Journal of Vestibular Research - Volume 1, issue 3

Authors: Takahashi, Masahiro | Okada, Yukihiro | Saito, Akira | Takei, Yasuhiko | Tomizawa, Ikuko | Uyama, Keiko | Takeuti, Izumi | Kanzaki, Jin

Article Type: Research Article

Abstract: To clarify the factors causing oscillopsia, we investigated head movement, gaze stability, and perception under various situations. High-frequency head movements, whether they were horizontal rotations or passively induced vertical oscillations, produced blurred vision and gaze fluctuations in patients with labyrinthine loss. However, this sensation differed from the oscillopsia perceived during walking, as it did not involve a sensation of oscillation of the surrounding space or a loss of body balance. Although patients with labyrinthine loss showed large irregular head perturbations during stepping, the resultant retinal velocity slips seemed too small to explain oscillopsia. Walking while wearing horizontal reversing prisms produced …loss of spatial orientation, dysequilibrium, and instability of vision in normal subjects, which resembled the symptoms found in patients with oscillopsia. The present study suggests that oscillopsia represents a perceptual inability to detect spatial orientation during head or body movements rather than a mere blurring of vision caused by deficient compensation. Show more

Keywords: oscillopsia, locomotion, head stability, gaze, spatial orientation

DOI: 10.3233/VES-1991-1301

Citation: Journal of Vestibular Research, vol. 1, no. 3, pp. 215-222, 1991

Authors: Cheron, G.

Article Type: Research Article

Abstract: This study was intended to test the adaptive plasticity of the vestibulo-ocular reflex before and after either a midsagittal or parasagittal incision in the brainstem. Eye movements were measured with the electromagnetic search coil technique during the vestibulo-ocular reflex (VORD ) in the dark, the optokinetic reflex (OKN), and the visuo-vestibular adaptive training procedure. Two types of visual-vestibular combined stimulation were applied by means of low frequency stimuli (0.05 to 0.10 Hz). In order to increase or decrease the VORD gain, the optokinetic drum was oscillated either 180∘ out-of-phase or in-phase with the vestibular stimulus turntable. This “training” …procedure was applied for 4 hours. Initial measurements of the VORD were normal with a mean gain value of 0.92 ± 0.08. After 4 hours of “training” with the out-of-phase condition (180∘ ), VORD gain reached mean values of 1.33 ± 0.11 (n = 6 cats). In the in-phase combination, the mean VORD gain decreased from 1.0 to 0.63 ± 0.02 (n = 2 cats). No significant change of VORD phase was found in any of the cats. Midsagittal or parasagittal pontomedullary brainstem incisions were performed in 4 cats. Recovery of the VOR was tested on the 2nd, 7th, and 30th day after operation. After the 30th day, recovery of the VORD gain stabilized at about 66% of the initial preoperative value. At this stage of the recovery, the optokinetic response (OKN) of the midsagittal-Iesioned cats was practically normal: in the parasagittal-Jesioned cats, the postoperative OKN responses were asymmetric. After stabilization of recovery, lesioned cats were trained with the same adaptation procedure. Although the direct effect of the visuo-vestibular combined stimulation during the training was still operative in all lesioned cats, the adaptive plasticity was completely abolished by the lesions. These results suggest that the commissural brainstem network may play a crucial role in the acquisition of the forced VOR adaptation. Show more

Keywords: vestibulo-ocular adaptation, brain stem commissural incisions, cat

DOI: 10.3233/VES-1991-1302

Citation: Journal of Vestibular Research, vol. 1, no. 3, pp. 223-239, 1991

Authors: Lapeyre, Pascale N.M. | Cazals, Yves

Article Type: Research Article

Abstract: Guinea pig isolated vestibular type I hair cells (VI HCs) were recently reported by our group to respond to high [KCl] solutions by an irreversible tilt of their neck region and sometimes by a sustained shortening and swelling. A possible osmotic contribution to these shape changes was investigated by substituting gluconate (G) for chloride in the test solution, so as to minimize water influx, and also by changing the osmotic pressure of the extracellular solution. For comparison, similar experiments were also undertaken on cochlear outer hair cells (OHCs). Utricular and ampullar type I hair cells were more difficult to isolate …than OHCs and, like them, responded to an isotonic high [KCl] solution by a sustained shortening and widening, which were found to be reversible for most cells when rinsed with the control solution. In a high [KG] solution, all OHCs showed a shortening reversible in the test solution; among the VI HCs tested, two-thirds presented a slight sustained shortening without widening and a third showed a spontaneously reversible shortening, particularly at the neck level. VI HCs exposed to a high [N-methyl-D-glucamine chloride] solution, this impermeant cation replacing K+ for control, presented only a slight sustained shortening. In response to osmotic changes of the bathing medium, both VI HCs and OHCs showed a sustained shortening or elongation (the latter to a lesser degree) for hypo- and hyperosmotic solutions, respectively. The VI HCs and OHCs that presented a reversible shortening in a high [KG] solution widened concomitantly with their shortening, but to a smaller extent compared with what was observed in a high [KCl] solution, and this diameter increase was reversible in the test solution, unlike the widening observed in a hypotonic solution. These results show that a reversible shortening occurred for some VI HCs; they also indicate the involvement of two components in the KCl-induced response: one osmotic and another potassium-dependent. Show more

Keywords: type I hair cells, reversible shortening, potassium, osmolarity

DOI: 10.3233/VES-1991-1303

Citation: Journal of Vestibular Research, vol. 1, no. 3, pp. 241-250, 1991

Authors: Niklasson, M. | Tham, R. | Larsby, B. | Eriksson, B.

Article Type: Research Article

Abstract: Eye movements were recorded in the pigmented rat during vestibular, optokinetic and combined visual-vestibular stimulation. The dominant time constant in pigmented rats, tested during angular vestibular stimulation in darkness, is about two times longer than the cupular time constant. The gain and the duration of nystagmus, achieved by angular vestibular stimulation, can be enhanced by visual impulses. This is most evident during an optokinetic temporonasal stimulation, but is also seen with a nasotemporal stimulation. A mere optokinetic monocular stimulation without a synchronous vestibular excitation causes nystagmus only when the stimuli has a temporonasal direction. The duration of nystagmus, achieved by …angular vestibular stimulation, is prolonged by disturbances of the neck proprioceptive system. This is more evident during a simultaneous visual input than in darkness. The ability to cancel nystagmus during conflicting vestibular and optokinetic impulses is well developed in the pigmented rat. Show more

Keywords: rat, eye movements, vestibulo-oculomotor reflex, optokinetic nystagmus, visual suppression, neck muscle lesion, velocity storage

DOI: 10.3233/VES-1991-1304

Citation: Journal of Vestibular Research, vol. 1, no. 3, pp. 251-262, 1991

Authors: Demer, J.L. | Goldberg, J. | Porter, F.I. | Jenkins, H.A. | Schmidt, K.

Article Type: Research Article

Abstract: Vestibularly and visually driven eye movements interact to compensate for head movements to maintain the necessary retinal image stability for clear vision. The wearing of highly magnifying telescopic spectacles requires that such compensatory visual-vestibular interaction operate in a quantitative regime much more demanding than that normally encountered. We employed electro-oculography to investigate the effect of wearing of 2×, 4×, and 6× binocular telescopic spectacles on visual-vestibular interactions during sinusoidal head rotation in 43 normal subjects. All telescopic spectacle powers produced a large, immediate increase in the gain (eye velocity/head velocity) of compensatory eye movements, called the visual-vestibulo-ocular reflex (VVOR). However, …the amount of VVOR gain augmentation became limited as spectacle magnification and the amplitude of head velocity increased. Optokinetic responses during wearing of telescopic spectacles exhibited a similar nonlinearity with respect to stimulus amplitude and spectacle magnification. Computer simulation was used to demonstrate that the nonlinear response of the VVOR with telescopic spectacles is a result of nonlinearities in visually guided tracking movements. Immediate augmentation of VVOR gain by telescopic spectacles declined significantly with increasing age in the subject pool studied. Presentation of unmagnified visual field peripheral to the telescopic spectacles reduced the immediate VVOR gain-enhancing effect of central magnified vision. These results imply that the VVOR may not be adequate to maintain retinal image stability during head movements when strongly magnifying telescopic spectacles are worn. Show more

Keywords: visual-vestibular interaction, vestibulo-ocular reflex, head motion, telescopic spectacles, plasticity

DOI: 10.3233/VES-1991-1305

Citation: Journal of Vestibular Research, vol. 1, no. 3, pp. 263-277, 1991

Authors: Brantberg, Krister | Magnusson, Måns

Article Type: Research Article

Abstract: The symmetry of primary and secondary optokinetic afternystagmus (OKAN I and OKAN II, respectively) was studied in 14 patients with vestibular neuritis, as well as in 50 normals. The patients were examined at onset of symptoms and at follow-up 3 and 12 months later. At onset, OKAN was found mainly to reflect the spontaneous nystagmus. Although the spontaneous nystagmus disappeared in all patients within 3 months, both OKAN I and OKAN II was asymmetric at the 3- and 12-month check-ups. OKAN beating toward the lesioned ear was weaker than the OKAN beating toward the healthy ear. Thus, the asymmetric vestibular …function was reflected not only in the OKAN I, but also by an asymmetry in OKAN II. Between the 3- and 12-month check-ups, asymmetry in OKAN declined, even among those patients who showed no improvement in caloric response during that time. The decreasing asymmetry in OKAN with time after lesion was, however, related to the disappearance of a positional nystagmus. Hence, the results may be interpreted as suggesting OKAN not only to be affected by vestibular side-difference, but also to be modified by the process responsible for vestibular compensation following a peripheral vestibular lesion. Show more

Keywords: optokinetic afternystagmus, primary, secondary, vestibular neuritis

DOI: 10.3233/VES-1991-1306

Citation: Journal of Vestibular Research, vol. 1, no. 3, pp. 279-289, 1991

Authors: Heimbrand, S. | Müller, M. | Schweigart, G. | Mergner, T.

Article Type: Research Article

Abstract: In patients with loss of vestibular functions, we studied psychophysically the self-motion perception for ‘trunk in space’ and ‘head in space’ during various combinations of horizontal head and trunk rotation in the dark. The results were compared to those of normal subjects. For their ‘trunk in space’ perception, the subjects relied on their internal image of space, derived from the vestibular receptors in the head, and referred their trunk to this as a reference by adding to it a nuchal trunk-to-head signal. The patients, by contrast, always considered the trunk as stationary. Obviously because they were devoid of any space …cues, they abandoned or suppressed a neck contribution to their ‘trunk in space’ perception, which, in fact, would yield an erroneous perception in almost all conditions in the dark. Both the patients and the subjects based their ‘head in space’ perception on their internal representation of ‘trunk in space’ and added to this a nuchal head-to-trunk signal. However, the patients’ head-to-trunk signal, unlike that of the subjects, was considerably larger than the actual head-to-trunk rotation at low stimulus frequency. We relate this finding to some unconscious modification of their neck muscle activity during passive head rotation. It appears that the patients’ gain of the neck input per se is not increased, but rather that subsets of this input are modified according to the particular function they serve. Show more

Keywords: self-motion perception, vestibular-neck interaction, spatial orientation, vestibular function loss

DOI: 10.3233/VES-1991-1307

Citation: Journal of Vestibular Research, vol. 1, no. 3, pp. 291-298, 1991

Authors: Brantberg, Krister | Magnusson, Måns

Article Type: Research Article

Abstract: Directional asymmetry of primary and secondary optokinetic afternystagmus (OKAN I and OKAN II, respectively) was studied in 20 patients with small acoustic neurinomas (⩽20 mm), and results were compared to those for 24 normal controls. The optokinetic afterresponse was induced by 60 s of horizontal whole-field optokinetic stimulation in both directions. Among patients, the optokinetic afterresponse was asymmetric, OKAN I and OKAN II beating toward the lesioned ear being significantly weaker than the OKAN I and OKAN II beating toward the healthy ear. Hence, in these patients with gradual deterioration of vestibular function, the vestibular side-difference was reflected both in …OKAN I and OKAN II. Although asymmetry in OKAN I was frequently observed among controls, it was significantly more pronounced among the patients. Moreover, patients could be distinguished by the occurrence of OKAN II, as it did not occur at all among controls exposed to the same stimulation. Show more

Keywords: optokinetic afternystagmus, acoustic neurinoma, primary, secondary

DOI: 10.3233/VES-1991-1308

Citation: Journal of Vestibular Research, vol. 1, no. 3, pp. 299-307, 1991

Authors: Böhmer, A. | Baloh, R.W.

Article Type: Research Article

Abstract: Vertical optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN) were recorded in 6 normal subjects using the magnetic scleral search coil technique in order to reevaluate the up-down symmetry of these responses. The effects of body position relative to gravity were investigated by comparing OKN and OKAN elicited with the subjects in an erect and in a lateral side position. No consistent up-down asymmetry in vertical OKN was found but OKAN was asymmetric (up slow phase velocity > down slow phase velocity). Most subjects had an immediate reversal in OKAN slow phase velocity after downward stimuli. No significant effects of static …head position (upright versus lateral position) on vertical OKN and OKAN were found. These features of human OKAN can be explained by the summation of two oppositely directed velocity storage mechanisms. Show more

Keywords: vertical eye movements, optokinetic nystagmus, optokinetic afternystagmus, velocity storage

DOI: 10.3233/VES-1991-1309

Citation: Journal of Vestibular Research, vol. 1, no. 3, pp. 309-315, 1991

Authors: Previc, Fred H. | Mullen, Thomas J.

Article Type: Short Communication

Abstract: This study compared the latencies of visually induced postural change and self-motion perception under identical visual conditions. The results showed that a visual roll stimulus elicits postural tilt in the direction of scene motion and an increase in postural instability several seconds before the subject begins to perceive illusory self-motion (vection) in the opposite direction. Postural and vection latencies correlate highly with one another, but bear little relationship with the magnitude of either sway or vection.

Keywords: visual-vestibular interaction, posture, vection, spatial orientation

DOI: 10.3233/VES-1991-1310

Citation: Journal of Vestibular Research, vol. 1, no. 3, pp. 317-323, 1991