Before revision: Neurons typically show two distinct dynamical regimes: Resting state, corresponding to a stable fixpoint, are often observed for low average input. Higher input commonly result in tonic spiking, which corresponds to a stable limit cycle . Some neurons , however, show an additional intermediate, bistable regime, with coexistence of resting-state fixpoint and limit-cycle spiking .
After revision: Neuronal voltage dynamics of regularly firing neurons typically has one stable attractor: either a fixed point (like in the subthreshold regime) or a limit cycle that defines the tonic firing of action potentials (in the suprathreshold regime). In two of the three spike onset bifurcation sequences that are known to give rise to all-or-none type action potentials , however, show an additional intermediate, bistable regime, with coexistence of resting-state fixpoint and limit-cycle spiking .