Inter-subject variability of skull conductivity and thickness in calibrated realistic head models

Antonakakis, M., Schrader, S., Aydin, Ü. ORCID: https://orcid.org/0000-0002-6327-7811, Khan, A., Gross, J., Zervakis, M., Rampp, S. and Wolters, C. H. (2020) Inter-subject variability of skull conductivity and thickness in calibrated realistic head models. NeuroImage, 223. 117353. ISSN 1053-8119 doi: 10.1016/j.neuroimage.2020.117353

Abstract/Summary

Skull conductivity has a substantial influence on EEG and combined EEG and MEG source analysis as well as on optimized transcranial electric stimulation. To overcome the use of standard literature values, we propose a non-invasive two-level calibration procedure to estimate skull conductivity individually in a group study with twenty healthy adults. Our procedure requires only an additional run of combined somatosensory evoked potential and field data, which can be easily integrated in EEG/MEG experiments. The calibration procedure uses the P20/N20 topographies and subject-specific realistic head models from MRI. We investigate the inter-subject variability of skull conductivity and relate it to skull thickness, age and gender of the subjects, to the individual scalp P20/N20 surface distance between the P20 potential peak and the N20 potential trough as well as to the individual source depth of the P20/N20 source. We found a considerable inter-subject variability for (calibrated) skull conductivity (8.44 ± 4.84 mS/m) and skull thickness (5.97 ± 1.19 mm) with a statistically significant correlation between them (rho = 0.52). Age showed a statistically significant negative correlation with skull conductivity (rho = -0.5). Furthermore, P20/N20 surface distance and source depth showed large inter-subject variability of 12.08 ± 3.21 cm and 15.45 ± 4.54 mm, respectively, but there was no significant correlation between them. We also found no significant differences among gender subgroups for the investigated measures. It is thus important to take the inter-subject variability of skull conductivity and thickness into account by means of using subject-specific calibrated realistic head modeling.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/111223
Identification Number/DOI	10.1016/j.neuroimage.2020.117353
Refereed	Yes
Divisions	No Reading authors. Back catalogue items
Uncontrolled Keywords	Adolescent, Adult, Brain/physiology, Calibration, Electric Conductivity, Electroencephalography, Electrophysiological Phenomena, Evoked Potentials, Somatosensory, Female, Humans, Magnetic Resonance Imaging, Magnetoencephalography, Male, Middle Aged, Models, Neurological, Scalp/physiology, Skull/physiology, Young Adult
Publisher	Elsevier
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