Schematic diagram illustrating the preparation used for the acute electrophysiological experiment.

<p>Dorsal roots (DRs), ventral roots (VRs), dorsal root ganglia (DRG) and the lumbar spinal cord are outlined. After intercollicular decerebration, the ether anesthesia is discontinued and a laminectomy exposes the lumbar cord, DRs L3 through S2 are cut, DRs L4 and L5 are mounted on stimulating electrodes, and finally VRs L4 and L5 are isolated and mounted on diphasic recording electrodes. A tiny fascicle of VR axons is initially cut and diverted on monophasic recording electrodes. After a series of antidromic (sciatic nerve) and orthodromic (DRs) stimulations are performed, while recording from VR axons both diphasically and monophasically, a further tiny bundle of axons is shifted to the monophasic recording electrodes and the stimulation series repeated. This procedure is reproduced about 10 times until most, although not all, VR axons are diverted to the monophasic recording electrodes. The cell bodies in the ventral horn and the axons of the motor neurons invaded antidromically (from spikes elicited in the sciatic nerve) are represented in black, while those <i>possibly</i> receiving an electrically-transmitted depolarization and their axons are represented in gray. Arrows and question marks depict the possible electrical coupling of motor neurons.</p