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Results for “Cortical Synchronization”

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PubMedDate not supplied

[The organization of human EEG rhythms in special states of consciousness].

In the paper the results are presented of studying of the electrical brain activity of a specific contingent of subjects which by subjective evaluations considered themselves a category of sensitives (extrasenses). The EEG of these subjects was studied in various functional states--a state of relative rest (background) during diagnostics, of directed influence on the percipient and during meditation. Specificity of spatial-temporal organization of the brain electrical processes of operators--sensitives was revealed, the structure of which correlated with the state of mind. The character of changes in the EEG of these subjects in the background and especially during autogenous activity allows to suggest the formation of a spontaneous focus of stimulation in regulatory brain systems with a leading role of the frontal cerebral regions in these processes as one of the ways of organization of cerebral functions for the regulation of the extrasensory activity.

Adult↗
PubMed1990

Disruptive effect of the mesencephalic reticular formation on tonic immobility in guinea pigs.

Cholinergic stimulation of the mesencephalic reticular formation with carbachol impairs the induction of tonic immobility (TI) by restraining maneuvers and reduces the duration of immobility episodes in guinea pigs. This finding apparently disagrees with the hypothesis that environmental monitoring occurs during TI which permits the animal to evaluate the best time for escape. It is possible that this monitoring involves circuits and neurotransmitters other than the ascending cholinergic system originating in the mesencephalic reticular formation.

Animals↗
PubMed1990

[Event-related desynchronization and the selection of an alpha-frequency band for quantifying cortical pre- and poststimulus activation].

The amount of event-related decrease of increase in alpha-band power is termed "Event-Related Desynchronization" or ERD. In this study, ERD is used as an index of cortical activation, which not only can be applied to monitor poststimulus but prestimulus processes as well. Usually, ERD is analyzed within a fixed range of alpha-frequency, typically within a range of 8-12 Hz. alpha-frequency, however, shows a considerable between subject variation, even in a sample of subjects with comparable age. The purpose of this study, thus is to show as to how the range of alpha-frequency affects the calculation of ERD. Two different methodological approaches were compared. First, ERD was calculated within a fixed range of 8-12 Hz. Second, ERD was calculated within an individual range, which was adjusted to the individually determined alpha-frequency of each subject. A sample of ten right handed subjects participated in an episodic memory experiment, in which target words, shown in a earlier session of the experiment, were to be identified. A time span of 375 ms preceding and following the presentation of a word was defined as the "pre-" and "poststimulus" interval. EEG-signals were recorded unipolarly from 29 leads. The results show a rather localized increase of ERD in the poststimulus interval. In the prestimulus interval on the other hand, the average magnitude of ERD is much lower and the topographical distribution less localized. Most importantly, however, when comparing the two methods of analyzing ERD, those ERD-values calculated within an individually determined alpha-band, are superior in order to differentiate between the pre- and poststimulus interval.

Adult↗
PubMed1990

[Relation between the functional state of cerebral hemispheres and the location and dynamics of the epileptic process].

Computer mapping of spatial synchronism of cortical potentials led away from 48 points was performed in 110 right-handed patients with primary- and secondary-generalized fits. The clinico-electrophysiological analysis was employed to demonstrate a special role played by the left hemisphere in the processes of epileptic activity generalization in different disease patterns and characteristic features of diagnosing the generalized patterns of epilepsy and determination of the focus of localization. The data obtained can be used for disease prediction and estimation of the treatment efficacy.

Action Potentials↗
PubMed1990

Differential effects of cholinergic antagonists on REM sleep components.

We examined the effects of cholinergic receptor blockers on changes in rapid eye movement (REM) sleep components. M1 and M2 muscarinic receptor antagonists or atropine were microinfused before an M2 muscarinic receptor agonist, and the effects on individual REM sleep components were assessed. All drugs were microinjected into the same locus within the medial pontine reticular formation in cats, and sleep recordings were made for at least 3 hours postinjection. Results suggest that desynchronized electroencephalogram (EEG) is influenced by the M1 muscarinic receptor, muscle atonia is influenced by the M2 muscarinic receptor, and ponto-geniculo-occipital (PGO) waves are affected by the nicotinic receptor.

Animals↗
PubMedDate not supplied

[The serotoninergic mechanism and the experimental therapy of sleep disorders in desynchronization].

The authors studied the dynamics of changes in the serotonin content in the brain of albino rats in development of experimental neurosis along the type of desynchronization and under the effect of essential amino acid L-tryptophan. It was found that disturbance in the sleep-awake cycle in desynchronization is attended with decrease in the serotonin level in the hemispheres and brain stem and leveling out the interhemispheric asymmetry. Injection of 80 mg/kg L-tryptophan in this condition leads to increase of the brain serotonin content and restoration of the normal physiological structure of the sleep-awake cycle.

Animals↗
PubMedDate not supplied

Reciprocal relationship between the major EEG rhythms and latencies of evoked potential intermediate components. A tentative explanation.

We recently demonstrated that there is a reciprocal relationship between the known brain wave rhythms (delta, 3.3 c/sec, 5 c/sec, theta, alpha, spindle, and beta) on the one hand, and the averaged evoked potential mid component latencies, on the other. In other words, the latter are closely related to the periods of the known brain wave frequencies. In this paper we offer a hypothetical explanation of this puzzling relationship, by assuming the following: 1) Whenever the fastest component of a sensory signal reaches the cortex it depresses EEG except for those waves of different frequencies which at that very instant exhibit a high amplitude peak of a preferential polarity. One half period later, different in real time for each brain wave frequency, high amplitude peaks will emerge from the record with opposite polarity to that which was preferential at the time of the signals' arrival. These segmental peaks are the same as those that express evoked potential components of mid latencies. For the somatosensory evoked potentials the time of occurrence of these peaks are defined by the following expression: (Formula; see text) where N is equal to successive numbers between 1 and 12, as well as to the fractions of 1; 20 msec is the moment of arrival of the fastest signal to the cortex. Some of the latencies correspond to the arrival of the delayed components of the somatosensory signals. Some correspond to the time of arrival of the auditory and visual signals, in an apparent expectation of multi-sensory signals.(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha Rhythm↗
PubMed1977

Spectral analysis of mouse EEG after the administration of N,N-dimethyltryptamine.

Mice were implanted with permanent cortical electrodes. The EEG was recorded during the sleep-wake cycle and after the administration of N,N-dimethyltryptamine (DMT). Based upon spectral analysis the EEG was classified into three categories: awake, slow-wave sleep (SWS), and rapid eye movement sleep (REM). The dominant frequencies were located below 2 Hz in the case of SWS and between 6 and 9 Hz for REM. When DMT was administered intraperitoneally at 20 or 40 mg/kg, a dose-dependent hypersynchrony at 2.5-4.5 Hz was always observed lasting for up to 60 min. Hypersynchronous activity in the same range was occasionally observed during awake. In this range DMT induced a different but unique frequency for each animal. This individual frequency was closely reproduced by repeated administrations of DMT to the same animal.

Animals↗