PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “ELECTROENCEPHALOGRAPHY”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources

The tortoise and the love-machine: Grey Walter and the politics of electroencephalography.

The life of the pioneer electroencephalographer, William Grey Walter, initially appears to be a paradigmatic example of the process of network building and delegation identified by Michel Callon and Bruno Latour. In his professional career, Walter continually repositioned himself, moving from an unhappy beginning as an expert in the apparently unless and suspect technology of the EEG, to become a self-styled crucial mediator in subjects as diverse as medical diagnosis, forensic detection, marriage counseling, and international diplomacy. This position was achieved moreover through the construction and co-option of human and mechanical accomplices - laboratory assistants, electrical tortoises, and mechanical analyzers - which sustained his research and propagated his arguments. However in contrast to Callon and Latour's atomistic account of scientific power and agency, this paper will extend their analysis to explore the impact of network building and delegation on domestic life, human desire, and personal identity. Walter's engagement with the complexities of love and the human brain demonstrates how the transformative power of scientific rhetoric extends simultaneously into both the organization of the world and the subjectivity of the individual.

Electroencephalography↗

Electroencephalography, magnetic resonance imaging and pathology in patients treated surgically for temporal lobe epilepsy.

In a consecutive series of 40 patients selected by EEG studies for surgical treatment of temporal lobe seizures, magnetic resonance imaging showed structural lesions in 25% and signal abnormalities, usually in the mesial temporal region, in another 35%. Pathological changes included structural lesions in over 30% of patients and sclerosis of the amygdala in almost half of the series. These findings further substantiate the implication of the amygdala in the pathogenesis of temporal lobe seizures with automatism and amnesia.

Amygdala↗

Quantitative electroencephalography in late-onset schizophrenia.

BACKGROUND AND OBJECTIVES: A variety of electroencephalogram (EEG) abnormalities may occur in schizophrenics who had a typical onset of the disorder in early adulthood. The purpose of this study was to investigate EEG findings in patients with late-onset schizophrenia (onset of illness between ages 40 and 60). METHODS: Ten patients (one male, nine female, average age 52.8 years old) with late-onset schizophrenia underwent magnetic resonance imaging (MRI) of the brain and recording of quantitative EEG. RESULTS: MRI results for seven of the subjects were within normal limits and the other three showed nonspecific changes. Quantitative analysis of EEG variables revealed that for eight of the subjects, absolute power and relative power for the four EEG frequency bands, overall mean frequency, mean frequency for each of the EEG frequency bands, and interhemispheric coherence values did not vary significantly from a normative database of age-matched normal subjects. CONCLUSIONS: Results obtained to some degree replicate the single previous EEG study of late-onset schizophrenia. These findings suggest that the neurophysiological etiology and mechanism of late-onset schizophrenia may differ from that of schizophrenia with a typical age of onset, and that brain abnormalities are not an inevitable accompaniment to late onset of schizophrenia.

Adult↗

Quantitative electroencephalography (QEEG) and neuropsychological syndrome analysis.

The ideographic, syndrome analysis and the nomothetic, standardized test battery approaches to neuropsychological assessment are compared and contrasted within the context of advances in noninvasive technology readily available for use within the examiner's office. By demonstrating the relative strengths and benefits of syndrome analysis, it is suggested that this approach provides a thorough and efficient method of neuropsychological assessment. Subsequently, the utility of an a priori hypothesis testing process approach as a critical technique in syndrome analysis will be supported. It will be proposed that QEEG procedures provide a useful method for further substantiating conclusions generated from a syndrome analysis approach to neuropsychological assessment. Two cases are described demonstrating the utility and flexibility of the QEEG as a confirmatory test of localization following syndrome analysis. In summary, the contributions that neuropsychologists make to the understanding of brain-behavior relationships may be strengthened by combining neuropsychological and neurophysiological assessment methods.

Adult↗

Assessing attention deficit hyperactivity disorder via quantitative electroencephalography: an initial validation study.

Spectral analysis of the electrophysiological output at a single, midline prefrontal location (the vertex) was conducted in 482 individuals, ages 6-30 years old, to test the hypothesis that cortical slowing in the prefrontal region can serve as a basis for differentiating patients with attention deficit hyperactivity disorder (ADHD) from nonclinical control groups. Participants were classified into 3 groups (ADHD, inattentive; ADHD, combined; and control) on the basis of the results of a standardized clinical interview, behavioral rating scales, and a continuous performance test. Quantitative electroencephalographic (QEEG) findings indicated significant maturational effects in cortical arousal in the prefrontal cortex as well as evidence of cortical slowing in both ADHD groups, regardless of age or sex. Sensitivity of the QEEG-derived attentional index was 86%; specificity was 98%. These findings constituted a positive initial test of a QEEG-based neurometric test for use in the assessment of ADHD.

Adolescent↗

From single-channel recordings to brain-mapping devices: the impact of electroencephalography on experimental psychology.

Since its discovery in 1920, the electroencephalogram (EEG) has become a widely used tool in experimental psychology. Although originally the merits of the method were seen first of all in an improvement of medical diagnostics it was soon understood by psychologists that EEG can also be used to study psychic processes in healthy participants. This article summarizes important events in the history of EEG research that laid the ground for this development, as fast Fourier transformation to analyze the spontaneous activity and signal averaging to improve the signal-to-noise ratio. The article shows how general technological developments were the prerequisite for these methodological improvements in EEG research and how they inspired new research questions. Key discoveries that proved unequivocally that psychic processes do become manifest in EEG signals are briefly reviewed, and the emerging paradigm of cognitive psychophysiology, which is closely linked to the development of EEG research, is described.

Electroencephalography↗

Distinguishing a benzodiazepine agonist (triazolam) from a nonagonist anxiolytic (buspirone) by electroencephalography: kinetic-dynamic studies.

BACKGROUND AND OBJECTIVES: Benzodiazepine agonists and azaperone derivatives are used clinically as anxiolytics but have different neuroreceptor mechanisms of action. This study evaluated clinical pharmacodynamic approaches to distinguishing these two classes of compounds. METHODS: Healthy volunteers received single oral doses of placebo, the benzodiazepine agonist triazolam (0.25 mg) or the azaperone anxiolytic buspirone (20 mg), in a double-blind, three-way crossover study. Ratings of mood and sedation, performance on the digit symbol substitution test (DSST), and quantitative measures of electroencephalographic (EEG) beta activity (13 to 31.75 cycles/sec) determined by fast-Fourier transform were obtained at multiple times after dosage. RESULTS: Triazolam significantly increased self- and observer-rated sedation, impaired DSST performance, impaired recall, and increased EEG beta activity. Pharmacodynamic changes were significantly intercorrelated; all effects were maximal 1 to 2 hours after dosage but were indistinguishable from placebo by 8 hours. Buspirone did not alter the EEG or DSST performance but did increase self-ratings of sedation and feeling "spacey" and impaired memory function; these effects generally were quantitatively less than with triazolam. Peak plasma triazolam concentrations preceded maximum pharmacodynamic effects; the mean plasma effect site equilibration half-life was 9.4 minutes. Kinetic-dynamic modeling procedures yielded significant relationships between hypothetical effect site triazolam concentrations and pharmacodynamic changes. CONCLUSIONS: Quantitative analysis of the EEG clearly distinguishes a typical benzodiazepine agonist from a nonagonist anxiolytic, in clinically relevant dosage, whose pharmacodynamic actions do not involve benzodiazepine receptor occupancy. EEG effects associated with triazolam are intercorrelated with other pharmacodynamic measures.

Administration, Oral↗

Intracellular brain pH, indicator tissue perfusion, electroencephalography, and histology in severe and moderate focal cortical ischemia in the rabbit.

Intracellular brain pH and indicator tissue perfusion were measured with a lipid-soluble, pH-sensitive fluorescent indicator in 10 rabbits who had either severe or moderate focal ischemia depending on whether the middle cerebral artery was occluded at its main trunk or bifurcation. Preocclusion tissue indicator perfusion was 50.1 ml/100 g/min and intracellular brain pH was 7.03. In severe focal ischemia, immediate postocclusion tissue perfusion was 12.7 ml/100 g/min and intracellular brain pH was 6.64. Four hours after occlusion, the perfusion was 5.2 ml/100 g/min and intracellular brain pH was 6.08. There was EEG and histological confirmation of infarction. In the moderate focal ischemia group, immediate postocclusion flow was 20.0 ml/100 g/min and intracellular brain pH was 6.92. At 3 h, postocclusion tissue perfusion was 22.6 ml/100 g/min and intracellular brain pH was 6.86. Therefore, for the first 3 h, this ischemic penumbra was stable. At the fourth hour, both cerebral tissue perfusion and intracellular brain pH worsened. This suggests that the ischemic penumbra is a dynamic state. The rabbit is a good experimental model for the production of both severe and moderate focal ischemia.

Animals↗

Quantitative electroencephalography of medetomidine, medetomidine-midazolam and medetomidine-midazolam-butorphanol in dogs.

The purpose of this study was to evaluate the effects of the administration of an alpha2-adrenoceptor agonist alone and in combination with other derivatives on brain wave activity. In addition, the diagnostic values of the electroencephalogram (EEG) for judging the depth of the balanced anaesthesia with an alpha2-adrenoceptor agonist was evaluated. The treatments comprised 20 microg/kg medetomidine (Me-20), 80 microg/kg medetomidine (Me-80), 20 microg/kg medetomidine and 0.5 mg/kg midazolam (Me-Mi) administered intramuscularly, and 20 microg/kg medetomidine with 0.5 mg/kg midazolam and 0.1 mg/kg butorphanol (Me-Mi-Bu). The EEG was recorded continuously at pre-administration, and at 7, 10, 20, 30, 45 and 60 min after administration. The recorded data were analysed by separating the power spectrum into 1-3, 4-7, 8-13 and 14-30 Hz bands. Spectral-edge analysis was used to calculate the spectral edge frequency 90 (SEF90) and the median edge frequency (MEF). Time-related changes in power spectrum analysis showed a significant increase in the Me-80 group in the 1-3 Hz band. The power for 1-3 Hz in the Me-80 group was significantly higher than in all the other groups. In the 14-30 Hz band, there was a significant reduction of power in all groups following administration of the agents. The SEF90 frequencies were significantly reduced in all groups except for the Me-20 group after administration of the agents. The SEF90 frequencies in the Me-20, Me-Mi and Me-Mi-Bu were all significantly higher than those in the Me-80 group. However, there was no significant difference between the Me-20, Me-Mi and Me-Mi-Bu groups in any analyses. Our results demonstrated that the changes in quantitative EEG made by the Me-Mi-Bu and Me-Mi groups were similar to those made by Me-20 groups. Present results suggest that the EEG should be interpreted with caution in assessing the anaesthetic level in balanced anaesthesia in dogs.

Adrenergic alpha-Agonists↗

Correlation between electroencephalography and heart rate variability during sleep.

It is known that autonomic nervous activities change in correspondence with sleep stages. However, the characteristics of continuous fluctuations in nocturnal autonomic nerve tone have not been clarified in detail. The study aimed to determine the possible correlation between the electroencephalogram (EEG) and autonomic nervous activities, and to clarify in detail the nocturnal fluctuations in autonomic nerve activities. Overnight EEGs and electrocardiograms of seven healthy males were obtained. These EEGs were analyzed by fast Fourier transformation algorithm to extract delta, sigma and beta power. Heart rate and heart rate variability (HRV) were calculated in consecutive 5-min epochs. The HRV indices of low frequency (LF), high frequency (HF) and LF/HF ratio were calculated from the spectral analysis of R-R intervals. The sleep stages were manually scored according to Rechtschaffen and Kales' criteria. Low frequency and LF/HF were significantly lower during non-rapid eye movement (NREM) than REM, and were lower in stages 3 and 4 than in stages 1 and 2. Furthermore, delta EEG showed inverse correlations with LF (r = - 0.44, P < 0.001) and LF/HF (r = - 0.41, P < 0.001). In contrast, HF differed neither between REM and NREM nor among NREM sleep stages. Detailed analysis revealed that correlation was evident from the first to third NREM, but not in the fourth and fifth NREM. Delta EEG power showed negative correlations with LF and LF/HF, suggesting that sympathetic nervous activities continuously fluctuate in accordance with sleep deepening and lightening.

Adult↗

Electroencephalography in juvenile neuronal ceroid lipofuscinosis: visual and quantitative analysis.

Fourteen patients with a confirmed diagnosis of juvenile neuronal ceroid lipofuscinosis (JNCL) (aged 6-12.5 years at the beginning of the study) were prospectively followed for 5 years. An electroencephalogram (EEG) was recorded and analysed both visually and quantitatively and a neuropsychological examination was performed once a year. In addition, a cross-sectional EEG study of 32 patients aged 5-27 years was performed. The EEG was often normal before the age of 9 years, and thereafter a progressive background abnormality and increase in paroxysmal activity took place. The EEGs were significantly slower than those of the controls, and the speed of slowing of EEG correlated to the decrease in intelligence quotients (IQ). Quantitative analysis was superior to visual analysis in detecting the deterioration of the background activity. The best parameter describing this was the fast/slow ratio. Peak frequency, percentage of theta and the fast/slow ratio correlated with IQ.

Adolescent↗

[Topographic electroencephalography: endotracheal intubation during anaesthesia with propofol/fentanyl].

OBJECTIVE: We used quantitative analysis of the electroencephalogram (EEG) during routine clinical practice to assess the effect of tracheal intubation following induction of anesthesia with propofol and fentanyl. METHODS: The topographic EEG was recorded from eight bipolar electrode derivations in 25 patients. Z-scores relative to age expected normative data were computed for relative power in the delta, theta, alpha and beta frequency bands. Multivariate statistics (Hotellings' t-sqare) were used to evaluate changes in regional brain electrical activity. RESULTS: Tracheal intubation induced an increase in alpha and beta frequencies, while delta power was reduced (F-values: Delta: 7.68, p = 0.011; Alpha 31.93; p < 0.001; Beta 12.85, p = 0.001). The most pronounced regional effect was seen for the alpha frequency band with the largest increase in both fronto-temporal regions (F-value 33.89, p < 0.001). During clinical practice the patients received propofol 2.7 (+/- 1.2; minimum: 0.5, maximum 6.9) mg kg (- 1) and fentanyl 2 (+/- 1; minimum 1, maximum 4) microg kg (- 1). Vital parameters did not change during intubation. CONCLUSION: Individual titration of the dose of propofol and fentanyl as done during routine clinical practice is not sufficient to block the strong noxious stimulation of intubation. Tracheal intubation resulted in "classical" cortical arousal. It remains open whether this cortical wake-up phenomenon has a clinical impact.

Adult↗