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Results for “Cortical Synchronization”

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At least 1,621 records · Page 90Linked to original sources
PubMed1980

The acute pretrigeminal rat.

In five rats the brainstem was transected at the pretrigeminal level. In the frontal cortex, desynchronized EEG activity dominated, while in the dorsal hippocampus theta activity of low frequency (about 4 cycle/s) was almost continuously present. Olfactory and visual stimuli and electrical stimulation of the posterior hypothalamus induced or increased cortical EEG desynchronization and increased the regularity and the frequency of the theta activity in the hippocampus. However, visual stimuli were effective only in three rats. Ocular responses (pupillary dilatation, eye movements) were never observed to any stimulation. It is suggested that similarly as in the pretrigeminal cat, the isolated cerebrum is awake in the pretrigeminal rat.

Animals↗
PubMed1981

[Electroencephalographic study of sleep in Sea of Azov porpoises].

ECoG of both hemispheres, EMG of neck muscles, ECG and respiration rate were recorded in 3 free swimming Black Sea porpoises. The sleep characteristics in the porpoises were similar to those in the bottlenose dolphins which have been investigated earlier. Unihemispheric slow sleep was the main type of the porpoise sleep. Paradoxical sleep has not yet been found in them. All ther types of the porpoise sleep occurred during swimming and therefore could not serve to spare energy and to immobilize the animal. The experiments with nembutal and diazepam administration suggest that the functional necessity of the unihemispheric sleep results from the impossibility of maintaining dolphins' respiration during bilateral delta-sleep.

Animals↗
PubMedDate not supplied

[Cooperative activity of adjacent visual cortex neurons in alert cats].

By means of auto- and crosscorrelation analysis, background activity of neighbouring neurones was studied in the visual cortex of alert cats. Four types of units differing in spike activity were found; each cortical microarea could consist of neurones of one or of different types. Analysis of configuration of mutual correlation histograms revealed four types of interdependent relations between the neighbouring neurones; definite types of spike activity of individual neurones were characteristic for each type of relations. Study of microsystems in which all or part of the neurones were united by the activity of a "common source" led to the assumption that the source was located outside the microsystems.

Action Potentials↗
PubMed1981

[Quantitative EEG in depression (author's transl)].

Evaluation of the treatment in clinical psychiatry is mostly based on the rating of mental symptoms prior and after treatment. There is an obvious need to supplement clinical observations by objective measurements. Based on EEG automatic analysis, three methods which appeared to be valuable in investigating patients with affective psychosis, are briefly reviewed. 1) The EEG drug profile, indicating changes of the EEG frequency pattern, which varies proportionally to the psychoactive properties of the drug and its metabolites. 2) The fluctuations of the vigilance level which monitor the sedative/excitatory effect of drugs. 3) The interhemispheral assymetry which is related to the intensity of depression.

Arousal↗
PubMedDate not supplied

[Electroencephalographic analysis of a conditioned reflex to time].

EEG parameters in different cortical territories of free moving dogs were analyzed during formation of conditioned reflex to time, in situation of instrumental alimentary conditioning. It was shown that in organization of a reflex to time as a complex reaction(present, trace and rhythmic processes), different brain systems play different roles in the formation of its stages. Sensory systems provide for the complex of trace processes underlying reaction to time. Associative structures are involved in the afferent synthesis necessary for the present moment. Integrative-triggering formations attach formed reaction to a strictly fixed time.

Animals↗
PubMedDate not supplied

[Inhibitory interneuronal interactions in microregions of the visual cortex].

The interactions between the neighbouring neurones of the visual cortex were studied in the background multineuronal activity of awake cats and of cats anaesthetized with Nembutal. The experiment was carried out on 64 trineuronal microsystems with the method of cross-correlation analysis. Those histograms of cross-correlation were analyzed, in which the parameters and configuration seemed to be determined by inhibitory interneuronal interactions. It is assumed that this inhibition is achieved via recurrent axonal collaterals. The duration and the intensity of inhibitory effect, observed in anaesthetized cats, greater than those in awake animals, may be due to a decrease in the general excitatory synaptic drive and to blocking of the unspecific brain system by Nembutal.

Anesthesia, General↗
PubMed1980

[Analysis of autonomic disorders of cerebral origin].

Clinico-encephalographic examinations of patients suffering from neuroses and neurosis-like states with marked vegetative disturbances were carried out. Regular connections between the integral electrographic phenomena and individual features of the EEG on the one hand, and the character and the depth of the vegetovascular, metabolic, endocrinal, emotional and neurotic disturbances on the other were revealed. The averaged models of EEGs constructed with the aid of an electronic computer can be used for ordinary practical evaluation of EEGs with the purpose of specifying the localization of the affection in individual links of the limboreticular system.

Adolescent↗
PubMed1980

[Clinico-electrophysiologic characteristics of non-process personality changes and schizophrenia in adolescence].

The paper deals with a study of spatial organization in the biological processes during their toposcopical registration. These studies were necessary to determine the clinical and electrophysiological criteria for the differential diagnosis of schizophrenic patients and nonprocess personality deviations in adolescency. The data obtained demonstrated several differences, as shown by bioelectrical indices, in the intrahemispheric, interhemispheric, intracortical and cortical-subcortical interrelationships in the general system of functional contacts. On the basis of literary and personal experience certain assumptions are made, related to the differentiated influence of each of the links in the dynamic organization of brain activity on the character of psychopathological signs.

Adolescent↗
PubMedDate not supplied

[Interhemispheric asymmetry of cat cerebral cortical electrical activity during hyperoxia].

In experiments on anaesthetised cats, studies have been made of the effect of hyperoxia (6 kgs/cm2 pressure) on the bioelectrical activity in the symmetrical parts of the cortex in the right and left hemispheres. At the initial stages of its action, hyperoxia makes more evident the existence of functional heterogeneity between the left and right hemispheres. On further oxygen intoxication, interhemisphere asymmetry in the electrical activity of the brain cortex is abolished.

Animals↗
PubMedDate not supplied

[Reproduction of a conditioned defense reflex in mice in a water maze].

The characteristics of formation of the reflex of water avoidance in a water maze and the dynamics of its reproduction during 24 hours after its elaboration were studied in mice. In case of incomplete initial learning the reflex reproduction had a phasic, oscillating nature. It is assumed that this oscillating dynamics is due to corresponding changes in the similarity of biopotentials in the cortical areas which participate in the formation of the conditioned connection.

Animals↗
PubMedDate not supplied

[Analysis of human EEG spectra in a state of relative and "operative rest" according to A. A. Ukhtomskii].

The analysis of EEG in 40 healthy subjects showed that power spectra, coherence and phase spectra strongly vary in different subjects and that their spatial distribution among cortical areas bears individual properties. General characteristics of the spectra and mean levels of EEG coherence are stable, but details of power spectra, coherence and phases in healthy subjects are very unstable even within short time intervals. In the process of developing in the subject of a stable, ordered by experimenter state of a strained expectation of the signal to immediate activity--of "operative rest", according to A. A. Ukhtomsky--a uniform for all subjects structure of connections is shaped in frontal-central cerebral parts, which is manifested in a specific pattern of coherence spectrum.

Alpha Rhythm↗
PubMed1980

Electroencephalographic correlates of human emotional stress.

Experiments showed that emotional stress is accompanied in humans by depression of the EEG alpha rhythm when the subject is attentive to the environment, and by alpha rhythm exaltation when he is imagining emotionally colored events. It is assumed that alpha rhythm reflects the activity of a mechanism quantitating the flow of external signals, whereas theta rhythm is connected with the quantity of engrams extracted from memory. Interaction of excited and inhibiting nervous structures, determining the dynamics of EEG changes, is discussed in terms of the mathematical model of V. Volterra.

Alpha Rhythm↗