Degenerate neural circuits perform the same function despite being structurally different. However, it is unclear whether neural circuits with interacting neuromodulator sources can themselves be degenerate while maintaining the same neuromodulator function. Here, we address this by computationally modelling the neural circuits of neuromodulators serotonin and dopamine, local glutamatergic and GABAergic interneurons, and their possible interactions, under reward/aversion-based conditioning tasks. We show that a single sparsely connected neural circuit model can recapitulate many separate experimental findings, but not all, suggesting multiple parallel circuits. Using simulations and dynamical systems analysis, we demonstrate that several different stable circuit architectures can produce the same observed network activity profile. Further, simulating dopamine (D2) receptor agonists in rewarding task can distinguish among sub-groups of these degenerate networks; a testable model prediction. Overall, this work suggests the plausibility of degeneracy within neuromodulator circuitry and has important implication for the stable and robust maintenance of neuromodulator functions.
bioRxiv Subject Collection: Neuroscience