Theta synchronization in the human EEG and episodic retrieval

Event-related desynchronization (ERD) and synchronization (ERS) was measure d during episodic retrieval in a specially designed recognition task which forces subjects to avoid semantic search strategies. ERD represents the per centage of a decrease, ERS an increase in band power. The results show that only the theta band differentiates between good and bad episodic memory pe rformers and that good performance is related to a large degree of theta sy nchronization. The delta and alpha bands did not yield significant effects. Topographical differences in theta ERS reveal that good performers use pri marily their right hemisphere to retrieve episodic information. This findin g agrees with respective results from PET studies. (C) 1998 Elsevier Scienc e Ireland Ltd. All rights reserved.