1. Department of Neurological Surgery, University of California, San Francisco, CA 94143, USA.
2. Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA 94143, USA.
3. Department of Anatomy, University of California, San Francisco, CA 94143, USA.
4. Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, CA 94143, USA.
5. Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA 94143, USA.