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Results for “Cortical Synchronization”

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At least 1,513 records · Page 84Linked to original sources
PubMed1987

[Mosaicism of excitatory and inhibitory processes in populations of cortical neurons during the brain activation response].

Comparative analysis of multiunit arousal response in the somatosensory I and the parietal associative brain areas of unanesthetized cats revealed the initial excitation of neuronal populations in both cortical areas to be independent of stimulus modality. The greatest firing rate was observed in the 1st period of the arousal response when the brain activation was maximal. Subsequent development of the multiunit response may be either tonic or phasic. The phasic responses are predominant in the somato-sensory neuronal populations (56-87%). The multiunit tonic responses (55-85%) occur mostly in the parietal associative area. The end of the inhibition phase coincided with the end of the arousal response. The relation of the response types to unspecific brain activation, is discussed.

Animals↗
PubMed1986

[Psychophysiologic interrelations in healthy subjects and alcoholics in remission].

Twenty male patients suffering from alcoholism (10 at the second and 10 at the third stage of disease) at the phase of a remission were subjected to electropolygraphic examination during night sleep and relaxed wakefulness. The mental state was examined by MIL and Spilberger's tests. A control group included 14 normal subjects in whom, additionally to the baseline examinations, the authors studied the effect of a single dose of ethanol taken before sleep on the nonspecific cerebral systems. The latter was associated with an increase in the deep stages of sleep and a reduction of the phase of rapid sleep as well as a decrease of the activation parameters. The electropolygraphic and psychological characteristics in patients with alcoholism of stage II and III showed no significant differences, yet both groups differed considerably from healthy subjects which was expressed in the intensified desynchronization of the cerebral bioelectrical activity in both sleep and wakefulness and in the presence of anxiety-depressive disorders. Hyperfunction of the ascending activating system of the brain seems to be responsible for the above psychophysiological changes.

Adult↗
PubMedDate not supplied

[Effect of learning on EEG characteristics of children during the third year].

Characteristics were studied of frequency spectrum and spatial-temporal organization of bioelectrical cerebral activity and also of heart rate dynamics in children of the third year of life in the state of quiet wakefulness and during orienting reaction. Changes were recorded in the parameters of the cerebral activity under the influence of developing learning and in particular of formation of symbolic thinking function. It has been established that the involvement of the child in the process of learning leads to definite shifts of the EEG of quiet wakefulness testifying to acceleration of the process of the CNS functional maturation. Mastering of a high degree of play symbolization causes not only changes in the EEG but also an increase of the child orientating-investigatory activity.

Autonomic Nervous System↗
PubMedDate not supplied

[Temporal organization of interneuronal relations in the cerebral cortex of the cat in relation to the level of alimentary motivation].

By means of records of multicellular activity, interneuronal relations and their modifications in two cortical zones (Visual and motor) were studied in cats at different levels of alimentary motivation. For quantitative evaluation of interneuronal relations the statistic method of cross-correlation analysis of impulse trains was used in determining the probability of the appearance of the discharge of one neurone after the impulse of the other one. For groups of neurones in both investigated cortical areas, three-neurones microsystems were singled out and their activity was analyzed by temporal parameters of interaction between neurones at the interval of 120 ms, both within one microarea (intraanalyzer connections) and between microareas of two cortical zones. The correlation of temporal parameters of interneuronal connections (temporal delays in the activity of neuronal pairs) changed depending on spatial localization of neurones and functional condition of the animals. The existence is suggested of "informational" (1-30 ms) and "motivational" (90-120 ms) values of interneuronal relations for interanalyser connections.

Animals↗
PubMedDate not supplied

[Bioelectical activity of the brain in parkinsonism before and after stereotaxic operations].

The bioelectrical activity of the brain was studied in 85 patients. The bioelectrical potentials were recorded directly from the cortex of the cerebral himispheres and the subcortical structures of the brain. Clinical and electroencephalographic comparisons were made. Functional reorganization of bioelectrical potentials after stereotaxic operations is shown.

Adult↗
PubMed1985

[Formation of "caudate spindles" in the sensomotor cortex of the rabbit during ontogeny].

The electrical activity elicited by electrical stimulation of the caudate nucleus in the sensorimotor and visual cortex was recorded in adult and 3-60-days old rabbits. It was shown that single stimuli applied to the caudate nucleus evoked bursts of synchronized rhythmical cortical waves similar in appearance to the so-called "caudate spindles" described in cats and monkeys. The latency of the "caudate spindles" in adult rabbit was about 200 ms, the duration--1-3 s and the frequency--11-3 c/s. The most prominent area for obtaining "caudate spindles" was the ipsilateral sensorimotor cortex. In spite of repeated efforts we have never recorded "caudate spindles" in rabbits of the youngest group. Beginning from the 15th postnatal day caudate stimulation induced bursts of rhythmical activity in the sensorimotor cortex which was similar to "caudate spindle", but with lower frequency (about 8 c/s), longer latency (350 ms) and high threshold. The definite type of spindles appears by the end of the first month of life, in the period of complication of conditioned reflexes.

Animals↗
PubMedDate not supplied

[Effect of serotonin and acetylcholine on the electrical activity of isolated cortex in the rabbit].

Neuronal isolation of the rabbit's cerebral hemisphere shifts the EEG spectrum in direction of slower processes. Application of acetylcholine on the cortex elicits EEG activation and appearance of the theta-rhythm. Initially serotonin application is accompanied by the appearance of the theta-rhythm periods; in the process of subsequent administration of the drug these periods are gradually substituted by slow delta-waves. Combined application of serotonin and acetylcholine on isolated cortex elicits bursts of high-amplitude activity, abruptly substituted by "silence" phases. In contrast to the intact cortex where serotonin elicited prolonged and rhythmic alternation on EEG of phases of high-amplitude activity and of "silence" periods, in the isolated cortex the bursts of activity of about 1 min duration appeared only after application of the acetylcholine to serotonin-saturated cortex. Repeated phases of activation were either absent or were of short duration and extinguished rapidly.

Acetylcholine↗
PubMedDate not supplied

[Correlation of neuronal reactions of different regions of the neocortex of the rabbit to conditioned positive and inhibitory stimuli].

The activity of neurones of the visual and sensorimotor areas of the neocortex was simultaneously recorded in rabbits under the action of conditioned, inhibitory stimuli (CS, IS) and at simultaneous presentation of CS and the unconditioned stimulus (US) after trans-switching of the positive and inhibitory conditioned reflexes. Mean time of conjugated reactions of simultaneously recorded pairs of neurons is similar under the action of CS, combined action of CS and US and under IS. During the IS action as compared with CS, the phasic activity of some neurones in different areas increased, and due to this the similarity of reactions also increased; in other pairs of neurones the reactions weakened and the responses similarity decreased. The frequency of the appearance of intervals of the conjugated excitation after CS corresponds to 4.3 Hz; under combined action of CS and US it increases up to 5.9 Hz, and after IS--it decreases to 3.6 Hz. The order of coming into conjugated action of different pairs of neurones changes depending on the signal significance of the stimuli.

Animals↗
PubMedDate not supplied

[Dynamics of the direction of static connections in the electrical activity of the cerebral cortex in the cat].

Data have been obtained on three cats for analysis of statistic connections of electrical activity in the visual, parietal and somatosensory cortical zones during development of evoked potentials to photic signal in these areas, and also in periods previous to photic stimulation and on traces of its action. An increase in shown of the influence of activity in the visual area on that of the somatosensory zone in post-stimulus periods and a sharp increase of two-way connections between these areas against the background of a relative equilibrium of direct and backward connections in trace periods.

Animals↗
PubMedDate not supplied

Desynchronized EEG activity in a case of post-traumatic coma.

The EEG pattern of diffused low-voltage non-reacting fast activity is exceptional in comatose patients. The authors report on clinical observations, CT scan and neurophysiological findings in one case showing this EEG pattern after a severe head injury. In serial EEG recording it is shown a progressive shift from fast activity towards the alpha and theta bands. The presence of abnormal auditory brainstem responses and of CT scan signs of brainstem lesion suggest that this peculiar EEG pattern may be due to a brainstem lesion.

Brain Injuries↗