Working memory load and EEG-dynamics as revealed by point correlation dimension analysis

The results of the present study showed a decreased dimensional complexity during working-memory load, which was induced by the Corsi-Bock-Tapping task as compared to a baseline task. This baseline task was similar to the Corsi-Block-Tapping with respect to both the required processes of perception and the motor performance. A load-specific change of brain dynamics was observed, which was most pronounced over frontal cortical areas. This finding is in agreement with the literature and encourages further research on the ongoing EEG, especially with clinical tests, where little is known about their psychophysiological correlates. From a methodological point of view, the point correlation dimension, which deals with non-stationary data, was applied to EEG-time series that were a concatenation of several EEG-subepochs of the same experimental conditions. From the results it is proposed that this procedure might offer an approach for EEG analysis, where the EEG-epochs are of short duration and non-stationary data are to be expected. (C) 1999 Elsevier Science B.V. All rights reserved.