The stomatogastric ganglion is a collection of about thirty
neurons that sits on the dorsal surface of the foregut (stomach)
in decapod crustaceans. The neurons it contains form two central
pattern generators (CPGs), namely the pyloric and gastric mill
CPGs. The pyloric CPG controls striated muscles that dilate and
constrict the pyloric region of the stomach in a cyclic three
phase rhythm. The gastric mill CPG produces a slower six phase
rhythm that control muscles that produce chewing by three
ossicles in the gastric mill. The system has special advantages
that make it one of the most well-studied invertebrate neural
circuits available. Its importance lies in the fact that the
cellular and synaptic properties used by this ganglion are the
same as those found in all nervous systems including the
mammalian brain but because there are only a few neurons in each
circuit the entire "wiring diagram" for the ganglion has been
determined. Besides, neurons of the stomatogastric ganglion
produce cell type-specific vol