The adequate functioning of the central nervous system requires that the various areas of the body operate together. For example, quadrupedal as well as bipedal locomotion is a complex motor behaviour which requires the simultaneous activation of most body parts including the trunk and neck, forelimbs, hindlimbs and tail. On this basis, therefore, the anatomical specialization of body parts involved in movements should be reflected at the neuronal level. However, the mammalian spinal cord should not be considered as an homogeneous chain of equipotent networks, as is the case, for example, in organisms which exhibit anguilliform locomotion such as lamprey, but as an interconnected ensemble. What are the central mechanisms responsible for coordinating such distributed network activity and to what extent does coupling arise at the spinal level? The present study was therefore undertaken to address the functioning of the entire spinal cord, studying it as a whole, rather than as separate elements, and to see how its various regions might interact to coordinate motor activity. To this end, simultaneous multisite extracellular recordings were performed at the thoracic, lumbar and sacral levels in an isolated spinal cord preparation of humanely killed newborn rat. Based on a method initially used by others (Bracci et al. 1996), a pharmacological approach involving bath-application of inhibitory synaptic blockers, strychnine and bicuculline, was employed for several reasons: (1) powerful and stereotyped bursts of action potentials are spontaneously produced; (2) the sharp onset of the bursts allows accurate determination of their timing; (3) the suppression of inhibitory connections within the spinal cord reveals underlying connectivity. It was therefore postulated that motor output recorded under these restrictive conditions might reveal coupling and other hard-wired properties of the system. Motor activity, elicited in the disinhibited network by bath-applying strychnine (glycinergic blocker) and bicuculline (GABAergic blocker), consisted of slow spontaneous bursting. Under these conditions, the recorded bursts were coordinated in 1: 1 relationships at all segmental levels. For each cycle, a leading segment initiated the activity that then propagated in a metachronal way through adjacent segments along the length of spinal cord. There was both regionality nonlinearity and directional asymmetry in this burst propagation: motor bursts propagated most rapidly in the thoracic spinal cord and the rostro-caudal wave traveled faster than the caudo-rostral one. Propagation involved both long projecting fibres and local intersegmental connections. Our results show that motor activity propagates along the spinal cord with a specific temporal pattern and that there is an asymmetry in the propagating characteristics from rostral to caudal, versus caudal to rostral directions. Moreover, it was found that intersegmental coupling relies on a combination of local circuit connectivity as well as long projection fibres. This preparation offers as simplified model for studying network interactions in the mammalian nervous system.