Pattern generation in non-limb moving segments of the mammalian spinal cord.

The ability of mammalian spinal cords to generate rhythmic motor patterns has been traditionally studied in hindlimb innervating segments of the spinal cord. The rhythmogenic capacity of these segments decreases substantially in the rostrocaudal direction so that the caudal lumbar segments are virtually incapable of producing the rhythm. Our recent studies of the sacrococcygeal segments of the neonatal rat spinal cord showed that these non-limb innervating segments have an intrinsic rhythmogenic capacity that is used to elicit rhythmic tail movements. The high viability of the sacrococcygeal segments, the specific behavior produced by them, and their simple functional organization, makes the isolated sacrocaudal network a new promising model for studies of neural automaticity in mammals. The present work summarizes the current knowledge on sacrococcygeal rhythmicity and discusses its functional implication.