Cat L4-S1 dermatomes determined using signal averaging.

In view of discrepancies in the earlier literature, a new procedure was devised which used (1) stimuli known to be subthreshold for deep receptor afferents and suprathreshold for hair afferents; (2) averaging techniques applied to dorsal root responses; (3) quantitative mapping of response magnitudes as a function of stimulus location. Dermatomes were obtained for cat L4-S1 dorsal roots which are somewhat larger than the majority of reported whole-root dermatomes, but which are larger than dermatomes approximated from single-unit recordings.