Fig. 4.

Manipulation of I_h conductance density altered cellular response to applied fields. A: removal of I_h abolished the asymmetric response of the neuron to static electric fields such that minimal membrane polarization occurred halfway between the axonal and apical ends of the model (left). Limiting I_h to compartments >850 µm from the soma likewise shifted the minimal membrane polarization point away from the soma (middle), whereas insertion of I_h in all compartments >100 µm shifted this point toward the soma (right). I_h conductance density was maintained at a uniform 10 pS/µm² in each case. Results are unity normalized. B: increasing I_h conductance density increased the resonance frequency observed in the tuft and hot zone. Uncertainties are estimated by the greater of the standard deviation of observed resonance frequencies in each compartment and the spacing of field frequencies simulated. C: the activation kinetics of the modeled I_h explain the results in A and B. Specifically, changes in membrane potential near rest (approximately −60 mV) alter I_h activation to oppose the change. The membrane time constant of the model is <28 ms, mediating the high-pass filtering of I_h.