Fig. 2.

Identification of dCINs in the lumbar region by the presence of an antidromic action potential.Ai–Aiii, The top traces show the raw data superimposed, and the bottom traces show the averaged trace. Ai, EPSP–IPSP evoked at low stimulus levels (<1 × VRT) in a neuron subsequently identified as a dCIN by the presence of an antidromic spike (Aii,Aiii). Antidromic spikes were elicited at a short, constant latency (Aii). The hump in the spike, as indicated by the arrowheads in Aii, is the subthreshold EPSP that was abolished on incubation with 20 μm AP-5 and 30 μm CNQX (Aiii). B, Collision test to verify the antidromic nature of the spike. a, Orthodromic spike elicited by a 2 msec suprathreshold depolarizing current pulse;b, antidromic spike; c, initial segment spikelet; d, complete abolition of the antidromic action potential. C, Location of neurons recorded from in the ventromedial area (as indicated by the box,inset) of L2–L3. Black squares, Caudally projecting dCINs; white squares, non-dCINs.