Intersegmental coordination of flight steering in locusts

Abstract

Correctional steering during flight involves the neuromuscular apparatus of nine segments and some 10% of the extracerebral CNS. Steering is initiated and coordinated intersegmentally by pleurisegmental sensory interneurons that report course deviation. These traverse the participating ganglia and contact a similar post-synaptic circuitry in each segment. The musculature and motor neurons involved are segmentally homologous, and so probably are the local circuits producing the different behaviours. In these circuits, exteroceptive sensory information sums with tonic or rhythmic drive from the flight motor. This summation is responsible for the context specificity of behaviour, and for recruitment, phase shifting within the wing-beat cycle and other motor effects.