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

Authors: Oman, Charles M.

Article Type: Introduction

DOI: 10.3233/VES-2007-175-601

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 207-208, 2007

Authors: Clément, Gilles | Denise, Pierre | Reschke, Millard F. | Wood, Scott J.

Article Type: Research Article

Abstract: Ocular counter-rolling (OCR) induced by whole body tilt in roll has been explored after spaceflight as an indicator of the adaptation of the otolith function to microgravity. It has been claimed that the overall pattern of OCR responses during static body tilt after spaceflight is indicative of a decreased role of the otolith function, but the results of these studies have not been consistent, mostly due to large variations in the OCR within and across individuals. By contrast with static head tilt, off-vertical axis rotation (OVAR) presents the advantage of generating a sinusoidal modulation of OCR, allowing averaged measurements over …several cycles, thus improving measurement accuracy. Accordingly, OCR and the sense of roll tilt were evaluated in seven astronauts before and after spaceflight during OVAR at 45°/s in darkness at two angles of tilt (10° and 20°). There was no significant difference in OCR during OVAR immediately after landing compared to preflight. However, the amplitude of the perceived roll tilt during OVAR was significantly larger immediately postflight, and then returned to control values in the following days. Since the OCR response is predominantly attributed to the shearing force exerted on the utricular macula, the absence of change in OCR postflight suggests that the peripheral otolith organs function normally after short-term spaceflight. However, the increased sense of roll tilt indicates an adaptation in the central processing of gravitational input, presumably related to a re-weighting of the internal representation of gravitational vertical as a result of adaptation to microgravity. Show more

Keywords: Human, ocular torsion, tilt perception, adaptation, microgravity

DOI: 10.3233/VES-2007-175-602

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 209-215, 2007

Authors: Kornilova, L.N. | Sagalovitch, S.V. | Temnikova, V.V. | Yakushev, A.G.

Article Type: Research Article

Abstract: The vestibular function was investigated in 13 Russian crew members of the ISS missions on days 1(2), 4(5), and 8(9) after prolonged exposure to microgravity (126 to 195 days). The static torsional otolith-cervico-ocular reflex was studied, as well as the dynamic vestibulo-cervico-ocular responses, vestibular reactivity, and spontaneous oculomotor activity using videooculography (VOG) and electrooculography (EOG) for simultaneous recording of eye movements. On days 1–2 of return to the gravity (R+1−2), the cosmonauts were found to increase the spontaneous oculomotor activity (floating eye movements, both typical and atypical forms of spontaneous nystagmus, square wave jerks, gaze nystagmus) with the head held …in the vertical position. The otolith function during static head inclinations to the right or left shoulder at 30° was suppressed as determined by the inversion or absence, or reduction by half of the amplitude of torsional compensatory eye counter-rolling and the vestibular reactivity during head yaw movements at 0.125 Hz was increased as revealed by a lowered threshold and an increased intensity of vestibular nystagmus. The pattern, depth, dynamics, and velocity of the vestibular function recovery varied with individual participants in the investigation. However, the suppressed otolith functioning in the period of readaptation to the normal gravity was, as a rule, accompanied by an exaggerated vestibular reactivity. Show more

Keywords: Dynamic vestibulo-ocular reaction, static torsional otolith-ocular reflex, microgravity

DOI: 10.3233/VES-2007-175-603

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 217-226, 2007

Authors: Clément, Gilles | Deguine, Olivier | Bourg, Mathieu | Traon, Anne Pavy-Le

Article Type: Research Article

Abstract: Pitch head-and-trunk movements during constant velocity rotation are a provocative vestibular stimulus that produces vertigo and nausea. When exposed to this stimulus repeatedly, motion sickness symptoms diminish as the subjects habituate. Acetylleucine is a drug that is used to treat acute vestibular vertigo. In this study, we wanted to ascertain whether this drug (a) lessened motion sickness or delayed habituation; (b) accelerated the recovery following habituation; and (c) whether changes in the subjective vertical accompanied habituation. Twenty subjects were administered acetylleucine or placebo in a double-blind study during a five-day vestibular training. Horizontal vestibulo-ocular reflex, optokinetic nystagmus, smooth pursuit, and …subjective visual vertical were evaluated before, during, and up to two months after the vestibular training. Based on Graybiel's diagnostic criteria, motion sickness decreased steadily in each vestibular training session, and there was no difference between the scores in the acetylleucine and placebo groups. Post-rotatory nystagmus peak velocity and time constant also declined in both groups at the same rate. Thus, acetylleucine neither reduced the nausea associated with this provocative stimulus, nor hastened the acquisition or retention of vestibular habituation of motion sickness and nystagmus. There was no difference in optokinetic nystagmus and smooth pursuit between the acetylleucine and placebo groups. However, subjects showed larger error in the subjective visual vertical after habituation, which indicates that spatial orientation is also affected by vestibular training. Show more

Keywords: Motion sickness, adaptation, acetylleucine, vestibulo-ocular reflex, habituation

DOI: 10.3233/VES-2007-175-604

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 227-237, 2007

Authors: Capelli, A. | Israël, I.

Article Type: Research Article

Abstract: Temporal intervals production of one second was found to be more variable during self-motion compared to no motion situations. Moreover, the temporal intervals production rhythm during self-motion deceleration decreased whereas it increased during self-motion acceleration, whatever the direction of motion [17]. As somatosensory cues were not excluded in this previous experiment, we now examined whether the same temporal perturbation would occur without variable somatosensory information. In order to isolate the contribution of the vestibular system from that of the somatosensory system, the participants were required to perform a one second temporal interval production task (pressing a button each second) during …the post-rotatory illusion following self-rotation. The intervals produced during the vestibular illusion were compared to those produced before the imposed rotation and during self-motion. The production regularity was affected as the temporal intervals were more variable with vestibular stimulation (real and illusory self-motion) than without. Furthermore, during post-rotatory illusion, the production rhythm decreased along the trial, as it was observed during self-motion deceleration. These findings suggest that vestibular stimulation (even vestibular illusion) impaired time estimation. Show more

Keywords: Post-rotation, temporal production, vestibular system

DOI: 10.3233/VES-2007-175-605

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 239-249, 2007

Authors: Hanes, Douglas A.

Article Type: Research Article

Abstract: It has been shown experimentally that under certain combinations of sensory stimuli, human subjects can perceive one of several distinct illusions about their overall orientation in or movement through space. In at least some cases, the structure of such multistable illusory perceptions of orientation can be efficiently described by perceptual transformations that act on a current orientation estimate to yield an updated perceptual construct. Repeated application of identified generating transformations yields a limited set of predicted illusions for a given sensory environment. This approach is especially valuable for perceptual data that exhibits discretely differing classes of illusions between subjects or …trials. In a previous study, application of a semigroup of perceptual centering transformations has succeeded in reproducing and simplifying data from an experiment in which subjects experiencing visual vection reported a range of illusions about the orientations of their gaze, head, and torso to gravity. After reviewing previously obtained results on perceptual centering, this article generalizes the approach, presenting the mathematics required to characterize perceptual transformations. The developed framework should be widely applicable in the understanding of perceptual illusions, particularly when these are guided by alignment with preferred constructs. Secondly, the article reveals the nontrivial mathematical process of perceptual semigroup formation and evaluation, deducing the complete description of the semigroup constructed in the previous study. Perceptual centering transformations identified in terrestrial experiments may predict illusions to be expected in spacefiight. For example, our results indicate that under certain conditions, many astronauts will misperceive a visual rotation axis to be centered in front of the head or even the torso. Show more

Keywords: Perception, illusion, mathematics, transformation, orientation

DOI: 10.3233/VES-2007-175-606

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 251-270, 2007

Authors: Jenkin, H.L. | Zacher, J.E. | Jenkin, M.R. | Oman, C.M. | Harris, L.R.

Article Type: Research Article

Abstract: Supine subjects inside a furnished room in which both they and the room are pitched 90° backwards may experience themselves and the room as upright relative to gravity. This effect is known as the levitation illusion because observers report that their arms feel weightless when extended, and objects hanging in the room seem to "levitate". This illusion is an extreme example of a visually induced illusion of static tilt. Visually induced tilt illusions are commonly experienced in wide-screen movie theatres, flight simulators, and immersive virtual reality systems. For technical reasons an observer's field of view is often constrained in these …environments. No studies have documented the effect of field-of-view (FOV) restriction on the incidence of the levitation illusion. Preliminary findings suggest that when concurrently manipulating the FOV and observer position within an environment, the incidence of levitation illusions depends not only on the field of view but also on the visible scene content. Show more

Keywords: Visual orientation, self tilt, perceived orientation, gravitational vertical

DOI: 10.3233/VES-2007-175-607

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 271-277, 2007

Authors: Grabherr, Luzia | Karmali, Faisal | Bach, Silvia | Indermaur, Kathrin | Metzler, Sibylle | Mast, Fred W.

Article Type: Research Article

Abstract: The aim of this experiment was to investigate the influence of gravity on the cognitive ability to mentally transform images of bodies or body parts. A total of eight participants were tested in two separate parabolic flight missions. In the main experiment, participants had to make a discrimination judgement (left or right) about pictures of a human figure with one arm outstretched, and pictures of a body part (hand). The stimuli appeared in varying views and orientations. Response times and error rates were measured. In microgravity, the participants showed increased response times overall as well as increased error rates when …compared to 1 g for both types of stimuli. Thus, a task that requires the mental transformation of one's own body or body parts becomes more difficult during microgravity. This is in contrast to previous studies showing no effect of microgravity on the mental rotation of abstract 3D objects and to our follow-up case study in which participants applied an object-based mental rotation strategy. Moreover, the analysis of response times suggests that in microgravity body-part stimuli are affected more strongly than body figures. Show more

Keywords: Embodiment, mental imagery, mental rotation, motor imagery, otolith, parabolic flight, vestibular system

DOI: 10.3233/VES-2007-175-608

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 279-287, 2007

Authors: Sanderson, Jeffrey | Oman, Charles M. | Harris, Laurence R.

Article Type: Research Article

Abstract: We demonstrate a new method for measuring the time constant of head-movement-contingent oscillopsia (HMCO) produced by vestibular Coriolis stimulation. Subjects briskly rotated their heads around pitch or roll axes whilst seated on a platform rotating at constant velocity. This induced a cross-coupled vestibular Coriolis illusion. Simultaneous with the head movement, a visual display consisting of either a moving field of white dots on a black background or superimposed on a subject-stationary horizon, or a complete virtual room with conventional furnishings appeared. The scene's motion was driven by a simplified computer model of the Coriolis illusion. Subjects either nulled (if visual …motion was against the illusory body rotation) or matched (if motion was in the same direction as the illusory motion) the sensation with the exponentially slowing scene motion, by indicating whether its decline was too fast or too slow. The model time constant was approximated using a staircase technique. Time constants comparable to that of the Coriolis vestibular ocular reflex were obtained. Time constants could be significantly reduced by adding subject-stationary visual elements. This technique for measuring oscillopsia might be used to quantify adaptation to artificial gravity environments. In principle more complex models can be used, and applied to other types of oscillopsia such as are experienced by BPPV patients or by astronauts returning to Earth. Show more

Keywords: Oscillopsia, head-movement-contingent oscillopsia, vestibular Coriolis effect, suppression, perceptual stability

DOI: 10.3233/VES-2007-175-609

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 289-299, 2007

Authors: Buckey Jr., Jay C. | Alvarenga, Donna L. | MacKenzie, Todd A.

Article Type: Research Article

Abstract: Background: Chlorpheniramine is effective against motion sickness, but produces sedation. To reduce chlorpheniramine's sedating effect and increase its effectiveness, ephedrine was combined with chlorpheniramine to prevent motion sickness. Methods: Chlorpheniramine (C) and chlorpheniramine plus ephedrine (Chlorphedra) were studied in a randomized, double blind, crossover trial. Eighteen normal subjects were randomized to six different orderings of placebo, C (12 mg) or Chlorphedra (12 mg C + 50 mg ephedrine). They ingested the medication 3.25 hours before off vertical axis rotation in a rotating chair. Cognitive testing with both objective and subjective tests was performed before drug ingestion, at peak …drug effect and following rotation. Results: Both C and Chlorphedra significantly increased chair time compared to placebo [6.6 to 10.3 minutes (C), 10.2 minutes (Chlorphedra), p < 0.01]. Subjects reported significantly more sleepiness on the Karolinska sleepiness scale after taking C (3.3 placebo, 4.9 C (p < 0.005)) but not with Chlorphedra (3.3 placebo, 3.1 Chlorphedra). Chlorphedra resulted in significantly higher reported alertness, clearheadedness and attentiveness compared to C. Deficits seen on objective tests with C were corrected with Chlorphedra. Subjects noted more side effects with Chlorphedra. Conclusion: Ephedrine does not increase the effectiveness of chlorpheniramine against motion sickness, but counteracts sedative and performance effects successfully. Show more

Keywords: Chlorpheniramine, ephedrine, motion sickness, neuropsychological tests

DOI: 10.3233/VES-2007-175-610

Citation: Journal of Vestibular Research, vol. 17, no. 5-6, pp. 301-311, 2007