1. Learning Algorithms and Systems Laboratory, Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland
2. Center for Innovative Medicine and Engineering, University of Tsukuba Hospital, Tsukuba, Japan
3. Artificial Intelligence Laboratory, Department of Intelligent Interaction Technologies, University of Tsukuba, Tsukuba, Japan
4. Faculty of Engineering and the Center for Cybernics Research, University of Tsukuba, Tsukuba, Japan