Figure 7. EAP at different time points in the physiological Nav model (left) and reduced Nav model (right). A, Intracellular APs in the soma (orange) and in the end of the AIS (blue). Dotted vertical lines show at which time points B–D are recorded. B–D, Extracellular potentials (colormap; see the colorbar on the right, red is positive and blue is negative) and electrical current (arrows) at different times of APs plotted for around the whole morphology (left) and around the soma–AIS region (right). B–D, Recordings were made as follows: at 0.15 ms before the peak of the AP in the AIS (B), at the peak of the AP in the AIS (C), and 0.4 ms after the peak of the AP in the AIS (D). In the physiological Nav model, the AP initiates in the AIS (red circles) giving rise to a dipolar potential (AIS negative, soma positive; C, left), which later reverses in polarity (AIS positive, soma negative; D, left). In contrast, the reduced Nav model produces a large dipole that encompasses the axon, soma, and proximal dendrites (soma–dendrites dipole).