[Quantification and analysis of the EEG].

Quantification and analysis are of major interest in modern electroencephalography. During recent years developments in mathematical-statistical analysis of time series and in electronics and computer technology have brought significant advances. A common feature of almost all procedures proposed so far is that they treat the EEG as a random variable. Various statistical descriptors are estimated either in the time or in the frequency domain, for one or several simultaneous EEG channels. This paper reviews the various methods available today to quantize and analyze the main categories of EEG activities, i.e. (1) spontaneous non-paroxysmal activities, (2) spontaneous paroxysmal activities and (3) activities evoked by external sensory stimulation. Due to personal preferences of the author, emphasis is put on analysis methods in the frequency domain. The main problem today lies much less in the technical installation of the one or the other analytical method than in the treatment of artifacts and in postprocessing the large amount of analyzer output. Therefore, applications must be restricted to carefully selected special questions. Clinical electroencephalography is still far from automatization.