Rhythms in Physiological Systems: Proceedings of the International Symposium at Schlo? Elmau, Bavaria, October 22-25, 1990

This book is based on invited lectures presented by top experts in the fieldof physiological rhythms. Until now, cardiovascular rhythms, respiratory rhythms, circadian rhythms, rhythms of electrical activity of the brain, rhythms in perception, and motor-coordination of rhythmic movements have always been considered independently. This is the first attempt to demonstrate the pronounced similarities between these phenomena and to identify their interrelations. The contributions shed new light on the origin and coordination of different kinds of rhythms.An important concept proposed here is that of quasi-attractors, according to which the total system remains in some attractor for a while before being pushed out to enter a new attractor, and so on. These attractors are characterized by properties such as mode-locking, free-running modes, and chaotic modes. The striking similarity between the different rhythms suggests that the mechanisms underlying their generation are of similar or even identical nature. The relationship between different rhythms is critically analyzed. It was generally felt by the workshop participants that a unified view of physiological rhythms had been developed for the first time and that this will lead in new directions in the study of complex physiological rhythms.

Rhythms are a basic phenomenon in all physiological systems. They cover an enormous range of frequencies with periods from the order of milliseconds up to some years. They are described by many disciplines and are investigated usually in the context of the physiology of the respective function or organ. The importance given to the research on rhythmicity is quite different in different systems. In some cases where the functional significance is obvious rhythms are at the center of interest, as in the case of respiration or locomotion. In other fields they are considered more or less as interesting epiphenomena or at best as indicators without essential functional significance, as in the case of cardiovascular or EEG rhythms. Recently the study of physiological rhythms has attracted growing interest in several fields, especially with respect to rhythm research in humans and its rapidly spreading applications in basic behavioral research, and as a diagnostic tool in clinical medicine. This development was favored by two methodological and conceptual ad- vances: on the one hand, the availability of non-invasive methods of continu- ous recording of physiological parameters and their computer-assisted evaluation, and on the other, the rapid development of theoretical analyses, for example, the understanding of dynamic systems, the generation of coordinated macroscopic pro- cesses in systems comprising many single elements, and the mathematical tools for treating nonlinear oscillators and their mutual coupling.

This book contains invited contributions by top experts in the field of physiological rhythms. It is the first attempt to demonstrate the pronounced similarities between the various types of physiological rhythms and to identify their interrelations. This integrative and interdisciplinary approach will be of interest to physiologists, physicists, physicians, and biologists.