1. Department of Mathematics, Astun University, Aston Triangle, B4 7ET, Birmingham, UK
2. Parietal, INRIA, NeuroSpin, bat 145 CEA Saclay, 91191, Gif sur Yvette, France
3. Department of Preventive Medicine, Northwestern University, 750 N Lake Shore Dr, 60611, Chicago, USA
4. Rehabilitation Institute of Chicago, 345 E Superior, 60611, Chicago, USA