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Biomedical subjects

M Matousek

Publications and source records attributed to M Matousek.

At least 37 records · Page 2Linked to original sources
PubMed1983

A method for assessing alertness fluctuations from EEG spectra.

The object of the study was to develop a method for automatic evaluation of the vigilance level using the EEG frequency pattern. Forty-one EEG records were selected as training material, being considered representative of either a fully alert EEG, or sleep stage I. In the same epochs, 22 different variables based on EEG spectral analysis were calculated. Multiple regression analysis was applied to determine the correlation between the spectral values and the assigned levels of vigilance. The coefficients obtained were applied to the spectral values of 265 epochs belonging to another set of tracings, for estimation of the vigilance level. The correlation between the automatic and visual finding was 0.89 in the training material and 0.86 in the test material. The method can be used to evaluate the mean vigilance level and its variance, rhythmicity and trend during the examination. The preliminary results suggest that objective measurement of alertness can be of value in many applications, such as in pharmacological research, in evaluation of certain psychic symptoms and in working environment studies.

Arousal↗
PubMed1983

EEG vigilance profile as a supplement of psychiatric data.

A vigilance measurement based on EEG spectra was employed to supplement the clinical data. In an experimental situation when the patient was left undisturbed after a standard stimulation, four typical patterns were observed. Besides the normal profile, a 'somnolent pattern' with pronounced vigilance decrease and an 'unquiet pattern' with high variance could be seen in treated and in untreated schizophrenic patients, respectively. A combination of both characteristics occurred in depressive patients with symptoms such as agitation, tension, and hypochondria. The outcome of treatment was predictable in the patients with a 'mixed pattern', while the drug effect was unpredictable in other patients with the same diagnosis.

Adult↗
PubMed1983

A quantitative EEG analysis of the effects of baclofen on man.

This investigation has been directed to estimate to what extent a GABA derivative, beta-(p-chlorophenyl)-gamma-aminobutyric acid (baclofen), is active at the cortical and subcortical level. Selected nonpsychotic patients with slight depression symptoms were given 30 mg of baclofen daily for a period of 3-5 weeks. Brief Psychiatric Rating Scale and Standardized Hamilton Interview for Depression were used for clinical evaluation. EEGs were recorded prior to and at different times during treatment. An automatic analysis completed by multivariant statistics of EEG spectral values was performed. EEG changes were characterized by a significant increase of slow waves and decrease of fast activity. These results can support the view that baclofen is effective even at the highest levels of the central nervous system.

Adult↗
PubMed1982

EEG antecedents of thievery.

In Gothenburg studies using clinical and electroencephalographic techniques have been undertaken continuously since 1958 on a large number of individuals of all ages. All individuals studied were without impairment to the central nervous system, according to a number of well-defined defined clinical criteria, and were termed normal. The term "normal" is used primarily because it is short. As part of the continued investigation, information has been gathered from social bureaus in Gothenburg and from federal registers. It was observed that youths and children who were found guilty of theft showed EEG abnormalities of some kind (in the EEGs taken several years earlier) statistically significantly more often than other youths and children belonging to our normal material. Among the characteristics discovered by EEG can be noted paroxysmal activity during sleep, slow alpha activity and spectral-analytical measurements corresponding to lower EEG ages than the individuals' actual ages.

Adolescent↗
PubMed1979

Serial quantitative electroencephalography.

Repeated EEG examinations are often used in diagnostically difficult cases to assess whether an EEG abnormality is progressive, regressive, or stationary. The conventional visual method is, however, poorly adapted to consider the variability when consecutive EEG recordings are compared. Using computer analysis of EEGs, the feature of the recordings as well as their variances can be measured, and the differences between the recordings can be tested statistically. The aim of the present study was to develop a practicable method for quantitative serial EEG examinations. Twenty EEGs from 5 volunteers were recorded to obtain reference data. The data acquisition was automated to obtain data without visual bias. The previously developed method using age ratios was employed for the primary analysis. The changes of the EEG activity during the observation period were evaluated statistically. Differences between consecutive EEGs could be observed even in normal subjects but the number of 'false positive' findings was reduced by the automatic data selection, by the choice of proper measures, and by adequate statistical treatment. The diagnostic value of the method was tested in 59 EEGs from 13 patients with well-defined brain disorders. Most EEG changes which could be attributed to the development of the disease were discovered and labelled as statistically significant.

Adult↗
PubMed1979

Automatic measurement of the vigilance level and its possible application in psychopharmacology.

The main object of the study was to separate the specific EEG effects of psychopharmaca from changes caused by drowsiness. The study was based on quantitative evaluation of the vigilance level during five minutes of EEG recording under standardized conditions. The equation for computing the vigilance level from EEG spectra was obtained by using a training material. The segments were classified visually either as alert EEG, or as EEG marked by drowsiness. As confirmed by independent test material, the coefficients derived by means of multiple linear regression were applicable to other EEGs for estimating the vigilance level. The procedure was used in the evaluation of the psychopharmacological treatment. It was concluded that the specific EEG drug profiles were certainly influenced by the accompanying drowsiness, but the main information was still preserved. In contrast to the specific drug effect, the drug-induced sleep activity could be isolated from other events and studied separately. It was also found that after a standard stimulation, both the general trend and periodicity of the vigilance fluctuations were closely related to the psychic state of the patient.

Arousal↗
PubMed1975

Central nervous system effects of local anaesthetic agents.

A review is given of an experimental study on cats where the influence of acid-base changes on central nervous system toxicity of local anaesthetic agents was studied. The conclusion of this study was that a respiratory acidosis increased the central nervous system toxicity of local anaesthetics and that the underlying metabolic conditions modified this increase. Thus a respiratory acidosis increased this toxicity more if it was based on a metabolic acidosis than on a metabolic alkalosis (Englesson, 1974; Englesson and Grevsten, 1974). An extended analysis is presented where automatic frequency analysis was performed on the e.e.g. recordings performed during the i.v. infusion of lignocaine, bupivacaine, L 134, HS 37 and its optical isomers. The preliminary results show that the electrical changes appearing in the e.e.g. from the start of the i.v. infusion until seizure activity were the same if this time interval was as short as 1 min or as long as 8 min. It also revealed remarkable individual differences between agents, for instance lignocaine displaying marked electrical changes already in the first third of this time period where bupivacaine showed no changes until shortly before seizures.

Acid-Base Equilibrium↗