Fig. 1.

Experimental setup. A, Schematic of the lumbar region of the neonatal rat spinal cord and the setup used to investigate the locomotor properties of dCINs. Suction electrodes were placed on the contralateral L4–L5 hemicord for electrical stimulation of caudally projecting axons, and on the cL2 to record ventral root activity. The patch electrode (dCIN) was lowered into a slit made in the ventral surface of L2–L3. B, The intensity of L4–L5 stimulation was increased manually (top trace). At higher levels, the stimulation (stim.) caused sustained activity in the cL2 ventral root (lower trace). The threshold for such activity, as indicated by the dashed line, was termed the VRT.