1. CRBM, Univ. Montpellier, CNRS, Montpellier, France.
2. Neurology Unit, Azienda Ospedaliero Universitaria di Modena, 41126 Modena, Italy.
3. Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia,G. Campi 287, 41125 Modena, Italy.