Figure 4. Responses are non-linearly related to stimulation location along the grey-white axis.

A. Schematic of localization measurements. B. Proportion of all channels per stimulation site and participant with above-threshold responses. C. Local (<15 mm, black lines and curves, left) and distant (>15 mm, grey lines and curves, expanded to the right) peak in the 1 second after stimulation (top left), AUC (bottom left), N1 peak (top right), and N2 peak (bottom right) relative to the distance to the grey-white matter boundary. For each measure (overall peak, AUC, N1, N2), the left plot includes the <15 mm and >15 mm recording sites and the right plot includes an expanded view of the >15 mm response. Data is from all contacts, not just the above-threshold responses. Green dots- responses at different distances to the grey-white boundary significantly different to responses at −4 mm, p<0.000062 (Wilcoxon rank sum test; multiple comparisons corrected; d.f.=718). F-statistics and p-values for the model fits as compared to a model fit with a constant term for the local (black print) and distant (grey print) sites. D. Binned distance from stimulation site versus distance to the grey-white boundary for the average overall peak (peak in the 1 second following stimulation), AUC, N1 peak, and N2 peak responses across brain regions. Colorbar to the right of each plot indicates the measure and scale. For C and D, y-axis units are normalized voltages relative to the baseline, in arbitrary units (a.u.).