1. Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
2. Neurosciences Graduate Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA.
3. Howard Hughes Medical Institute, Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA, USA.
4. Biological Sciences Graduate Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA.