1. Institute of GeophysicsETH-Hönggerberg, 8093 Zurich, Switzerland
2. Department of Earth and Environmental Science, University of Munich80333 München, Germany
3. Department of Neurosurgery, University Hospital Zurich8091 Zurich, Switzerland
4. Neurology/EEG, University Hospital Zurich8091 Zurich, Switzerland
5. Institute for Science & Technology in Medicine, Keele UniversityStoke-on-Trent ST4 7QB, UK