[1] Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA
[2] Univ Paris 06, CNRS, EAC 7180, F-75252 Paris 05, France
[3] Carl von Ossietzky Univ Oldenburg, IBU, AG Neurosensor Anim Navigat, D-2900 Oldenburg, Germany
[4] Goethe Univ Frankfurt, FB Biowissensch, Frankfurt, Germany