Plots of the extracellular potential recorded at an electrode (located at z = -59 mm) a distance R from the axon as the impulse travels from z = -100 mm to z = 100 mm. The geometry is that of the plane conducting boundary placed as in Figure 5. When the electrodes are located close to the axon (R = 10 mm), the peak in the potential occurs as the nerve impulse passes near the electrodes. For electrodes far from the axon (R = 1014 mm) a step change in potential is seen as the impulse passes through the boundary between the two regions. The values of the potential are arbitrary and are for purposes of comparison of the different graphs within this figure only.