Conductivities of three-layer human skull

In this study, electrical conductivities of compact, spongiosum, and bulk l ayers of cadaver skull were determined at varying electric fields at room t emperature. Current was applied and withdrawn over the top and bottom surfa ces of each sample and potential drop across different layers was measured using the four-electrode method. We developed a model, which considers of v ariations in skull thicknesses, to determine the conductivity of the tri-la yer skull and its individual anatomical structures. The results indicate th at the spongiform and the two compact layers of the skull have significantl y different and inhomogeneous conductivities ranging from 0.76 +/- .14 to 1 1.5 +/- 1.8 milliS/m.