Treatment of some nonstationarities in the EEG

In many situations, EEG recordings cannot be assumed to be second-order stationary. The definition of stationarity is reviewed and the implications of the nonstationarity of the EEG are investigated. Some methods to overcome the problem caused by the nonstationarity are discussed. They include measures of variability, condensed time series and segmentation. The discussion is restricted to FFT spectral estimators and broad-band parameters derived thereof.