Journal of Vestibular Research - Volume 17, issue 5-6

Authors: Matsnev, E.I. | Sigaleva, E.E.

Article Type: Research Article

Abstract: The purpose of this investigation was to evaluate the efficacy of the histaminergic drug "Betahistine dihydrochloride" in experimental motion sickness in 10 healthy volunteers (mean age 19.4 y.o.) with high susceptibility to motion sickness. Motion sickness was modeled using Coriolis (precession) accelerations (cumulative Coriolis stimulation test – CCST). Each subject took 32 mg of "Betahistine dihydrochloride " or placebo under "double – blind" conditions 1 hour before testing. The duration and slow phase velocity of the post-rotational nystagmus, the pursuit eye tracking test, and the latency, velocity and accuracy of saccades were estimated. The tolerability level of the CCST in …volunteers in the betahistine series was shown to be significantly (p < 0.001) higher, as compared to placebo and baseline. The mean illusory sensations score for the experimental series was significantly lower than that in the placebo and baseline series (p < 0.01). It was found that "Betahistine" demonstrated antimotion sickness efficacy and improved oculomotor activity (increased gain during pursuit movements, faster and more accurate saccades). Show more

Keywords: Motion sickness, coriolis stimulation, histaminergic system, Betahistine dihydrochloride, motion sickness treatment

DOI: 10.3233/VES-2007-175-611

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 313-321, 2007

Authors: Nooij, Suzanne A.E. | Bos, Jelte E.

Article Type: Research Article

Abstract: It has been found that sustained centrifugation on Earth may evoke sickness symptoms that are similar to those of the Space Adaptation Syndrome (SAS). As in SAS, incidence of this 'Sickness Induced by Centrifugation' (SIC) is about 50% and the symptoms are particularly evoked by head movements. By systematically varying the G-load and duration of centrifugation, the current study investigated the characteristics of the gravitational stimulus that is required for SIC to occur. Subjects were exposed to centrifugation at 2 and 3Gx , for a duration of 45 and 90 minutes. A standardized head movement protocol was used to evoke …SIC after centrifugation. The results show that in six out of 12 subjects (50%) no serious symptoms were elicited. In the remaining subjects, the effects of the 3G runs exceeded those of the 2G runs, and within each G-level symptom intensity was higher for the 90 min than for the 45 min exposure. An exponential fit on this data showed that the time constant of adaptation to the gravitational stimulus was about 60 minutes. This suggests that short duration exposures (i.e. < 60 min) are not likely to induce serious SIC. Show more

Keywords: Space adaptation syndrome, artificial gravity, hypergravity, centrifugation, vestibule

DOI: 10.3233/VES-2007-175-612

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 323-332, 2007

Authors: Holly, Jan E.

Article Type: Research Article

Abstract: Artificial gravity by centrifugation can lead to perceptual disturbances in the form of motion sickness and/or misperception of motion during head movements, but the degree of perceptual disturbance during centrifugation in 0-g has not been thoroughly investigated. It is known that during whole-body on-axis yaw rotation in 0-g, head movements in pitch and roll cause very little disturbance, despite significant disturbance in 1-g. Therefore, 1-g experimental results do not apply directly to 0-g without further analysis. A modeling approach was used here to predict disorienting effects in 0-g and 1-g environments, with different rotation speeds, centrifuge radii, and directions …of head movement. The results were based upon investigation of the stimulus itself, in the form of angular and linear accelerations, and their consequences due to linear-angular interactions in three dimensions. The results explain known differences in 0-g and 1-g, for head turns toward and away from the direction of motion, and for head movements on- and off-axis. Additional predictions include an increase in perceptual disturbance with the magnitude of the gravito-inertial acceleration (GIA), therefore an increase off-axis, but a decrease in 0-g. Also predicted is that head-movement direction makes a difference, with rotation outward relative to the centrifuge axis causing the least disturbance. Show more

Keywords: Model, self-motion, perception, vestibular

DOI: 10.3233/VES-2007-175-613

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 333-346, 2007

Authors: McCollum, Gin

Article Type: Research Article

Abstract: While some aspects of neuroanatomical organization are related to packing and access rather than to function, other aspects of anatomical/physiological organization are directly related to function. The mathematics of symmetry groups can be used to determine logical structure in projections and to relate it to function. This paper reviews two studies of the symmetry groups of vestibular projections that are related to the spatial functions of the vestibular complex, including gaze, posture, and movement. These logical structures have been determined by finding symmetry groups of two vestibular projections directly from physiological and anatomical data. Logical structures in vestibular projections are …distinct from mapping properties such as the ability to maintain two- and three-dimensional coordinate systems; rather, they provide anatomical/physiological foundations for these mapping properties. The symmetry group of the direct projection from the semicircular canal primary afferents to neck motor neurons is that of the cube (O, the octahedral group), which can serve as a discrete skeleton for coordinate systems in three-dimensional space. The symmetry group of the canal projection from the secondary vestibular afferents to the inferior olive and thence to the cerebellar uvula-nodulus is that of the square (D8), which can support coordinates for the horizontal plane. While the mathematical relationship between these symmetry groups and functions of the vestibular complex are clear, these studies open a larger question: what is the causal logic by which neural centers and their intrinsic organization affect each other and behavior? The relationship of vestibular projection symmetry groups to spatial function make them ideal projections for investigating this causal logic. The symmetry group results are discussed in relationship to possible ways they communicate spatial structure to other neural centers and format spatial functions such as body movements. These two projection symmetry groups suggest that all vestibular projections may have symmetry groups significantly related to function, perhaps all to spatial function. Show more

Keywords: Mathematical, symmetry, group, vestibular, projection

DOI: 10.3233/VES-2007-175-614

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 347-359, 2007