Neuromodulation of Small Neural Networks in Crustacea

One of the important goals of motor systems research is to elucidate the neural networks that underlie simple rhythmic movements.1 In some cases, the component neurons and synaptic connectivity of such networks (sometimes called Central Pattern Generators, or CPGs) have been partially or even fully elucidated.2 Despite a relatively fixed neuroanatomical structure, the motor patterns that these networks generate are extremely flexible and plastic, allowing the animal to adapt its behavior to changing demands of the environment. This flexibility arises from sensory feedback and from modulatory inputs to the motor networks from other neural centers. Modulatory inputs can change the intrinsic electrophysiological properties of the neurons in the network and alter the strength of the synaptic connections within the network.3 This causes a reconfiguration of the network’s motor output, leading to an altered behavior.