1. Univ Lyon, Université Claude Bernard Lyon 1 Inserm U1208 Stem Cell and Brain Research Institute Bron 69500 France
2. Primastem Bron 69500 France
3. Present address: International Institute for Integrative Sleep Medicine (WPI‐IIIS) University of Tsukuba Tsukuba Ibaraki 305‐8575 Japan
4. Present address: Laboratory of Molecular Diagnostics Department of Biotechnology Inter‐collegiate Faculty of Biotechnology University of Gdańsk and Medical University of Gdańsk Gdańsk 80‐307 Poland
5. Present address: Laboratory of Experimental Embryology Institute of Genetics and Animal Biotechnology Polish Academy of Sciences Warsaw 05‐552 Poland
6. National Centre for Optics Vision and Eye Care Faculty of Health and Social Sciences University College of Southeast Norway Kongsberg N‐3603 Norway
7. Institute of Neuroscience State Key Laboratory of Neuroscience Chinese Academy of Sciences (CAS) Key Laboratory of Primate Neurobiology Shanghai 200031 China
8. Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society Frankfurt 60528 Germany