Figure 12

Contour maps showing modulation of the volume of the target toroid for a simple, circular coil with increasing strength, n, of stimulation, compared to the standard model (n = 1). The multiplier, n, applies to either the number of turns in the coil, or alternatively the fold increase in dI/dt, or the fold increase in the projection distance, L cos θ, when other variables are held constant. The width of each contour map is two coil diameters, and the height of each map is 1 coil diameter. Legends show maximal transmembrane voltage changes in millivolts.