The proposed research will endeavor to determine: (1) afferent projections of hindlimb cutaneous nerves to cat lumbosacral dorsal horn (using both anatomical and physiological methods); (2) physiological connectivities among dorsal horn cells, using cross-correlation techniques; (3) properties of substantia gelatinosa neurons, using waveform recognition and source-sink mapping; and (4) responses of dorsal horn cells to a variety of quantitatively controlled inputs, such as single action potentials, action potential pairs, and larger inputs evoked by stimulating larger areas of skin.