Skip to main content

Currently Skimming:

EXPERIMENTAL STUDIES OF THE ELICITING MECHANISM OF MOTION SICKNESS
Pages 7-28

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.


From page 7...
... It thus seems justifiable to assume that the symptom complex of motion sickness arises from the two receptor systems of the labyrinth: the otoliths and the ampullar cristae. The intermittent headache and some of the psychic symptoms accompanying motion sickness may be largely due to the intracranial pressure variations caused by the linear acceleration movements.
From page 8...
... In 1903, Kreidl succeeded in inducing seasickness experimentally in animals subjected to artificial ship movements. Remarkably enough he does not seem to have published his results, but he is said to have shown "qu'apres section bilaterale du nerf auditif, les animaux sont insensibles aux mouvements artificiels" (ref.
From page 9...
... It is thus seen that the path of P consists approximately of harmonic pendulous motions in both the vertical and the horizontal plane and, in addition, of an angular motion. The general motion to which a passenger is subjected takes place under varying axes and comprises a superposition of three pure sine curves with different amplitudes and numbers of oscillations.
From page 10...
... . EYE MOVEMENTS ON LINEAR ACCELERATIONS Now we come to a very important problem in seasickness.
From page 11...
... It seems justifiable, then, to conclude that seasickness symptoms are most probably not induced by angular accelerations but by harmonic oscillatory space motions in the horizontal and vertical planes on pitching, rolling, and plunging. Of the different motion components, the up-and-down harmonic oscillatory movements would seem to play the principal role.
From page 12...
... The simplest way of testing motion sickness is in large hoisting cranes or in rapid passenger elevators that are driven up and down with amplitudes of 4 to 6 meters and accelerations of I -- 9 FIGURE 6. -- Apparatus for producing vertical harmonic pendulous motion and inducing motion sickness experimentally, (a)
From page 13...
... Clinical Picture To these up-and-down movements in hoisting cranes, adult dogs, varying in weight from 9 to 21 kilograms, reacted with typical symptoms of motion sickness after periods varying between 10 and 30 minutes. The symptom complexes occurred in two forms: agitated and asthenic.
From page 14...
... To determine the importance of optical and proprioceptive impulses for the elicitation of motion-sickness symptoms, we made animal experiments in which these impulses were successively eliminated. The optical impulses were excluded by an occlusive bandage and by suturing the eyelids together.
From page 15...
... There seems to be good reason to suppose that, in the perilymphatic and endolymphatic spaces, similar pressure variations occur. On the basis of this supposition, it would seem suitable to use one single canal system when making a simple labyrinth model for analysis of the hydromechanical conditions in linear acceleration motions.
From page 16...
... The motion of the container consists of a vertical harmonic pendulous oscillation, for example, between points A and B in figure 10; in other words, a motion with a variable acceleration. Above the middle point O in section OA where the acceleration is directed downward, a pressure reduction results.
From page 17...
... . To show that the above theoretical reasoning is also applicable to our closed model of the labyrinth, we have demonstrated with a graphic recording that such pressure variations can also occur in a closed container on vertical harmonic pendulous oscillations.
From page 18...
... One conclusion from our hydromechanical studies and experiments was, therefore, that, in the labyrinth model closed with an elastic rubber membrane and filled with fluid, pressure variations occur at each point of its contents and especially in its walls under harmonic oscillatory motions in both the vertical and the horizontal plane. The same applies to other horizontal and vertical motions with varying accelerations.
From page 19...
... It seems plausible to me that the hydromechanical results can, on the whole, be applied to the living labyrinth. LABYRINTHINE PRESSURE VARIATIONS We must thus consider that, in persons who are subjected to ship movements in rough seas, or at any rate to linear motions in a vertical or horizontal plane where the accelerations are of such magnitude as to correspond to those on rough seas, each point of the labyrinth and its contents is affected by pressure variations.
From page 20...
... Since the labyrinthine fluids are practically noncompressible, the "safety valves," the labyrinth windows, have to be displaced outward as pressure increases inside the labyrinth. In the same way as the writing arm in our labyrinth model illustrated the pressure variations which occur on up-and-down or side-toside harmonic oscillatory motions, the outward displacement of the stapes should be able to serve as a norm, or be an approximate expression of the magnitude of the intralabyrinthine fluid displacement produced by such motions.
From page 21...
... The Eliciting Mechanism We have seen from the foregoing that, on rough seas or in elevators where persons are subjected to linear acceleration movements in the vertical and horizontal planes, it can be expected that pressure variations will occur simultaneously in the two labyrinths. But the momentary pressures at corresponding points within the two labyrinths are probably seldom of the same magnitude.
From page 22...
... How then can we explain that (1) in weightlessness, as a result of rapid movements of the head, i.e., linear accelerations, a sudden sensation of vertigo and symptoms of motion sickness occur?
From page 23...
... FIGURE 20. -- Open container in linear horizontal motion with 2-gcentripetal acceleration.
From page 24...
... These new moderate, unexpected afferent impulses will suddenly produce a strong excitatory effect on the sensory epithelium of the vestibular apparatus, inducing manifest symptoms of vertigo and motion sickness. Spatial Illusions The extremely important question of the spatial illusion, in weightlessness, of the body being in an upside-down position can also be plausibly explained.
From page 25...
... In other words, the membrane can easily change its position in relation to the sensory epithelium. By deviation of the sensory hairs in the viscous, gelatinous superficial mass, a mechanical transformation takes place, and the macula functions both as a position indicator and as an accelerometer.
From page 26...
... After, for example, a posteriorly directed acceleration, the individual may well have a sensation of being in the face-downward position. In figure 24, finally, we attempt to visualize the mechanism of such a vestibular macular spatial illusion.
From page 27...
... Second Symposium on the Role of the Vestibular Organs in Space Exploration, NASA SP-115,1966, pp.
From page 28...
... Sjoberg: I believe that the pressure variations with flows and displacements probably are transmitted to the perilymph and endolymph, there inducing in the two receptor systems of the labyrinth, the otoliths and the ampullarcristae, a strong excitation of the sensory epithelium, resulting in manifest symptoms of motion sickness. Money: I understood you to say that neither the impulses from the eyes nor from the proprioceptors was necessary.


This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More information on Chapter Skim is available.