1. Weizmann Institute, Department of Neurobiology, Rehovot, Israel 76100; Center for Theoretical Neuroscience, Columbia University, New York, NY 10032, U.S.A.; and Donders Centre for Neuroscience, Radboud University, 6525 Nijmegen, The Netherlands
2. Weizmann Institute, Department of Neurobiology, Rehovot, Israel 76100
3. Weizmann Institute, Department of Neurobiology, Rehovot, Israel 76100, and Center for Theoretical Neuroscience, Columbia University, New York, NY 10032, U.S.A.