Potentialities of the wavelet and multifractal techniques to evaluate changes in the functional state of the human brain
The task is to estimate quantitatively the changes in functional states arising in the human brain with different neural disruptions. To solve the task we analyze long-lasting recordings from patients with epilepsy and subjects with chronic psychogenic pain disorders. Using the wavelet transform of the electroencephalographic (EEG) segments and the wavelet-transform modulus maxima method we evaluate the maximal global energy of the segment and its multifractal parameters such as the width and the asymmetry of the singularity spectrum. By contrast to the segments gained for functional probes like opening eyes or hyperventilation in recordings without the epileptic discharges, the segments immediately preceding the epileptic seizure are characterized by the significant changes in the global energy and the width of the singularity spectrum. It gives promise that the applied methods can not only serve for automatically detecting the epileptic patterns but also predict modifications in the epileptic brain activity before epileptic discharges. For the patients with psychogenic pain syndromes we demonstrate the efficiency of the used parameters to evaluate objectively the improvement of the functional state connected with the pain disappearance.
multifractality eeg global energy singularity spectrum epileptic psychorelaxation