1Biomedical magnetic resonance, University of tuebingen, Tuebingen, Germany, 25Department of Psychiatry, Psychotherapy and Psychosomatics, University Hospital Aachen, Aachen, Germany, 3Department of Neurology/Epileptology, University of tuebingen, Tuebingen, Germany, 4Max-Planck-Institute for Biological Cybernetics, Tuebingen, Germany