Role of the medial frontal wall for readiness of motor execution

The sensorimotor area and supplementary motor area and cingulate cortex of the frontal medial wall are reported to be important for the generation and control of movements, according to neuroimaging studies and electroencephalography (EEG) recordings with subdural electrodes. 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 simple self-initiated left and right motor execution activated different areas: the left movement activated the presupplementary motor area (pre-SMA), putamen, 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.