Head models used in this study: The first column indicates the name of the head model and the remaining columns the conductivities for the respective tissue compartments.

The compartments that were (were not) distinguished are indicated by a slash (dash) sign. Isotropic conductivity values were taken from the literature [29], [34], [35], [39], [52]–[55] or were determined in our SEP/SEF skull conductivity calibration procedure (*_Cal models; see sections 1.11 and 2.1). # indicates that conductivity tensors were determined as described in section 1.4.3. In all 6C models, the ratio of skull spongiosa to compacta was kept constant to the mean of the ratio measured by [34].