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At least 19 recordsLinked to original sources
PubMed1992

Fast (beta) rhythms in the hippocampus: a review.

Spontaneous or evoked brain activity in the hippocampus showed a 20-70 Hz beta rhythm under some conditions, typically during behavioral activation and accompanied by a theta rhythm. Beta rhythms are generated locally, perhaps by a recurrent feedback loop involving pyramidal cells and inhibitory interneurons. Modulation of the local circuit and rhythm by cholinergic inputs has also been demonstrated. Under some behavioral states, neural impulses modulated at the beta frequency may transmit preferentially through the trisynaptic circuit in the hippocampus. It is suggested that the beta rhythm may serve to establish transient physiological connections, reflected in coherence at the beta frequency, among neurons in the hippocampus and related structures. Thus, the beta rhythm may play an essential role in hippocampal function.

Animals↗
PubMed1992

Nucleus reticularis thalami participates in sleep spindles, not in beta rhythms concomitant with attention in cat.

In the awake cat, characteristic electrocortical synchronized oscillations (beta rhythms) can develop on the parietal cortex in specific behavioural situations such as during attentive fixation of a target. These activities differ from other synchronized rhythms which accompany slow sleep ("spindles") and are more widespread. It is shown here through single unit recording from the thalamic nucleus reticularis (RET), that the latter structure participates in spindles (as already postulated by other authors), but not in the beta rhythms which seem to depend on a more restricted thalamic focus in the posterior thalamic nucleus. These data thus support the idea that RET plays a role in slow-wave sleep but not in the cognitive operations involved in focussing attention.

Animals↗
PubMed1992

The effects of acetylcholine, dopamine and noradrenaline on the visceral ganglion of Helix pomatia. II. Stimulus evoked field potentials.

1. Neurophysiological effects of acetylcholine (ACh), dopamine (DA) and noradrenaline (NA) on stimulus evoked field potentials in the Helix pomatia visceral ganglion were investigated. Electrical stimuli were applied to nerve trunks. 2. For frequency analysis of evoked potentials (EPs) the Fourier transform was performed. For quantification of pre- as well as poststimulus activities, root-mean-square (RMS)-voltages of digitally filtered signals were used. 3. ACh at 10(-4)-10(-3) M selectively enhances the 4-15 Hz as well as the 30-70 Hz components and DA at 10(-5)-10(-3) M increases the 30-70 Hz activity. NA at 10(-5)-10(-4) M augments the 15-30 Hz response and only at 10(-5) M increases the 30-48 Hz response. 4. All transmitters at 10(-2) M show a strong tendency to suppression. 5. Prestimulus activities of ACh and DA are damped by 40-50% compared to the ongoing induced activities in the non-stimulus study (cf. Part I). These damped prestimulus activities may be considered as a late part of the prolonged evoked activity. 6. The 4-15, 15-30 and 30-70 Hz responses selectively increased by the transmitters may be compared to theta-alpha combined rhythm, beta-rhythm and 40 Hz rhythm in the mammalian EEG.

Acetylcholine↗
PubMedDate not supplied

The use of computer analysis for diagnosis in routine electroencephalography.

1. Frequency power spectra and mutual coherence functions of 8 stimulatenously recorded E.E.G. derivations have been computed in approximately 500 non-specially selected patients referred to the department for E.E.G. recording. 2. On basis of the data obtained some provisionnal conclusions have been drawn, the most important of those being that the analyses contribute significantly and in some cases essentially to the understanding of the E.E.G. and therefore should be carried out in all E.E.Gs recorded to our department. 3. It has been observed that mu rhythms and beta rhythms appear to be essentially different from alpha rhythms by exhibiting no bilateral coherence whereas alpha rhythms almost invariably are considerably bilateral coherent.

Alcoholism↗
PubMed1977

Component activities in the autoregressive activity of physiological systems.

The higher-order autoregressive (AR) activity of a physiological system (Sato 1975a,b; Sato et al., 1977) was decomposed into first- and second-order activities. The former time-pattern displays a fast rise and an exponential decay, while the latter exhibits a damped sine wave. Application of this component analysis to EEG showed the first-order activity to coincide with the nonoscillatory delta component. The frequency distribution of the natural, damped and resonance frequencies of the second-order activities was found to show one, two or three modes in each frequency range of the delta, theta and beta rhythms in ninety normal adult EEGs. Hence, the second-order activities agree with the oscillatory delta, theta, alpha and beta rhythms. Some changes were induced not only in the frequency of theta and beta rhythms but also in that of alpha rhythm by over-breathing for about three minutes.

Electroencephalography↗
PubMed1979

Electroencephalographic quantification by time domain analysis in normal 7--15-year-old children.

Automatic EEG analysis was performed on 239 apparently healthy school age children. The children were classed in 3 age groups: (1) average age of 7; (2) average age of 11; (3) average age of 15. A time analysis method, comparable to classical visual analysis, permitted quantification of the records. The mean amplitude, frequency and percentage time for alpha and theta rhythms were determined for each subject for fronto-central and centro-occipital derivations bilaterally. Records were performed during periods of rest with eyes open and eyes closed. During hyperventilation, records were taken with eyes closed. The normal ranges of parameters were determined by calculating their means and standard deviations, for each age group under each recording condition. Delta and beta rhythm values were not calculated, because of their rarity in this apparently normal sample. The precision obtained by automatic analysis could not have been obtained by means of classical visual analysis. The present findings suggest that the statistical analysis of well-defined groups of normal and pathological children could be of significant value.

Adolescent↗
PubMedDate not supplied

[Electroencephalographic correlates of a pathologic inert motor reaction in dogs].

Changes in EEG were examined during setting in of a pathological inert motor reaction in dogs with parts of the tongue brought out and electrodes implanted in the motor cortical area and limbic structures. The reaction was formed when combining stimulation by a salt solution of the part of the tongue with electrical stimulation of the paw. The inert motor reaction is characterized by enhanced synchronization (theta-rhythm) in the hippocampus and increased amplitude of the beta-rhythm in the motor cortical areas. A frequency-amplitude analysis of the summary EEG has shown that the highest correlation was established at the beginning of elaboration of the inert motor reaction only between a small number of limbic structures (the hippocampus, the hypothalamus and the cingulate gyrus), then between all the examined structures of the brain; when the inert reaction became elaborated the number of structures with a high correlation coefficient diminished again and was reduced to the hippocampus, the hypothalamus and the cortical motor area.

Animals↗
PubMed1976

[An analysis of EEG rhythm changes following micropolarization of several brain structures].

With the aid of the EEG special statistical analysis, micropolarization of the temporal cortex of hypothalamus was shown to entail abrupt alterations of the theta-, alpha-, and beta-rhythms in the temporal and motor cortex, hypothalamus, and the midbrain RF. The changes of the biorhythms (their correlation, thresholds of occurring, connection of the local and distant shifts) are regarded as reflecting some fine regulation of the structures' functional condition as well as mutual influences of the cortex and the deep brain structures which tell on modulation of mnemic processes.

Animals↗
PubMedDate not supplied

[Interrelationship between spatial synchronization and rhythmic components of the human EEG].

The main object of the work was to elucidate the functional significance of different human EEG rhythms. Cross-correlation and spectral characteristics at the background and during mental work were studied in thirteen subjects by recording from four points of the left hemisphere. During intellectual load, spatial synchronization is enhanced between the biopotentials of most areas: interrelations between remote points are intensified which leads to the smoothing of the synchronization gradient existing in a state of rest. The alpha-rhythm becomes less pronounced everywhere in parallel to the decrease in synchronism of its fluctuations in different zones; at the same time low-frequency activity (delta-theta) increases both by the amplitude of oscillations and the capacity for its unidirectional shifts over the whole cortex. The least distinct change is observed in the beta-rhythm.

Adolescent↗
PubMedDate not supplied

Reversibility of the chronic post-stroke state.

Forty patients with cerebral infarction associated with occlusion of the internal carotid artery (ICA) or the middle cerebral artery (MCA) were treated with hyperbaric oxygenation (HO). EEG analyses were performed regularly in order to assess the course of the cerebral lesion. Patients in an early post-stroke stage (III B) and patients in a chronic post-stroke stage (IV) had the changes in EEG analysis and neurological distributed evenly between these two groups.

Adult↗
PubMed1976

Statistical evaluation of polygraphic investigations of pentoxifylline.

Changes in the electro-encephalogram, and in the electro-oculogram electromyogram, ECG, blood supply, blood pressure, electrical skin activity and neurological/psychiatric findings, were investigated in 100 patients given single administrations of 200 mg of pentoxifylline (BL 191). It is concluded from the changes in the EEG wave patterns that pentoxifylline produces a beneficial effect on the cerebral processes contributing to bio-electrical brain activity. Pentoxifylline can be classed as a substance with microcirculatory/metabolic effects on the brain, which lead to stimulation of psychomotor behaviour.

Adult↗
PubMed1979

On some EEG patterns in children and adults.

The EEGs of 76 children (6--9 years of age) were classified into five types for the occipital regions (O1 and O2) and into seven types for the central regions (C3 and C4) by the method of EEG pattern discrimination (Sato, Ono et al., 1977). The five types of EEG patterns observed in the occipital regions were: (1) low frequency alpha wave of about 8--9 Hz, (2) Hz alpha wave, (3) low frequency alpha and theta wave, (4) 10 Hz alpha wave and theta wave and (5) irregular wave patterns, while two more types, (6) the low pass and (7) theta wave types, were observed in the central regions. These same types were also observed in the EEGs of 41 adults (20--25 years of age). The amount of difference between the above five and seven types in children and adults were obtained by the generalized (Mahalanobis') distances. In the occipital regions, the percentage frequency of the alpha wave type was the highest followed by that of the alpha and theta wave type, while the frequency of the alpha and theta waves type was the highest in the central regions, followed, next and third in order by the low pass type and the alpha type, respectively.

Adult↗
PubMed1975

[Electroencephalography in organic and functional cerebrovascular disorders at a young age].

The paper summarizes the results of a quantitative analysis of the EEG in 106 patients under 45 years. Among these patients 32 had cerebro-vascular paroxysms of a functional angiodystonic character and 74 with mild initial signs of organic vascular lesions of the brain. The authors give a detailed analysis of statistically significant changes in the EEG picture in both groups of the patients.

Adult↗
PubMed1979

[Behavior of the Berger effect in boys brain-damaged in early childhood and in brain-healthy boys in a conditioning trial].

Berger effect behavior was tested in a group of 15 boys with early brain damage and a control group of 15 boys without an anamnesis of brain damage, with a view to development, conditioning ability and habituation. In the group of brain-damaged test persons the proportion of BE-positive subjects was markedly less in all trials. Habituation occurred earlier and in a larger percentage. The conditioning capacity was worse in each series. The phenomena observed suggest that subjects with early brain damage suffer from a disturbance in the general reticular action system.

Acoustic Stimulation↗