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Biomedical subjects

G N Boldyreva

Publications and source records attributed to G N Boldyreva.

At least 19 recordsLinked to original sources
PubMed1993

[The characteristics of epilepsy in left-handed people (a clinico-electroencephalographic study)].

As many as 16 epileptic patients with the sings of sinistrality in the motor and sensory spheres were examined. The authors demonstrate the clinical characteristics of epilepsy in the left handed, that distinguish them from the right-handed; dissimilarity of each psychopathological symptom and syndrome to their analogs in the right-handed, the occurrence of unusual phenomena, impossible in the right-handed. Depict specific features of the EEG that distinguish the patients examined from healthy right- and left-handed. The data obtained are interpreted as evidence that the clinical characteristics and the EEG appearance of epilepsy are determined to a considerable measure by the profile of asymmetry of each patient as well as by the fact that the left-handed may demonstrate diverse varieties of functional brain asymmetry, differing from the type of asymmetry of cerebral hemisphere functions common to all the right-handed in the maintenance of integral neuropsychic activity.

Adolescent↗
PubMed1991

Interhemispheric asymmetry of EEG coherence as a reflection of different functional states of the human brain.

EEG coherence analysis was used to study aspects of the synchronisation of electrical processes in the left and right cerebral hemispheres of right-handed and left-handed healthy subjects in a state of calm wakefulness. Right-handed subjects showed a greater coherence in the left hemisphere and left-handed subjects in the right hemisphere. There were also differences between right-handed and left-handed subjects in the regional profiles of interhemispheric asymmetry and in the interhemispheric asymmetry of individual spectral bands. These differences may reflect variations in the involvement of cortical and subcortical cerebral structures in the formation of the hemispheric specificity. Changes in interhemispheric coherence with the onset of drowsiness were also observed. This suggests that changes in the interconnections of neural networks are also involved in changes in arousal. Certain characteristic regional interhemispheric asymmetry patterns and asymmetries in the spectral bands appear to be necessary for normal human brain function.

Adult↗
PubMedDate not supplied

[The reflection of different levels of the regulation of human brain activity in spectrally coherent EEG parameters].

On the basis of clinico-anatomo-electroencephalographic studies it was shown, that in early terms of cerebral trauma, at gross disturbances of the cortical functions and safety in some cases of only vital regulation, the parameters of the EEG stability or variability are of distinct information value for estimation of the functional state of patients. It was established, that changes of stability of the frequency, power, and coherent EEG characteristics correlate with different parameters of changes of the structural-functional brain organization. At this stage the greatest connection with the disease outcome reveals the EEG coherence parameters of the cortical symmetrical points reflecting the state of predominantly median formations and general brain reactions to traumatic action. In the process of restoration of disturbed neuromental functions priority prognostic significance is acquired by parameters of intrahemispheric coherence as well as by frequency-regional properties of interhemispheric asymmetry of coherence of the brain electrical processes, characterizing functional features of the lesion focus.

Brain↗
PubMedDate not supplied

[Intracerebral EEG functioning as a reflexion of the systemic brain organization in norm and pathology].

The authors summarized the EEG findings and defined the nature of intercentral EEG relationships in different functional states of healthy subjects and patients with organic cerebral pathology based on coherence analysis. The EEG features typical of healthy subjects were identified: an anterior-posterior gradient of the mean coherence and the character of cortical-subcortical relationships in the anterior cerebral structures. Right- and lefthanded subjects showed the frequency and regional differences in EEG coherence, which reflected, mainly, specific intracortical relationships. Development and regression of pathologic signs in right- and lefthanded patients with organic brain lesions are thought to be determined by these differences. As distinct from cortical pathology, lesions of regulatory structures (diencephalic, brainstem, and limbic) were shown to produce more diffuse changes in intercentral relationships with a tendency to reciprocity. Intercentral relations, including their interhemispheric differences, varied with changes in the functional state of healthy subjects (increase and decrease in the level of functioning). A certain time course of changes in intercentral relationships was also revealed in patients with organic brain lesions during recovery of their consciousness and mental activity. Changes in the dominance of activity of individual regulatory structures are considered to be one of the most important factors that determine the dynamic character of EEG coherence.

Brain Injuries↗
PubMedDate not supplied

[Characteristics of the interhemispheric EEG relationships in assessing the functional state of the human brain].

In healthy subjects (11 right-handed men) reorganization was studied of intra- and interhemispheric correlation of the electrical brain activity at transition from the state of alertness to drowsiness. At the lowering of alertness level, the coherence of hemispheres symmetrical points changed not abruptly, with a tendency towards an increase at differently directed character of changes of combinations of separate physiological rhythms ranges. Comparison of the EEG coherence changes within the right and left hemispheres revealed a greater reactivity of the left (dominant) hemisphere. The reduction of the predominance (observed in the dominant hemisphere in alertness) of the degree of EEG conjunction, at transition to drowsiness, leads to smoothing of interhemispheric asymmetry in the organization of electrical brain processes.

Adult↗
PubMedDate not supplied

[Dependence of the organization of human brain electrical activity on hemispheric dominance].

In healthy subjects, in a state of relative rest, with different individual profiles of asymmetry (20 right-handed and 10 left-handed subjects), a greater conjunction of electrical brain processes (estimated by mean EEG coherence levels) has been found in the dominant hemisphere as compared to the subdominant one, more distinctly expressed in the right-handed subjects. The maximum degree of interhemispheric asymmetry of the EEG coherence is observed in the posterior associative cortical areas. Specific interhemispheric theta-range differences are revealed as compared with other EEG frequency bands. Greater values are obtained of the correlation of the EEG symmetrical hemispheres points in the whole frequency band and in alpha- and beta-ranges in the right-handed subjects than in the left-handed ones.

Adult↗
PubMedDate not supplied

[EEg changes after removal of craniopharyngiomas in children].

Electroencephalograms (EEG) were studied after removal of craniopharyngioma in 75 children. Correlation of the character of ECG changes with the severity of the clinical condition was revealed. Maximally manifested pathological EEG activity of the central areas of the cortex and a phase character of the EEG changes with different duration of the phases determined by the patient's condition were common to all patients, irrespective of the severity of their condition which was determined by the degree of the pathological changes in the thalamo-hypothalamic structures. Prognostic signs of the EEG changes were identified, which characterized a favorable or a complicated course of the postoperative process.

Action Potentials↗
PubMedDate not supplied

[Dynamics of the spectral-coherent characteristics of the human EEG in healthy subjects and brain pathology].

EEGs of 15 healthy subjects and 30 patients in early period after surgical ablation of tumours with basal localization, were investigated by means of monitor "Neuro-1" which allows to obtain in continuous regime characteristics of EEG dynamics according to power spectra and reveal the characteristics of intercentral relations of electrical brain processes by coherence and phase shifts. In healthy subjects in the period of transition from wakefulness to drowsiness highly coherent beta-rhythm (16-18 Hz) was revealed, preceeding typical picture of drowsiness and sleep. Study of the patients shows that certain characteristics of coherence and phasic shifts have an important prognostic value. Conclusion is made that for estimation of the functional state of healthy subjects during transition from wakefulness to drowsiness and of patients in early postoperative period the data on spectra of coherence are most informative.

Beta Rhythm↗