Analysis of the response of a pacemaker neuron model to transient inputs

The response of a pacemaker neuron model to a train of transient inhibitory impulsive perturbations is examined. The model reproduces the heterogeneous discharge forms and abrupt switchings displayed by the crayfish slowly adapting stretch receptor organ (Segundo et al., 1994, Neuroscience 62(2), pp. 459-480). The non-monotonous aspect of the instantaneous firing rate of the model reflects the fact that in some regimes input and output rates are both increasing, despite the inhibitory effect of the former. We determine how such paradoxical acceleration takes place by analyzing the response of the model using its phase transition curve. We show that paradoxical acceleration results from the fact that the phase transition curve exhibits a large slowly increasing, almost linear section similar to that of living preparations.