Extrinsic Inputs

Abstract

The pyloric and gastric networks are amazing little machines which can produce rhythmic motor patterns for hours in the isolated stomatogastric nervous system. When the stomatogastric ganglion (STG) itself is completely isolated, there is, however, complete cessation of activity in both CPGs. Just as the most sophisticated engine needs gas to function, the pyloric and gastric CPGs require extrinsic inputs in order to operate and produce a rhythmic output. Moreover, in the intact animal (as shown by electromyographic recordings) as well as in isolated preparation of the stomatogastric nervous system, pyloric and gastric networks do not produce only a stereotyped pattern, but a relatively large “repertoire” of outputs. It is also the activity of extrinsic inputs projecting onto the stomatogastric CPGs that determines such a flexibility of expression.