Contour plots of transmembrane potential as a function of (parallel to the fibers) and (perpendicular to the fibers) during and following a 20 ms duration anodal S2 stimulus. In (a), S2 has a threshold strength of 2.0 mA and is applied at 318 ms. In (b), S2 has a threshold strength of 0.65 mA and is applied at 319 ms. Only one quadrant of the - plane is shown. The black rectangular box is the electrode [10].
