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Z F Zvereva

Publications and source records attributed to Z F Zvereva.

17 recordsLinked to original sources
PubMed2003

[Evaluation of functional brain condition by EEG biopotential power asymmetry].

The fluctuations of functional brain condition level are evaluated by interhemispheric asymmetry of bioelectric activity power that is a consequence of both hemispheres interplay and involvement of nonspecific brain system in this process. Using neurological examination and electroencephalography, functional CNS condition analysis in patients with chronic brain ischemia and healthy controls was carried out. The results were compared to the indices of interhemispheric asymmetry of biopotential power (IHABP). Different functional CNS condition of both the patients and controls was characterized by different ratio of IHABP for fore- and back brain cortical regions. Controls exhibited a predominance of IHABP for frontal neocortex areas comparing to back ones. In the patients, the identical IHABP indices were detected for both neocortex areas.

Adolescent↗
PubMed2000

[Electrophysiological aspects of the indicators of hemispheric asymmetry during reparative processes in the brain after unilateral lesions].

The gears of the conjugate activity of hemispheres in the presence of damage in one were studied before and after removal of a tumor by using an interhemispheric asymmetry index. On left hemispheric exposure, the index decreased in the anterior brain regions having mainly morphofunctional connections with the activating structures of the stem. The posterior cortical regions changed the index on exposures of the right hemisphere or synchronizing stem structures. In an operated-on patients, the damaging action at any site reduced the index in the anterior cortical regions. Interhemispheric asymmetry of the posterior regions increased or unchanged with left hemispheric damage and decreased with right hemispheric one. These changes are interpreted as a reflection of compensatory rearrangements of interhemispheric interactions which are accomplished under the influence of the activating and synchronizing systems of the brain stem.

Adult↗
PubMed1995

[Interhemisphere bioelectric asymmetry in the process of recovery in dysfunctions of the brain after unilateral lesion].

The interhemispheric organization of brain electrical processes was shown to depend on the lateralization of an injury. The EEG asymmetry was significant with a tumor being in the right hemisphere as compared with that of healthy subjects. When a tumor was in the left hemisphere, the asymmetry was more considerable than that in healthy persons. An analysis of electrophysiological findings and clinical symptomatology makes the author to regard interhemispheric asymmetry as a significant index of the functional interactions of the hemispheres and the nature of a postoperative process.

Adult↗
PubMed1988

[Experimental validation of the use of an ultrasonic surgical instrument in neurophysiology].

The effect of ultrasonic and surgical instruments on nervous tissue in chronic experiments on the cats were investigated with electrophysiological and morphological methods. The authors compared the results of removal of the neocortex zones using ultrasonic and surgical instruments or routine methods. Electrophysiological and morphological studies have shown small injury effects made by ultrasonic and surgical instruments on the surrounding brain tissue.

Animals↗
PubMed1986

[Advantages of ultrasonic surgical instruments in experimental neurophysiology].

The effect of ultrasonic neurosurgical instruments on the functional state of the brain and its individual structures was studied to establish the most adequate and the least traumatic method of brain structures extirpation. Cortical zones were destroyed by ultrasound, thermocoagulated or extirpated. Parallel recordings of evoked potentials to single and paired stimuli were performed in adjacent neocortical areas. It was established that ultrasonic instruments permit the least traumatic extirpation of brain cortical zones.

Animals↗
PubMed1980

[Interhemispheric interactions following unilateral injury to the cerebral cortex].

The object of the study was to examine the time-course of interhemispheral relations under unilateral injury to the somatic or optical cortical pathways. Special attention was paid to the characteristics of the function of the associative parietal cortex and areas that are symmetrical to the location of injury. Transcallosal stimulation allows changing the functional condition of the studied zones. This can be considered as a possible factor inducing development of compensatory-rehabilitative processes in the central nervous system.

Animals↗
PubMed1980

[Effect of exclusion of projection (somatosensory and visual) areas of the brain on evoked potentials of the association (parietal) areas of the opposite hemisphere].

The method of evoked potentials was used in acute experiments on cats anesthetized with chloralose-nembutal to study the participation of the cortical associative areas in the recovery of disturbed functions of the brain after experimental injury to projection (somatosensory and visual) areas of the contralateral hemisphere. It was shown that temporal exclusion of the projection areas (somatic or visual) potentiates positive modification in the associative areas of the contralateral hemisphere, with the activity of the areas being considerably increased.

Animals↗
PubMedDate not supplied

[Asymmetry of power in the EEG rhythms as a parameter of the brain function].

Comparison of power asymmetry (PA) has shown that low PA values occurred in the posterior cortical parts in adult examinees free of focal brain pathology, in anterior and posterior cortical parts in children and in patients with affected left hemisphere. In view of immaturity of the brain and unbalanced subcortical-cortical relationships in children there was enhanced functional activity of diencephalo-truncal structures. It is suggested that in patients with damaged left hemisphere functional activity of the right hemisphere dominates, therefore dominates functional activity of synchronizing diencephalo-truncal structures. High interhemispheric asymmetry was detected in anterior parts of the cortex in patients free of focal brain pathology as well as in anterior and posterior parts of the neocortex in patients with damaged right hemisphere. This can be explained by prevalence of activating stem structures in brain functioning. Damage to the right hemisphere affects more synchronizing truncal structures and intact left hemisphere becomes leading in CNS activity. This hemisphere has primarily functional relations with activating stem structures. Thus, the value of interhemispheric asymmetry of EEG biopotentials' powers may characterize brain function forming in participation of nonspecific stem system regulating functional condition of the brain.

Adult↗
PubMedDate not supplied

[The electrophysiological characteristics of the compensatory and restorative processes in the central nervous system of neurosurgical patients in relation to the lateralization of the injury].

The authors studied the functional condition of the brain during the restorative period after operative damage to one of the hemispheres. In the early stages of the restorative period in neurosurgical patients with a slow rhythm afferent stimuli (rhythmic light stimulation) induced the appearance of a marked alpha-rhythm, which is evidence of restoration of the functional condition of the cortical and subcortical structures taking part in the generation of this rhythm. Such dynamic changes in the condition of the structures may be considered as a manifestation of their activation and evaluated as a favourable prognostic sign. Data were obtained which characterized the features of the restorative-compensatory process depending on which hemisphere, right or left, the damage was inflicted. According to the indices of the various rates of EEG, high-frequency waves of beta-range prevailed in the intact left hemisphere on the 12th-25th day; this phenomenon was not recorded in an intact right hemisphere in damage to the left hemisphere.

Adaptation, Physiological↗
PubMedDate not supplied

[Interaction between the projection (visual and somatic) zones of the cortex and the parietal association area after application of neurotropic drugs to them].

Recording of EPs and local application of strychnine and KCl on the associative parietal and projection (visual I, somatic I) neocortical areas of the cat under Nembutal anaesthesia, revealed distinct interaction of these structures. Their different mutual effects are being considered, depending on their modality and functional significance as well as on properties of the stimuli which activate the associative structures (the parietal cortex and the posterior lateral thalamic nucleus, LP). The data obtained confirm and develop the concept previously outlined by the authors on different types of interaction between the studied cortical areas, the ways of their realization at cortical and subcortical levels, and the specific role of LP in the process. The distinctions of joint activity of the projection areas from various types of their interaction with the parietal associative cortex are discussed.

Animals↗
PubMedDate not supplied

[Interhemispheric asymmetry in patients in the rehabilitation period after unilateral damage to the cerebral cortex].

The studies revealed that the level of interhemispheric bioelectric asymmetry, which reflects the functional relations between the hemispheres, is one of the major indices of the functional interaction of the two hemispheres. There were changes in interhemispheric asymmetry in relation to the tumor damage to the right or left hemisphere. The structural lesion of the left hemisphere did not appear to affect interhemispheric asymmetry, whereas right hemispheric dysfunction led to its significantly marked asymmetry, i. e. the mechanisms ensuring the stability and symmetry of electric activity of the two hemispheres are mainly associated with the structures of the right hemisphere.

Adult↗
PubMedDate not supplied

[Interhemispheric asymmetry in the anterior and posterior sections of in the normal human brain and in unilateral cortical damage].

The study of interhemispheric bioelectrical asymmetry (IBA) of the brain as a result of pair activity of the hemispheres has shown that in normal subjects IBA was greater in the frontal lobes than in the occipital ones. In patients with injured right hemisphere the asymmetry increased in the occipital lobes. In patients with injured left hemisphere the asymmetry diminished in the frontal lobes.

Adult↗