High resolution DC EEG of the bereitschaftspotential preceding anatomically congruent versus spatially congruent bimanual finger movements

The purpose of the present study was to observe how the supplementary, cing ulate and primary motor areas (SCMA, MI) participate in the spatiotemporal coordination of bimanual index finger movement and what role the SCMA plays . The Bereitschaftspotential (BP) was recorded using 64 channel direct curr ent EEG (DC-EEG) to compare the anatomically congruent movements (abduction , adduction) with spatially congruent movements (both fingers to the right or left) in 16 normal volunteers. Subjects were required to move their two index fingers simultaneously in the horizontal plane (1) away from the midl ine (abduction), (2) toward the midline (adduction), (3) both index fingers to the right or (4) both fingers to the left. The results showed that ther e were significant differences (p<0.001) among the four tasks, across the 5 6 electrodes, and within the 20 different time points of the 3.5 s analysis epoch. BP amplitudes of the spatially congruent movements were significant ly higher (p<0.05) than the ones of the anatomically congruent movements, a nd they were higher over the mesial wall motor areas SCMA than they were ov er the Mis. However, the significant differences differed between the left and right hemisphere in their amount and onset. The values of the differenc e ratio statistics between the SCMA and the MI indicated that the left hemi sphere was more active than the right in our right-handed subjects for ail tasks, particularly in the early (BP1) as compared to the late (BP2) compon ent. Current source density mappings revealed that BP1 had its earliest ons et in SCMA (6a alpha and 6a beta) for all four tasks. The onset times of BP 2 were earlier and BP densities were higher in the spatially congruent task s 3 and 4 as compared to the anatomically congruent tasks 1 and 2. Also, pr eparation (early component BP1) tended to start earlier and BP amplitudes t ended to be higher for the spatially congruent tasks as compared to the ana tomically congruent tasks.