1. Departments of Physiological Science, University of California, Los Angeles, CA 90095‐1606, USA
2. Departments of Physiology and Biophysics Department, 1959 NE Pacific Street, Seattle, WA 98195‐7290, USA
3. Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
4. Department of Ophthalmology and Molecular Cardiology Research Institute, New England Medical Center, Program in Genetics and Tufts Center for Vision Research, Tufts University School of Medicine, Boston, MA 02111, USA
5. Departments of Ophthalmology, University of California, Los Angeles, CA 90095‐1606, USA