The frontal ganglion (FG) is part of the insectudstomatogastric nervous system and is found in most insectudorders. Previous work has shown that in the desert locust,udSchistocerca gregaria, the FG constitutes a major source ofudinnervation to the foregut. In an in vitro preparation,udisolated from all descending and sensory inputs, the FGudspontaneously generated rhythmic multi-unit bursts ofudaction potentials that could be recorded from all itsudefferent nerves. The consistent endogenous FG rhythmicudpattern indicates the presence of a central patternudgenerator network. We found the appearance of in vitroudrhythmic activity to be strongly correlated with theudphysiological state of the donor locust. A robust patternudemerged only after a period of saline superfusion, if theudlocust had a very full foregut and crop, or if the animaludwas close to ecdysis. Accordingly, haemolymph collectedudat these stages inhibited an ongoing rhythmic patternudwhen applied onto the ganglion. We present this noveludcentral pattern generating system as a basis for futureudwork on the neural network characterisation and its roleudin generating and controlling behaviour.
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