Somatotopic Arrangement of the Corticospinal Tract at the Medullary Pyramid in the Human Brain

Objectives: Somatotopic arrangements of the corticospinal tract (CST) in the human brain have been generally elucidated; however, very little is known about the somatotopy at the medullary pyramid (MP). Using diffusion tensor tractography (DTT), we investigated the somatotopic arrangement of the CST at the MP in the normal human brain. Methods: We recruited 30 healthy volunteers for this study. Diffusion tensor images were scanned using 1.5 T and the CSTs for hand and leg were obtained using FMRIB software. Normalized DTT was reconstructed using the Montreal Neurological Institute echo-planar imaging template supplied with the SPM software. Results: The hand somatotopy of the CST was located at the medial portion of the MP; in contrast, the leg somatotopy occupied the lateral portion of the MP. Conclusions: We found that the somatotopies for hand and leg were arranged in the mediolateral direction at the MP in the human brain. Copyright (C) 2011 S. Karger AG, Basel