Noise-induced destruction of equilibrium regimes and spiking patterns formation in calcium dynamics

The problem of identifying the conditions that cause the formation of oscillatory patterns in the calcium dynamics of cells is considered. This problem is studied in this article on the basis of a stochastic version of the Li-Rinzel model of calcium dynamics. The study is carried out for mono- and bi-stability zones, where the initial deterministic version of the model has only stable equilibria as attractors. For the monostability parameter zone, conditions have been found under which even small noise destructs the equilibrium mode and forms the spiking oscillatory patterns. In the bistability zone with two coexisting stable equilibria, mechanisms of two-stage transformations from stochastic preference to noise-induced excitement are revealed. To study these stochastic phenomena, we apply the method of confidence ellipses.