Redwood Center for Theoretical Neuroscience, University of California, Berkeley, Berkeley, California, United States of America.|Department of Applied Physics, Stanford University and Khan Academy, Palo Alto, California, United States of America.|Department of Cell Biology and Neuroscience, Montana State University, Bozeman, Montana, United States of America.|Redwood Center for Theoretical Neuroscience, University of California, Berkeley, Berkeley, California, United States of America.