1. Department of Behavior and Brain Organization, Center Advanced European Study and Research (Caesar), Bonn 53175, Germany
2. Department of Neurobiology, Graduate School of Biomedical and Health Sciences (Medicine), Hiroshima University, Hiroshima 734-8553, Japan
3. Laboratory for Neural Coding and Brain Computing, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
4. Neural Coding and Brain Computing Unit, Okinawa Institute of Science and Technology, Okinawa 904-0495, Japan