Hanna Goszczyńska

Analysis of Variability of Isopotential Areas Features in Sequences of EEG Maps

The aim of the study was to analyse differences in dynamics of variability of extreme isopotential areas in sequences of EEG maps containing seizure activity episode. Analysis of dynamics of alternating variability of extreme isopotential areas was performed in the three steps: visual examination, calculation of the differencing coefficient and statistical analysis. Results of the study performed on two groups of totally 17 subjects reveal the different dynamics of isopotential areas variability in considered groups of patients.

Analysis of Dispersion of Isopotential Areas Values in EEG Maps Sequences

The aim of the study was to develop the method for objective evaluation of differences in alternation variability of isopotential areas in the EEG maps sequences for activity episode. The method was based on the analysis of EEG map images histograms and concerns the evaluation of the isopotential areas changes. The principle of the present method is analysis of the ratio of extreme isopotential areas and of the dispersion of values of extreme isopotential areas. The method was tested on sequences of amplitude maps for 17 subjects with seizure episodes with different characteristics divided into two groups. Visual evaluation of obtained results confirms that ratio of extreme isopotential areas and coefficients of the symmetry and elongation of extreme isopotential areas values dispersions may be useful for describing the variability of EEG maps. Influence of the potential range scale of EEG maps on the quantitative estimation of the isopotential areas variability was also analyzed.

Relationships between Isopotential Areas in EEG Maps before, during and after the Seizure Activity

The aim of the study was to analyse relationships between isopotential areas in sequences of EEG top maps recorded before, during and after seizure activity. Method of the analysis of isopotential areas in sequences of EEG maps consists on the comparison of the changes of values of areas before and after seizure activity and estimation of mutual changes of the areas for the extreme isopotential regions during seizure activity. Results of the study performed on two groups of totally 17 subjects suggest that selected image features like area of given range of potentials and the analysis of the relationships between areas of the isopotential regions before, during and after seizure episode reveal the differences in considered groups of subjects.

Ontology of EEG mapping --- preliminary research

The paper presents the preliminary results of the project concerning the development of the system for objective semantic interpretations of the image features used in the description, analysis and processing of the EEG mapping. Formal representation of knowledge in the form of ontological model is necessary to standardize the terminology used to describe the EEG mapping. Those standardized descriptions can help to more efficiently exploit the information contained in the EEG maps and could also play an important educational role. The paper contains the basic notions concerning ontological models and review of selected ontologies of nervous system. Ontology presentation provides: applied building methodology, the details of the knowledge acquisition process, the ontology structure, finally examples of applying ontology class definitions to the descriptions and interpretation of real regions of EEG activity on the EEG maps.

Are There Modifiable Environmental Factors Related to Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal adult-onset neurodegenerative disorder of unknown etiology and no preventive treatment. It is characterized by degeneration of both upper motoneurons in the primary motor cortex and lower motoneurons in the brainstem and spinal cord. It results in progressive muscular weakness and atrophy, leading eventually to respiratory insufficiency and death. Approximately 50% of patients with ALS die within 30 months of symptom onset (1). Although ALS is considered a rare disease (incidence between 0.6 and 2.6 new cases per year per 100,000, prevalence 3–8 per 100,000), it is in fact more common than generally recognized, with an adult lifetime risk of 1 in 400 (2). Approximately 10% of all ALS cases are familial (fALS), and the remaining 90% are sporadic (sALS). Genetic factors are involved in the pathogenesis of fALS and up to 15% of sALS (3, 4). Nowadays, the only established risk factors for ALS are advanced age, male gender, and certain genetic mutations (1). Given that no more than 25% of all ALS diagnosis has genetic basis, for the remaining percentage of cases gene–environmental interaction may be responsible. In the recent years, a vast number of studies addressing ALS risks related to the exposure to environmental factors have been published [for a recent review, see Ref. (5)]. Their analysis is difficult, since they applied various methods of data collection and analysis, from studying of toxicants’ content in tissue samples, through case–control studies and analysis of death certificates, to reviews and meta-analyses. Original studies were usually performed on small local patient cohorts, and their results are ambiguous and often contradictory. Virtually all so far published reviews on ALS risk factors were inconclusive and called for further investigations. Nevertheless, as mentioned earlier, at least 75% of ALS cases do not have established genetic basis, so the search for modifiable environmental factors continues. The research in this field is important, since it may lead to formulation of measures, which could prevent this fatal disease or at least delay its development. Therefore, we decided to put forward some thoughts that arose from studying published literature, hoping that they could help to design future successful studies on ALS risk factors.

Correlation Matrices as a Tool to Analyze the Variability of EEG Maps

The aim of this paper is to present the selected examples of possible applications of image of correlation coefficients matrix of EEG map series in the analysis of variation of the topography of the isopotential areas in EEG maps, and thus in the assessment of stationarity, spatio-temporal variability and trends of changes of bioelectric activity of the brain. The image of correlation coefficients matrix shows similiarity of all pairs of maps in a series. The choice of segmentation threshold of characteristic areas in images of the correlation coefficients matrix of EEG map series corresponding to the sequence similarity relationships in a series of maps was based on the results of research conducted on test series. Determining of the segmentation threshold value allowed for the presentation of research results of similar sequences in the examplary series of real EEG recordings. The obtained results consistent with the visual assessment of the similarity of the topographic distributions of isopotential areas in EEG maps form the basis for further research of usefulness of the analysis of the correlation coefficients matrix in the assessment of the dynamics of EEG mapping topography.

Bilateral changes in afterhyperpolarization duration of spinal motoneurones in post-stroke patients.

This paper extends the observations presented in the previously published work on the afterhyperpolarization (AHP) duration changes in motoneurones (MNs) on the paretic (more affected) side of 11 post-stroke patients by the same analysis on the non-paretic (less-affected) side. The estimated AHP duration for patients’ MNs supplying more-affected muscles was significantly longer than control values and the elongation decreased with patient age and disorder duration. For MNs supplying less-affected muscles, dependency of AHP duration on age was closer to the control data, but the scatter was substantially bigger. However, the AHP duration estimate of less-affected MNs tended to be longer than that of controls in the short time elapsed since the stroke, and shorter than controls in the long time. Our results thus suggest that the spinal MNs on both sides respond to the cerebral stroke rapidly with prolongation of AHP duration, which tends to normalize with time, in line with functional recovery. This suggestion is in concert with the published research on post-stroke changes in brain hemispheres. To our knowledge, these dependencies have never been investigated before. Since the number of our data was limited, the observed trends should be verified in a larger sample of patients and such a verification could take into account the suggestions for data analysis that we provide in this paper. Our data are in line with the earlier published research on MN firing characteristics post-stroke and support the conclusion that the MUs of the muscles at the non-paretic side are also affected and cannot be considered a suitable control for the MUs on the paretic side.

The Procedure for SPECT and BEAM Images Adjustment Visualisation of EEG Electrodes in SPECT Images

The Procedure for SPECT and BEAM Images Adjustment Visualisation of EEG Electrodes in SPECT Images Preliminary results of research to devise a method allowing spatial alignment of BEAM maps obtained from EEG examinations with SPECT data are presented. The main concept of the method presented lies in simultaneous recording of multi-channel EEGs during SPECT examination, and also in visualizing location of EEG electrodes on SPECT images that provide spatial three dimensional coordinates assignment. The proposed methodology of simultaneous SPECT and EEG examinations could be a significant complement to results of epileptic focus localisation obtained with the ISAS method used for the last few years. The ISAS method allows localisation of focuses with 80% confidence, but it requires carrying out MRI examinations for alignment of compared anatomical structures on two SPECT images. Complementing these results with a BEAM map analysis would improve significantly the effectiveness of the examinations. This work presents results of experiments carried out on the Jaszczak phantom.