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M Kowalczyk

Publications and source records attributed to M Kowalczyk.

80 records · Page 5Linked to original sources
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Computer-aided analysis of the epileptic EEG.

An introductory review of a comprehensive approach to the problem of automatic evaluation of the epileptic EEG in the frame of syntactic analysis is presented. The aims and merits of the syntactic approach are discussed and the viability of the method is demonstrated on a few chosen examples. Working procedures for automatic segmentation and classification of patterns in single- as well as in multi-channel case of the epileptic EEG are briefly described. These include algorithms for segmentation by a finite-state automaton technique (single channel) and, in multi-channel case, a sparsely updated Kalman filter algorithm. Inherent possibilities of the approach presented are shown to open the way for a global description of a seizure in terms of the Markov chains theory.

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PubMedDate not supplied

Effects of antiepileptic drugs in electrophysiological tests.

Methods of the study of antiepileptic drugs activity by means of analysis of their effects on bioelectrical ictal phenomena in the animal brain are described. The paper deals especially with EEG signal processing methods. Application of various nonparametric models (e.g. interval-amplitude scatter plots, power spectra analysis) as well as parametric models (e.g. autoregressive model, segmentation analysis) is discussed. A discriminative approach to some of these methods (especially to autoregressive model) is also presented. Special attention is stressed on the value of these methods for the study of anticonvulsant drugs activity.

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PubMedDate not supplied

Effects of pralidoxime applied locally into the midbrain reticular formation on the hippocampal theta rhythm induced by acetylcholinesterase inhibition.

After local administration into the midbrain reticular formation of an acetylcholinesterase reactivator--Pralidoxime, a significant decrease of intensity of hippocampal theta rhythm induced by previous inhibition of acetylcholinesterase by DFP was observed already after 10 min. This result suggests that cholinergic structures are localized in midbrain reticular formation and that they play a role in the origin of hippocampal theta rhythm.

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PubMedDate not supplied

Effects of thermal pain stimulus on EEG.

Experiments were carried out on conscious rabbits with electrodes chronically implanted into sensorimotor cortex (MSC), ventro-postero-lateral thalamic nuclei (NVPL), periaqueductal grey matter (PAG) and midbrain reticular formation (MRF). Thermal pain stimulus (52 degrees C) lasted 10 s and was applied to the forepaw of the animal. Analysis of bioelectrical activity (20 sec periods) before and after the stimulation was performed by means of automatic methods using the algorithm of Fast Fourier Transform (FFT). It was found that pain stimulation resulted in a characteristic response in every studied structure and that this response was blocked by morphine.

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PubMedDate not supplied

Quantitative and qualitative automatic evaluation of afterdischarges in the study of antiepileptic drugs.

An automatic analysis of bioelectrical activity in some structures of the rabbit's brain was performed after i.v. administration of diazepam, phenytoin or phenobarbital. It was found that diazepam raised the ratio of fast activity in the afterdischarges pattern but paralelly decreased the total energy involved in the production of after-discharges in the cortex and midbrain reticular formation. Phenobarbital caused a significant shift in frequencies, increasing the ratio of slow activities (in the exception of hippocampus) and decreased the power spectra of afterdischarges in all structures (in the exception of midbrain reticular formation). Phenytoin, similarly to phenobarbital, decreased the ratio of fast activities. This effect was significant only in thalamus and midbrain reticular formation. At the same time it increased the total power of signal from hippocampus and midbrain reticular formation.

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