Development of Insect Nervous Systems
As this is the first of a series of articles presented on the development of the nervous system in hemimetabolous insects, I would like to sketch the general sequence of events in this process as it is now understood and to indicate some major current approaches and problems. Most of the work in this area has involved orthopteran insects, primarily locusts, crickets, and cockroaches. These are large insects with a surprisingly sophisticated behavioral repertoire. Interest has focused on the simpler, highly stereotyped behavior patterns such as rhythmic or episodic behavior. The basic coordination underlying such patterns has been shown to be generated within the central nervous system by circuits of motor neurons (MNs) and interneurons (INs), whose output is then modulated to varying degrees by sensory input. The behavior is thus encoded in the physiological and structural properties of the central neural elements, all of which may be unique cells (Bullock, 1974; Goodman, 1976). We are interested in discovering how these neural programming circuits and their composite neurons are uniquely differentiated during development. The analysis currently involves three primary questions: (1) What are the sources of information which specify the properties of these networks? (2) How, in a descriptive sense, is a circuit constructed; that is, what are the directly observed changes in physiological and structural features during construction? (3) What are the underlying mechanisms guiding construction? How is the information translated from original sources into differentiation?
KeywordsAbdominal Ganglion Postembryonic Development Flight Pattern Campaniform Sensilla House Cricket
Unable to display preview. Download preview PDF.