Normalized-Hill toy network model. A) Schematic of the 5-species toy network, including two inputs, an AND reaction, and a positive feedback loop. B) Characteristics of sample normalized-Hill functions (n = 4 for both curves). C) Simulated signaling dynamics in response to transient inputs A, B, and A + B. Output E remains active after removal of input A due to a bistable positive feedback loop, though this memory is erased with addition of B. Addition of both stimuli at the same time transiently activates output E. Parameters used are: τ = 1, W = 1, n = 1.4, and EC50 = 0.5.