A, schematic of an isolated spinal cord mouse preparation illustrating the recording arrangement used to record locomotor-like activity. B, locomotor-like bursting pattern recorded from the L2 and L5 ventral roots following bath application of α-methyl-5-HT (4 μm). C, schematic showing the recording arrangement from an in vitro leg attached mouse preparation. Electroneurogram recordings were obtained from the common peroneal (CP) and lateral gastrocnemius/soleus(LGS) nerve. D, top panel, flexor/extensorand left/rightalternating pattern recorded from the LGS and CP nerves following bath application of 5-HT/dopamine and NMA. Data modified from Whelan et al. (2000) with permission; bottom panel, EMG data recorded from the tibialis anterior (TA) and medial gastrocnemius (MG) muscles of an adult mouse walking on a treadmill. Data modified from Fortier et al. (1987) with permission.