[1] Salk Inst Biol Studies, Computat Neurobiol Lab, La Jolla, CA 92037 USA
[2] Univ Calif San Diego, Inst Neural Computat, La Jolla, CA USA
[3] Univ Pittsburgh, Dept Computat & Syst Biol, Pittsburgh, PA USA
[4] CALTECH, Div Biol & Biol Engn, Pasadena, CA USA