Fig. 1. Schematic diagrams of  in vivo patch-clamp recordings from the substantia gelatinosa (SG) and identification of SG neurons and surgical incision. (  A ) Left, the spinal cord is exposed, and the superficial dorsal gray matter lateral to the L4 dorsal root entry zone is discernible as a relatively translucent band under Lissaner’s tract (gray zone). The pia-arachnoid membrane was cut to make a window to penetrate the patch electrode in the spinal cord. Right, Schematic drawing depicting an electrode in the transverse plane. The electrode was advanced into the SG at an angle of 30 to 45°. (  B ) Location of a recorded cell that was identified by an intracellular injection of biocytin. The soma is located in the SG, and dendrites expand dorsally and ventrally. (  C ) Schematic drawings of a 1-cm-long incision and wound closures by using skin staplers. A 1-cm-long line, to be incised, was drawn in the most sensitive region of a receptive field. Air-puff and pinch stimuli were applied 1 to 2 mm from the line in the most sensitive site of the receptive field. After determination of basal responses, a 1-cm-long incision was made on the marked line through the skin, fascia, and muscle of the hindquarter, and then the wound was closed with two skin staples.