Abstract
Central pattern generators (CPGs) are groups of neurons responsible for the generation of specific rhythmic behaviors. The 14 neurons of the pyloric system of the stomatogastric ganglion (STG) of decapod crustaceans make up one such CPG. Work on this system is refining our understanding of how small ensembles of neurons can be ‘tuned’ by neuronal inputs using different neurotransmitters. In this way a variety of neural outputs can be produced from very simple, anatomically fixed neuronal circuits.