Geometric and Electric Characteristics

Geometic and electric characteristics of the layered sphere as reported by Roth et. al.[1]
Tissue Radius (mm) Conductivity(S/m)
Scalp 92.0 0.450
Skull 85.0 0.00563
Cortex 80.0 0.450

 

Conductivity (S/m) of the head tissues
  Source 1 [3] Source 2 [4] Source 3 [2]
Bone   0.010  
White matter 0.117 0.133 0.129
Grey matter 0.228 0.400 0.200
Skin 0.346 0.778 0.270
CSF 1.611 1.538 1.668

 

[1] Roth,B.J.,Saypol.J. M., Hallet.,M. and Cohen,L.G. (1991 ) A theoretical calculation of the electric field induced in the cortex during magnetic stimulation. Electroencephalogaphv and Clinical Neurophyswlogy, 81 , 47-56.

[2] Holton, K. S. and Walker C. F. (1990) Correlation of a magnetic resonance brain image and tisue impedance. IEEE EMBS 92-93.

[3] Geddes L.A. and Baker L.E. (1967) 'The specific resistance of biological material: a compendium of data for the biomedical engineer and physiologist. Medical and Biological Engineering, 5 271 - 219.

[4] Geddes, L. A. (1989) Optimal stimulation duration for extracranial cortical stimulation. Neurosuyey, 20, 94-99.