Causal Measures of Structure and Plasticity in Simulated and Living Neural Networks
In panel a) the synaptic weights from N1 to N2 and N4 to N5 have been synaptically coupled. N3 is left uncoupled to demonstrate that a pairwise GC will indicate null connectivity. Equivalent but independent random processes drive each of the five neurons. 100 realizations of this network using Izhikevich's simple neuron model with these weights yields the results shown in panel b) using pairwise Granger causality. These results demonstrate that pairwise Granger causality can not only resolve the difference between null and actual connectivity, but also determine the directionality of those influences.