| Electrical conductivities of compact, spongiosum, and bulk layers of the cadaver, live, and dead (corpse) human skull were determined at a number of frequencies and electric fields at room temperature using the four-electrode method. Current was applied and withdrawn over the top and bottom surfaces of each sample and potential drop across different layers was measured. A model that considers variations in skull thicknesses is used to determine the conductivity of the tri-layer skull and its individual anatomical structures. The results indicate that the conductivities of the spongiform (cadaver ∼ 5.4–11.5, live skull ∼ 16.2–41.1, dead ∼ 39.7–99.3 milliS/m), the top compact (cadaver ∼ 0.8–1.8, live ∼ 5.4–7.2, dead ∼ 5.4–12.3 milliS/m) and lower compact (cadaver ∼ 2.8–5.1, live ∼ 2.8–10.2, dead ∼ 5.2–19.3 milliS/m) layers of the skull have significantly different and inhomogeneous conductivities. The conductivities of the skull layers are frequency dependent in the 10–90 Hz region and are non-ohmic in the 0.45–2.07 A/m2 region. |
