Two-compartment biophysical model of an IO cell. The somatic ionic currents include a low-threshold calcium inward current (ICal), an anomalous inward rectifier current (Ih), the Hodgkin-Huxley type inward sodium (INa) and outward delayed rectifier potassium (IKdr) currents, and a leakage current (Ils). The dendritic currents include a high-threshold inward calcium current (ICah), an outward calcium-dependent potassium current (IKCa), and a leakage current (Ild). Because the dendritic potassium current IKCa is calcium-dependent, Ca2+ concentration dynamics is included in the model. gint is the coupling conductance between the two compartments. The electrotonic coupling between this cell and multiple other cells is not shown.