1. Sue and Bill Gross Stem Cell Center, University of California, Irvine, Irvine, California, USA.
2. Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, California, USA.
3. Department of Pediatrics, Children's Hospital Los Angeles, Los Angeles, California, USA.
4. Physical Medicine and Rehabilitation, University of California, Irvine, Irvine, California, USA.
5. Anatomy and Neurobiology, University of California, Irvine, Irvine, California, USA.