Slide 3 of 29

The rhythmic movement of the wings of crickets during song production is accomplished and coordinated by an internal clock. This is a schematic of a central pattern generator, a small neural circuit in a ganglion that specifies the particular motor output pattern for a number of muscle responsible for a particular behavior pattern. There is a great deal of evidence suggesting that the pulse rhythms in the songs of crickets are generated by such a CPG in the mesothoracic ganglion. A command signal is produced in the brain that basically sets the central pattern generator going. Once started the behavior pattern (in this case the song pattern) is produced by the output of motor units from the CPG.