Strange responses of the Hodgkin-Huxley model to highly fluctuating inputs

A cortical neuron generates irregular spike sequences including highly variable intervals. This seems to suggest that the neuron receives highly fluctuating synaptic inputs. The simple leaky integrate-and-fire(LIF) model driven by fluctuating inputs exhibits high variability in their spike sequences. The variability of inter-spike intervals(ISIs) becomes larger as the input fluctuation becomes larger. But the Hodgkin-Huxley (HH) model is found to exhibit inverse relationships. The ISI variability becomes smaller as the input fluctuation becomes larger, although the effective strength of inputs is kept to be constant. We report the strange responses of the Hodgkin-Huxley model to highly fluctuating inputs