[1] Graz Univ, Dept Neurol, A-8036 Graz, Austria
[2] Graz Univ, MRI Ctr, A-8036 Graz, Austria
[3] Vrije Univ Hosp, Amsterdam, Netherlands
[4] Univ Milan, Dept Neurosci, Neuroimaging Res Unit, Sci Inst Osped San Raffaele, I-20122 Milan, Italy
[5] Univ Penn, Med Ctr, Philadelphia, PA 19104 USA
[6] Univ British Columbia, Vancouver, BC V5Z 1M9, Canada
[7] Inst Neurol, London WC1N 3BG, England
[8] NIH, Bethesda, MD 20892 USA
[9] Univ Colorado, Hlth Sci Ctr, Denver, CO USA
[10] Univ Texas, Sch Med, Houston, TX USA