High resolution DC-EEG mapping of the Bereitschaftspotential preceding simple or complex bimanual sequential finger movement

The present set of experiments investigated the Bereitschaftspotential (BP) preceding voluntary bimanual sequential simple (task 1) and complex moveme nts (task 2) in supplementary/cingulate and primary motor areas (SCMA, MIs) using 64-channel direct current electroencephalography analysis in 16 righ t-handed healthy subjects. The results showed that: (1) onset times of BPs preceding the two tasks were significantly earlier at Ct than at C3 and C4, (2) the complex task induced significantly larger amplitudes than the simp le task over the SCMA 1.1 s before EMG onset (BP1 period), over the SCMA an d both MIs for the BP2 period, extending from the SCMA and MIs to all front ocentral, central, centroparietal, and frontal areas during the motor poten tial period, (3) task difference prior to 0.96 s mainly appeared in the SCM A rather than in either MI, (4) the BP had a significantly larger amplitude in the SCMA than in the MIs, the differences being asymmetric between the left and the right hemisphere motor areas, and (5) the sinks of BP current source density (CSD) preceding the two tasks were found in the frontocentra l midline; and the regions and intensities of CSD maps were larger and stro nger in task 2 than they were in task I at the same times of the epoch. The results suggested that: (1) the SCMA and MIs participate in bimanual seque ntial simple or complex movements, (2) the SCMA appears to not only serve a s a trigger command for voluntary movement but also seems to design the dif ferent motor modes, (3) the amplitude, duration, onset time, CSD region, an d intensity of BP all increase with the level of complexity of the movement , (4) the greater the complexity of the action, the earlier the preparation and the larger the extent of activated neuronal populations in the SCMA, ( 5) activation of the SCMA occurred prior to that of the MI, and (6) the act ivation suggests an asymmetry between left and right MIs in simultaneous bi lateral finger movement, but this asymmetry seems to be less pronounced for complex movements.