A Comparison of Point and Complete Electrode Models in a Finite Difference Model of Invasive Electrode Measurements

Invasive electrophysiological measurement of brain activity is commonly employed during epilepsy surgery to provide final validation of required resection regions. These data are critical to clinical decision making, but manual expert analysis of these data can be complicated by the need to relate individual electrode measurements to specific brain regions. To improve analysis of these data with source analysis, accurate bioelectric models are needed. Given the proximity of the measurement locations to the generating cortical sources, modeling of electrodetissue interactions is particularly important for invasive measurements. Here, we evaluate the effect of a finite difference complete electrode model on the accuracy of leadfield computations for invasive electrocorticography. Our results show that in the vicinity of electrode locations, use of the simpler point electrode model produces large topographic and magnitude differences that will likely impact the accuracy of computed source localizations.