Figure 11.

Extracellular responses recorded from L4 level. Insets show the recording sites. A, M1 stimulation. At L4 spinal level, extracellular responses were recorded from dorsal corticospinal tract (dCST, left) and from ventral horn (right). Three volleys were recorded from dCST (see asterisks) with latencies of 1.25, 2.25, and 3.00 ms. Responses recorded from the ventral horn showed dCST volleys with a delayed response (11 ms). B, Sciatic nerve stimulation. At the L4 spinal level, extracellular recording showed two main responses (marked with asterisks), a fast first response with 0.8 ms latency and a delayed second response with 2.6 ms latency. C, Spinal cord stimulation. The spinal cord was stimulated at the level of L1, and recording was obtained from the L4 ventral horn, which showed an onset latency of 1 ms. Arrow marks the deflection caused by stimulus artifact. Asterisks mark the two spinal responses.