Figure 1. Two examples of lumbar ventral root rhythmic activity that did not meet criteria for locomotor-like activity.

A, rhythmic alternating right (R) L2 and L5 was evoked in response to electrical stimulation of the brainstem, consistent with an alternating pattern of flexor and extensor activity, respectively. However, rhythmic activity was absent on the left (L) side and therefore side-to-side alternating activity could not be documented. B, in this example, left–right alternation is present at the L2 segmental level. However, the recording was not considered locomotor-like for the purposes of this series because of the absence of flexor (L2)–extensor (L5) alternation. Horizontal lines in spinal cord diagrams indicate hemisection levels. Regular occurring spikes in ventral root recordings are artifacts related to brainstem electrical stimulation.