A network of spontaneously active interneurons that emit modulated rhythmical activity. Those situated in the spinal cord are implicated in the coordination rhythmical activities such as locomotion. Some of these neurons are excitatory and others inhibitory. Thus, in the case of locomotion, when the agonist extensor muscles are activated, the antagonist flexors are inhibited. On completion of the extensor phase, they are inhibited and the flexors activated, with the cycle of excitation-inhibition repeating itself. In terms of energetics, CPGs minimize antagonism of antagonistic muscles. There are problems with this theory that still have to be resolved satisfactorily (e.g., the mechanisms by which sensory input adjusts the output of the network to changing environmental circumstances and whether there are a variety of CPGs governing the different muscle groupings involved in rhythmical movements like locomotion, chewing and respiration).
See Agonist muscle, Antagonist muscle, Coordination, Energy, Gait, Gamma aminobutyric acid (GABA), Interneurons, Locomotion, Motilty, Movement coordination, Preyer-Tracy hypothesis of autogeneous motility, Spinal cord, Spontaneous motor activity