1. The Picower Institute for Learning and Memory, RIKEN–MIT Neuroscience Research Center, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
2. Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
3. Department of Psychology, University of California–Los Angeles, Los Angeles, CA 90095, USA.
4. Division of Endocrinology, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.