(A) Phase coordination between right and left ventral roots during sural nerve evoked locomotion in control (cyan, n = 16 step cycles from two spinal cords) and dI3OFF (magenta, n = 12 step cycles from two spinal cords). Comparisons were made between right and left flexor-related (L1–L3) ventral root activity or from right and left extensor-related (L4–L6) ventral root activity. Phase coordination was similar between control and dI3OFF spinal cords, p>0.15, two-tailed Student’s t-test assuming unequal variances. (B) Frequency of locomotor activity evoked by sural nerve stimulation (10 s train, 3 Hz, 0.25 ms pulses) was similar between control (cyan) and dI3OFF (magenta) spinal cords. Frequencies were measured for stimulation strengths where rhythmic bursts were most defined. (ns non-significant, p>0.63, two-tailed Student’s t-test assuming unequal variances.) (C) Left, experimental setup of sural-nerve attached isolated spinal cord preparation. Recording electrodes (grey electrodes) are attached to ventral roots. The sural nerve is in continuity with the spinal cord and is stimulated (orange electrode) to evoke locomotor activity. Inset, right L5 dorsal root potential evoked by sural nerve stimulation. Asterisk denotes stimulation artifact, arrow denotes the A-wave. Ths is defined as threshold for evoking short-latency L5 dorsal root potential in response to sural nerve stimulation. Right, ventral root recordings during right sural-nerve stimulation (10 s train, 3 Hz, 0.25 ms long pulses, thick orange line) in dI3OFF spinal cord. Brief voltage deflections in the recordings are stimulation artifacts. Top and bottom traces are from two separate applications of the stimulation with recording electrodes attached to different sets of ventral roots. (D) Same setup as in C except that stimulation was applied to the left L4 dorsal root (orange electrode). Ventral root recordings during dorsal root stimulation in the same dI3OFFmouse as in C showing rhythmic locomotor-like activity. Thdr is defined as threshold for evoking short-latency L5 dorsal root potential in response to dorsal root stimulation. ∫Rt L5, ∫Lt L3: rectified and integrated ventral root recordings. Scale bar, 2 s, applies to C and D.