The aim of this book is to focus on the important relationships between the heart and the brain in health and disease. The brain and nervous system may cause or influence heart disease, e. g. , by causing arrhythmias or modi- fying the response to ischemia. Disorders of the heart and circulation may cause brain damage, e. g. , by releasing emboli resulting in cerebral infarc- tion. Furthermore, both the brain and the heart are frequently targets of the same disease process. The heart and brain have electrophysiologically active cells, which may respond in similar ways to diseases and various interventions. Finally, many drugs affect both the brain and the heart, and drugs used for heart diseases usually have side effects on the brain and vice versa. With today's increasing subspecialization in medicine, we feel the time has come to present a book that integrates basic and clinical aspects of cardiology, neurology, cardiovascular surgery, and neurosurgery. We hope this cross fertilization will broaden horizons and advance both understand- ing and practice. This book is based on a symposium held at the University of TromS!/l, Norway, 24-27 June 1987, organized by Ilmar A. Sulg, Knut Rasmussen, Svein Ivar Mellgren, Dag S!/lrlie, and Helge Refsum of the Departments of Clinical Neurophysiology, Medicine, Neurology, Surgery, and Physiology, respectively. Weare grateful to the distinguished group of contributors for not only outlining their pioneering studies, but also describing their recent work and indicating important possibilities for the future.