These files contain the model for the paper: Shu Y, Yu YG, Yang, J. and McCormick DA Selective control of cortical axonal action potentials by a slowly inactivating K+ current. Proceedings of the National Academy of Sciences (PNAS) 27: 11453-11458, (2007). A simple model of a soma and axon was constructed by using Neuron. The soma had a diameter and length of 20 mm (1 compartment) and contained a leak conductance (reversal potential -70 mV) Rm = 30,000 Ohm/cm2 with membrane capacitance Cm = 0.75 mF/cm2. The axon had a diameter of 1 mm and a length of between 20 and 200 mm, with the later containing 10 compartments. In the axon, the leak conductance Rm = 125,000 Ohm/cm2, and the membrane capacitance Cm = 0.75 mF/cm2. The axonal axial resistance was 150 W-cm. Kv1.2 current exists in axon initial segment, which play important roles in modulating spike duration and threshold of action potentials. Running Neuron_Dcurrent.hoc, then analyze the output data file soma_axon_id.dat to see D current effect on action potentials These files were contributed by Yuguo Yu 2007 Yale yuguo.yu@yale.edu