scholarly journals Beyond the vestibulo-ocular reflex: Vestibular input is processed centrally to achieve visual stability

2018 ◽  
Author(s):  
Edwin S. Dalmaijer
Keyword(s):  
Linear Models ◽  
Clinical Neurophysiology ◽  
Vestibular Stimulation ◽  
Exponential Model ◽  
Ocular Torsion ◽  
Visual Stability ◽  
Vestibular Input ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
The Relationship

AbstractThe current study presents a re-analysis of data from Zink et al. (1998, Electroencephalography and Clinical Neurophysiology, 107), who administered galvanic vestibular stimulation through unipolar direct current. They placed electrodes on each mastoid, and applied both right and left anodal stimulation. Ocular torsion and visual tilt were measured under different stimulation intensities. New modelling introduced here demonstrates that directly proportional linear models fit reasonably well to the relationship between vestibular input and visual tilt, but not to that between vestibular input and ocular torsion. Instead, an exponential model characterised by a decreasing slope and an asymptote fitted best. These results demonstrate that in the results presented by Zink et al., ocular torsion could not completely account for visual tilt. This suggests that vestibular input is processed centrally to stabilise vision when ocular torsion is insufficient. Potential mechanisms and seemingly conflicting literature are discussed.

scholarly journals Finding a Balance: A Systematic Review of the Biomechanical Effects of Vestibular Prostheses on Stability in Humans

2020 ◽  
Vol 5 (2) ◽  
pp. 23
Author(s):  
Felix Haxby ◽  
Mohammad Akrami ◽  
Reza Zamani
Keyword(s):  
Vestibular System ◽  
Postural Sway ◽  
Vestibular Function ◽  
Vestibular Stimulation ◽  
Significant Heterogeneity ◽  
Vestibular Loss ◽  
Ocular Reflex ◽  
Gait Characteristics ◽  
Vestibulo Ocular Reflex ◽  
Meta Analyses

The vestibular system is located in the inner ear and is responsible for maintaining balance in humans. Bilateral vestibular dysfunction (BVD) is a disorder that adversely affects vestibular function. This results in symptoms such as postural imbalance and vertigo, increasing the incidence of falls and worsening quality of life. Current therapeutic options are often ineffective, with a focus on symptom management. Artificial stimulation of the vestibular system, via a vestibular prosthesis, is a technique being explored to restore vestibular function. This review systematically searched for literature that reported the effect of artificial vestibular stimulation on human behaviours related to balance, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) technique. A total of 21 papers matched the inclusion criteria of the literature search conducted using the PubMed and Web of Science databases (February 2019). The populations for these studies included both healthy adults and patients with BVD. In every paper, artificial vestibular stimulation caused an improvement in certain behaviours related to balance, although the extent of the effect varied greatly. Various behaviours were measured such as the vestibulo-ocular reflex, postural sway and certain gait characteristics. Two classes of prosthesis were evaluated and both showed a significant improvement in at least one aspect of balance-related behaviour in every paper included. No adverse effects were reported for prostheses using noisy galvanic vestibular stimulation, however, prosthetic implantation sometimes caused hearing or vestibular loss. Significant heterogeneity in methodology, study population and disease aetiology were observed. The present study confirms the feasibility of vestibular implants in humans for restoring balance in controlled conditions, but more research needs to be conducted to determine their effects on balance in non-clinical settings.

scholarly journals Magnetic Resonance Imaging of Human Extraocular Muscles During Static Ocular Counter-Rolling

2005 ◽  
Vol 94 (5) ◽  
pp. 3292-3302 ◽  
Author(s):  
Joseph L. Demer ◽  
Robert A. Clark
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Three Dimensions ◽  
Eye Position ◽  
Ocular Torsion ◽  
Resonance Imaging ◽  
Central Target ◽  
Ocular Reflex ◽  
Adult Humans ◽  
Vestibulo Ocular Reflex

The rectus extraocular muscle (EOM) pulleys constrain EOM paths. During visual fixation with head immobile, actively controlled pulleys are known to maintain positions causing EOM pulling directions to change by one-half the change in eye position. This pulley behavior is consistent with Listing's law (LL) of ocular torsion as observed during fixation, saccades, and pursuit. However, pulley behavior during the vestibulo-ocular reflex (VOR) has been unstudied. This experiment studied ocular counter-rolling (OCR), a static torsional VOR that violates LL but can be evoked during MRI. Tri-planar MRI was performed in 10 adult humans during central target fixation while positioned in right and left side down positions known to evoke static OCR. EOM cross-sections and paths were determined from area centroids. Paths were used to locate pulleys in three dimensions. Significant ( P < 0.025) counter-rotational repositioning of the rectus pulley arrays of both orbits was observed in the coronal plane averaging 4.1° (maximum, 8.7°) from right to left side down positions for the inferior, medial, and superior rectus pulleys. There was a trend for the lateral rectus averaging 1.4°. Torsional shift of the rectus pulley array was associated with significant contractile cross-section changes in the superior and inferior oblique muscles. Torsional rectus pulley shift during OCR, which changes pulling directions of the rectus EOMs, correlates with known insertions of the oblique EOM orbital layers on rectus pulleys. The amount of pulley reconfiguration is roughly one-half of published values of ocular torsion during static OCR, an arrangement that would cause rectus pulling directions to change by less than one-half the amount of ocular torsion.

Relationship between Motion Sickness and Accuracy of Vestibulo-ocular Reflex

2020 ◽  
Vol 64 (1) ◽  
pp. 765-769
Author(s):  
Hikaru Sato ◽  
Yuki Sato ◽  
Takahiro Wada
Keyword(s):  
Mathematical Model ◽  
Motion Sickness ◽  
Head Movement ◽  
Visual Image ◽  
Simulation Experiments ◽  
Strong Negative Correlation ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
The Central Nervous System ◽  
The Relationship

The vestibulo-ocular reflex (VOR) is the reflexive eye movement occurring in the opposite direction of head movement to stabilize the visual image during head movement. We hypothesize that there exists a correlation between motion sickness and the accuracy of VOR because motion sickness and VOR are thought to be related to the head movement signals estimated in the central nervous system. The first purpose of the present research is to investigate the relationship between motion sickness and VOR accuracy using a mathematical model, which simultaneously describes motion sickness and VOR. The result of numerical simulation experiments shows a strong negative correlation between VOR accuracy and the severity of motion sickness. The second purpose is to investigate the relationship between motion sickness and VOR accuracy by experiments on humans. The result shows moderate negative correlations between the VOR accuracy and the severity of motion sickness among participants.

The relationship between cerebral T2 hyperintensity and fixation suppression of vestibulo-ocular reflex in elderly patients with dysequilibrium symptoms

2007 ◽  
Vol 34 (2) ◽  
pp. 165-171 ◽  
Author(s):  
Norihiko Murai ◽  
Naoharu Oda ◽  
Ikuko Hori ◽  
Masanobu Shabana ◽  
Youichi Kurozawa ◽  
...  
Keyword(s):  
Elderly Patients ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
T2 Hyperintensity ◽  
The Relationship

scholarly journals A Method for Studying the Effects of Neurochemicals on Long-Term Compensation in Unilaterally Labyrinthectomized Rats

1997 ◽  
Vol 6 (2) ◽  
pp. 105-113 ◽  
Author(s):  
Lars Andersson ◽  
Mats Ulfendahl ◽  
Richard Tham
Keyword(s):  
Experimental Model ◽  
Virtual Instrument ◽  
Vestibular Stimulation ◽  
Slow Phase ◽  
Intact Side ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Repeated Analysis ◽  
Adaptation Processes

A new method has been developed to study the influence of drugs and toxicants on longterm recovery of dynamics in the horizontal vestibulo-ocular reflex of the rat after hemilabyrinthectomy (HL). HL was performed by injecting sodium arsanilate into the middle ear. The lesion was confirmed by histology. Eye movements elicited by sinusoidal vestibular stimulation, in both light and darkness, were recorded by a search-coil technique and then analyzed by a computer program created with virtual instrument soft-ware, which calculated the gain of the slow-phase velocity (SPV) and the saccades para-meters (frequency, amplitude, and peak velocity) to the lesioned side and to the intact side separately. During the 2-10 week period after HL, repeated analysis of the spontaneous long-term recovery of such parameters revealed a slight but significant reduction of the post-HL asymmetry between SPV gain to the lesioned side and to the intact side. During the follow-up period, a post-HL increase of the phase lead remained unchanged. The reduced number of saccades/min was not completely restored. To test the usefulness of the experimental model for neurochemical investigation of such adaptation, we administered baclofen and toluene to rats 8–12 wk after hemilabyrinthectomy. Baclofen, a specificGABABagonist, immediately restored the symmetry of SPV gain. By contrast, toluene, which has some effects on the central vestibular system that are related toGABABtransmission, aggravated the asymmetry in both the SPV gain and the number of saccades. We suggest that the experimental model would be useful for studying neurochemical mechanisms in vestibular adaptation processes.

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