  Using a stochastic generalization of the Hodgkin&#8211;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.
