We have studied in the in vitro spinal cord preparation of juvenile mice (P7-10) with intact brainstem and hindlimb peripheral nerves the organization of pathways mediating primary afferent depolarization (PAD) of sensory afferents. PAD was inferred from dorsal root potentials (DRPs) elicited by stimulation of low threshold sensory afferents, and recorded from ipsilateral L3-L5 dorsal roots. Spatial facilitation between DRPs produced by stimulation of two selective hindlimb nerves was taken as an evidence of convergence in common pathways underlying PAD (Brink et al. J. Neurophysiol. 51:432, 1984). As in juvenile mice PAD is produced by activation of low threshold flexor and cutaneous afferents (Garcia & Quevedo, SFN abstr. 4766, 2001), interactions between DRPs evoked by stimulation of flexor (PBSt and DP) and cutaneous (CCS and SP) nerves with single shocks (1.2-2T and intervals of 0 ms) were examined. In all the tested combinations: cutaneous+flexor (CCS+PBSt and CCS+DP), flexor+flexor (PBSt+DP) and cut...