1. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California
94720, United States
2. Department
of Neurosciences, University of California at San Diego School of Medicine, La Jolla, California 92093, United
States
3. Departments of Physics
and Molecular
and Cell Biology, University of California at Berkeley, Berkeley, California 94720, United States
4. California Institute for Quantitative
Biosciences (QB3), University of California at Berkeley, Berkeley, California 94720, United States