Figure 6

Compound neural integrator and differentiator models. Boxes show model simulations in arbitrary units and parameter values. Conventions are same as Fig. 1. A. Primary differentiator-secondary integrator is realized by activity-dependent habituation-sensitization in corresponding primary-secondary pathways. Step application of primary input at a constant firing rate (inset) induces synaptic STD and STP in primary and secondary pathway, respectively, resulting in temporal differentiation and integration of the transmitted signals (lower and upper boxes). Resultant response (last box) at output neuron shows a compound differentiator-integrator characteristic. B. A double integrator may arise from STP in both primary and secondary pathways. C. A double differentiator is similar to a double integrator but with STD instead of STP in both pathways. D. A primary integrator-secondary differentiator can be realized in a similar fashion with a STP-STD combination. Structurally, primary differentiator (A, C) and secondary differentiator (B, D) are comprised of the primary reflex in conjunction with an inverted primary and secondary integrator, respectively, demonstrating the complementarities of integrator and differentiator. See text and Appendix.