Effects of vestibular cerebellum lesion on motion sickness in rats.

Uno A, Takeda N, Kitahara T, Sakata Y, Yamatodani A, Kubo T.

Department of Otolaryngology, Suita Municipal Hospital, Osaka, Japan. auno ent.med.osaka-u.ac.jp

The importance of the vestibular apparatus in the development of motion sickness is widely accepted, although the role of the vestibular cerebellum remains controversial. We examined the effects of vestibular cerebellum lesion on the development of motion sickness in rats. Rats do not vomit, but the behaviour known as "pica", the eating of non-nutritive substances, such as kaolin, can be used as an index of motion sickness. A 2 h load of hypergravity induced pica in rats, indicating that they suffered from motion sickness. Pica was induced by hypergravity load even after surgical lesion to the bilateral cerebellar flocculus or to the cerebellar vermis. We concluded that the vestibular cerebellum was not essential in the development of motion sickness in rats.

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The correlation between aerobic fitness and motion sickness susceptibility.

Rawat N, Connor CW, Jones JA, Kozlovskaya IB, Sullivan P.

Queen's School of Medicine, Queen's University, Kingston, ON, Canada.

Susceptibility to motion sickness has been linked to aerobic fitness in several studies, however, these studies have not elucidated the underlying physiological mechanism by which increased aerobic fitness is related to a decreased ability to tolerate motion sickness stimuli. This pilot study provides further evidence of a relationship between aerobic fitness and motion sickness susceptibility. It also suggests that aerobic capacity is more specifically linked to signs and symptoms of vasomotor origin including stomach discomfort, nausea and/or vomiting, headache, and diaphoresis. By independently correlating vasomotor susceptibility and neurogenic susceptibility to maximum oxygen uptake, we find that vasomotor symptoms in particular are significantly increased in aerobically fit individuals. Larger studies should be conducted to confirm this relationship.

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Motion sickness and migraine: optokinetic stimulation increases scalp tenderness, pain sensitivity in the fingers and photophobia.

Drummond PD.

School of Psychology, Murdoch University, Perth, Western Australia. drummond central.murdoch.edu.au

The aim of this study was to determine whether scalp tenderness and photophobia, two well-recognized symptoms of migraine, develop during the motion sickness induced by optokinetic stimulation. To investigate whether motion sickness has a general influence on pain perception, pain was also assessed in the fingertips. After optokinetic stimulation, nausea increased more and headache persisted longer in 21 migraine sufferers than in 15 non-headache controls. Scalp tenderness increased during optokinetic stimulation in nauseated subjects, and pain in the fingertips increased more and photophobia persisted longer in migraine sufferers than controls. These findings suggest that the disturbance responsible for nausea also sensitizes trigeminal nociceptive neurones or releases inhibitory controls on their discharge. A low nausea threshold and a propensity for sensitization to develop rapidly in nociceptive pathways may increase susceptibility to migraine.

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The prevention of motion sickness in orbital flight.

Graybiel A.

Naval Aerospace Medical Research Laboratory, Pensacola, Florida, USA.

A question has arisen whether zero gravity qualifies as just another "motion environment" in which motion sickness may be elicited, or if one or more undetermined etiological factors are present which render such terms as "motion environment" and "motion sickness" inappropriate. The question is of more than academic interest for the reason that in the forthcoming Shuttle Program we have either one problem or two: one if we are concerned solely with prevention, but two if we must tackle the problem of covert etiological factors as well. This problem points up the need to define motion sickness if investigators, world-wide, hope to resolve the matter in the most economical manner. Meanwhile, substantial reliance must be placed on the use of antimotion sickness drugs and some recent findings are presented based on tests carried out in a rotating room using a new procedure. Whereas previous findings in our laboratory dealt with group responses, the new findings are not only valid for a group, but also valid for each subject tested. It was demonstrated that the effects of a drug may be efficacious for a group yet may be detrimental for one or more individuals in that group.

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Eye movements to yaw, pitch, and roll about vertical and horizontal axes: adaptation and motion sickness.

Bos JE, Bles W, de Graaf B.

Equilibrium and Orientation Research Group, TNO Human Factors, Soesterberg, The Netherlands. Bos tm.tno.nl

BACKGROUND: In the search for parameters to predict motion sickness that can be measured in the laboratory, we performed a longitudinal investigation in aviators. Since the vestibular system is involved in the generation of motion sickness as well as eye movements, vestibulo-ocular reflex (VOR) parameters seemed relevant. We investigated three topics: 1) the effect of axis orientation and its orientation to gravity on the VOR; 2) changes in VOR parameters depending on flight experience; and 3) differences in VOR parameters in aircrew with high and low susceptibility to motion sickness. HYPOTHESIS: Nystagmus decay after angular velocity steps would be faster for non-susceptible and trained aviators. METHODS: We recorded eye movements evoked by angular on-axis velocity steps (+/- 90 degrees x S(-2), to and from 90 degrees x S(-1)) in yaw, pitch, and roll, about both the Earth vertical and Earth horizontal axes in 14 subjects with a low susceptibility to motion sickness. These data were compared with those of 10 subjects with a high susceptibility. RESULTS: Horizontal axis rotations are nauseogenic. We found that during (per) and post-condition, left- and rightward rotation responses were equal, and the orientation with respect to gravity did not alter the basic nystagmus decay, apart from a sinusoidal modulation. Moreover, pitch and roll rotations show equal nystagmus decays, significantly faster than for yaw; yaw and pitch peak velocities were equal and were larger than for roll. With regard to changes in VOR parameters depending on flight experience, we found that repeated vestibular stimulation reduced nystagmus decay as well as the otolith modulation. With respect to the changes in VOR parameters and motion sickness susceptibility, we found that subjects highly susceptible to motion sickness showed a slower decay of nystagmus with a larger peak velocity than less susceptible subjects. CONCLUSIONS: Group averages indicate a difference in eye movement parameters, only in yaw, depending on flight experience; and between subjects with low and high susceptibility to motion sickness. The involvement of the velocity storage mechanism as realized by an internal model is given as a plausible explanation.

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[The human alpha(2A)-AR gene and the genotype of site -1296 and the susceptibility to motion sickness]

[Article in Chinese]

Liu L, Yuan L, Wang HB, Yu LS, Zheng J, Luo CQ, Wang Y.

Key Laboratory of Molecular Biology, General Hospital of Airforce, Beijing 100036, China. kjliuli yahoo.com.cn

The gene sequences of alpha(2A)-adrenergic receptor(alpha(2A)-AR) in 39 Chinese and 1 Englishman showed 13 differences of g or c insertion or deletion in its regulation region, coding region and 3' untranslated region, compared with that reported in GenBank. The gene sequences from all the samples respectively were identical except for 2 single nucleotide polymorphisms, including the sequence of sense and antisense strand sequenced. It was found that: (1) the frequency of gg genotype in Chinese and Japanese, who are high susceptible to motion sickness, were 5.8 and 7.8 fold higher than that in Englishmen; (2) g allele frequencies in Chinese and Japanese were higher than latter ( P 0.01 ); (3) gg genotype frequency in population susceptible to motion sickness was 1.6 fold higher than that in population unsusceptible to motion sickness, and g allele frequency was higher than latter ( P 0.01 ). All the populations were in Hardy-Weinberg equilibrium. The results suggested that gg genotype and g allele at site -1296 in alpha(2A)-AR gene could associate with the susceptibility to motion sickness.

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[Effect of Gastrodia on rotation induced motion sickness in mice]

[Article in Chinese]

Wang SP, Liu XM, Shang WF, Song J, Yu SR, Sun SM.

Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.

Objective: To observe the effect of Gastrodia on motion sickness induced by rotation in mice. Method: Clockwise and anticlockwise accelerated rotations up to 180 degrees/s for 10 min were used to induce symptoms of motion sickness such as condition taste aversion (CTA), decrease of spontaneous locomotion and impaired ability of space identification in water-maze. Result: Gastrodia could improve the response of CTA, increase spontaneous locomotion, and enhance the ability of learning and memory in water-maze in mice after the rotation. Conclusion: Symptoms of motion sickness induced by rotation could be improved by Gastrodia treatment.

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Effect of frequency and direction of horizontal oscillation on motion sickness.

Griffin MJ, Mills KL.

Human Factors Research Unit, Institute of Sound and Vibration Research, University of Southampton, England. M.J.Griffin soton.ac.uk

BACKGROUND: Low frequency horizontal oscillation can cause motion sickness in some transportation systems, but the influence of the frequency, magnitude, direction, and duration of oscillation are poorly understood. Hypothesis: It was hypothesized that motion sickness was independent of the direction of horizontal oscillation (fore-and-aft or lateral) and that there was no difference in the motion sickness produced by different frequencies of horizontal oscillation (between 0.2 and 0.8 Hz) when subjects were exposed to the same peak velocity of motion at each frequency. METHOD: The 192 subjects were exposed within a closed cabin to sinusoidal oscillation with a velocity of +/- 0.50 ms(-1). Each subject experienced up to 30 min of motion while sitting with eyes open on a seat with a low backrest. The 16 conditions involved either fore-and-aft or lateral oscillation at 8 different frequencies: (i) 0.20 Hz, (ii) 0.25 Hz, (iii) 0.315 Hz, (iv) 0.40 Hz, (v) 0.50 Hz, (vi) 0.63 Hz, (vii) 0.80 Hz, or (viii) a stationary control condition. Subjects provided ratings of their motion sickness symptoms at 1-min intervals during the 30-min exposures. RESULTS: Each frequency of oscillation produced significantly more sickness than the static control conditions. Overall, there were no significant differences in the sickness produced by the seven different frequencies or between the sickness produced by fore-and-aft or lateral oscillation. Self-ratings of motion sickness susceptibility provided by subjects before participating in the experiment were positively correlated with their illness ratings during the experiment. CONCLUSIONS: With horizontal oscillation over the range 0.2 to 0.8 Hz, motion sickness is very approximately dependent on the peak velocity of oscillation. An acceleration frequency weighting having a gain inversely proportional to frequency would provide a convenient simple method of evaluating this type of motion in transport. However, the results suggest that a more complex weighting, reflecting decreased nauseogenicity at higher and lower frequencies would be more accurate. The direction of motion (i.e., fore-and-aft or lateral) had no effect on the sickness experienced.

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