Figure 5.

Causal state machines (CSMs) reconstructed and their corresponding relative frequency distributions obtained from facilitating FD model driven by Poisson spike train with mean firing rates (A) 50, (B) 77, (C)100, (D) 125, (E) 200, and (F) 250 Hz. State “0” is the baseline state. Similar graph structure is seen for mean firing rates of 50 and 70 Hz. Under mean firing rate of 100 Hz, the graph structure is more complex with more edges, vertices, and one set of parallel edges from state “3” to “6”. This increase in complexity is somewhat not surprising as this is inflection point where the concavity of the normalized response fixed point for this synapse model changes at this firing rate, (see Figure 1). In non-physiological range from 125 to 250 Hz, the complexity of graph structure decreases.