Event-related beta synchronization after wrist, finger and thumb movement.

Pre-movement event-related desynchronization (ERD) and post-movement event-related synchronization (ERS) were studied in a group of normal subjects during voluntary thumb, index finger and wrist movement. The band power time courses were computed for the upper alpha band (10-12 Hz) and for two frequency bands in the range of beta (16-20 Hz and 20-24 Hz). While a similar mu ERD was found during motor preparation for the 3 movement tasks, significant differences concerning beta synchronization were observed after movement off set. The contralateral percentage beta increase (ERS) was significantly larger in gross movements of the wrist as compared to index finger and thumb movements, which is discussed under the assumption of a cumulative effect. Summarizing, pre-movement desynchronization seems relatively independent of the forthcoming type of movement, whereas the post-movement beta synchronization might depend on the activated muscle mass.