RESUMEN
A new way of processing and presenting multichannel EEG recordings is introduced, called dynamic imaging frequency analysis (DIFA). Firstly power spectral analysis is applied to 14 EEG signals simultaneously. The cross-power spectra or transfer functions of 13 EEG signals are calculated in relation to the 14th EEG signal, thus obtaining not only the average amplitude but also the relative phase of diffusely occurring frequencies. The information per electrode obtained in this way can be presented in a numerical form, for quantification and statistical evaluation. Also, the information from 14 electrodes per significant frequency can be presented as a dynamic image display (frequency animation) yielding immediate information on the average amplitude and relative phase of the average activity per frequency of the EEG record. Application of the DIFA technique to several dozen patients demonstrates the value of phase information in EEG analysis.