The VCN model described in this paper consists of a single electrical compartment with a membrane capacitance (Cm) connected in parallel with a fast-inactivating A-type K+ current (IA), a fast-activating slow-inactivating low-threshold K+ current (ILT), a high-threshold K+ current (IHT), a fast-inactivating TTX-sensitive Na+ current (INa), a hyperpolarization-activated cation current (Ih), a leakage current (Ilk), an excitatory synaptic current (IE), and an external electrode current source (Iext). For such an electrical circuit, the membrane potential V is described by the following first-order differential equation1 Equations for IA, ILT and IHT were derived from experimental data, as previously described (Rothman and Manis 2003b), and are collectively given in the APPENDIX. Because INa and Ih were not studied in our voltage-clamp experiments, their models were derived from other studies, as described in the following text. Equations for Ilk and IE are also described in the following text. Except for the current-clamp simulations, Iext = 0. For all simulations, Cm = 12 pF, the average value computed from our population of isolated VCN cells (Rothman and Manis 2003a). Given a typical neuronal specific membrane capacitance of 0.9 μF/cm2 (Gentet et al. 2000), the diameter of the soma model comes to ～21 μm, a value also in agreement with our isolated VCN cells (Rothman and Manis 2003a).