  Recent in vitro data show that neurons respond to input variance with varying
sensitivities. Here, we demonstrate that Hodgkin-Huxley (HH) neurons can
operate in two computational regimes, one that is more sensitive to input
variance (differentiating) and one that is less sensitive (integrating). A
boundary plane in the 3D conductance space separates these two regimes. For a
reduced HH model, this plane can be derived analytically from the V nullcline,
thus suggesting a means of relating biophysical parameters to neural
computation by analyzing the neuron's dynamical system.
