Fig. 3.

Representative DRP patterns showing the relationship of L2 DRPs with motor output and limb endpoint forces during locomotion. Each panel shows representative patterns for L2 DRPs (iL2 DRP, blue) during locomotion relative to L2 ventral root activity (iL2 or cL2 VR, black; rectified and integrated envelope, gray) and ipsilateral (green) and contralateral (red) forces. Ipsilateral (i) always indicates the side of the iL2 DRP. Dashed vertical lines emphasize the relative timing. A: DRPs consistently occurred immediately following contralateral force onset and scaled with contralateral force amplitude, but were independent of ipsilateral force timing and amplitude. B: waxing and waning locomotor patterns were occasionally induced by dopamine (n = 3/13 with DA). DRPs occurred only during contralateral force bouts, independent of ipsilateral force and contralateral motor output. Force scale bars = 10 mN. VR and DRP scale bars = 400 μV in (A) and VR and DRP scale bars = 100 μV in (B).