Propagation and enhancement of the noise-induced signal in a coupled cell system

The response of an array of unidirectional coupled cells to local external noise is investigated. The cells are all tuned near the Hopf bifurcation point for calcium oscillation. It is found that when the first cell of the chain is perturbed by noise, stochastic calcium oscillation can be induced and propagates along the chain with considerable enhancement and a rather regular signal output is obtained at the end of the chain. It indicates that noise can result in the internal order, which is likely to show the rhythm of life in life systems. It is demonstrated that the occurrence of such a phenomenon depends on the coexistence of three factors: being close to the Hopf bifurcation point, unidirectional coupling and optimal coupling strength. It is important to note that this phenomenon is quite different from the noise enhanced signal propagation, where a larger coupling strength is always more favorable. Our result may find important applications in calcium signaling processes in vivo.