Figure 5.
Distal AP initiation. A–C, Local input resistance (A), axial current (B), and Vax (C) in the different model compartments for the standard parameters (black traces), the model with shorter internode lengths of 50 μm (magenta traces), and thicker axonal diameter of 1.5 μm (cyan traces). D, Exemplary voltage traces in different compartments (colors as indicated). Filled colored circles show the AP-initiating segment for each suprathreshold response (see legend). E–H, Example events (from D) for subthreshold response (E), and evoked APs generated in the AIS (F), R1 (G), and R2 (H). I–K, Fraction of distally initiated APs (D-AP; for a fixed AP probability of 15%), with varying internode length (I), axonal diameter (J), and sodium conductance in the nodes of Ranvier (K). L, Fraction of distally initiated APs for different somatic input resistances. M, Fraction of distally initiated APs without and with inhibition for several input frequencies.