This is a network of three point neurons (PTNRN10). The neurons are connected by "synapses" that resemble electrical synapses. When a neuron reaches firing threshold, the other neurons are given a "synaptic" current equal to the amount specified in the parameters times the coupling coefficient for that pair. In the initial settings for this model, neuron 1 is designated as a "pacemaker" neuron, and is given a steady current to depolarize it and cause it to fire.
A feature of this implementation of the model is that it can run continuously. Check "run contin." in the "Display" dialog box. You can change the parameters as it runs to see the effect.