Coherent response of the Hodgkin-Huxley neuron in the high-input regime

We analyze the response of the Hodgkin-Huxley neuron to a large number of uncorrelated stochastic inhibitory and excitatory post-synaptic spike trains. In order to clarify the various mechanisms responsible for noise-induced spike triggering we examine the model in its silent regime. We report the coexistence of two distinct coherence resonances: the first one at low noise is due to the stimulation of "correlated" subthreshold oscillations; the second one at intermediate noise variances is instead related to the regularization of the emitted spike trains.