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Results for “Cortical Synchronization”

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At least 1,441 records · Page 80Linked to original sources
PubMed1975

[Methyl bromide poisoning. 3 cases, 1 fatal. Neruopathological study of one case of coma with myoclonus followed for 5 years].

Three new cases of methyl bromide poisoning (leakage from a fire extinguisher) are reported. Two of these were characterized, after an initial period of coma and myoclonic status, by an action myoclonus. Electrical data are presented. A follow up of 4 and 8 years allowed to study the effect of drugs, two of which (clonazepam and baclofene) being pecularly contributive. The third patient outlived for 5 years in a stuporous state with myoclonus. The anatomical findings consisted mainly of a necrosis of both inferior colliculi with gliosis in the upper brain stem reticular formation and moderate changes in the dentate and pontine nuclei. Their significance is discussed in view of physiological and experimental knowledge.

Adolescent↗
PubMed1975

[Long- and short-term changes in engorgement in the cerebral vessels under rhythmic photic stimulation].

In 50 patients with cerebrovascular pathology, the EEG and REG were simultaneously recorded during an increase in the cerebral blood volume in response to rhythmic photostimulation. General, local, and short-term reactions of increased cerebral blood volume could be distinguished. The relationship between the EEG changes and cerebral blood volume was most obvious during the short-term reactions: EEG-desynchronization was always followed by increased blood volume. This suggests a possible neurogenic element in vascular reactions. Cerebrovascular pathology was concluded to affect both the neurogenic and the metabolic components of the regulatory mechanism of local circulation.

Blood Volume↗
PubMed1975

The effect of serotonin microinjections into the nuclei amygdalae on EEG and behavior in the rabbit.

In chronic experiment with rabbits the influence of 5-HT on the behaviour and bioelectric activity of different brain structures had been examined. Bilateral 5-HT microinjections mostly into the basal amygdaloid nucleus cause the increase of motor activity as well as the arousal in EEG. Agents considered to be inhibitors of central serotonin receptors (cypropheptadine, methysergide) weaken the above mentioned reactions only slightly. Atropine causes the inhibition of effects produced by 5-HT. On the ground of the results obtained it seems that the stimulation caused by injecting 5-HT into amygdaloid nucleus proceeds through the mediation of acetylcholine neurons.

Amygdala↗
PubMed1975

[Comparative study of the changes in the EEG and cholinesterase activity in experimental Dipterex poisoning].

A systematic study is conducted on cats, poisoned with the organophosphorus insecticide Dipterex. The changes in spontaneous and induced cortical activity along with those in serum and erythrocyte cholinesterase after intraperitoneal and intramuscular injection of Dipterex are investigated. Against the background of lowered cholinesterase activity, recorded in all the experiments , the changes in EEG appear to be discrete and inconstant. Uron single treatment with Dipterex, desynchronization prevails in the spontaneous EEG, whereas in the responses induced by light stimulants an increase of delayed negative potentiale prevails. Upon repeated Dipterex introduction, theta-like waves appear, associated with activation of paroxysmal manifestations existing in advance. Finally, the correlation between changes in cholinesterase activity and EEG is discussed.

Animals↗
PubMed2002

Cortical source estimate of combined high resolution EEG and fMRI data related to voluntary movements.

OBJECTIVES: In this paper, we employed advanced methods for the modeling of human cortical activity related to voluntary right one-digit movements from combined high-resolution electroencepholography (EEG) and functional magnetic resonance imaging (fMRI). METHODS: Multimodal integration between EEG and fMRI data was performed by using realistic head models, a large number of scalp electrodes (128) and the estimation of current density strengths by linear inverse estimation. RESULTS: Increasing of spatial details of the estimated cortical density distributions has been detected by using the proposed integration method with respect to the estimation using EEG data alone. CONCLUSION: The proposed method of multimodal EEG-fMRI data is useful to increase spatial resolution of movement-related potentials and can also be applied to other kinds of event-related potentials.

Brain Mapping↗
PubMedDate not supplied

On the choice of so-called placebo solution for the intranigral microinjection in the rat.

Rats moving freely in their cages were injected into substantia nigra with bidistilled water, with NaCl solutions of various concentrations or with a multionic Merle's solution. The solutions were administered uni- or bilaterally at volumes of 1-5 mul through chronically implanted chemitrodes. The behavior of animals and the EEG of frontal cortex, hippocampus, caudate nucleus and substantia nigra were observed. A part of the usual EEG record analysis two channels of EEG were evaluated with amplitude integrators. The main goal of the experiment was to find the optimal solvent for microinjection into the substantia nigra. So-called physiological saline solution (0-9% NaCl) was found to be most toxic and the multionic Merle's solution most suitable among the control fluids tested. The influence of "pressing effect", of pH as well as the influence of ionic concentrations of solutions tested are discussed.

Animals↗
PubMed1992

Theta waves in the Papez circuit during alertness and dreaming in the rat.

An electro-oscillographic study of the hippocampus, thalamic anterior nuclei and cingulate and pericingulate cortical areas was performed in the rat during the wakefulness-sleep cycle. High voltage (usually from 100 to 200 microV) theta waves, oscillating at regular frequencies from 6 to 10 Hz, were found to occur simultaneously in all of these components of the Papez circuit during attentive behavior and dreaming.

Animals↗
PubMedDate not supplied

[Sex differences in EEG power changes in retention of dichotically and monaurally presented verbal stimuli].

EEG power mapping was used to study gender differences in hemispheric functional organization during memorizing dichotically and monaurally presented verbal information. Right-handed students (12 men and 14 women) participated in experiments. The EEG was recorded from 16 electrodes placed at homologous sites of the left and right brain hemispheres. Task-related changes in the thetal power in men differentiated between monaural presentations to different ears, i.e., situations of oppositely directed attention. In women the thetal power reactivity (the difference between the band power logarithms under baseline conditions and in task interval) differentiated between dichotic and monaural presentations of words, i.e., situations with different memory loads. Gender differences were also found in the alpha frequency band. Power changes in the alpha 1 band in all memory tasks and power changes in the alpha 2 were more evident in the right hemisphere in men but in the left hemisphere in women. In contrast, in the posterior temporal lead the alpha 2 power reactivity in men was higher in the right hemisphere, whereas in women the lateral differences were absent. As compared to men, the alpha 2 desynchronization in women was also more pronounced in posterior regions of both hemispheres. There were no gender differences in efficacy of memorizing. It is suggested that different processing strategies rather than different behavioral performance may be responsible for the revealed specific spatiotemporal EEG patterns.

Adult↗
PubMed2004

EEG deblurring techniques in a clinical context.

OBJECTIVES: EEG scalp potential distributions recorded in humans are affected by low spatial resolution and by the dependence on the electrical reference used. High resolution EEG technologies are available to drastically increase the spatial resolution of the raw EEG. Such technologies include the computation of surface Laplacian (SL) of the recorded potentials, as well as the use of realistic head models to estimate the cortical sources via linear inverse procedure (low resolution brain electromagnetic tomography, LORETA). However, these deblurring procedures are generally used in conjunction with EEG recordings with 64-128 scalp electrodes and with realistic head models obtained via sequential magnetic resonance images (MRIs) of the subjects. Such recording setup it is not often available in the clinical context, due to both the unavailability of these technologies and the scarce compliance of the patients with them. In this study we addressed the use of SL and LORETA deblurring techniques to analyze data from a standard 10-20 system (19 electrodes) in a group of Alzheimer disease (AD) patients. METHODS: EEG data related to unilateral finger movements were gathered from 10 patients affected by AD. SL and LORETA techniques were applied for source estimation of EEG data. The use of MRIs for the construction of head models was avoided by using the quasi-realistic head model of the Brain Imaging Neurology Institute of Montreal. RESULTS: A similar cortical activity estimated by the SL and LORETA techniques was observed during an identical time period of the acquired EEG data in the examined population. CONCLUSIONS: The results of the present study suggest that both SL and LORETA approaches can be usefully applied in the clinical context, by using quasi-realistic head modeling and a standard 10-20 system as electrode montage (19 electrodes). These results represent a reciprocal cross-validation of the two mathematically independent techniques in a clinical environment.

Aged↗