[Vigilance--its EEG determination].

The definition of vigilance was based primarily on criteria of overt behaviour and concomitant electrographic patterns of functional states as well as on psychometrically tested performance. It turned out that the combination of well defined electroencephalographic activity patterns is an utile and reliable measure for the classification of different vigilance levels, even when there is no experimental testing of performance possible or the observation of behaviour misleading. We know today defined mixtures of characteristic regional EEG activities for the estimation on different levels of vigilance between supervigilance and subvigilance. There are however also deviations from regularly observed combinations of signs with dissociations between behaviour, performance and EEG-activity patterns. For the theory of vigilance one can use the analyses of topological and chronological organization of EEG-activities as starting point. Not only characteristic frequency mixtures are correlated with given vigilance levels; moreover the diffusion of regional activities interfering with all other regional activities builds up the socalled "vigilance profile". This profile varies with time slowly or quickly. The regular topological process distribution of activities is commonly the expression of a dominating mental process interfering with other submental processes. The chronological variations of vigilance profiles show their dynamism with transitions from fixed, strictly bound interest or "concentration" on selected objects to freely fluctuating interest, rapidly jumping from object to the other.