Root mean square error (RMSE) computed between simulated and real spike maximal potentials, with respect to variations of parameters S (extended source area) and σ (brain conductivity), for both volume conductor models, (a) In the infinite case, a global RMSE minimum (RMSEinf = 56.67) was obtained for Sinf= 20 cm2 and σinf= 25×10−5 S/mm (black dotted line), (b) In the spherical case, the global RMSE minimum (RMSEsph = 47.32) corresponded to Ssph = 22 cm2 and σsph = 32.5×10−5 S/mm (black solid line).