Figure 1.

(a) Longitudinal cut along a primate spinal cord depicting the internuncial system (gray matter motor highway) and the nano-size of the proposed severance (left). The red circle on the right side of this panel is the pyramidal tract, shown in two exploded views of a sharply transected cord (middle right) and of the cord in the vertebral canal (lower middle right). (b)Visualization of the severed pyramidal tract. The uppermost image depicts a motor neuron in the cortex sending forth the axonal prolongation. Middle panel: The pyramidal tract (red) and a portion of its severed axons. Lower panel: The sharply severed axonal extensions (adapted from Laruelle 1937 and several images in the public domain)