The sensitivity of instantaneous coherence for considering elementary comparison processing. Part I: The relationship between mental activities and instantaneous EEG coherence.

In this study the sensitivity of instantaneous EEG coherence for the description of the processual evolution of thinking processes is investigated. The adaptive estimation approach presented allows the calculation of the coherence function with high time and frequency resolution. On this basis the detection of time intervals with high synchronization phenomena is possible. The strength of coupling between different EEG channels may therefore be measured even for very short mental activities. The inclusion of the time component enables the calculation of very sensitive coherence parameters, such as the maximal coherence value or the length of time intervals with high synchronization during information processing. Based on these dynamic examinations, conceptual and imaginal representations are distinguishable for elementary cognitive processes.