Location of recorded SDH and DDH neurons in lumbosacral spinal cord. The location of each recorded neuron was plotted on templates of the L3, L4, and L5 spinal cord segments. Approximately 30 neurons were recorded in each segment. For SDH neurons, recordings were obtained across the entire medio-lateral extent of the dorsal horn. For DDH neurons, recordings were concentrated in the medial two thirds of the dorsal horn because dense myelination impedes visualizing neurons in lateral DDH.