Figure 1: Influence of Na activation characteristics on spike threshold. Threshold as a function of the ratio gNa/gL for the 9 types of voltage-gated sodium channels [27] with characteristics reported in [28]. For each channel type, threshold obtained across the dataset is plotted. Nav1.[1-3,6] are expressed in the central nervous system, Nav1.[4,5] are expressed in cardiac and muscle cells and Nav1.[7-9] are expressed in the peripheral nervous system. Nav1.6 is expressed at the action potential initiation site [29–31] (Figure taken from [26]: J. Platkiewicz and R. Brette, A Threshold Equation for Action Potential Initiation, PLoSComput. Biol. 6, e1000850, (2010)).