MORPHOLOGICAL AND ELECTRO-PHYSIOLOGICAL CHARACTERISTICS OF A DORSAL UNPAIRED MEDIAN NEURON OF THE CRICKET, ACHETA-DOMESTICUS

1. 1. The dorsal unpaired median neuron (DUMDL) of the metathoracic dorsal longitudinal flight muscle was studied using cobalt and neutral red staining, various pharmacological agents and extracellular recording of electrical activity. 2. 2. The soma of DUMDL is posterior in the group of dorsal unpaired median neurons of the metathoracic ganglion; DUMDL does not degenerate following histolysis of its muscle. 3. 3. Slow, regular spontaneous activity of DUMDL is generated in the isolated metathoracic ganglion and is suppressed following stimulation of DUMDL and by discharges of the flight motor neurons. This spontaneous activity is increased by acetylcholine and eserine and blocked by anticholinesterase agents. 4. 4. The neurite of DUMDL appears to have several impulse initiation zones characterized by a low safety factor. © 1979.