Vestibular System Part 1 Basic Mechanisms

The details of the receptor mechanism are not yet fully understood for any sensory system. However, sufficient data are available (for the vestibular system and for other systems) to permit meaningful tracking of the sensory messages through the nervous system and via conscious experience. The reception, process ing, storage and output of information in man and other animals, as done by means of receptors, neurons, secretory cells and muscle fibers, are collectively referred to as mind. Sensory physiologists tend to disbelieve in extrasensory perception. Sensory physiology in general is an area upon which different sciences and methods converge. Anatomists, physiologists, psychologists, physicists, chemists, and engineers have made important contributions to sensory physiology. What is special about vestibular physiology is the fact that many research workers are clinicians, living under the constant pressure of their patient's demands. This is a disadvantage when it comes to writing handbooks, but an advantage for the pa tient, since research is guided by clinical practice and can be quickly applied. Modern methods, such as recording from single nerve units and the correlation of electrophysiological and psychophysical data, have greatly contributed to our knowledge, yet the study of lesions is still important, especially in the vestibular field.

The details of the receptor mechanism are not yet fully understood for any sensory system. However, sufficient data are available (for the vestibular system and for other systems) to permit meaningful tracking of the sensory messages through the nervous system and via conscious experience. The reception, process ing, storage and output of information in man and other animals, as done by means of receptors, neurons, secretory cells and muscle fibers, are collectively referred to as mind. Sensory physiologists tend to disbelieve in extrasensory perception. Sensory physiology in general is an area upon which different sciences and methods converge. Anatomists, physiologists, psychologists, physicists, chemists, and engineers have made important contributions to sensory physiology. What is special about vestibular physiology is the fact that many research workers are clinicians, living under the constant pressure of their patient's demands. This is a disadvantage when it comes to writing handbooks, but an advantage for the pa tient, since research is guided by clinical practice and can be quickly applied. Modern methods, such as recording from single nerve units and the correlation of electrophysiological and psychophysical data, have greatly contributed to our knowledge, yet the study of lesions is still important, especially in the vestibular field.

The Vestibular System is a collection of papers presented at the 1973 Symposium on the Vestibular System, organized and held at the University of Chicago. This symposium provides a body of reviews and observations on the anatomical, physiological, and clinical aspects of the vestibular system. This book is composed of seven parts encompassing 28 chapters. The first part focuses on the ultrastructure of the peripheral organs and the vestibular pathways to the cerebellum, the spinal cord, and the nuclei of the extraocular muscles. The subsequent part presents the basic information on knowledge of peripheral mechanisms and the functional relations between the vestibular system, cerebellum, oculomotor system, spinal cord and cortex. These topics are followed by descriptions of vestibular disorders induced by a variety of influences or procedures, such as nuclear lesions, motion sickness, and drugs. The next section describes the methods of testing vestibular function, such as electronystagmography. This section serves as an introduction to a panel discussion on eye movements. Lastly, reviews and points of view on peripheral and central vestibular disorders are covered in the remaining sections. This work is of great benefit to anatomists, physiologists, and clinicians.

Basic Aspects of Central Vestibular Mechanisms

The function of the vestibular system is not as obvious as those of vision, hearing, touch or smell. Vestibular dysfunction, however, is clearly apparent where lesions are present. It is probably for this reason that the vestibular sense was not discovered until the nineteenth century and that clinicians have continued to playa major role in basic vestibular research right up to the present. The relationship between basic and clinical research is certainly stronger in the vesti bular field than in that of tactile sensation, for instance, as testified by the work of clinicians as MENIERE, BREUER, BARANY, DEKLEIJN and FRENZEL. In this respect the situation is similar in vestibular physiology and in endocrinology, and for the same reason. This second part of the vestibular volume of the Handbook of Sensory Physio logy will be of interest to neurologists, otologists, neurosurgeons, ophthalmologists and physiotherapists on the one hand, and psychologists, physiologists, engineers and aviation specialists on the other. For a full understanding of Part 2, it is necessary to have assimilated the basic anatomy, physiology, and biochemistry of Part 1.

Vestibular physiology has acquired new interest in the past few years. The development of fast aircraft, beginning during the Second World War and continuing through modern supersonic jets and space travel, has increased dramatically the acceleration range to which man is subjected, from prolonged weightlessness to several gs. The labyrinth measures all kinds of acceleration, including gravity. and therefore has taken on particular impor tance in the study of human health in the Space Age. It is understandable. then, that NASA sponsored the Symposium on Vestibular Function and Morphology. a satellite of the Eighth Annual Meeting of the Society of Neuroscience. held October 30-November 1. 1978, at the University of Pittsburgh, which also supported the symposium. The present volume was developed from papers originally presented there. My strategy in editing this book has been to focus upon the vestibular end organ and its direct connections. both peripheral and central, in order to as sure a coherent discussion of the basics of vestibular function, structure, and ultrastructure. Fortunately, it was possible to secure the contributions of a number of outstanding investigators from both the United States and abroad, including functionally oriented morphologists. ultrastructuralists, biophysicists, and vestibular physiologists. The result is a comprehensive discussion of the main mechanisms of the labyrinth: the transduction pro cess at the receptor level, in the semicircular canals, and in the utricular and saccular maculae; the information transfer through neuronal pathways to the nuclei and the cerebellum; and the general organization of the system.