To the Editor: Rao et al.1 used functional magnetic resonance imaging (fMRI) to map the somatotopic organization of the human primary motor cortex. Eight neurologically intact right-handed subjects performed voluntary movements of the hand, arm, and foot while undergoing echo-planar imaging. Statistically significant MRI signal changes were noted in the left motor cortex in all subjects and in all movement conditions. In contrast, no functional activity was observed in the right hemisphere. Finger movements, which consisted of self-paced repetitive tapping of the fingers on a flat surface, produced the most robust signal changes. In summary, the findings of Rao et al. support the notion that discrete limb movements are represented in localized regions of the contralateral motor cortex consistent with the motor “homunculus” of Penfield and Boldrey.2 Given the findings of Rao et al.,1 and the potential utility of fMRI in mapping the human …