1. P.-M. Lledo, Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94143, USA.
2. X. Zhang and T. C. Südhof, Department of Molecular Genetics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
3. R. C. Malenka, Departments of Psychiatry and Physiology, University of California, San Francisco, CA 94143, USA.
4. R. A. Nicoll, Departments of Cellular and Molecular Pharmacology and Physiology, University of California, San Francisco, CA 94143, USA.