imary motor cortex tuning to intended movement kinematics in humans with tetraplegia. J. Neurosci. 28,1163-1178. Turner. RS.. Grafton. 5J.. Votaw, J.R. Delong. AIR_ Hoffman. J.M., 1998. Motor subcircuits mediating the control of movement velocity: a PET study. J. Neurophysiol. 80 2162-2176. van Hemmer,.