stimulus presentation), between the left frontal and left posterior temporo-parietal areas (250-500 ms), and, finally, between the left temporal and right fronto-centro-temporal areas. These findings are in good agreement with the results of the previous PET and ERP studies and supplement them with the circuitry of cortical information transfer. Also, they suggest some differences in information processing during automated reading and performance of more complicated use-generation task.

Adolescent↗
PubMedDate not supplied

[The mapping of brain biopotentials during the solving of a verbal task].

Reverse averaging of cortical potentials from the moment of the motor response followed the verbal task solving (anagram riddle) revealed some brain potentials correlations with the process of a decision making. In the case of task solving the negative frontal wave with the latency 900-400 ms from the motor response was recorded. Intracortical interaction mapping of this potential showed the regular patterns of cortical functional connections in different frequency ranges (alpha, beta). Successful solving of the task was characterized with predominant interaction foci topography in the frontal and left-temporal cortical areas in alpha band and parietal zones in beta. The absence of the task solution was characterized with the parieto-occipital interaction foci in alpha band and their frontal localization in beta.

Adolescent↗
PubMedDate not supplied

[Selective attention and memory: evoked potentials in visual and auditory verbal competition].

The brain mechanisms of the selective verbal attention were studied using evoked potential (EP) technique. It was shown that the late "cognitive" EP components (400-800 ms) related to memory function were more positive to the words presented via a relevant sensory channel and more negative to irrelevant words. The hypothesis is advanced that words delivered via two competing sensory channels, such as visual and auditory, are perceived, i.e., the subject sees and hears them. However, irrelevant signals are not stored in episodic memory due to the active inhibition of the information transmission to the hippocampal structures.

Adult↗