Threshold map and the migration of low threshold region with increasing electrode size.

<p>(A) Threshold map for 25, 50 and 100 µm radius electrodes. Red box, AIS. Number next to the ‘+’ and ‘Δ’ symbols is the threshold at that location. Dots, locations within 1% of the lowest threshold. (B1 and C1) Electric potential of the 100 µm electrode delivering threshold stimulus at pos1 (B1) and pos2 (C1). Each circular contour represents 10% relative change in field potential. Red box, AIS. (B2 and C2) Response initiation and propagation along the subcellular structures with the 100 µm stimulating electrode at pos1 (B2) and pos2 (C2).