Ion channel noise shapes the electrical activity of endocrine cells
Fig 1
Spikes, bursts and the effect of noise.
(A) The duration of an event is determined by the time that V spends above some threshold (chosen throughout as −45 mV). Events are classified as spikes if the event duration is less than 100 ms and there are no oscillations in V (e.g. first, yellow event). Events of longer duration or events with oscillations are identified as bursts (e.g. second, orange event). (B) The deterministic model with gBK = 0.5 nS leads to pure periodic spiking. (C) The stochastic model with the same parameters shows that noise can convert some spikes into bursts. (D) Increasing gBK to 1 nS leads to pure bursting in the deterministic model. (E) The equivalent stochastic model shows a mixture of spikes and bursts, with noise responsible for converting some bursts into spikes. (F) The deterministic model with gCa doubled to 4 nS simply sits at a depolarised steady state (gBK = 0.5 nS). (G) However, the stochastic model with the same parameters shows bursts as noise continually drives the system away from the steady state.