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Computational Intelligence and Neuroscience
Volume 2010, Article ID 397272, 7 pages
Research Article

The Influence of Age and Skull Conductivity on Surface and Subdermal Bipolar EEG Leads

1Department of Biomedical Engineering, Tampere University of Technology, Korkeakoulunkatu 3, P.O. Box 692, 33101 Tampere, Finland
2Institute of Biomedical Engineering, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany

Received 1 July 2009; Accepted 8 October 2009

Academic Editor: Fabrizio De Vico Fallani

Copyright © 2010 Katrina Wendel et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Bioelectric source measurements are influenced by the measurement location as well as the conductive properties of the tissues. Volume conductor effects such as the poorly conducting bones or the moderately conducting skin are known to affect the measurement precision and accuracy of the surface electroencephalography (EEG) measurements. This paper investigates the influence of age via skull conductivity upon surface and subdermal bipolar EEG measurement sensitivity conducted on two realistic head models from the Visible Human Project. Subdermal electrodes (a.k.a. subcutaneous electrodes) are implanted on the skull beneath the skin, fat, and muscles. We studied the effect of age upon these two electrode types according to the scalp-to-skull conductivity ratios of 5, 8, 15, and 30 : 1. The effects on the measurement sensitivity were studied by means of the half-sensitivity volume (HSV) and the region of interest sensitivity ratio (ROISR). The results indicate that the subdermal implantation notably enhances the precision and accuracy of EEG measurements by a factor of eight compared to the scalp surface measurements. In summary, the evidence indicates that both surface and subdermal EEG measurements benefit better recordings in terms of precision and accuracy on younger patients.