Resonant propagation of spike trains in delay-coupled neural subthreshold oscillators

We study the propagation of spike trains through one-dimensional chains of coupled neurons exhibiting subthreshold oscillations. We consider the existence of a synaptic delay that provides a time scale in addition to the ones given by the periods of the input train and of the subthreshold oscillations. These three time scales affect the evolution of the phase of the neural oscillators, preparing the state of the postsynaptic neuron for the presynaptic input, which can trigger a suprathreshold response according to that phase. In the case of pulsed chemical coupling, results from two coupled neurons help infer the success of the propagation through a larger chain. This situation exhibits a resonant behavior with respect to the period of the input spike train, by which successful propagation arises for certain values of the input period, irrespective of the delay. In the presence of additional electrical coupling via gap junctions, the synaptic delay starts to play a relevant role, and a second resonance appears with respect to that time scale.