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NASA SP-187 FOURTH SYMPOSIUM ON THE ROLE OF THE VESTIBULAR ORGANS IN SPACE EXPLORATION Held under the auspices of the Committee on Hearing, Bioacoustics, and Biomechanics, National Academy of Sciences - National Research Council, and assisted by the Office of Advanced Research and Technology, National Aero- nautics and Space Administration. Naval Aerospace Medical Institute Naval Aerospace Medical Center Pensacola, Florida September 24-26, 1968 General Chairman: ASHTON GRAYBIEL NAVAL AEROSPACE MEDICAL INSTITUTE Scientific and Technical Information Division OFFICE OF TECHNOLOGY UTILIZATION 1970 NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Washington, D.C.
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Foreword Although the main topics chosen for presentation and discussion at this symposium were motion sickness and central vestibular mechanisms, the scope was broadened, as on previous occasions, by extending invitations to heads of NASA laboratories and to principal investigators of NASA-sponsored projects to report on any progress in related areas. Sessions I through IV were designed to review the historical aspects, etiology, symptomatology, and treatment of motion sickness. But at the end of these sessions, despite many excellent presentations and much discussion, there was no escape from the conclusion that our limited knowledge of motion sickness represents a highly unsatisfactory state of affairs. It soon became evident that tln- use of the term "motion sickness" was not always restricted to its literal meaning and that even when it was, there were differences of opinion, either with regard to its definition or with regard to the criteria used in making a diagnosis. The effects of these differences became even more evident when the discussion cen- tered on etiology, symptomatology, and the central mechanisms underlying motion sickness and its abolition through adaptation. The situation we face is that there are too few facts known about motion sickness and that those available have not been structured conceptually. More- over, we need to identify the precise role motion sickness plays in the total symp- tomatology evoked by exposure to unusual force environments, and to differentiate between these and other circumstances not involving "motion" but evoking similar symptoms. It is pertinent to inquire why the challenge presented by such a frequently occurring fascinating constellation of symptoms has received so little attention. Some of the answers are probably contained in the following statements: (1) Scientific studies must to a large extent be conducted under controlled laboratory conditions, and such studies are costly in terms of subjects, facilities, equipment, and the time required to carry them out. (2) Motion sickness is a reversible illness which annoys but does not worry mankind and consequently holds little interest for the clinician whose services are not needed either to make the diagnosis or to prescribe treatment. But the clinical scientist should note the analogy between motion sickness and psycho- somatic disorders involving the visceral nervous system. For example, the experi- menter, through selection of subject and manipulation of vestibular input, can create conditions for studying influences of a psychological nature on physical symptoms. (3) The study of motion sickness has held little interest for the physiologist or psychologist, partly because of the "cost" mentioned above but mostly because it is a problem in the area of operational or environmental medicine. To regard motion sickness solely in this light is to ignore both its intrinsic theoretical interest and its relatedness to continuing areas of psychological and
THE ROLE OF THE VESTIBULAR ORGANS IN SPACE EXPLORATION physiological concern. The techniques which are currently used to study motion sickness in the laboratory offer an excellent means of investigating the central mechanisms of adaptation involved in accommodating to an "atypical" environ- ment and subsequently reaccommodating to the "typical" environment once the atypical conditions have been removed. Moreover, the very large yet rela- tively consistent variability that is observed among individuals in the extent to which they are susceptible to motion sickness suggests the existence of some stable and enduring characteristic of the individual. Thus, these individual differences are likely to be of considerable interest to those investigators con- cerned with identifying the important parameters of psychophysiological variation. The subsequent presentations by anatomists and electrophysiologists were outstanding and exemplified the widening growth of interest in vestibular mech- anisms and the high degree of specialization required to obtain the information which one day will allow conceptualization of the roles of the semicircular canals and the otolith apparatus. At the moment, the anatomists seem to face fewer obstacles than the physiologists in that all of the powerful tools of the former can be brought to bear in revealing fine structural differences among receptor cells and properties of specialized synapses and by tracing pathways in the central nervous system and depicting communication channels and topographical arrange- ments. Their important accomplishments edge ever closer to "function," and some of their findings are of great significance for physiology. In contrast to the anatomist, who can apply his techniques as well to the vestib- ular as to any other system, the electrophysiologist works under severe con- straints in dealing with the vestibular system, especially when comparison is made with research on vision and hearing. His problem does not lie in recording electrical "responses" in the central nervous system but rather in presenting a normal stimulus to the end organ. Angular and rectilinear accelerations cannot be manipulated as can light and sound. Moreover, the employment of "releasing stimuli" evoking innate patterned responses, which accounts for recent major advances in our understanding of auditory and especially visual mechanisms, has scarcely been used in vestibular neurophysiology. Difficulties with stimulation is only the beginning. The electrophysiologist has yet to distinguish sharply between canalicular and otolithic inputs which perforce must produce different effects. The physiologic inertial accelerative stimulus to the canals is gravity independent as is its resting discharge. The otolithic receptors, in addition to whatever gravity independent resting discharge might be exhibited in weightlessness, are never without the stimulus of gravity when properly positioned in the gravitational field. This stimulus pattern changes with changing position of the head and is complicated by whatever inertial accelera- tion transients are generated in the act of moving. The electrophysiologists are the first to point out that, in stimulating electrically a vestibular branch or the whole vestibular nerve, the sensory input is preternaturally "strong" and always abnormal in its temporal and spatial pat- terning. It is important to recognize that in the intact organism, not only is a right-left imbalance a cause for "disturbance" in the vestibular system, but even an acceleration, normal in all respects save its patterning, usually causes a dis- turbance. This extreme sensitivity to abnormal patterning of inputs may well result from the fact that of all sensory nuclei, the vestibular, perhaps to the greatest extent, combine the functions of analysis and integration. The disturbances
FOREWORD caused by abnormal stimulation are manifested by many indicators which suggest that vestibular influences may reach cell assemblies never stimulated under natural circumstances. Until normal stimuli are applied, the physiologist will be studying not only the physiological pathways but also the polysynaptic "dis- turbance pathways" of the central nervous system. These constraints are pointed out only to demonstrate the great difficulty in conducting electrophysiological studies and to underscore the need for additional support in the long task ahead. Recent progress, as indicated by the elegant studies reported in this sym- posium, emphasize the importance of the triadic interrelations of vestibular nuclei, cerebellum, and reticular formation together with their direct and indirect reciprocal connections with the brainstem, cord, and cerebral cortex. ASHTON GRAYBIEL Naval Aerospace Medical Institute Naval Aerospace Medical Center
Contents PAGE WELCOME 1 WALTON L. JONES SESSION I Chairman: W. J. McNally EXPERIMENTAL STUDIES OF THE ELICITING MECHANISM OF MOTION SICKNESS 7 ARNE SJOBERG EXPERIENCES WITH RESEARCH ON MOTION SICKNESS 29 GEORGE RICHARD WENDT SESSION II Chairman: Martin P. Lansberg NEURAL MECHANISMS UNDERLYING THE SYMPTOMATOLOGY OF MOTION SICKNESS 35 K. E. MONEY AND J. D. WOOD CONFLICTING SENSORY ORIENTATION CUES AS A FACTOR IN MOTION SICKNESS 45 FRED E. GUEDRY, JR. THE OTOLITH ORGANS AS A PRIMARY ETIOLOGICAL FACTOR IN MOTION SICKNESS: WITH A NOTE ON "OFF-VERTICAL" ROTA- TION 53 ASHTON GRAYBIEL AND EARL F. MILLER II SESSION III Chairman: Thomas C. D. Whiteside THE SEMICIRCULAR CANALS AS A PRIMARY ETIOLOGICAL FACTOR IN MOTION SICKNESS 69 EARL F. MILLER II AND ASHTON GRAYBIEL SECONDARY ETIOLOGICAL FACTORS IN THE CAUSATION OF MO- TION SICKNESS 83 WALTER H. JOHNSON THE SYMPTOM A TOLOGY OF MOTION SICKNESS 89 JACK E. STEELE
viii THE ROLE OF THE VESTIBULAR ORGANS IN SPACE EXPLORATION SESSION IV Chairman: E. J. Baldes PAGE USE OF DRUGS IN THE PREVENTION OF MOTION SICKNESS 101 CHARLES D. WOOD PREVENTION OF MOTION SICKNESS IN THE SLOW ROTATION ROOM BY INCREMENTAL INCREASES IN STRENGTH OF STIM- ULUS 109 ASHTON GRAYBIEL RESUME OF SESSIONS ON MOTION SICKNESS 117 HERBERT L. BORISON SESSION V Chairman: Bo E. Gernandt THE FIRST-ORDER VESTIBULAR NEURON 123 HANS ENGSTROM COMPUTER ANALYSIS OF SINGLE-UNIT DISCHARGES IN THE VES- TIBULAR NERVE OF THE FROG 137 JORGE HUERTAS AND RUTH S. CARPENTER VESTIBULAR AND SOMATIC INPUTS TO CELLS OF THE LATERAL AND MEDIAL VESTIBULAR NUCLEI OF THE CAT 145 VICTOR J. WILSON SESSION VI Chairman: Cesar Fernandez ELECTROPHYSIOLOGICAL EXPERIMENTS ON THE ISOLATED SURVIVING LABYRINTH OF ELASMOBRANCH FISH TO ANALYZE THE RESPONSES TO LINEAR ACCELERATIONS 161 OTTO E. LOWENSTEIN ANATOMICAL ASPECTS ON THE FUNCTIONAL ORGANIZATION OF THE VESTIBULOSPINAL PROJECTION, WITH SPECIAL REFER- ENCE TO THE SITES OF TERMINATION 167 ROLF NYBERG-HANSEN THE CEREBELLOVESTIBULAR INTERACTION IN THE CAT'S VES- TIBULAR NUCLEI NEURONS 183 MASAO ITO SESSION VII Chairman: Wolfgang A. Precht MULTISENSORY INFLUENCE UPON SINGLE UNITS IN THE VES- TIBULAR NUCLEUS 203 JOHN M. FREDRICKSON AND DIETRICH SCHWARZ
CONTENTS PAGE INTERACTION BETWEEN VESTIBULAR AND NONVEST1BULAR SENSORY INPUTS 209 OTTAVIO POMPEIANO VESTIBULAR ACTIVITY IN THE DESCENDING MEDIAL LONGITU- DINAL FASCICULUS 237 Bo E. GERNANDT SESSION VIII Chairman: William D. Neff EVOKED POTENTIAL AND MICROELECTRICAL ANALYSIS OF SEN- SORY ACTIVITY WITHIN THE CEREBELLUM 245 RAY S. SNIDER AND KARL LOWY CORTICAL PROJECTION OF LABYRINTHINE IMPULSES: STUDY OF AVERAGED EVOKED RESPONSES 259 E. A. SPIEGEL, E. G. SZEKELY, H. MOFFET, AND J. EGYED SESSION IX Chairman: William E. Collins EXPERIMENTAL AND CLINICAL EXPERIENCES AND COMMENTS ON ULTRASONIC TREATMENT OF MENIERE'S DISEASE 271 ARNE SJOBERG PATTERNS OF COCHLEAR HAIR-CELL LOSS IN GUINEA PIGS AFTER INTENSE STIMULA TION BY SINUSOIDAL SOUND 285 HARLOW W. ADES, CHARLES W. STOCKWELL, LYNN B. POCHE, AND HANS ENGSTROM THRESHOLDS FOR THE PERCEPTION OF ANGULAR ACCELERA- TION ABOUT THE THREE MAJOR BODY AXES 299 BRANT CLARK AND JOHN D. STEWART EFFECT OF INSTABILITY DURING ROTATION ON PHYSIOLOGIC AND PERCEPTUAL-MOTOR FUNCTION 307 BERNARD D. NEWSOM SESSION X Chairman: Lawrence F. Dietlein CERTAIN ASPECTS OF ONBOARD CENTRIFUGES AND ARTIFICIAL GRAVITY 331 RALPH W. STONE, JR., W. M. PILAND, AND WILLIAM LETKO WALKING IN SIMULATED LUNAR GRAVITY 347 WILLIAM LETKO AND AMOS A. SPADY, JR.
THE ROLE OF THE VESTIBULAR ORGANS IN SPACE EXPLORATION PROGRESS IN VESTIBULAR MODELING PAGE Part I: Response of Semicircular Canals to Constant Rotation in a Linear Acceleration Field 353 ROBERT W. STEER, JR. Part II: A Model for Vestibular Adaptation to Horizontal Rotation 363 LAURENCE R. YOUNG AND CHARLES M. OMAN Part III: A Quantitative Study of Vestibular Adaptation in Humans 369 RICHARD MALCOLM PARTICIPANTS 381