1. Neurology Department, University of Zurich, CH-8008 Zurich, Switzerland.
2. Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland.
3. Center for Neuroprosthetics, School of Engineering, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland.
4. Automatic Control Laboratory, Swiss Federal Institute of Technology (ETH), CH-8092 Zurich, Switzerland.