Journal of Vestibular Research - Volume 12, issue 4

Authors: Wubbels, R.J. | de Jong, H.A.A. | van Marle, J.

Article Type: Research Article

Abstract: The appearance of vestibular sensory cells and their progressive development has been the subject of many ontogenetic studies. Because deteriorating hair cells are supposed to play a role in balance disorders of the elderly, the final stage of development (i.e. senescence) has been investigated as well. It is generally assumed that the number of hair cells in crista ampullaris, saccule and utricle slowly but steadily decreases with age. However, actual data covering the period between maturation and senescence are scarce. In the present study, rat vestibular epithelia were labeled for actin and tubulin. Morphology was inspected from immediately after weaning …until the age of 12 months. Although, postnatal development was no part of this study some data on one day old epithelia are presented for comparison. At postnatal day 1, hair bundles are still shorter than in mature sensory organs, the width of the zonula adherens is less, and the apical cross-sectional area of the epithelial cells is smaller. After one month, maturation is complete. Total cell density is 400âĂŞ500 per 0.01 mm 2 , both in the otolith maculae and in the cristae ampullares. During the first year after maturation, no changes in epithelial morphology were observed and cell density remains constant. Show more

Keywords: utricle, saccule, crista ampullaris, actin, tubulin, hair cell, supporting cell

DOI: 10.3233/VES-2003-12401

Citation: Journal of Vestibular Research, vol. 12, no. 4, pp. 145-154, 2003

Authors: Valli, Paolo | Buizza, Angelo | Botta, Laura | Zucca, Giampiero | Ghezzi, Luciano | Valli, Stefano

Article Type: Research Article

Abstract: The mechanisms underlying caloric nystagmus are still matter of debate. The original theory proposed by Barany [2] and more recently by Pau and Limberg [14] suggested that convective endolymphatic currents were involved. In contrast Gentine et al. [5,6,7,8,9] suggested that the main mechanism responsible for caloric nystagmus is buoyancy due to calorization of the endolymph, without the need of continuous convective currents. Finally, other authors (Scherer and Clarke [16], Arai et al. [1]) proposed that thermal expansion or contraction of the endolymph were involved. In the present study experimental conditions have been considered able to discriminate between these different models. …The experiments, were carried out on isolated labyrinth preparations of the frog. Only the predictions of the model based on buoyancy were fully consistent with the experimental results whereas those provided by the other models were not. Show more

DOI: 10.3233/VES-2003-12402

Citation: Journal of Vestibular Research, vol. 12, no. 4, pp. 155-165, 2003

Authors: Li, Hongyan | Dokas, Linda A. | Godfrey, Donald A. | Rubin, Allan M.

Article Type: Research Article

Abstract: To determine if synaptic remodeling in the vestibular nuclear complex (VNC) may be involved in vestibular compensation, expressions of growth-associated protein-43 (GAP-43) and synaptosome-associated protein of 25~kDa (SNAP-25) were examined by immunoblotting and immunocytochemistry after unilateral vestibular ganglionectomy (UVG) in rats. GAP-43 expression increased bilaterally in the VNC after UVG, but more rapidly on the lesioned side, and remained high through 60 days. It was mainly associated with boutons at all survival times but was also present in some axonal processes and, at 7 days after UVG, in some somata. SNAP-25 expression also increased bilaterally, more rapidly on the lesioned …side, but decreased bilaterally after peaking at 14 days. Its distribution in the VNC resembled that of GAP-43 but was more completely localized to boutons. Comparisons were made with auditory centers of the same rats, since the lesion also deafferented that system. Our results combined with those of previous studies suggest that degeneration of the vestibular nerve fibers is required for increased expression of GAP-43 in the VNC. The results suggest that axonal sprouting and synaptogenesis are involved in synaptic remodeling bilaterally in the rat VNC after UVG. Show more

Keywords: cochlear nucleus, growth associated protein-43, neural plasticity, synaptosome- associated protein of 25 kDa, unilateral vestibular ganglionectomy, vestibular compensation

DOI: 10.3233/VES-2003-12403

Citation: Journal of Vestibular Research, vol. 12, no. 4, pp. 167-183, 2003

Authors: Hilbig, Reinhard | Anken, Ralf H. | Rahmann, Hinrich

Article Type: Research Article

Abstract: Humans taking part in parabolic aircraft flights (PAFs) may suffer from motion sickness (SMS, a kinetosis; it comprises a dynamic and a static component). It has been argued that the so-called static variety of SMS during PAFs might be based on asymmetric statoliths (i.e., differently weighed statoliths on the right and the left side of the head), with asymmetric inputs to the brain being disclosed in microgravity. Since it has been repeatedly shown earlier that some fish of a given batch reveal a kinetotic behaviour during PAFs (especially so-called spinning movements and looping responses), we investigated whether fish swimming kinetotically …in microgravity have a pronounced inner ear otolith asymmetry. Therefore, the swimming behaviour of larval cichlid fish was video-recorded during PAFs and subsequently, size and asymmetry (size difference between the left and the right side) of inner ear otoliths were determined. The asymmetry of utricular otoliths of kinetotic samples was found to be significantly higher than that of normally behaving experimental specimens. Regarding the asymmetry of saccular otoliths of the two groups, statistically different results were not obtained. The findings strongly support the earlier theoretical concept, according to which otolith asymmetry causes (static) SMS. Show more

Keywords: otolith, sagitta, lapillus, asymmetry, space sickness

DOI: 10.3233/VES-2003-12404

Citation: Journal of Vestibular Research, vol. 12, no. 4, pp. 185-189, 2003

Authors: Cheung, Bob | Hofer, Kevin

Article Type: Research Article

Abstract: It has been reported that females are more susceptible to motion sickness than males. Supporting evidence is primarily based on retrospective survey questionnaires and self-reporting. We investigated if there is a gender difference in motion sickness susceptibility using objective and subjective measurements under controlled laboratory conditions. Thirty healthy subjects (14 males and 16 females) between the ages of 18-46 years were exposed to Coriolis cross-coupling stimulation, induced by 120°/s yaw rotation and a simultaneous 45° pitch forward head movement in the sagittal plane every 12 seconds. Cutaneous forearm and calf blood flow, blood pressure, and heart rate were monitored. Graybiel's …diagnostic criteria were used to assess sickness susceptibility before and after motion exposure. Golding and Kerguelen's scale was used to assess the severity of symptoms during motion exposure. A significant (p < 0.01) increase of forearm and calf blood flow during cross-coupling stimulation was observed in both sexes. However, the subjective symptoms rating and blood flow measurements indicate that there was no significant difference between male and female subjects. Our data also suggests that females may be more inclined to admit discomfort as indicated by their responses to a survey of motion sickness history prior to the experiment. Show more

Keywords: coriolis, gender, motion sickness

DOI: 10.3233/VES-2003-12405

Citation: Journal of Vestibular Research, vol. 12, no. 4, pp. 191-200, 2003