[Human supplementary motor area: a role in voluntary movements and its clinical significance]

Clinically, seizures from supplementary motor area (SMA) are characterized by asymmetric bilateral tonic posturing without loss of awareness, and its dysfunction is also strongly related to the clinical cardinal features in patients with Parkinson's disease and dystonia. By investigating Bereitschaftspotentials (BPs) from SMA, the following normal functions are elucidated. 1) SMA proper, a caudal part of SMA showed a somatotopy of BP generators in accordance with each part of the voluntary movements in the body, 2) bilateral SMAs were involved in each side of the body movements equally, and the amplitude did not differ from one in the contralateral primary motor area (MI), 3) pre-SMA was strongly related sensorimotor integration, decision making, repetitive rate of voluntary movements, voluntary motor inhibition and negative motor response. We look forward to clinical application of brain potentials from SMA in the field of brain-computer interface such as assessment and restorative approach in patients with spinal cord injury, paraplegia or motor neuron disease.