Structure and function of corticospinal projection originating from supplementary motor area

The importance of supplementary motor area (SMA) for motor function and compensation for primary motor area (M1) has received increased attention. We used diffusion tensor imaging (DTI) and transcranial magnetic stimulation (TMS) to evaluate structure and function of corticospinal projection originating from SMA. Fibers of corticospinal projection originating from M1 (CST) and SMA (ACST) were analyzed. ACST originating from mesial SMA area formed separate white matter bundles leaving the anterior part of M1 area, which then entered the posterior limb of the internal capsule. Projection and overlap of both CST and ACST were detected on medulla. Fibers of contralesional ACST were more than that of ipsilesional ACST in patients with SMA tumors (p