Methods for determining electroencephalograms parameters

Electroencephalograms represent a broadband oscillatory process that is inherently random and non-stationary. Therefore, it is difficult to determine its parameters precisely. In this article, two methods for determining the information parameters of electroencephalograms are considered.A method for determining the interhemispheric symmetry of electroencephalograms (EEG) based on the calculation of sum and difference EEG spectra calculation of symmetric electrodes is presented. A symmetry coefficient has been introduced, which makes it possible to obtain a quantitative objective assessment of interhemispheric symmetry. The symmetry coefficient is shown to be different for healthy and sick patients that allow to greatly simplify the diagnostic procedure and can be used as the basis of the screening analysis. It is shown that an objective assessment of interhemispheric symmetry can also be obtained from the power values of the difference EEG spectra. The relative power values for healthy and sick patients are given.A method for estimation of the EEG instantaneous frequency based on frequency detection by sliding window is also presented. A block diagram describing this method is designed. The instantaneous frequency obtained from the results of calculation does not depend on the signal amplitude and in the same time the standing out of the weak frequency components is possible. Higher accuracy of this method in comparison with Window Fourier Transform and Wavelet Transform is shown.Simplicity, clarity and accuracy of the developed methods are their undoubted advantages.