Differences in areas of human frontal medial wall activated by left and right motor execution: dipole-tracing analysis of grand-averaged potentials incorporated with MNI three-layer head model.

Electroencephalography (EEG) is a non-invasive technique for monitoring electrical activity and has good time resolution. Combining these advantages of EEG with dipole-tracing analysis incorporating a realistic three-layer head model (scalp-skull-brain head model; SSB/DT) allows for the detection of dipoles in the millisecond range and investigation of the processing of cognitive function and movement execution. In this study, we constructed a scalp-skull-brain head model from Montreal Neurological Institute standard brain images and detected dipole localizations in the millisecond range from grand-averaged negative slope (NS) to motor potentials during a simple pinching movement. The left movement activated the presupplementary motor area (pre-SMA), rostral cingulate cortex and rostral premotor area, which are associated with cognitive functions and self-initiated decisions. These areas were associated with the early NS potential during left pinching movement preparation. The right movement activated the caudal cingulate cortex, pre-SMA and caudal premotor area, and these areas were activated just before the execution of movement.