Discerning ionic currents and their kinetics from input impedance data

The excitable nature of a biological cell is manifested in the many voltage gated ion channels that perforate its membrane. The forms of the associated ionic currents, and in particular the functions that govern their kinetics, permit one to distinguish, electrophysiologically, between various cell types. We show, in the context of FitzHugh-Nagumo and Morris-Lecar models and without recourse to voltage or space clamping, that such currents and kinetics may be stably inferred from a cell's voltage response to a specified input current. (C) 2001 Society for Mathematical Biology.