Modeling phase synchronization in a biologically-based network

The phase relationships between motorneuron firing in invertebrate central pattern generators (CPGs) determine the sequence of muscle contractions and therefore the behavior of the animal. In the lobster stomatogastric ganglion, all of the neurons comprising two CPGs were identified. Physiologically determined parameters from identified neurons were incorporated in a new biophysically based model. To study the role of reciprocal inhibition the most common type of synaptic interaction in the CPGs, chains of neurons and 5×5 matrices, both with reciprocal inhibitory connections, were modeled. Oscillatory neurons at the ends of long odd-numbered chains could be brought into synchronization very rapidly. Pairs of oscillatory neurons embedded in the matrix, but bursting at different frequencies, became entrained at intermediate frequencies and phase relationships. The results suggest a mechanism for producing CPG motor patterns