Fig. 1. Decentralization effects in biological and model systems.

(a) Frequency changes over time during the recovery process of the pyloric network rhythmic activity. At time = 0 the input nerve carrying neuromodulatory inputs to the STG was severed (stn blocked, arrow). Inset: expanded view of bouting activity as marked. Stable pyloric activity was recovered in this case after ~65 hours. (b) Schematic diagram of intracellular activity- and neuromodulator-dependent regulation pathways and target molecules. G_K(V) (including both G_A and G_Kd) and G_Ca(V) are the voltage-dependent conductances of I_K and I_Ca, respectively; G_MI(V) is the voltage-dependent conductance of the modulator activated inward current, I_MI, which activates via a neuronal receptor upon binding to a ligand such as proctolin (not shown), and is assumed to directly regulate S_M. All conductances have fast kinetics of activation. S_A is the activity-dependent intracellular Ca²⁺ sensor and in turn (negatively) regulates G_Ca with slow kinetics given by τ_g. S_M is the neuromodulator-dependent sensor that detects changes in G_MI, and in turn (negatively) regulates the endoplasmic reticulum Ca²⁺ pump with slow kinetics given by τ_p > τ_g. G_MI(V) and [Ca]_cyt positively regulate the intracellular sensors S_M and S_A, respectively. ER represents the endoplasmic reticulum or any intracellular Ca²⁺ store. (C) Frequency changes over the recovery process in the full model when E_Ca was set to vary freely with [Ca]_cyt