An Isolated Insect Ganglion-Nerve-Muscle Preparation*

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Abstract
1. A preparation is described which consists of an isolated locust metathoracic ganglion, together with one motor nerve and the skeletal muscle which it supplies (the anterior coxal adductor) in a state suitable for tension recording. 2. Mechanical responses were recorded from the whole muscle, or bundles of fibres and electrical responses of single fibres were recorded intracellularly. Some fibres were found in the muscle which have unusual properties. A single excitatory axon supplies the muscle. 3. Preganglionic stimulation applied to cut nerve trunks may excite an inhibitory-conditioning axon supplying the same muscle. 4. Direct stimulation of the motor nerve was combined with preganglionic stimulation in order to excite the two axons, and their interaction in relation to contraction of the muscle was studied. 5. The preparation shows spontaneous activity in the single excitatory axon supplying the muscle. 6. Various preganglionic stimulations were found to cause prolonged changes in the spontaneous motor output. By correlating the stimuli to the output in certain ways, long-lasting changes in mean output frequency were obtained. These may be regarded as a simple form of learning.