Channel noise and synchronization in excitable membranes

Using a stochastic generalization of the Hodgkin–Huxley model, we consider the influence of intrinsic channel noise on the synchronization between the spiking activity of the excitable membrane and an externally applied periodic signal. For small patches, i.e., when the channel noise dominates the excitable dynamics, we find the phenomenon of intrinsic coherence resonance. In this case, the relatively regular spiking behavior is practically independent of the applied external driving; therefore no synchronization occurs. Synchronization takes place, however, only for sufficiently large ion channel assemblies. The neuronal signal processing is thus likely rooted in the collective properties of optimally large assemblies of ion channels.