1. University of Cagliari; Department of Biomedical Sciences; Citta Universitaria di Monserrato (Cagliari) Monserrato (Cagliari) Italy 09042
2. University of Pisa; Neurorehabilitation Unit, Department of Neuroscience; Via Paradisa, 2 Pisa Italy 56100
3. University College London; Department of Statistical Science; 1-19 Torrington Place London UK WC1E 6BT
4. California Pacific Medical Center; Forbes Norris ALS Research Center; 2324 Sacramento Street, Suite 150 San Francisco USA 94115
5. California Pacific Medical Center; Research Institute; 475 Brannan St Suite 220 San Francisco CA USA 94107