EVENT-RELATED BETA-SYNCHRONIZATION AFTER WRIST, FINGER AND THUMB MOVEMENT

Pre-movement event-related desynchronization (ERD) and post-movement e vent-related synchronization (ERS) were studied in a group of normal s ubjects during voluntary thumb, index finger and wrist movement. The b and power time courses were computed for the upper alpha band (10-12 H z) and for two frequency bands in the range of beta (16-20 Hz and 20-2 4 Hz). While a similar mu ERD was found during motor preparation for t he 3 movement tasks, significant differences concerning beta synchroni zation were observed after movement off set. The contralateral percent age beta increase (ERS) was significantly larger in gross movements of the wrist as compared to index finger and thumb movements, which is d iscussed under the assumption of a cumulative effect. Summarizing, pre -movement desynchronization seems relatively independent of the forthc oming type of movement, whereas the post-movement beta synchronization might depend on the activated muscle mass. (C) 1998 Elsevier Science Ireland Ltd.