Alpha band power changes in unimanual and bimanual sequential movements, and during motor transitions

Objective: To investigate the cortical activation during execution of unima nual and bimanual synchronous and asynchronous finger sequences, as well as during transitions between those sequences. Methods: Task-related power (TRPow) analysis of multichannel surface EEG wa s used to examine the regional oscillatory brain activity in the lower (7.8 -9.8 Hz) and upper (10.8-11.8 Hz) alpha band. Unimanual to bimanual, bimanu al to unimanual, and unimanual to unimanual transitions, prompted by visual cues, were studied in 10 right handed subjects. Results: (1) Execution of unimanual and bimanual movements was accompanied by a bilateral activation over the central regions. (2) The 7.8-9.8 Hz TRPo w decrease was more prominent for left and bimanual movements, suggesting s ensitivity of the lower alpha band to task difficulty. (3) No difference in alpha oscillatory activity was found between bimanual synchronous and asyn chronous sequences. (4) Transitions between motor sequences were invariably accompanied by a mesioparietal TRPow decrease in the lower alpha band. (5) This mesioparietal activation was contingent to the change of motor pro-ra m, and could not be accounted for by the change of visual cue, or related a ttentional processes. Conclusion: The 7.8-9.8 Hz mesioparietal activation most likely reflects a posterior parietal motor command initiating transition between motor pro.-r ams. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.