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At least 217 records · Page 12Linked to original sources
PubMed2000

[Electroencephalography inverse problem by subspace decomposition of the fourth-order cumulant matrix].

It is an important topic in electroencephalography (EEG) research to localize the EEG activity sources from the scalp recordings. In this paper, based on the fourth-order cumulant matrix, a new sub-space decomposition algorithm is proposed for the EEG inverse problem. As the second-order moments (cumulants) has the drawback of being sensitive to the noise covariance. Using the fourth-order cumulants we need not know the noise covariances, as long as the noise is Gaussian. Computer simulation study on a three-layer concentric sphere head model shows its better performance than the two-order cumulate method in depressing the spatial coherent Gaussian noise.

Algorithms↗
PubMed2002

Pharmaco-electroencephalography and pharmacokinetic/pharmacodynamic modeling in basic research: focus on human pharmacology.

Pharmacokinetic/pharmacodynamic modeling, together with electroencephalography (EEG), have been successfully applied to obtain in vivo pharmacological information of different drugs acting on the central nervous system (CNS) in humans and of the systems with which the drugs interact. Almost all types of variables used to assess the activity of drugs in the human CNS have already been applied in pharmacokinetic/pharmacodynamic research. However, compared with more traditional approaches to quantify the pharmacodynamics of neuropsychotropic drugs, the EEG method has the advantage of being objective, sensitive, continuous and reproducible. The present review focuses mostly on benzodiazepine pharmacology. A selection of some basic aspects that can be covered using pharmaco-EEG and pharmacokinetic/pharmacodynamic modeling from in vivo studies performed in humans in pharmacological research will be introduced: i) determination of the pharmacological characteristics of a compound; ii) comparison of potencies among drugs; iii) comparison of efficacy among drugs; iv) tolerance development; v) metabolite role; vi) enantiomers; vii) drug-drug interactions; viii) circadian rhythms; ix) factors affecting the observed effect; and x) the gain of physiopathological information about the systems with which drugs interact. Looking at the quantity and quality of the results obtained for the benzodiazepines, pharmacokinetic/pharmacodynamic modeling using EEG measures appears to be an ideal tool, and is potentially useful for other drugs acting on the CNS.

Benzodiazepines↗
PubMed2002

Combination of magneto- and electroencephalography in studies of monoamine modulation on attention.

The brain monoamines serotonin and dopamine have an important role in the regulation of human cognitive functions. Neural correlates of attention can be studied in millisecond resolution with magnetoencephalography (MEG) and electroencephalography (EEG), which provide complementary views on attentional processing. During "selective attention", a processing negativity (PN) overlaps EEG response to the attended tones. This component can be modulated with drugs affecting dopamine transmission in the brain, such as haloperidol and droperidol, whereas no effects seem to be caused by acute tryptophan depletion (ATD), decreasing serotonin synthesis in the brain. Distinct responses are associated with "involuntary attention". Responses reflecting sound-change detection and initiation of involuntary attention, the mismatch negativity and its magnetic counterpart, appear to be modulated by ATD, but not with haloperidol. Subsequent P3a elicited by actual attention shifting, as well as reorienting negativity reflecting orienting back to a relevant task, are in turn decreased by haloperidol, but not affected by ATD or other serotonin modulators. Serotonin may affect the earliest "preattentive" phases on auditory processing, indexed by mid-latency magnetic responses and NIm, but haloperidol's effects on these parameters are insignificant. Taken together, serotonin and dopamine may have differential effects on attentional processing depending on time after stimulus presentation.

Attention↗
PubMed1992

Spectral analysis of electroencephalography data in athletes with low erythrocyte magnesium.

In a population of high level athletes (kayakists) we compared quantitative electroencephalography data in those with low erythrocyte (magnesium magnesium deficit) and those with normal magnesium (controls). Logistic regression showed that the relative power of the alpha frequency band in the occipital lead is the most discriminant (P < 0.05). There was a significant positive correlation between low erythrocyte magnesium and alpha relative power (P < 0.05). An alteration of magnesium homeostasis could explain the occurrence of magnesium deficiency in athletes.

Adult↗
PubMed1992

Simultaneous use of rheoencephalography and electroencephalography for the monitoring of cerebral function.

Many of the changes in human performance under stress or in hazardous environments may be attributed, in part, to altered cerebral functions. These changes may take place in either the cerebral neurologic or cerebral circulatory systems. Investigation of the interaction between intracranial blood flow and neural activity during these exposures would provide a better understanding of the human response to these conditions. Experimental and analytical procedures are described whereby the combination of rheoencephalography (REG) and electroencephalography (EEG) may provide additional information during the study of cerebral function. Examples are given to demonstrate the simultaneous use of these techniques during mental arithmetic and antiorthostatic bed rest. Results of these tests in both the time and frequency domains show that REG and EEG can be used to provide graded quantitative measures of cerebral responses to externally applied stressors.

Cerebrovascular Circulation↗
PubMed1992

Electroencephalography.

Recent advances in electroencephalography (EEG) research are presented. Particular emphasis is placed on sleep and epilepsy research in humans. In this context, among others, studies on the modifications of EEG epileptic activity during sleep are discussed in more detail. A large number of reports come from EEG monitoring during presurgical evaluation and surgical treatment of drug-resistant epilepsy; information provided by these studies is therefore considered with special attention.

Brain↗
PubMedDate not supplied

Effects of citicholine in subcortical dementia associated with Parkinson's disease assessed by quantified electroencephalography.

Two groups of patients with idiopathic Parkinson's disease underwent quantified electroencephalography (EEGq) using fast Fourier transfer to assess the effects of treatment with citicholine. Evidence of cortical cognitive impairment was seen in one group but not in the other. Certain parameters were established which enabled the two groups to be distinguished by examining specific EEGq indices. Specifically, differences were found in the overall potentials of the delta and alpha bands, in the alpha/theta index, in posterior activity, in the anteriorization index of the delta and alpha rhythms, and in the spatialization index of the alpha rhythm. The implications of these differences in the potential involvement of the frontal lobes in subcortical dementia in Parkinson's disease are discussed.

Aged↗
PubMed2002

Quantitative electroencephalography: preliminary report--tinnitus.

This preliminary report is an account of 21 consecutive patients who had tinnitus of the severe disabling type and were examined with quantitative electroencephalography (QEEG). A multimetric analysis of the raw data was highlighted by an abnormal incidence of significant central nervous system electrical dysfunction identified in each patient (21 of 21). Relative power was increased or decreased in the temporal region in 10 of 21 patients. Relative power was reported to be increased or decreased in temporal frontal regions in 20 of 21 patients. Coherence irregularity was identified in all 21 patients. QEEG preliminary data support the hypothesis of a final common pathway for tinnitus and the significant role of the temporal and temporofrontal regions of interest in patients with tinnitus of the severe disabling type. QEEG with multimetric analysis is considered a significant addition to the medical audiological tinnitus patient protocol as one of a battery of electrophysiological tests for the clinical identification of a predominantly central type of tinnitus.

Adult↗
PubMedDate not supplied

[A semiconductor photostimulator for electroencephalography with USB control].

The paper contains a description of electroencephalography (EEG) photostimulator for examining the induced cerebral potentials. The device was designed to function within the EEG computer complexes; a high-intensity irradiation LED matrix is used as the light source. The 1.1 USB control bus serves as the communication interface; there is an extra external synchronization bus. It is possible to preset the frequency, brightness, on-off time ratio and pattern of light stimuli. A library of application programmer is supplied to monitor the photostimulation.

Electroencephalography↗
PubMed2005

[Evaluation of electroencephalography grading standard in severe cerebrovascular disease].

OBJECTIVE: To compare the prognostic value of different electroencephalography (EEG) grading standards of cerebral dysfunction after cerebrovascular diseases. METHODS: The EEG of all the 40 patients who suffered from acute cerebrovascular disease of the cerebral hemisphere were recorded continuously, and three different EEG grading standards (Lavizzari, Synek and Young) were analyzed and compared. RESULTS: All three different EEG grading standards showed significant correlation with outcome (all P<0.001), i. e. the higher the EEG grade was, the poorer the outcome was. Logistic regression showed that the Synek standard was the best for survival rate and comprehensive prognostic accuracy (90.9%, 89.2%, respectively), Young standard (81.8%, 83.8%) was lower than Synek standard in predicting accuracy but higher than Lavizzari standard (75.%, 80.% respectively). CONCLUSION: The EEG grading standard of Synek might well reflect the cerebral dysfunction and appear to be a reliable predictor for outcome.

Adult↗
PubMed1992

The experience with electroencephalography at the Kenyatta National Hospital, Nairobi.

Review of electroencephalography (EEG) requests at KNH over a 3 year period is presented. Majority of patients were aged between 0 and 10 years. None was older than 80 years. The epilepsies were the commonest reason for requesting EEG (58.5%). SSPE had the highest positivity rate of 91.7% followed by convulsive states of uncertain aetiology. The symptom of headache by itself was the least rewarding to study by EEG. It was more rewarding to first attempt to make a diagnosis of the headache. Hysteria had an EEG positivity rate of 40%, most of them being epilepsy. EEG picture for petit-mal, epilepsy focal seizure and generalized seizures are included in the text.

Adolescent↗
PubMedDate not supplied

Electroencephalography and magnetic resonance imaging in neurological decompression sickness.

The purpose of this study was to evaluate the use of electroencephalography (EEG) and magnetic resonance imaging (MRI) in the clinical evaluation of acute decompression sickness (DCS) in the central nervous system (CNS). Twenty-one patients treated because of acute DCS in the CNS during 1999-2001 were included, 15 patients with clinical cerebral DCS and five with clinical spinal cord DCS. Seven patients had abnormalities in their EEG, five with cerebral DCS and two with spinal cord DCS. MRI showed high intensity lesions in the spinal cord in four patients with clinical spinal cord DCS and in one with clinical cerebral DCS. Cerebral lesions were not identified by MRI in any patient. In conclusion, EEG showed unspecific abnormalities in only one third of the cases. Conventional MRI with a 1.5 T scanner may be of help in the diagnosis of DCS in the spinal cord, but not in the brain. EEG and MRI have low sensitivity in the diagnosis of acute DCS in the CNS. Recompression treatment of DCS should still be guided by clinical neurological examination and assessment of symptoms.

Adolescent↗
PubMed2006

Amplitude-integrated electroencephalography in full-term newborns without severe hypoxic-ischemic encephalopathy: case series.

AIM: To assess the diagnostic value of amplitude-integrated electroencephalography (EEG) in comparison to standard EEG in newborns without severe hypoxic-ischemic encephalopathy who were at risk for seizures. METHODS: The study included a consecutive series of 18 term newborns without severe hypoxic-ischemic encephalopathy, but with clinical signs suspicious of epileptic seizures, history of loss of social contact, disturbance of muscle tone, hyperirritability, and/or jitteriness. Amplitude-integrated and standard EEG tracings were assessed for background pattern, epileptiform activity, and sleep-wake cycling. RESULTS: Amplitude-integrated EEG and standard EEG recordings of 15 newborns were suitable for analysis. Only two different background patterns were seen on amplitude-integrated EEG and standard EEG, with the absence of severely abnormal background patterns. Of 15 newborns, epileptiform discharges were present on amplitude-integrated EEG in 3 newborns, and on standard EEG in 6 newborns. Sensitivity of seizures discharges on amplitude-integrated EEG to correspond with epileptiform discharges on standard EEG was 50%; specificity 100%,positive predictive value 100%, and negative predictive value 75%. Of 4 newborns suspected of having sleep myoclonus, amplitude-integrated EEG correctly identified the newborn who had epileptiform activity on standard EEG. CONCLUSION: The diagnostic value of amplitude-integrated EEG monitoring of term newborns without severe hypoxic-ischemic encephalopathy is limited, but could have a role in evaluating presence or absence of epileptiform activity and in differentiating non-epileptic movement from seizures.

Electroencephalography↗
PubMed2006

[A review on measurement of craving of drug addicts and its relationship with electroencephalography].

Craving of drug addicts for drugs is the most important factor that causes relapse. On-line, objective and quantificational measurement of craving is of certain value in predicting relapse and drug-seeking behavior of addicts. Some common methods used to measure craving are reviewed and their shortcomings are analyzed. Aiming at characteristics, analysis methods, typical application of electroencephalography (EEG) and characteristics of craving, we have a discussion about the possibility of using EEG to measure craving. In addition, some related problems and difficulties are probed. These analyses are helpful to the study of craving.

Behavior, Addictive↗
PubMed2006

[Effects of electro-acupuncture on electroencephalography in patients with vascular dementia].

OBJECTIVE: To study the effects of electro-acupuncture (EA) on electroencephalography (EEG) in vascular dementia (VD) patients. METHODS: According to the Hasegawa dementia scale (HDS), the severity of 46 VD patients were classified into three grades as gentle, medium and severe, in the same time, they were divided into the EA group (n = 23) and the nimotop group (n = 23) randomly. Changes of EEG in the patients were observed before and after treatment. RESULTS: The degree of normality of EEG in VD patients were positively correlated with the severity of their illness, i. e. the severer VD, the more obvious the abnormal EEG changes. CONCLUSION: EEG can be accessible for evaluating the severity of VD, and the electrical activity of brain in VD patients could be improved by EA therapy.

Acupuncture Therapy↗
PubMed2006

[Effect of electroacupuncture on bispectral index of electroencephalography in patients undergoing subtotal thyroidectomy].

OBJECTIVE: To investigate the effects of electroacupuncture on bispectral index (BIS) of electroencephalography in patients undergoing subtotal thyroidectomy. METHODS: Sixty patients were equally randomized into group A given electroacupuncture combined with cervical plexus block (CPB) and group B given CPB alone. After needling sensation was reached in bilateral "Hegu" and "Neiguan" acupoints, 5 min of high frequency electrical stimulation by electrical stimulation device followed with CPB was applied to group A, while only CPB was performed in group B. Visual analog scale (VAS) and verbal stress scale (VSS) were monitored, complication and adverse reaction were observed and BIS, mean arterial pressure (MAP), heart rate (HR) and arterial oxygen saturation (SaO2) were monitored continuously in the perioperative period. RESULTS: HR increased and BIS decreased in group A, both were lower significantly than those in group B (P < 0.01); MAP, the complementary dosage of fentanyl and lidocaine used and scores of VAS and VSS were also lower in group A than those in group B (P < 0.01). CONCLUSION: Electroacupuncture could enhance the anesthetic effect of CPB, lower the BIS value during subtotal thyroidectomy.

Acupuncture Analgesia↗
PubMedDate not supplied

[Frontal lobe involvement and cortical and subcortical deterioration in Parkinson's disease evaluated using quantified electroencephalography].

Quantified electroencephalography (EEGq) by means the Fast Fourier Transformed system (FFT) was carried out on two groups of patients with idiopathic Parkinson's Disease (PD). The first one was with symptoms of cortical deterioration, and the second group consisting of subjects without signs of cortical impairment. The study of the specific EEGq indices has led to the establishment of parameters which establish differences between these two groups. Specifically, a difference has been found with regard to the total potentials of delta and alpha frequency bands; alpha/theta index; posterior activities; changes in the lobular antero-posterior of delta and alpha rhythms; and in the distribution of the spatialization index of alpha rhythm. We discuss the implications of this electrophysiological differentiation between the two groups, regarding the possible frontal lobe affection in the subcortical dementiation of the Parkinson's disease.

Aged↗