Quantitative Electroencephalographic Analysis Research Articles

A comparative study of automatic techniques for ocular artifact reduction in spontaneous EEG signals based on clinical target variables: A simulation case

Eye movement artifacts represent a critical issue for quantitative electroencephalography (EEG) analysis and a number of mathematical approaches have been proposed to reduce their contribution in EEG recordings. The aim of this paper was to objectively and quantitatively evaluate the performance of ocular filtering methods with respect to spectral target variables widely used in clinical and functional EEG studies. In particular the following methods were applied: regression analysis and some blind source separation (BSS) techniques based on second-order statistics (PCA, AMUSE and SOBI) and on higher-order statistics (JADE, INFOMAX and FASTICA). Considering blind source decomposition methods, a completely automatic procedure of BSS based on logical rules related to spectral and topographical information was proposed in order to identify the components related to ocular interference. The automatic procedure was applied in different montages of simulated EEG and electrooculography (EOG) recordings: a full montage with 19 EEG and 2 EOG channels, a reduced one with only 6 EEG leads and a third one where EOG channels were not available. Time and frequency results in all of them indicated that AMUSE and SOBI algorithms preserved and recovered more brain activity than the other methods mainly at anterior regions. In the case of full montage: (i) errors were lower than 5% for all spectral variables at anterior sites; and (ii) the highest improvement in the signal-to-artifact (SAR) ratio was obtained up to 40 dB at these anterior sites. Finally, we concluded that second-order BSS-based algorithms (AMUSE and SOBI) provided an effective technique for eye movement removal even when EOG recordings were not available or when data length was short.

Sleep Quality and the Sleep Electroencephalogram in Women with Severe Premenstrual Syndrome

Women with severe premenstrual syndrome (PMS) or premenstrual dysphoric disorder (PMDD) commonly report sleep disturbances, but the few studies using conventional polysomnographic measures have produced conflicting results. We investigated sleep quality and sleep composition using conventional and quantitative electroencephalographic analyses in women with severe PMS, as compared with that of controls. Women (aged 18-40 years) were screened to ensure that their PMS symptoms were severe and that they had ovulatory menstrual cycles. Nine women with PMS or PMDD and 12 asymptomatic control subjects then had laboratory-based polysomnographic recordings at 2 phases of the menstrual cycle: follicular phase and late luteal (premenstrual) phase. Women with severe PMS reported a significantly poorer subjective sleep quality during the late luteal phase (P = 0.02), but there was no evidence of disturbed sleep based on the polysomnogram specific to premenstrual symptom expression: both groups of women had increased wakefulness after sleep onset (P = 0.02) and increased sigma power (P < 0.01), especially in the 14-to 15-Hz band during non-rapid eye movement sleep, in the late luteal phase compared with the follicular phase. There were, however, some group differences in electroencephalographic measures regardless of menstrual phase, including decreased delta incidence (P = 0.02) and increased theta incidence and amplitude (P < 0.05) in women with PMS, suggesting the possibility of sleep electroencephalogram trait markers in women with PMS. Perceived poor quality sleep is a characteristic of severe PMS, but sleep composition based on polysomnographic measures and quantitative electroencephalographic analysis does not differ in association with premenstrual symptom expression in the late luteal phase.

Bcl-w Protects Hippocampus during Experimental Status Epilepticus

Experimentally evoked seizures can activate the intrinsic mitochondrial cell death pathway, components of which are modulated in the hippocampus of patients with temporal lobe epilepsy. Bcl-2 family proteins are critical regulators of mitochondrial dysfunction, but their significance in this setting remains primarily untested. Presently, we investigated the mitochondrial pathway and role of anti-apoptotic Bcl-2 proteins using a mouse model of seizure-induced neuronal death. Status epilepticus was evoked in mice by intra-amygdala kainic acid, causing cytochrome c release, processing of caspases 9 and 7, and death of ipsilateral hippocampal pyramidal neurons. Seizures caused a rapid decline in hippocampal Bcl-w levels not seen for either Bcl-2 or Bcl-xl. To test whether endogenous Bcl-w was functionally significant for neuronal survival, we investigated hippocampal injury after seizures in Bcl-w-deficient mice. Seizures induced significantly more hippocampal CA3 neuronal loss and DNA fragmentation in Bcl-w-deficient mice compared with wild-type mice. Quantitative electroencephalography analysis also revealed that Bcl-w-deficient mice display a neurophysiological phenotype whereby there was earlier polyspike seizure onset. Finally, we detected higher levels of Bcl-w in hippocampus from temporal lobe epilepsy patients compared with autopsy controls. These data identify Bcl-w as an endogenous neuroprotectant that may have seizure-suppressive functions.

Sleepwalking, a disorder of NREM sleep instability

Background and purpose Thirty-two chronic sleepwalkers who were part of a larger, previously reported sleepwalking group all achieved control of sleepwalking after undergoing treatment for an associated sleep disorder. In the current study, all records were blindly scored to perform a cyclic alternating pattern (CAP) analysis. Patients and methods Thirty-two young adult chronic sleepwalkers had polysomnography (PSG) on initial nights without sleepwalking events, as did age-matched normal controls and patients with mild sleep-disordered breathing (SDB). More than 90% of these patients with mild SDB had upper airway resistance syndrome (UARS). Ten randomly selected PSGs for sleepwalkers and matched controls also had quantitative electroencephalographic (EEG) analysis using Fast Fourier Transformation (FFT) with determination of delta power for each non-rapid eye movement (NREM)–REM sleep cycle. Results Compared to normal controls, an investigation of CAP in sleepwalkers demonstrated the presence of an abnormal CAP rate with a decrease in phase A1 and an increase in phases A2 and A3 on non-sleepwalking nights. The results of CAP analysis in sleepwalkers were similar to those obtained in age-matched UARS patients. Furthermore, the analysis of the first four NREM–REM sleep cycles reconfirmed the presence of an important decrease in delta power in sleep cycles 1 and 2 during a non-sleepwalking night in sleepwalkers compared to normal controls. Conclusions The presence of both ‘hypersynchronous slow delta’ and ‘burst of delta waves’ have been reported in sleepwalkers, but their significance is controversial. These EEG patterns are similar to phase A1 (and possibly A2) of the CAP. Proper analysis of the sleep EEG of sleepwalkers should integrate CAP analysis. Sleepwalkers on a non-sleepwalking night present instability of NREM sleep, as demonstrated by this analysis. This instability is similar to the one noted in UARS patients. Subtle sleep disorders associated with chronic sleepwalking constitute the unstable NREM sleep background on which sleepwalking events occur. A subtle associated sleep disorder should be systematically searched for and treated in the presence of sleepwalking with abnormal CAP.

Predictive Model for Assessing Cognitive Impairment by Quantitative Electroencephalography

To assess the utility of quantitative electroencephalographic analysis as an indicator of cognitive impairment, we examined the correlation between Mini-Mental State Examination (MMSE) scores and quantitative electroencephalographic (QEEG) power values in elderly patients and constructed a regression model to predict MMSE scores. Because of the growing number of elderly individuals with cognitive deficits, there is an increasing need for simple and objective methods with which to evaluate cognitive function. Although QEEG is reportedly a useful method for this purpose, few researchers have constructed a QEEG-based model for predicting the degree of cognitive impairment in clinical settings. We evaluated brain function using QEEG in 44 elderly patients with memory complaints and compared the results with their MMSE scores. In the correlation analysis, no significant correlation was found between MMSE scores and QEEG power values. However, a regression model created using relative QEEG and gender for predicting MMSE scores had an adjusted R2 of 0.471. This finding suggests that QEEG analysis may be a useful indicator of cognitive decline in patients with memory complaints.

Relationship Between Brain Glucose Metabolism Positron Emission Tomography (PET) and Electroencephalography (EEG) in Children With Continuous Spike-and-Wave Activity During Slow-Wave Sleep

We studied the relationship between brain glucose metabolism patterns and objectively measured interictal epileptiform abnormalities in six children with intractable epilepsy and continuous spike-and-wave activity during slow-wave sleep. Five of the six patients showed lateralized positron emission tomographic (PET) findings, with the hemisphere showing a relative increase in glucose metabolism concordant with the presumed origin of the generalized interictal spike activity delineated by quantitative electroencephalographic (EEG) analysis. One of these five patients achieved seizure freedom following cortical resection involving the areas of unilateral multifocal hypermetabolism, and another patient has been approved for cortical resection. The results in the present study add further support to the hypothesis that the generalized spike-waves in most cases of continuous spike-and-wave activity during slow-wave sleep are the result of secondary bilateral synchrony. Resective surgery can be effective in selected patients with uncontrolled seizures associated with continuous spike-and-wave activity during slow-wave sleep provided that there is concordance between focal abnormalities on PET and EEG.

Changes in cortical electrical activity during induction of anaesthesia with thiopental/fentanyl and tracheal intubation: a quantitative electroencephalographic analysis

There are regional differences in the effects of anaesthetics agents and perioperative stimuli on the EEG. We studied the topography of the EEG during induction of anaesthesia and intubation in patients receiving thiopental and fentanyl to document regional electrical brain activity. EEG was recorded in 25 patients in the awake state, after pre-medication, during induction, at loss of consciousness and after intubation. Eight bipolar recordings were made and the relative power of the frequency bands delta, theta, alpha, and beta were used (after z-score transformation for age) to measure changes in regional EEG activity. Noxious stimulation during tracheal intubation partially reversed the slowing of the EEG caused by anaesthesia. During induction of anaesthesia alpha activity was most reduced in temporal and occipital regions. The most prominent EEG changes after intubation were an increase in alpha and a decrease in delta power (P<0.001). The largest changes were in the frontal and temporal leads for alpha and in the frontal and central leads for delta. Heart rate and arterial pressure remained constant during intubation. Changes in alpha and delta power were identified as the most sensitive EEG measures of regional changes in electrical brain activity during anaesthesia and noxious stimulation.

Waking quantitative electroencephalogram and auditory event-related potentials following experimentally induced sleep fragmentation.

Experimental sleep fragmentation involves inducing arousals by administering intrusive auditory stimuli throughout the night. It is intended to model the frequent and periodic disruption experienced in common sleep disorders. Sleep fragmentation leads to daytime sleepiness, although evidence of performance impairment has been inconsistent. The purpose of this study was to investigate brain physiology associated with this level of sleep disruption. Specifically, quantitative analysis of electroencephalography was carried out, and auditory event-related potentials were recorded during daytime performance assessment following sleep fragmentation in good sleepers. Participants spent 4 consecutive 24-hour periods in the laboratory. On nights 2 and 3, sleep was fragmented using auditory stimuli that were delivered with increasing intensity until an arousal was noted. This design aimed to investigate the cumulative effects of sleep fragmentation on daytime functioning. Data were collected in a sleep research laboratory during a 96-hour protocol. Eight healthy adults (mean age = 33.25) with no sleep complaints. During the day, participants performed a 40-minute computerized test battery at 2-hour intervals (9:00 am -7:00 pm). The battery was presented in a fixed order and included measures of mood, sleepiness, reaction time, and serial addition or subtraction. Results indicated that subjective sleepiness and mood were impaired following sleep-fragmentation nights, compared to both baseline and recovery conditions. No performance deficits were apparent. The alpha:theta ratio, reflecting relative slowing of the electroencephalogram, was dramatically reduced following the second night of sleep fragmentation. Reductions in N1 amplitude of the event-related potentials indicated that attention was impaired with respect to early encoding processes following sleep fragmentation. Electroencephalographic and event-related potentials data illustrate impairment in information-processing capabilities associated with reduced arousal elicited by experimental sleep fragmentation. This subtle degree of sleep disruption, where total sleep time is not reduced, leads to sustained impairment in alertness and attention.

Parametric and Non-Parametric Analysis of QEEG: Normative Database Comparisons in Electroencephalography, a Simulation Study on Accuracy

SUMMARY Quantitative electroencephalography (QEEG) as a tool for the diagnosis of neurological and psychiatric disorders is receiving increased interest. While QEEG analysis is restricted to the scalp, the recent development of electromagnetic tomography (ET) allows the study of the electrical activity of all cortical structures. Electrical measures from a patient can be compared with a normative database derived from a large sample of healthy individuals. The deviance from the database norms provides a measure of the likelihood that the patient's electrical activity reflects abnormal brain functioning. The focus of this article is a method for estimating such deviance. The traditional method based on z-scores (parametric) is reviewed and a new method based on percentiles (non-parametric) is proposed. The parametric and the non-parametric methods are compared using simulated data. The accuracy of both methods is assessed as a function of normative sample size and gaussianity for three different alpha leve...

Comparison of QEEG Reference Databases in Basic Signal Analysis and in the Evaluation of Adult ADHD

SUMMARY Introduction. Despite the relatively widespread investigation of potential quantitative electroencephalographic (QEEG) characteristics of childhood attention deficit hyperactivity disorder (ADHD), relatively little is known about the possible QEEG characteristics of adult ADHD. In addition to general magnitude or power measures, or ratios of these measures, the additional analyses and comparisons provided by QEEG reference databases may prove useful in providing unique markers for adult ADHD. Method. This investigation reports the findings of evaluations using three QEEG reference databases for a sample of ten adults previously diagnosed with ADHD. The packages used in the current investigation included the NeuroRep QEEG Analysis and Report System, the SKIL Topometric QEEG software package, and the NovaTech EEG EureKa3! QEEG analysis package. Results. As compared with the respective databases, adults with ADHD appear to demonstrate higher levels of 8–10 Hz activity during both eyes-closed and eyes...

Use of Databases in QEEG Evaluation

SUMMARY Background. Quantitative electroencephalography (qEEG) analysis incorporating the use of normative or reference database comparison has developed from being primarily a research tool into an increasingly widely used method for clinical neurophysiological evaluation. Method. A survey of several of the most widely used qEEG databases as well as issues surrounding the construction and use of these databases is presented, comparing and contrasting the various features of these databases, followed by a discussion of critical issues in this developing technology. Results. This review considers the concept of normalcy, norming of qEEG features, and validation of clinical findings. Technical issues such as methods for recording and analysis, filter use, broad bands versus single Hz finer frequency resolution, the number of variables relative to the number of cases, and the problem of multiple statistical testing are addressed. The importance of the recording electrode and montage reformatting for normativ...

Increased alpha activity in REM sleep in de novo patients with Parkinson's disease.

We compared the sleep structure including a quantitative electroencephalographic (EEG) analysis and the frequency of periodic limb movements (PLM) in 17 patients with Parkinson's disease (PD; 10 men, seven women, mean age 65.9 years, mean Hoehn and Yahr stage 1.8) who had never been treated with dopaminergic agents (de novo), and 10 healthy controls (six men, four women, mean age 64.5 years). The REM sleep EEG of the PD patients was characterized by a sustained increase in the high-theta/alpha (7.8-10.5 Hz) frequency range during the first one-third (i.e., 11.00 p.m. to 01.40 a.m.) of the night. There was no significant difference in the sleep continuity and sleep architecture as well as in the PLM index between both groups. The analysis of the temporal dynamics of the observed changes suggests a dysregulation of the REM sleep homeostasis in the patients with PD.

465 Staging alzheimer's disease by quantitative EEG spectral profiles

In the present study, quantitative electroencephalographic (EEG) analysis was performed at rest and during photic stimulation (5, 10, and 15 Hz) in nine patients with presenile dementia of the Alzheimer type (AD; mean age at onset, 55 years) and nine sex- and age-matched control subjects. Compared with the normal controls, the AD patients had a significantly lower alpha-2 and beta band power in the resting EEG as well as a significant increase in delta and theta band power. EEG analysis during photic stimulation demonstrated that the AD patients had a significantly lower EEG power during photic stimulation for the alpha (9.8–10.2 Hz) and beta bands (14.8–15.2 Hz) corresponding to photic stimulation at 10 Hz and 15 Hz, respectively. In addition, when we examined EEG changes from rest to the stimulus condition, the AD patients were found to show significantly smaller changes in EEG power mainly over the posterior regions, irrespective of the stimulus frequency. These findings provide evidence that AD patients have EEG abnormalities in both non-stimulus and stimulus conditions, and suggest diminished EEG reactivity to photic stimulation.

Quantitative electroencephalographic analysis of the biphasic concentration-effect relationship of propofol in surgical patients during extradural analgesia

We studied effects on the EEG of propofol infused at a rate of 0.5 mg kg-1 min-1 for 10 min in 10 healthy male surgical patients under extradural analgesia. The EEG amplitude in six frequency bands was related to arterial blood propofol concentrations and responsiveness to verbal commands. The EEG amplitude showed a characteristic biphasic response to increasing blood propofol concentrations in all frequency bands. During the infusion, patients lost responsiveness when EEG amplitudes in the high frequency bands were decreasing after having reached a maximum. EEG changes were different during infusion and emergence. Pharmacodynamic modelling, using two effect compartments with dissimilar equilibration constants, resulted in satisfactory fits. We conclude that propofol exerts a biphasic effect on the EEG amplitude in all frequency bands. The dissimilarity of EEG changes during infusion and during emergence suggests that two effect compartments with different equilibration constants exert opposing effects on the EEG.

Electroencephalographic abnormalities in patients with presenile dementia of the Alzheimer type: Quantitative analysis at rest and during photic stimulation

In the present study, quantitative electroencephalographic (EEG) analysis was performed at rest and during photic stimulation (5, 10, and 15 Hz) in nine patients with presenile dementia of the Alzheimer type (AD; mean age at onset, 55 years) and nine sex- and age-matched control subjects. Compared with the normal controls, the AD patients had a significantly lower alpha-2 and beta band power in the resting EEG as well as a significant increase in delta and theta band power. EEG analysis during the photic stimulation demonstrated that the AD patients had a significantly lower EEG power during photic stimulation for the alpha (9.8-10.2 Hz) and beta bands (14.8-15.2 Hz) corresponding to photic stimulation at 10 Hz and 15 Hz, respectively. In addition, when we examined EEG changes from rest to the stimulus condition, the AD patients were found to show significantly smaller changes in EEG power mainly over the posterior regions, irrespective of the stimulus frequency. These findings provide evidence that AD patients have EEG abnormalities in both non-stimulus and stimulus conditions, and suggest diminished EEG reactivity to photic stimulation.

Quantitative electroencephalography: A method to assess cerebral injury after hypothermic circulatory arrest

Although hypothermic circulatory arrest and low-flow cardiopulmonary bypass are routinely used for surgical correction of congenital cardiac anomalies, use of long durations of arrest, often required for more complex repairs, raises serious concerns about cerebral safety. Searching for an intraoperative assessment that can reliably predict cerebral injury, we have found an excellent correlation between changes in quantitative electroencephalography intraoperatively and immediately postoperatively after prolonged hypothermic arrest, and neurologic and behavioral evidence of cerebral injury. After epidural placement of four recording electroencephalographic electrodes and baseline neurologic/behavioral and electroencephalographic assessment, 32 puppies were randomly assigned to one of four groups: hypothermic controls in which cooling to 18° C was followed immediately by rewarming, 30 minutes of hypothermic circulatory arrest at 18° C, 90 minutes of arrest at 18° C, and 90 minutes of low-flow cardiopulmonary bypass at 25 ml/kg per minute at 18° C. An electroencephalogram was recorded at baseline, after cooling, during rewarming, and at 2, 4, and 8 hours after the start of rewarming, as well as before the operation and 1 week after the operation. Postoperative neurologic and behavioral outcome was assessed 24 hours after cardiopulmonary bypass and daily for 1 week by means of a graded scale in which 0 is normal and 12 and 13 indicate severe neurologic injury (coma and death). Thirty animals survived the experimental protocol: two animals in the 90-minute hypothermic arrest group died before neurologic evaluation could be completed, and the remainder exhibited various degrees of neurologic and behavioral impairment, more severe on day 1 than on day 6. No animal in the remaining groups had a significant neurologic deficit. Quantitative electroencephalographic analysis shows marked differences between the 90-minute arrest group and the controls in the percent electroencephalographic silence during rewarming and at 2 hours, and in the percent recovery of baseline power at 2, 4, and 8 hours. At 2 hours after the start of rewarming, a correlation between electroencephalographic amplitude and neurologic/behavioral score on day 1 was carried out, which predicts with great certainty ( p < 0.00001) that if electroencephalographic power at this time is less than 500 μV 2 , overt neurologic injury will subsequently become apparent. In addition, a significant shift from higher to lower frequency in the day 6 postoperative electroencephalogram compared with baseline occurs only in the 90-minute arrest group. Although clinical neurologic injury was not apparent in any but the 90-minute arrest group, further quantitative electroencephalographic comparisons of postoperative with baseline power show a much more rapid return of electroencephalographic power in the control than in either the 30-minute hypothermic arrest or the low-flow cardiopulmonary bypass group Between-group comparisons show significant differences between the 90-minute arrest and low-flow cardiopulmonary bypass groups at several time points, and fewer and less marked differences between 90-minute and 30-minute arrest groups. These results demonstrate that quantitative electroencephalographic logic injury after 90 minutes of hypothermic circulatory arrest at 18 ° C. The presence of milder but significant differences from control quantitative electroencephalographic values after 30 minutes of arrest at 18 ° C suggest that there may be subtle cerebral injury undetected by neurologic/behavioral evaluation in this group, although this interval is clinically accepted as safe. In contrast, no quantitative electroencephalographic evidence of cerebral dysfunction was apparent after 90 minutes of low-flow cardiopulmonary bypass at 18 ° C. The study as a whole suggests that quantitative electroencephalographic is a sensitive indicator of cerebral injury and may prove extremely valuable in future studies of strategies for cerebral protection during cardiac surgery. (J T HORAC C ARDIOVASC S URG 1995;109:925-34)

C STAGE, Automated Sleep Scoring: Development and Comparison With Human Sleep Scoring for Healthy Older Men and Women

Using the sleep records of 200 men and women (age 55-85 years), we have developed a human-assisted computer scoring system, C STAGE. The system can have many applications, including quantitative electroencephalographic (EEG) analysis during specific stages of sleep. C STAGE classifies sleep/wake stages using power spectral analysis and other techniques applied to one channel of EEG data. Here we report comparability data between C STAGE- and human-rated sleep-stage scoring using Rechtschaffen and Kales criteria for 70 normal subjects (a subset of the 200). Because the method was developed using these subjects, we also report comparability data for an independent validation sample of 45 normal older men and women. For waking measures, sleep stages 3 and 4, and total sleep time, C STAGE yielded ratings comparable with the human rater (r = 0.73-0.91; p < 0.001). For sleep stages 1 and 2 and REM sleep, C STAGE correlated less well with human ratings (r = 0.59-0.81; p < 0.001). Overall, these correlations compare well with other currently available computer stage-scoring methods. Epoch-by-epoch comparisons in the validation sample revealed a mean proportion of agreement of 0.74 and a mean Kappa coefficient of 0.57, indicating the two methods provide reasonable agreement on an epoch-by-epoch basis. We conclude that C STAGE is a valid sleep/waking scoring system for healthy older adults.

Effects of muscarinic receptor agonists and anticholinesterase drugs on high voltage spindles and slow waves

The effects of muscarinic agonists (AF102B, pilocarpine, oxotremorine) and anticholinesterases (physostigmine, tetrahydroaminoacridine) were investigated on the incidence of thalamically generated rhythmic high voltage spindles and on scopolamine (0.2 mg/kg)-induced neocortical slow wave activity (i.e. increased sum amplitude value of the 1–20 Hz band in a quantitative electroencephalography (qEEG) analysis). AF102B and pilocarpine decreased high voltage spindles and scopolamine increased sum amplitude values at 3 and 9 mg/kg, but not at 1 mg/kg. Oxotremorine was less potent than AF102B or pilocarpine in suppressing high voltage spindles. Oxotremorine had no effect on the scopolamine-induced qEEG changes. Tetrahydroaminoacridine decreased high voltage spindles at 1, 3 and 9 mg/kg and slow waves at 9 mg/kg. Physostigmine decreased high voltage spindles and slow waves at 0.12 and 0.36 mg/kg. Based on the present results we propose that agonists possessing muscarinic M 1 receptor activity are effective in decreasing high voltage spindles and scopolamine-induced slow wave activity, but agonists showing predominant muscarinic M 2 receptor activity may be less effective in decreasing high voltage spindles and slow waves. Furthermore, tetrahydroaminoacridine decreased high voltage spindles at doses lower than those required to decrease scopolamine-induced slow waves. Physostigmine decreased high voltage spindles and slow waves over the same dose range. This result may indicate that non-cholinergic mechanisms are involved in the tetrahydroaminoacridine-induced decrease in high voltage spindles.

Quantitative electroencephalographic profile of 3-(4-hydroxy-1-piperidinyl)-6-(2,4-dichlorophenyl)-pyridazine (SR 41378) in the rat.

Quantitative electroencephalographic (QEEG) analysis was performed in rats following the oral administration of SR 41378 [3-(4-hydroxy-1-piperidinyl)-6-(2,4-dichlorophenyl)-pyridazine], a novel aminopyridazine derivative, which has been shown to possess anticonvulsant, antianxiety and hypnotic activities in mice and rats. The EEG effects of SR 41378 (10, 30 and 100 mg/kg) were compared to those of secobarbital (30 and 60 mg/kg) and diazepam (1, 3 and 10 mg/kg). SR 41378 and secobarbital increased the power of the middle-frequencies (8-16 Hz) of the EEG, reduced that of 4-8 Hz (theta) activities and did not affect 1-4 Hz (delta) activities. Diazepam also increased the power of middle-frequency activities and decreased that of both delta and theta activities. Quantitative EEG profiles were calculated from the mean integrated power (MIP) of selected frequency bands. The QEEG profile of SR 41378 was found to share common characteristics with those of secobarbital and diazepam: dose-dependent decrease of theta band MIP and increase of 8-20 Hz (middle beta bands) MIP. However, both SR 41378 and secobarbital induced a reduction of the 28-32 Hz (fast beta bands) MIP, whereas diazepam diminished the delta band. These results suggest that SR 41378, a novel chemical structure, shares common psychotropic properties with barbiturates and benzodiazepines.

Evaluation of a syntactic pattern recognition approach to quantitative electroencephalographic analysis

This paper reports an experiment designed to evaluate the usefulness of a syntactic pattern recognition approach to quantitative EEG analysis. This approach provides a systematic way of organizing and interpreting spatially and temporally distributed activity in an EEG record. Many automated scoring systems evaluate only background activity, ignoring the significant transient events that may occur in an EEG. In contrast, syntactic methods allow evaluation of background activity in combination with transient events. In this paper, 454 EEGs recorded from a population of renal patients are evaluated using (1) the syntactic approach, and (2) a method based on discriminant analysis. The main finding is that the syntactic approach outperforms the discriminant analysis method when each technique is compared to visual scoring.