title: Preface.
authors: Department of Neurology, Oslo University Hospital and Institute of Health and Society, University of Oslo, Oslo, Norway.
authors: E G
authors: EG
authors: Celius
authors: Division of Neuroscience, Institute of Experimental Neurology, Hospital San Raffaele, University of Milan, Milan, Italy.
authors: M
authors: M
authors: Rocca
authors: Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors: O
authors: O
authors: Andersen