[1] Univ Calif San Diego, Inst Nonlinear Sci, La Jolla, CA 92093 USA
[2] Salk Inst Biol Studies, Syst Neurobiol Lab, La Jolla, CA 92037 USA
[3] Univ Calif San Diego, Scripps Inst Oceanog, Dept Phys, La Jolla, CA 92093 USA
[4] Univ Calif San Diego, Scripps Inst Oceanog, Marine Phys Lab, La Jolla, CA 92093 USA