The Third International Symposium on Neurotransmitter Receptors was held in Hiroshima at a time when the entire field of neurotransmitter receptors in the brain is progressing at an unprecedented pace. The sym posium also marked my retirement as Professor and Chairman of the Third Department of Internal Medicine, Hiroshima University School of Medicine, and a new beginning as a Professor of the University of the Air. The symposium was remarkably successful, and there were enthusiastic responses from scientists allover the world, proving that the meeting was timely. The selected papers contained in this volume constitute a state of-the-art survey of the most advanced aspects of neurotransmitter recep tor mechanisms in the brain. lowe thanks for the great success of the symposium to Prof. Richard Olsen of UCLA, Prof. Tomio Segawa of Hiroshima University, Prof. Kinya Kuriyama of Kyoto Prefectural University of Medicine, and Prof. Masaya Tohyama of Osaka University. I express my sincere gratitude to many friends for making this publication possible. I especially thank Dr. Rie Miyoshi, whose devoted efforts as secretary-general were vital to the success of the symposium. Dr. Miyoshi is currently an instructor in the Department of Pharmacology at Tokyo Women's Medical College. I would also like to acknowledge the excellent secretarial work of Misses Ritsuko Sato and Yuko Wakita.