The effect of taking timing into account in this way is dramatic as demonstrated by Fig. 2. The horizontal axis shows the frequency of the incoming periodic signal with their phase along the vertical axis. Small changes in the input clearly produce huge shifts in the output behavior. For instance, frequencies below about 550 Hz produce periodic firing with two spikes per cycle. Just above this frequency, output rapidly changes to chaotic firing, followed by further quasi-periodic and chaotic periods.
Clean lines show where the output signal is cleanly phase-locked with the input.
The fuzzy areas show where order and chaos mix. Diagonal lines show how the neural output tends to phase-lock with the incoming dendritic oscillation. The fuzzy areas are regions of chaos and ordered chaos, where the neural output is effectively unpredictable. In fact the artificial bifurcation neuron that produced the results shown is much better than the simple glow-lamp circuit. The neuron was fabricated using 11 transistors and one capacitor in analog VLSI electronics, which is a precursor to a full neuronal array.