Conductivity of living intracranial tissues

Resistivity values were measured from living human brain tissue in nine patients. A monopolar needle electrode was used with a measurement frequency of 50 kHz. Mean values were 3.51 Ohm m for grey matter and 3.91 Ohm m for white matter. Cerebrospiral fluid had a mean value of 0.80 Ohm m. Values for tumour tissues were dependent on the type of tumour and ranged from 2.30 to 9.70 Ohm m.