Central Pattern Generators in the Spinal Cord: Absences provides new clues of its organization

The neural networks inside the spinal cord are capable of generating rhythmic alternated activity in antagonist muscles (i.e. extensor and flexor) on the same limb; these networks are called Central Pattern Generator (CPG). Numerous attempts have been made in order to explain and reproduce this activity. By means of electrical recording the dorsal aspect of the spinal cord with a multielectrode array, we have recently observed a wave‐like cord dorsum potential during the scratching in the decerebrated cat. This wave propagates in a rostro‐caudal direction of the spinal cord; also we have observed that this wave persists during spontaneous absences of extensor activity, while the flexor maintains its alternation regularly. This provides al clue of the CPG structure responsible of generating such activity. Those elements lead us to propose a model for the CPG. This model integrates a rostro‐caudal distribution proposed by Grillner (1979) and a bi‐layer architecture as Lafreniere‐Roula & McCrea (2005) suggests.