Influence of a visual display and frequency of whole-body angular oscillation on incidence of motion sickness.

Guedry FE Jr, Benson AJ, Moore HJ.

Visual search within a head-fixed display consisting of a 12 X 12 digit matrix is degraded by whole-body angular oscillation at 0.02 Hz (+/- 155 degrees/s peak velocity), and signs and symptoms of motion sickness are prominent in a number of individuals within a 5-min exposure. Exposure to 2.5 Hz (+/- 20 degrees/s peak velocity) produces equivalent degradation of the visual search task, but does not produce signs and symptoms of motion sickness within a 5-min exposure.

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[Visual prevention from motion sickness in cars]

[Article in German]

Probst T, Krafczyk S, Buchele W, Brandt T.

The differential effects of vision on motion sickness in cars were tested under real road conditions using linear accelerations, in order to confirm earlier laboratory results on visual modulation of vestibular nausea induced by angular accelerations of the body. The 18 voluntary subjects were exposed to repetitive braking maneuvers (linear accelerations: 0.1-1.2 g) on a highway. The simultaneous visual stimulus conditions for the 3 separate days were: I) eyes open, visual control of car motion; II) eyes closed; III) eyes open, artificial stationary visual field (reading). The severity of motion sickness (magnitude estimation 1-10) was a function of the visual stimulus condition with significant differences among these conditions: I) moderate nausea (less than 1) with adequate visual motion perception; II) medium nausea (approximately equal to 2) with eyes closed and somatosensory-vestibular excitation only; III) strong nausea (greater than 5) with conflicting sensory input, when vestibular acceleration is in disagreement with the visual information of no movement. Providing ample peripheral vision of the relatively moving surround is the best strategy to alleviate car sickness.

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Diazepam as an anti-motion sickness drug.

McClure JA, Lycett P, Baskerville JC.

Diazepam has been used empirically for the relief of vertigo and, in addition, there are animal studies to suggest that this drug suppresses the vestibular system. One might anticipate therefore that diazepam would be an effective antimotion sickness drug. To study this, motion sickness was generated in four groups of normal subjects by having the subject make controlled head movements while rotating at constant velocity. Every subject was subjected (using a double-blind technique) to four different drug states, namely no drug, placebo, dimenhydrinate, and diazepam. Each group of subjects received the drug state at a different time interval (i.e. 30, 60, 90, and 120 min) prior to the motion sickness exposure. Motion sickness endpoints were measured subjectively using a nausea scale and objectively using a sweat sensor. The results showed significant antimotion sickness properties for both dimenhydrinate and diazepam as compared to the placebo. For the time intervals studied, the maximum effect was obtained at 120 min for both drugs.

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A comparison of some effects of three antimotion sickness drugs on nystagmic responses to angular accelerations and to optokinetic stimuli.

Collins WE, Schroeder DJ, Elam GW.

While the basic efficacy of antimotion sickness drugs is rooted in the reduction of motion sickness symptoms, adverse side effects are important practical considerations of their usage in aviation. This study examined the influence of three established antimotion sickness drugs on nystagmic eye movement responses to angular acceleration (whole-body movement) with vision either permitted or denied, and to optokinetic stimulation (visual field movement). Dimenhydrinate and promethazine hydrochloride, particularly at higher dose levels, reduced optokinetic nystagmus, thereby making less accurate the following ability of the eye. During whole-body motion in darkness, there was little placebo-drug difference in the vestibular response under alert conditions; under relaxed conditions, dimenhydrinate and promethazine hydrochloride produced significant declines in the vestibular eye movements. These same drugs also interfered with the ability of the individual to fixate adequately on a visual task during motion. Subjects who received a combination of promethazine plus d-amphetamine were able to suppress vestibular eye movements and maintain good visual fixation under the task condition. Thus, the effect of a drug on nystagmus may be a poor indicator of its value in preventing motion sickness. Moreover, assessments of antimotion sickness drugs for many practical situations should include, as a possible adverse side effect, the inability to maintain visual fixation during motion.

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Dynamics of subjective discomfort in motion sickness as measured with a magnitude estimation method.

Bock OL, Oman CM.

Eight subjects, wearing left-right vision reversing goggles, executed sequences of controlled active head movements to provoke motion sickness. Head movement sequences were interspaced with periods of eye closure and no head movement to permit partial remission of symptoms between sequences. Subjects reported the level of discomfort experienced by using a magnitude estimation technique derived from Stevens' (1957) ratio scaling method. Using this approach, we demonstrated that the time course of subjective discomfort exhibits a profile, similar in all our subjects, characterized by both fast and slow response components. The potential usefulness of magnitude estimation for research on the dynamic properties of the mechanism generating motion sickness symptoms is discussed.

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Dependence of motion sickness in automobiles on the direction of linear acceleration.

Vogel H, Kohlhaas R, von Baumgarten RJ.

Thirty-eight normal volunteers were tested in an ambulance car while being accelerated in one of the following positions: (1) sitting upright facing forward in the car, (2) lying supine on a stretcher head forward, (3) supine position head backward. Consecutive short period of negative horizontal acceleration (0.7-0.95 g) were achieved by brisk braking manoeuvres of the car, followed by weak reacceleration (0.15 g). Motion sickness symptoms were observed and recorded after each experiment using a special motion sickness scaling index which was weighted according to the strength of any particular symptom. The results indicate that horizontal linear acceleration in a car, such as experienced during multiple breaking manoeuvres, is an effective motion sickness provoking stimulus. Negative X-axis stimulation is more nauseogenic then acceleration in the Z-axis stimulation is more nauseogenic then acceleration in the Z-axis of the body.

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Age-related differences for motion sickness in the rat.

McCaffrey RJ, Graham G.

The relationship between motion sickness and age was examined in three groups of male rats in order to determine whether or not age related differences in susceptibility are due to experiential factors or unspecified changes in the central nervous system. The results revealed no difference in susceptibility between 2-month old and 11-month old group. However, the 20-month old group was significantly less susceptible to motion sickness than either of the other groups. These findings indicate that general age related changes in the central nervous system are more likely to account for the relationship between motion sickness and age tha are experiential factors.

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Motion sickness caused by rotations about Earth-horizontal and Earth-vertical axes.

Leger A, Money KE, Landolt JP, Cheung BS, Rodden BE.

Rotation at constant angular velocity about the head's Z-axis, with the rotational axis horizontal (barbecue-spit rotation), causes motion sickness and illusory perceptions of bodily movement. To determine whether such rotations about the head's X- and Y-axes cause similar effects, and to test the validity of the mismatch theory of motion sickness, more than 200 tests (using vertical axes as well as horizontal axes) were administered to 14 subjects. Three different visual conditions were also investigated: normal external vision, vision of only the inside walls of the rotating capsule, and eyes closed in the dark. In Earth-horizontal rotation, the X- and Y-axis stimuli were found to be equally as effective in provoking sickness as was the original Z-axis stimulus, and a comparable loss of perception of gravity occurred for all three stimuli. The horizontal axis stimuli were found to be very effective in producing sickness in all the three visual conditions, but the external vision condition was significantly less effective than the other two conditions. The findings were generally inconsistent with the mismatch theory.

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