PHYSIOLOGY AND BIOCHEMISTRY OF PEPTIDERGIC COTRANSMISSION IN APLYSIA

The marine mollusc Aplysia, whose simple nervous system facilitates st udy of the neural basis of behavior, was used to investigate the role of peptidergic cotransmission in feeding behavior. Several novel modul atory neuropeptides were purified and localized to identified choliner gic motorneurons. Physiological and biochemical studies demonstrated t hat these peptides are released when the motorneurons fire at frequenc ies that occur during normal behavior, and that the peptides modify th e relationship between muscle contraction amplitude and relaxation rat e so as to maintain optimal motor output when the intensity and freque ncy of feeding behavior change.