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Updated: May 4, 2026
Studying Brain Function in Children Using Magnetoencephalography
Published on: April 8, 2019
Magnetoencephalography signals are influenced by skull defects
S Lau1, L Flemming2, J Haueisen3
1Institute of Biomedical Engineering and Informatics, Ilmenau University of Technology, P.O. Box 100565, D-98684 Ilmenau, Germany; Biomagnetic Center, Department of Neurology, Jena University Hospital, Erlanger Allee 101, D-07747 Jena, Germany; NeuroEngineering Laboratory, Department of Electrical & Electronic Engineering, The University of Melbourne, Parkville 3010, Australia; Department of Medicine - St. Vincent's Hospital, The University of Melbourne, Fitzroy 3057, Australia.
Skull defects significantly impact electroencephalography (EEG) and magnetoencephalography (MEG) signals. This study experimentally demonstrates these effects, showing EEG amplitude increases and MEG amplitude decreases, necessitating skull defect inclusion in head models.
Area of Science:
- Neuroscience
- Biophysics
- Medical Imaging
Background:
- Magnetoencephalography (MEG) and electroencephalography (EEG) are crucial for brain activity monitoring.
- Previous hypotheses suggested minimal impact of skull defects on MEG signals.
Purpose of the Study:
- To experimentally investigate the influence of conducting skull defects on MEG and EEG signals.
- To assess the impact of skull defects on signal amplitude and spatial characteristics.
Main Methods:
- In vivo implantation of a miniaturized electric dipole in rabbit brains.
- Simultaneous recording of EEG and MEG signals above intact and defective skulls.
- Using agar gels with tissue-like conductivity to fill skull defects for controlled experiments.
Main Results:
- EEG signal amplitude increased 2-10 times, while MEG signal amplitude decreased by up to 20%.
- Signal deviations showed distinct patterns for EEG (edge-related) and MEG (central defect-related).
- Changes in MEG field-map topography were geometrically linked to the skull defect's edge.
Conclusions:
- Skull defects substantially affect both MEG and EEG signals.
- Accurate MEG source modeling necessitates head models that realistically incorporate skull defects.
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