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At least 163 records · Page 9Linked to original sources
PubMed1991

Quantitative EEG during progressive hypocarbia and hypoxia. Hyperventilation-induced EEG changes reconsidered.

To investigate the role of cerebral hypoxia as a causative factor in the alteration of the qEEG during hyperventilation, qEEG changes caused by progressive hypocapnia were compared with qEEG changes due to progressive normobaric hypoxia in two parallel groups of 12 and 10 healthy male subjects (age 20-27 years), respectively. In the first group, qEEG records were obtained before and during hyperventilation to pCO2 levels of 4.0, 3.0 and 2.0 kPa. In the second group, the qEEG samples were taken before and during hypoxia with hemoglobin oxygen saturations of 80, 70 and 60%. In both groups, blood flow velocity in the middle cerebral artery was also recorded. Hyperventilation caused an exponential increase in slow activity and a decrease in alpha power. No shift in the alpha mean frequency and alpha peak frequency was observed, except with the pCO2 level of 4.0 kPa, which caused an increase in both variables. Hypoxia with a hemoglobin oxygen saturation of 60% caused a much less pronounced increase in slow activity. No change in total power in the alpha band was found, but both the alpha peak frequency and alpha mean frequency decreased. Lesser degrees of hypoxia caused only minimal EEG changes. Blood flow velocity was decreased by hyperventilation but increased by hypoxia. It is concluded that the EEG changes observed during hyperventilation must mainly or totally be attributed to factors other than cerebral hypoxia.

Adult↗
PubMed2005

Pharmacological modulation of cholinergic brain activity and its reflection in special EEG frequency ranges from various brain areas in the freely moving rat (Tele-Stereo-EEG).

Due to the electrochemical nature of the communication structure of the brain an intimate relationship between neurotransmitter activity on one side and field potentials (EEG) on the other side can be suspected. In order to learn more about this relationship pharmacological manipulation of the cholinergic transmitter system by means of agonistic and antagonistic receptor active drugs was used. Continuous recording of electrical activity from four selected brain areas (frontal cortex, hippocampus, striatum and reticular formation) in freely moving day-night converted Fisher rats was used (Tele-Stereo-EEG). Frequency analysis of telemetrically transmitted data and special definitions of frequency ranges were used to analyse the data from 45 min pre-drug and 180 min postdrug periods. Pharmacological modulation of brain activity by the selective nicotinic agonist metanicotine as well as the alpha 7 selective nicotinic antagonist methyllycaconitine revealed major changes in delta (1-4.5 Hz) and alpha2 (9-12.5 Hz) frequencies. In general blockade of the cholinergic system resulted in electrical power increases and activation in decreases. Unspecific modulation of cholinergic activity by using the cholinesterase inhibitors physostigmine, tacrine and galantamine led to alpha1 frequency (7-9.5 Hz) changes in addition to the delta and alpha2 changes. These three drugs produced a nearly identical pattern of frequency changes. Theta (4.75-6.75 Hz) and beta1 frequencies (12.75-18.5 Hz) changed to a lesser degree. A peculiar finding arose with respect to the effects of the antagonistic drugs scopolamine and biperiden since biperiden-besides the massive increase of delta and alpha1 power in common-induced a general decrease of alpha2 frequencies within all brain areas opposite to the effect of scopolamine. This special property of biperiden gives a plausible explanation for its efficacy in Parkinsonian patients since decreases of alpha2 waves in this model indicate enhancement of dopaminergic transmission [Dimpfel, W., Spüler, M., Koch, R., Schatton, W., 1987. Radioelectroencephalographic comparison of memantine with receptor-specific drugs acting on dopaminergic transmission in freely moving rats. Neuropsychobiology 18, 212-218]. Except for the effects of methyllycaconitine (p<10%) all results were statistically significant at least at the p<5% level. The results are best explained by assuming that electrical delta activity reflects cholinergic transmitter control followed by and closely linked to changes in dopaminergic transmission as indicated by additional concomitant changes in alpha2 electrical power.

Alpha Rhythm↗
PubMedDate not supplied

Long-term EEG-video-audio monitoring: detection of partial epileptic seizures and psychogenic episodes by 24-hour EEG record review.

Twenty-seven patients with medically refractory paroxysmal disorders underwent EEG-video-audio (EVA) monitoring in an inpatient neurology-neurosurgery unit over 1-15 (mean 8.9) days. Fast visual review of all EEG records (5,784 h) and subsequent analysis of synchronized EVA patterns demonstrated a total of 208 partial epileptic seizures (ES) in 12 individuals and 87 psychogenic episodes (PE) in 15 subjects. Clinical ES lasted 83.3 s on the average and were most frequent from day 7 to 9 of monitoring (42.3%) and during sleep (56.4%). PE were longer in duration (mean 724.5 s), most numerous during the first 2 days of monitoring (41.4%), and occurred exclusively during wakefulness. Subjects with PE signaled (by pressing on a push button) more events (35.6%) than did the individuals with ES (27.9%). Multiple observers raised the proportion of alarms to 69.0% of PE compared to 39.9% of ES. Following the alarm, nurses reached the patients' bedside within a brief time (mean 22.2 s). To differentiate partial ES from PE or to establish the association of these disorders, EVA monitoring is best performed around the clock over a period of 1-2 weeks. The limited number of paroxysmal events, especially ES, signaled by the patients should be considered when designing studies of the effectiveness of pharmacologic, surgical, and other treatments.

Adolescent↗
PubMed1993

Restriction to a limited set of EEG-target variables may lead to misinterpretation of pharmaco-EEG results.

The number and types of target variables quantified from the spectrally analyzed EEG used in topographic pharmaco-EEG studies are still being discussed. Drug-induced changes of target variables obtained in the alpha frequency band--four absolute and four relative powers as well as three frequency measures--were utilized to assess the effects of xantinolnicotinate in demented patients using a parallel group design and the effects of buspirone in a double-blind, placebo-controlled crossover design. We conclude that for the proper evaluation of the different drug effects on the alpha activity, all these target variables should be considered. Descriptive p values of multiple comparisons within the framework of descriptive data analyses are important tools in interpreting drug effects.

Adolescent↗
PubMed1993

EEG, quantitative EEG, BAEP and ERP in centenarians.

In 11 healthy centenarians, the principal EEG and qEEG abnormalities were background frequency slower and power lower than in younger adults. The frequency and amplitude of anterior and posterior head regions on the EEG showed no difference, but qEEG demonstrated that posterior was higher than anterior. In 5 of 11 persons the frequencies of the temporal lobe were asymmetric. BAEP and ERP were measured in 6 persons. The latencies of I, III waves of BAEP were prolonged in only 1 subject. The latencies of exogenous components (P80, N100) of ERP were in the normal range. The latencies of endogenous components (N200, P300) of these 6 persons were prolonged, but in 1 person the N200 was normal and in 2 the P300 was normal.

Activities of Daily Living↗
PubMed1979

[Spectral analytical study on the developmental properties of EEG in children: variability of EEG in normal and mentally retarded children (author's transl)].

The present study aimed at clarifying the characteristics of variability of the resting arousal EEGs in normal and mentally retarded children. Their ages ranged from 3 to 15 years in 58 normal and from 7 to 18 in 63 retarded. The EEG was recorded monopolarly from six regions of the scalp. The data analysed by a multipurpose digital computer comprised auto-power spectra and a coefficient of variation of power at each frequency. The variability of power at peak within the theta frequency band in both groups of children showed a notably higher value as compared with other frequency bands in all regions. We discussed some of the problems of treating this variability of power as a general characteristic of theta waves or as a developmental one.

Adolescent↗
PubMed1978

[The mathematical rationale for the clinical EEG-frequency-bands. 1. Factor analysis with EEG-power estimations for determining frequency bands].

In order to determine whether the clinically used frequency bands of the EEG can also be obtained by a mathematical system we did a factor analysis with 480 EEG recordings, 5 minutes each, in 60 healthy male volunteers. A power spectrum analysis was done and 57 frequency bands between 1.5 and 30.0 Hz in a half Hz steps were calculated. The factor structure obtained made the following frequency bands (Hz) reasonable: deltaF = 1.5 - 6.0, thetaF = 6.0 - 8.5, alpha1F = 8.5 - 10.5, alpha2F = 10.5 - 12.5, beta1F = 12.5 - 18.5, beta2F = 18.2 - 21.0, beta3F = 21.0 - 30.0. Except for alpha1F all other 6 frequency bands were represented by one general factor with the complexity 1. The variance of the alpha1F band is explained by several of the 6 factors. The clinically known and the by factor analysis obtained frequency bands in the beta-range are similar. The clinically alpha-band is subdivided into two frequency bands alpha1F and alpha2F by the factor analysis. The clinically known border line between delta- and theta-band of 3.5 Hz cannot be found by factor analysis.

Adult↗
PubMedDate not supplied

[Sleep EEG as a nonlinear dynamic process: a comparison of global correlation dimension of human EEG and measures of linear interdependence between channels].

The goal of this work was to study (1) whether the estimation of correlation dimension (D2) using spatial embedding distinguishes between sleep stages and (2) whether information gained from the application of global D2 is redundant to measures of linear interdependence between channels. Twenty one-channel EEG segments of 12 healthy male subjects recorded during waking and sleep stages REM, I, II, and III-IV (according to the Rechtshaffen and Kales criteria) were analyzed with global (multichannel) D2, mean square correlation coefficients (MS) and proportion of variance accounted for by the first principal component (PC1). D2 was found to decrease progressively from stage I to stage III-IV with D2 values of waking and REM being close to those of stages I and II. MS and PC1 did not distinguish among sleep stages but yielded significant differences between waking and sleep. The results suggest that global D2 extracts information from human EEG. That sort of evidence cannot be obtained with measures of linear interdependence between channels.

Adolescent↗
PubMed1990

[An analysis of ictal EEGs by a newly developed ambulatory cassette EEG system].

We evaluated the efficiency of a newly developed cassette EEG recording device and our system for detecting and analyzing ictal EEGs in epileptic children. We got 13 ictal records from 16 epileptic children. We could precisely differentiate and diagnose their classifications of seizures by comparative analyses of ictal records and clinical symptoms. We discussed the characteristics of our system, and described actual analysis methods in 3 cases as examples. It was concluded that our system offered valuable information about ictal events in epileptic children.

Adolescent↗
PubMed1989

Mental retardation and EEG abnormalities in Waardenburg's syndrome: two case reports (EEG anomalies in Waardenburg's syndrome).

Waardenburg's Syndrome (WS), a rare disorder inherited as an autosomal dominant trait with variable penetrance, is characterized by white forelock, eye-ear symptoms and signs, and dysmorphic features. The authors describe two cases of WS with mental retardation and developmental and EEG anomalies. Therefore they suggest to perform an EEG in all suspected cases of WS.

Abnormalities, Multiple↗
PubMed1988

Intraoperative EEG monitoring: (I). Parametric representation of processed EEG during anesthesia.

One of the most common techniques of EEG monitoring during operations is to produce a three dimensional image by displaying the frequency distributions with respect to time as in compressed spectral array (CSA) and density-modulated spectral array (DSA). In order to characterize these images by numerical parameters, we defined two parameters; the percent spectral edge frequency as the frequency at which the one-sided-power sum reaches the designated percentage of the total; and the mean frequency as the power-weighted mean within the interval that includes a dominant spectrum in the frequency distribution. These parameters were superimposed on displays to characterize EEG changes, and they proved to be a very powerful tool to quantitate variations in data among anesthetic techniques and thus efficiently control the depth and duration of anesthesia. We report a number of actual cases.

Adult↗
PubMed1983

Interferon modifies EEG and EEG-like activity recorded from sensory, motor, and limbic system structures in freely behaving rats.

The finding of major interest in the present experiment is that interferon injection in normal animals modifies the EEG and EEG-like activity in all the structures examined independently (unsynchronized in time). The initial effects were observed in the hypothalamus followed by limbic, somatosensory, and motor structures, respectively. The effects observed were mainly increases in the amplitude of the dominant frequency and irregular spiking. The irregular change in the amplitude remained during the six hours of the recording sessions. Complete recovery was observed twenty-four hours after drug injection.

Albumins↗
PubMed1976

[Psychophysiological studies of EEG, operational performance and the dynamics of vigilance regulation. II. EEG activity and reactivity during tracking performance in a control loop with varying degrees of difficulty (author's transl)].

In ten male students the EEG occipital activity was recorded during a visuo-motor task consisting of pursuit-tracking. The degree of task difficulty varied systematically depending on the modification of the transfer function of control element dynamics. The EEG data were evaluated by serial spectral analysis. The distribution functions of the total power estimates and their minima and maxima reflect the dynamics of the regulation of cortical vigilance and permit to differentiate the degree of effort which corresponds to the varying degree of task difficulty. The study of task-irrelevant acoustically evoked potentials showed that with increasing cortical activation the amplitudes of N1-P2 and P2-N2 are diminished. These results might suggest that evoked potentials induced by task-irrelevant stimuli can serve as indicators of the neuronal capacity available for information processing that is not task-oriented.

Adult↗
PubMedDate not supplied

[The EEG characteristics and EEG toposelective mapping in patients with chronic suppurative otitis media before and after a sanitizing operation on the ear].

Spontaneous bioelectric activity of the brain was studied by means of EEG monitoring with toposelective EEG mapping in 45 patients with otitis media purulenta chronica before and after ear surgery. A correlation was found between the presentation of slow rhythms and the initial stage of otogenic intracranial complications in the examinees. This is an additional criterium for establishment of early diagnosis of local pachymeningitis.

Adolescent↗
PubMedDate not supplied

EEG power spectra and behavioral correlates in rats given chronic morphine. Lack of residual long-term EEG and neuronal changes.

The short-term (during tolerance to behavioural effects and withdrawal) and long-term (3, 6, 9 and 12 months after treatment) effects of morphine on mean total electroencephalographic spectral power (analysed by means of fast Fourier transform) and band distribution (delta, theta, alpha, beta) were studied in freely moving young rats implanted with chronic cortical bilateral recording electrodes. Morphine was administered i.p. daily for 1 month at weekly increasing doses of 20, 50, 100 and 200 mg kg-1, and the electroencephalogram was evaluated for 2 h at every change of dose. Treatment with 20, 50 and 100 mg kg-1 led to a significant increase in mean total spectral power 30-60 min from treatment. However, the dose of 100 mg kg-1 led to a smaller increase than that obtained with 50 mg kg-1 and no change was shown with the highest dose, suggesting the progressive development of tolerance. The modification observed for 100 mg kg-1 was accompanied by a relative increase in the delta and decrease in the theta and alpha power spectra. Between the last day of morphine and the first 3 days of abstinence, a progressive decrease in mean total spectral power accompanied by a significant increase in delta and beta and a decrease in theta and alpha frequency was observed. Long-term EEG activity and the counting of the pyramidal cells of the hippocampus failed to reveal any pathological findings after 3, 6, 9 and 12 months.

Analgesics, Opioid↗
PubMed1992

Typical absence seizures in adults: clinical, EEG, video-EEG findings and diagnostic/syndromic considerations.

Eighteen women and five men had typical absences. These included 10% of a consecutive hospital series of 200 adult patients with epileptic disorders. The absences began between the ages of seven and 46 years and varied in type and severity. Twenty patients also had generalised tonic-clonic seizures, ranging in frequency from one in a lifetime to one per month. Myoclonic jerks of the limbs occurred in 11 patients but were not associated with the absence attacks. Eyelid myoclonus consistently occurred with absence attacks in four patients and perioral myoclonus in two patients. Absence status occurred in five patients. Absence seizures were frequently unrecognised or misdiagnosed as complex partial seizures. Satisfactory control was achieved with sodium valproate. Electroencephalography, particularly video-electroencephalography, was invaluable in the diagnosis, but focal abnormalities in seven patients might have been erroneously interpreted as indicating partial seizures. This series showed that clinical and EEG manifestations are often syndrome-related and that there are more epileptic syndromes with typical absences than those presently recognised.

Adult↗
PubMed1998

Possible EEG sequelae of very long duration marihuana use: pilot findings from topographic quantitative EEG analyses of subjects with 15 to 24 years of cumulative daily exposure to THC.

In previous work we demonstrated and replicated a significant association between increased absolute and relative power and interhemispheric coherence of EEG alpha activity over the bilateral frontal-central cortex ("alpha hyperfrontality") in daily marihuana users as contrasted with nonusers. In this report we focused our analyses on subjects who reported smoking marihuana on a daily basis for 15 to 24 consecutive years. Compared to nonuser controls and subjects who had used marihuana on a daily basis for shorter periods of time, subjects with excessively long cumulative exposures to THC were found to have significantly elevated absolute power of theta activity over bilateral frontal-central cortex, as well as significantly increased interhemispheric coherence of theta activity across central and posterior regions. Concurrent reaction time studies conducted in our laboratory suggest that very long duration cumulative marihuana exposure might be associated with slowed cognitive processing.

Adult↗
PubMed1976

[Spectral analytical study on the developmental properties of EEG in children: Generalized and localized components of EEG spectra in the normal and the mentally retarded children (author's transl)].

The purpose of the present study was to elucidate the developmental properties of EEG in the normal and the mentally retarded children through regional differences and regional regional interrelationships. The localized components appearing at 1 or 2 regions tended to show low coherences in relation to the occipital region. The generalized component, observed over all regions, indicated lower coherences in the theta component than in the alpha one. It may be inferred that the theta component shown in the developing children may be differenciated from the component around 10 Hz.

Adolescent↗