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Results for “Cortical Synchronization”

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At least 1,495 records · Page 83Linked to original sources
PubMedDate not supplied

[Clinical physiological effects of electrostimulation and destruction of the ventrolateral portions of the cerebellar dentate nuclei in different forms of motor pathology].

The effect of electrostimulation and destruction of the ventrolateral parts of the cerebellar dentate nuclei is described on the basis of 27 dentotomies performed on patients with different forms of motor pathology. The dento-cortical connections were studied by advancing electrodes to the cerebral and cerebellar cortex through trephination openings made in the postero-frontal-parasagittal area for ventriculography and in the occipital area for the insertion of a stereotaxic cannula. It was found that the principal test for operative identification of the ventro-oral parts of the dentate nucleus in electrostimulation are motor reactions and changes in the muscular tonus in the homolateral limbs and reactions of the cortex of the central and precentral areas of the cerebral hemispheres revealed by electrocorticography. The main clinical effect produced by the destruction of these parts of the dentate nuclei is diminution of the spastic component of muscular hypertonus; hardly any effect is caused on the rigidity component. Redistribution of muscular tonus is among the factors inducing postoperative changes in hyperkinesia.

Cerebellar Nuclei↗
PubMedDate not supplied

[Effect of isorhythmic and heterorhythmic stimulation of the septum and mammillary bodies on the EEG of the rabbit].

The influence was studied of combined isorhythmic and heterorhythmic stimulations of the septum and mammillar bodies (S + MB) on spatial organization of brain biopotentials and on the speed of acquisition of defensive conditioned reflex (CR) to light. Analysis of the effect of the isorhythmic stimulation on learning showed that CR elaboration was impeded and in some situations was even impossible. Apparently, isorhythmic S + MB stimulation did not prevent closing of the temporary connection but disturbed CR realization. At simultaneous heterorhythmic electric S + MB stimulations, in most cases cortical parts reproduced only one rhythmic process corresponding to the frequency of the septal stimulation. Combined heterorhythmic S + MB stimulation promoted successful defensive CR elaboration though prolonged action of such stimulations led to development of neurotic state in animals.

Animals↗
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

[Comparison of dynamic cortical electroencephalotopograms of the human left and right cerebral hemispheres in quiet wakefulness].

The differences of spatial-temporal organization of potentials in the left and right hemispheres were studied in healthy subjects at calm alertness by means of comparison of successive electroencephalotopograms (EETGs). In all subjects episodes were found of discordance resemblance coefficient of successive EETGs of the left and right hemispheres--one of the main characteristics of potentials spatial-temporal organization. The episodes of such discordance took as a whole 5--57% of observation time; the duration of each episode could vary from the sampling interval (1/128 s) to the period of resemblance coefficient oscillations.

Adolescent↗
PubMed1988

[Neurologic functions of patients after open-heart surgery under perfusion-less deep (26-25 degrees C) hypothermic protection].

Neurological investigation was performed in 47 children and adults in which no brain functions damage was detected after their cardiac defects repaired under perfusion-less deep (26 to 25 degrees C) hypothermia. Apart of these, 35 patients were studied in which cerebral complications immediately followed the surgery. EEG was recorded in selected patients. The relationship between the neurological complications incidence and duration of major vessels occlusion in surgery was analyzed. Perfusion-less deep hypothermia was efficient means of brain protection against hypoxic damage.

Adolescent↗
PubMed1988

Alexithymia and the split brain: VI. Electroencephalographic correlates of alexithymia.

Electroencephalographic recordings of eight corpus callosotomy patients and eight precision-matched control subjects were obtained as subjects watched a film symbolically depicting death. A content-analytic measure of alexithymia was regressed on eight auto-spectral alpha-band intensity averages and on subsets of alpha-band coherence averages. Results were interpreted on the basis of three possible mechanisms of alexithymia: (1) Alexithymic subjects had more right-temporal alpha-band intensity, suggesting inadequate understanding of the film. (2) A possible lack of inner speech in alexithymics was suggested by their relative alpha abundance of the left frontal and left temporal channels but left parietal alpha desynchronization, and by their lower left frontotemporal but higher left parietofrontal and left parietotemporal coherences. (3) Alexithymic subjects had higher right frontal-left parietal and left frontal-left parietal coherences, suggesting possible interhemispheric inhibition of expression. Expressive subjects had higher right frontal-left temporal (and homologous interhemispheric frontal, parietal, and frontal) coherences, suggesting interhemispheric facilitation of verbal expression.

Adult↗
PubMed1988

[Experimental studies on changes in cerebral bioelectrical activity during combined exposure to benzene and tobacco smoke].

Four persons of average age--25 years, put in exposure chamber, were subject to single and combined effect of benzene, in the limits of MAC and tobacco smoking for a period of 5 days. An examination of the cerebral bioelectric activity was performed by EEG at the beginning and the end of each experiment. Functional changes in the EEG were established expressing disorganization and depression of the basic rhythm, increase of the number of theta waves and weakened reaction in the hyperventilation activity. These changes are explained with the increased excitability of the CNS.

Adult↗
PubMedDate not supplied

[Reflection in the electrical activity of the brain of the activities of the mechanisms regulating the functional state].

On the basis of analysis of the results of author's studies and literature data, theoretical notions are developed, according to which spatial-temporal organization of cortical biopotentials is a result of activity of nonspecific different level systems subtly regulating current alertness in conformity with needs of the actual and forthcoming activities. In the hierarchy of regulating systems, in conditions of alertness, nonspecific thalamic and midbrain system is leading. Activity of these regulation levels provides in alertness for formation and destruction of functional neuronal ensembles which realize elementary informational transformations. The role is emphasized of asynchronous processes in the central nervous system activity.

Animals↗
PubMed1988

[Neurophysiological analysis of the central mechanisms of glossalgia].

Bioelectrical activity of the brain was studied in 20 patients with glossalgia characterized by a most severe clinical symptomatology. Neurophysiological analysis has shown a marked imbalance of the leading neuromediator cerebral systems, namely, deficiency of ascending activating reticular effects, tense functioning of syncronizing systems, and involvement into the chain of impaired relationships of the limbic-reticular complex and inhibitory systems of the brain. It has been established that general disorganization of the activity of the cerebral mechanisms is attended by impaired control of ascending afferentation. As a result, any type of chronic stimulation of the peripheral receptors is no longer blocked when entering the central nervous system and manifests in a clinically marked syndrome of glossalgia. On the basis of clinico-physiological correlations the authors draw a conclusion that the syndrome of glossalgia should be considered as one of the links in the chain of chronic emotional stress manifestations.

Adult↗
PubMedDate not supplied

[Features of sleep in the water by the northern fur seal Callorhinus ursinus].

The peculiarities of sleep in water and on land were investigated in four adult Northern fur seals (Callorhinus ursinus) of both sexes. The electrocorticogram of both hemispheres, the neck electromyogram, the electrooculogram and electrocardiogram were recorded with implanted electrodes. The interhemispheric asymmetry of EEG during slow wave sleep was observed in all the animals sleeping in water and on land. The relative amount of interhemispheric slow wave asymmetry was higher during the sleep in water comparing to that on land. The fur seals maintain their special sleep posture on the water surface by moving only one of their front flippers. The asymmetric EEG in fur seals sleeping in the water may be attributed to the asymmetric motor activity of their flippers.

Adaptation, Biological↗