Journal of Vestibular Research - Volume 5, issue 4

Authors: Baloh, Robert W. | Furman, Joseph M.R. | Halmagyi, G. Michael | Allum, John H.J.

Article Type: Review Article

Abstract: In recent years, owing to significant technological developments and an increased number of investigators entering the field, there have been spectacular advances in our understanding of the basic anatomy and physiology of the vestibular system. Unfortunately, these advances in basic science are slow to impact the clinical management of patients. We have selected a few important advances in clinical neurotology that have impacted the diagnosis and treatment of patients with vestibular disorders. This material was originally presented at the “Mechanisms of Vestibular Function and Dysfunction” symposium of the 1994 Neural Control of Movement meeting in Waikoloa, Hawaii.

Keywords: positional vertigo, vestibuloocular reflex, otoliths, posturography

DOI: 10.3233/VES-1995-5401

Citation: Journal of Vestibular Research, vol. 5, no. 4, pp. 231-252, 1995

Authors: Probst, Thomas | Katterbach, Tanja | Wist, Eugene R.

Article Type: Research Article

Abstract: We recorded vestibularly evoked potentials (VESTEPs) using natural vestibular stimuli simulating the form of a normal head movement (“raised cosine”). Its smooth course was designed to minimize all possible sources of artifacts of mechanical, electrical, and physiological origin. This motion profile was applied to subjects (Ss) sitting upright, thus stimulating the horizontal semicircular canals alone, as well as when they were tilted in different positions in steps of 30° about the interaural y-axis, which had the effect of modulating the otolithic contribution to the horizontal VESTEP. The transient bell-shaped VESTEP recorded in the upright sitting S was more and more superimposed …or replaced by a sustained negativity the more the S was tilted toward a horizontal position. Thus, the VESTEP gradually changes from a velocity response in the upright S (canals only) to a position response in the lying S (canals plus otoliths). Differences in the VESTEPs obtained for clockwise (cw) and counterclockwise (ccw) turns in the tilted S were found. The reason for this is not clear at present and requires further experimentation. However, the VESTEPs obtained under conditions involving backward tilts and cw turns corresponded to those obtained with forward tilts and ccw turns. A similar relationship was found for the VESTEPs obtained with backward tilts and ccw turns and those obtained with forward tilts and cw turns. The physiological basis of this is discussed. Show more

Keywords: vestibularly evoked potentials (VESTEPs), canal-otolith interaction, 3-D-rotary chair (MARDER), body tilt

DOI: 10.3233/VES-1995-5402

Citation: Journal of Vestibular Research, vol. 5, no. 4, pp. 253-263, 1995

Authors: Umetani, Takehiko

Article Type: Research Article

Abstract: The mediolateral topographic organization of olivocerebellar projections to the nodulus in rats was investigated by a retrograde WGA-HRP method. The nodulus received olivary afferents from the contralateral dorsal cap, nucleus β , ventrolateral outgrowth, and dorsomedial cell column. The mediolateral extent of terminal areas of the olivocerebellar fibers arising from these subnuclei differed. The dorsal cap projected to the entire mediolateral area of the contralateral nodulus; the rostral and caudal parts of the dorsal cap projected to the lateral and medial parts of the nodulus, respectively. The nucleus β projected to the medial and intermediate parts of the nodulus. …Differential projections from the nucleus β were observed in a rostrocaudal direction as those from the dorsal cap; the rostral and medial parts of the nucleus projected to the intermediate and medial parts of the nodulus, respectively. The ventrolateral outgrowth projected only to the intermediate part of the nodulus. The dorsomedial cell column projected to the lateral half of the nodulus, including its lateral tip. These and previous findings are compared with respect to this mediolateral topography. Show more

Keywords: olivocerebellar projection, nodulus, inferior olivary nucleus, topography

DOI: 10.3233/VES-1995-5403

Citation: Journal of Vestibular Research, vol. 5, no. 4, pp. 265-276, 1995

Authors: Mesland, B.S. | Wertheim, A.H.

Article Type: Research Article

Abstract: The perception of ego-velocity (PEV) during sinusoidal linear acceleration (otolith stimulation) is investigated with a psychophysical method proposed by Wertheim (1990;1). This method is based on the threshold for object motion perception measured during ego-motion. In a first experiment, PEV was measured both with and without illumination of the experimental room. It was shown that, for the particular frequency and amplitude of ego-motion used, PEV in the light approached physical ego-velocity, whereas in darkness PEV was significantly smaller than physical ego-velocity. In a second experiment the PEV was measured again without illumination of the experimental room. It was found that …in response to a sinusoidal ego-velocity stimulus, PEV was sinusoidal as well with a gain of 0.8 and a phase-lead of 4° at 0.15 Hz. Show more

Keywords: ego-motion, object-motion, otoliths, Filehne-illusion

DOI: 10.3233/VES-1995-5404

Citation: Journal of Vestibular Research, vol. 5, no. 4, pp. 277-288, 1995

Authors: Kenyon, R.V. | Kerschmann, R. | Sgarioto, R. | Jun, S. | Vellinger, J.

Article Type: Research Article

Abstract: Sixty-four fertilized chicken eggs, half at developmental Day 2 and half at Day 9, were exposed to micro-gravity for 5 days aboard the shuttle. Postflight examination showed that none of the Day 2 flight embryos had survived, whereas the Day 9 flight group and both groups of synchronous ground control embryos appeared viable. One-half of the Day 9 flight and ground control embryos were dissected and the temporal bones preserved in acetone for morphological examination. The other half was allowed to hatch to examine vestibularly related behavioral changes. Morphology of the lagenar otoconia was evaluated by scanning electron microscopy. Behavioral …changes were accessed by a battery of reflex tests and recordings of spontaneous and vestibularly driven head movements. The results from both the morphological and behavioral studies showed no consistent difference between the flight and the control animals. Several hypotheses may account for this negative result. Because all the Day 2 embryos failed to survive, the remaining Day 9 chicks may have passed the critical developmental period of the chick’s vestibular system. Also, the reexposure of the developing chick embryo to earth’s 1-g environment may have masked any adverse behavioral effects that exposure to Microgravity may have caused. Show more

Keywords: spaceflight, head movements, vestibular morphology, electron-microscopy, chickens, motor behavior, Otoconia

DOI: 10.3233/VES-1995-5405

Citation: Journal of Vestibular Research, vol. 5, no. 4, pp. 289-298, 1995

Authors: Huebner, William P. | Paloski, William H. | Reschke, Millard F. | Bloomberg, Jacob J.

Article Type: Research Article

Abstract: Neglecting the eccentric position of the eyes in the head can lead to erroneous interpretation of ocular motor data, particularly for near targets. We discuss the geometric effects that eye eccentricity has on the processing of target-directed eye and head movement data, and we highlight two approaches to processing and interpreting such data. The first approach involves determining the true position of the target with respect to the location of the eyes in space for evaluating the efficacy of gaze, and it allows calculation of retinal error directly from measured eye, head, and target data. The second approach effectively eliminates …eye eccentricity effects by adjusting measured eye movement data to yield equivalent responses relative to a specified reference location (such as the center of head rotation). This latter technique can be used to standardize measured eye movement signals, enabling waveforms collected under different experimental conditions to be directly compared, both with the measured target signals and with each other. Mathematical relationships describing these approaches are presented for horizontal and vertical rotations, for both tangential and circumferential display screens, and efforts are made to describe the sensitivity of parameter variations on the calculated results. Show more

Keywords: geometric relationships, head geometry, eye eccentricity, gaze modification

DOI: 10.3233/VES-1995-5406

Citation: Journal of Vestibular Research, vol. 5, no. 4, pp. 299-322, 1995

Authors: Furman, Joseph M. | Durrant, John D.

Article Type: Research Article

Abstract: Head-only rotational testing has been suggested as a method of assessing the vestibuloocular reflex in patients with reduced vestibular function as a result of ototoxicity. The purpose of this study was to investigate the influence of vision and volition on horizontal vestibuloocular reflex responses during head-only rotation in normal subjects to better define the test parameters for future clinical application. Ten asymptomatic, healthy subjects were tested using various combinations of volitional and visual conditions during head-only rotation. Results indicated that visual fixation enhanced responses slightly and that response dynamics were altered somewhat by volition. These findings provide motivation for future …studies to further define head-only rotation test parameters for patients with suspected vestibular abnormalities. Show more

Keywords: vestibuloocular reflex, diagnostic testing, human

DOI: 10.3233/VES-1995-5407

Citation: Journal of Vestibular Research, vol. 5, no. 4, pp. 323-329, 1995