The role of certain parts of the central nervous system in the control of feeding behaviour, and especially of chewing, has been investigated by the use of lesions.Cutting the connectives behind the suboesophageal ganglion disinhibits chewing, so that continuous rhythmic mandibular movements occur even in the absence of mechano- or chemostimulation of the mouthparts. Stimulation of the mouthparts with plant material leads to an increased rate of chewing and to maintained ingestion.Isolating the suboesophageal ganglion from the protocerebrum does not prevent the induction of chewing and maintained ingestion. Severing the frontal connectives (uni- or bilaterally) eliminates maintained ingestion but not the ability to chew.The centrally isolated suboesophageal ganglion is capable of producing a co-ordinated chewing behaviour, but not of ingesting food.

Like other flying animals, locusts must maintain course stability despite turbulence and motor errors. Accordingly, they must detect course deviations and then correct them. The compound eyes, the ocelli and the cephalic wind hairs all detect different sensory consequences of flight instability1–3,and descending interneurones bring this information to the thorax4–9. One such interneurone of this population (the tritocerebral commissure giant neurone) is known to elicit correctional steering10.Here we characterize three additional pairs of descending deviation detector neurones and show how their information is translated into altered drive to the flight motoneurones. The central pattern generator for flight11–13,modulated by proprioceptive feedback14, gates the signal of the detector neurones in thoracic premotor interneurones9,ensuring that the flight motoneurones are affected only during flight. Further, the gating process transforms the phase-independent information of the deviation detectors into a phase-dependent signal modulated at wing-beat frequency, and transfers it to those flight motoneurones active at the time and appropriate to the corrective action required.