Topology selection by chaotic neurons of a pyloric central pattern generator

The pyloric Central Pattern Generator (CPG) in the lobster has an architect ure in which every neuron receives at least one connection from another mem ber of the CPG. We call this a "non-open'' network topology. An "open" topo logy, where at least one neuron does not receive synapses from any other CP G member, is found neither in the pyloric nor in the gastric mill CPG. Here we investigate a possible reason for this topological structure using the ability to perform a biologically functional task as a measure of the effic acy of the network. When the CPG is composed of model neurons that exhibit regular membrane voltage oscillations, open topologies are as able to maxim ize this functionality as non-open topologies. When we replace these models by neurons which exhibit chaotic membrane voltage oscillations, the functi onal criterion selects non-open topologies. As isolated neurons from invert ebrate CPGs are known in some cases to undergo chaotic oscillations, this s uggests that there is a biological basis for the class of non-open network topologies that we observe.