1. Center of Neuroscience and Neuroengineering, Department of Experimental Medicine, University of Genoa, Italy
2. Department of Cellular and Molecular Physiology and Pharmacology, University of Pavia, Italy
3. San Raffaele Scientific Institute, `Vita Salute' University and I.I.T. Unit of Molecular Neuroscience, Milan, Italy
4. Center of Excellence for Biomedical Research, University of Genoa, Italy
5. Unit of Neuroscience, The Italian Institute of Technology, Morego Central Laboratories, Genoa, Italy