FIG. 1.
A: spontaneous bursting recorded from the right L5 ventral root 25 min after application of bicuculline (20 μM) and strychnine (1 μM). B: comparison of the percentage of roots from thoracic (T11–13) to L6 in which stimulation evoked locomotor-like bursting in control (29 experiments) vs. the percentage of roots in which stimulation evoked bursting in the presence of bicuculline and strychnine (31 experiments). C: averages of 4 DC recordings of the left L6 ventral root during 4-Hz trains applied to the left L5 ventral root (4 stimuli, 50 μA) in control (top) and under bicuculline (20 μM) and strychnine (1 μM; bottom). Under control conditions, each stimulus of the train evoked a slow long-latency potential (↓) superimposed on a tonic depolarization. In the presence of bicuculline and strychnine these potentials were not observed and the stimulus train evoked a burst after a delay. D: alternating locomotor-like activity recorded from the left and right L2 ventral roots and induced by a 4-Hz train, 50 μA applied for 10 s to the left L5 ventral root (same experiment as in C).