Reliable circuits from irregular neurons: A dynamical approach to understanding central pattern generators

Central pattern generating neurons from the lobster stomatogastric ganglion were analyzed using new nonlinear methods. The LP neuron was found to have only four or five degrees of freedom in the isolated condition and display ed chaotic behavior. We show that this chaotic behavior could be regularize d by periodic pulses of negative current injected into the neuron or by cou pling it to another neuron via inhibitory connections. We used both a modif ied Hindmarsh-Rose model to simulate the neurons behavior phenomenologicall y and a more realistic conductance-based model so that the modeling could b e linked to the experimental observations. Both models were able to capture the dynamics of the neuron behavior better than previous models. We used t he Hindmarsh-Rose model as the basis for building electronic neurons which could then be integrated into the biological circuitry. Such neurons were a ble to rescue patterns which had been disabled by removing key biological n eurons from the circuit. (C) 2000 Elsevier Science Ltd. Published by Editio ns scientifiques et medicales Elsevier SAS.