1. Laboratory for Neuronal Circuit Development, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198 Japan.
2. Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, Zurich, CH-8057 Switzerland.
3. Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH), Winterthurerstrasse 190, Zürich, CH-8057 Switzerland.