Intracellular recordings from interneurons and motoneurons in intact flying locusts

Abstract

A preparation is described in which it is possible to record intracellularly from identified motoneurons and interneurons during flight in intact tethered locusts. Intracellular recordings could be obtained from either the large somata of the motoneurons or from the neuropil processes of interneurons and motoneurons in either the meso- or metathoracic ganglion. Intracellular recordings from motoneuron somata were sufficiently stable to allow surgical manipulations, e.g. deafferentation, of the nervous system without the loss of penetration. Recordings from neuropil processes required stabilizing the ganglion by sandwiching it between two supports. The preparation is suitable for the cellular analysis of many aspects of motor patterning in the flight system of the locust. So far we have used it to make a direct comparison between the patterns of synaptic activity in intact and deafferented animals. This comparison shows that sensory feedback from wing proprioceptors strongly influences the activity in elevator motoneurons and flight interneurons. From these and other observations we conclude that proprioceptive feedback is essential for generating important features of the intact motor pattern and that wing receptors are integral elements of the intact flight pattern generator.