Fig 4. Different complete circuits may underly similar effective circuits.

A: A circuit very similar to that in Fig 3, except that neuron 1 also provides excitatory input to neuron 4, which in turn provides inhibitory input to neuron 3. The self-history coupling of neuron 3 to itself has also been removed in this example. B: Leftmost, the effective interaction from neuron 1 to 2, which is qualitatively and quantitatively similar to the effective interaction shown in Fig 3. Subsequent plots indicate each path through the circuit that neuron 1 can send a signal to neuron 2 through the hidden neurons 3 and 4. C. Leftmost, the effective interaction from neuron 1 to 2. Subsequent plots decompose this interaction into contributions from the paths shown above in B.