NEURAL MODEL WITH PROBABILISTIC FIRING BEHAVIOR .2. ONE-NEURON AND 2-NEURON NETWORKS

A detailed analysis is undertaken of one- and two-neuron networks of W. A. Little's model neurons. A single model neuron can produce a wide range of average output patterns, including spontaneous bursting and tonic firing. The probability distribution of interspike intervals in the model compares well with the various types of experimental interval histograms. The authors consider some specific examples from the pyloric system of the lobster stomatogastric ganglion. Model neurons are found which reproduce the mainfeatures of the output from various pyloric neurons. These are then used to model four distinct types of two-neuron interaction found in the system. Despite the fact that specifying the synaptic connectivity considerably limits the range of possible outputs, it is found that in every case the model can successfully simulate the physical behavior. Further, it is shown that two reciprocally inhibitory tonic model neurons can generate a clear-cut alternate bursting pattern. It was found that model units with physically significant output always had order (as defined in Part I), but the converse was not true. Finally, the significance of Little's neuron as a basis for the modeling of more complex system is discussed.