1. Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada;
2. Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada;
3. Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois;
4. Division of Biological Sciences, University of Chicago, Chicago, Illinois;
5. Center for Integrative Brain Research, Seattle Children's Hospital, Seattle, Washington; and
6. Department of Pediatrics, University of Washington, Seattle, Washington