1. a ICORP Computational Brain Project, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 351-0198, Japan, ATR Computational Neuroscience Laboratories, 2-2-2 Hikaridai Seika-cho, Soraku-gun, Kyoto 619-0288, Japan;, Email: jhale@atr.jp
2. b ATR Computational Neuroscience Laboratories, 2-2-2 Hikaridai Seika-cho, Soraku-gun, Kyoto 619-0288, Japan, Institut für Technische Informatik (ITEC), Universität Karlsruhe, 76131 Karlsruhe, Germany
3. c ICORP Computational Brain Project, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 351-0198, Japan, ATR Computational Neuroscience Laboratories, 2-2-2 Hikaridai Seika-cho, Soraku-gun, Kyoto 619-0288, Japan
4. d ATR Computational Neuroscience Laboratories, 2-2-2 Hikaridai Seika-cho, Soraku-gun, Kyoto 619-0288, Japan, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0101, Japan
5. e ATR Computational Neuroscience Laboratories, 2-2-2 Hikaridai Seika-cho, Soraku-gun, Kyoto 619-0288, Japan, Ecole Nationale Supérieure des Mines de Paris, 60 Bd St Michel, 75006 Paris, France
6. f ICORP Computational Brain Project, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 351-0198, Japan, ATR Computational Neuroscience Laboratories, 2-2-2 Hikaridai Seika-cho, Soraku-gun, Kyoto 619-0288, Japan