scholarly journals Gravity Dependence of Subjective Visual Vertical Variability

2009 ◽  
Vol 102 (3) ◽  
pp. 1657-1671 ◽  
Author(s):  
A. A. Tarnutzer ◽  
C. Bockisch ◽  
D. Straumann ◽  
I. Olasagasti
Keyword(s):  
Inertial Force ◽  
Semicircular Canals ◽  
The Body ◽  
Otolith Organs ◽  
Subjective Visual Vertical ◽  
Visual Vertical ◽  
Head Roll ◽  
Static Head ◽  
Experimental Findings ◽  
Vertical Variability

The brain integrates sensory input from the otolith organs, the semicircular canals, and the somatosensory and visual systems to determine self-orientation relative to gravity. Only the otoliths directly sense the gravito-inertial force vector and therefore provide the major input for perceiving static head-roll relative to gravity, as measured by the subjective visual vertical (SVV). Intraindividual SVV variability increases with head roll, which suggests that the effectiveness of the otolith signal is roll-angle dependent. We asked whether SVV variability reflects the spatial distribution of the otolithic sensors and the otolith-derived acceleration estimate. Subjects were placed in different roll orientations (0–360°, 15° steps) and asked to align an arrow with perceived vertical. Variability was minimal in upright, increased with head-roll peaking around 120–135°, and decreased to intermediate values at 180°. Otolith-dependent variability was modeled by taking into consideration the nonuniform distribution of the otolith afferents and their nonlinear firing rate. The otolith-derived estimate was combined with an internal bias shifting the estimated gravity-vector toward the body-longitudinal. Assuming an efficient otolith estimator at all roll angles, peak variability of the model matched our data; however, modeled variability in upside-down and upright positions was very similar, which is at odds with our findings. By decreasing the effectiveness of the otolith estimator with increasing roll, simulated variability matched our experimental findings better. We suggest that modulations of SVV precision in the roll plane are related to the properties of the otolith sensors and to central computational mechanisms that are not optimally tuned for roll-angles distant from upright.

Body-Tilt and Visual Verticality Perception During Multiple Cycles of Roll Rotation

2008 ◽  
Vol 99 (5) ◽  
pp. 2264-2280 ◽  
Author(s):  
R.A.A. Vingerhoets ◽  
W. P. Medendorp ◽  
J.A.M. Van Gisbergen
Keyword(s):  
Constant Velocity ◽  
Interaction Model ◽  
The Body ◽  
Body Tilt ◽  
Subjective Visual Vertical ◽  
Egocentric Bias ◽  
Leaky Integrator ◽  
Visual Vertical ◽  
Multiple Cycles ◽  
Roll Tilt

To assess the effects of degrading canal cues for dynamic spatial orientation in human observers, we tested how judgments about visual-line orientation in space (subjective visual vertical task, SVV) and estimates of instantaneous body tilt (subjective body-tilt task, SBT) develop in the course of three cycles of constant-velocity roll rotation. These abilities were tested across the entire tilt range in separate experiments. For comparison, we also obtained SVV data during static roll tilt. We found that as tilt increased, dynamic SVV responses became strongly biased toward the head pole of the body axis (A-effect), as if body tilt was underestimated. However, on entering the range of near-inverse tilts, SVV responses adopted a bimodal pattern, alternating between A-effects (biased toward head-pole) and E-effects (biased toward feet-pole). Apart from an onset effect, this tilt-dependent pattern of systematic SVV errors repeated itself in subsequent rotation cycles with little sign of worsening performance. Static SVV responses were qualitatively similar and consistent with previous reports but showed smaller A-effects. By contrast, dynamic SBT errors were small and unimodal, indicating that errors in visual-verticality estimates were not caused by errors in body-tilt estimation. We discuss these results in terms of predictions from a canal-otolith interaction model extended with a leaky integrator and an egocentric bias mechanism. We conclude that the egocentric-bias mechanism becomes more manifest during constant velocity roll-rotation and that perceptual errors due to incorrect disambiguation of the otolith signal are small despite the decay of canal signals.

Counterrolling of the eyes and its dependence on the magnitude of gravitational or inertial force acting laterally on the body

1959 ◽  
Vol 14 (4) ◽  
pp. 632-634 ◽  
Author(s):  
Richard C. Woellner ◽  
Ashton Graybiel
Keyword(s):  
Incident Angle ◽  
Inertial Force ◽  
Current Theory ◽  
The Body ◽  
Otolith Organs ◽  
Straight Line ◽  
Independent Variable ◽  
The Subject ◽  
Acting Force ◽  
Healthy Persons

Counterrolling of the eyes was measured in five healthy persons when inclined on a tilt-chair and when exposed to a change in direction of force on a human centrifuge. For equivalent changes in direction of force incident to the subject, the magnitude of the force was greater on the centrifuge. When the amount of roll was plotted as a function of the incident angle of force, divergent curves were obtained for tilt-chair and centrifuge data. When the amount of roll was plotted as a function of magnitude of laterally-acting force as the independent variable, a single curve resulted indicating a straight line relation within the range of 1 g. These findings not only constitute definitive proof that the counterrolling reflex can be released by gravitational (and inertial) force but also are consistent with the current theory of the functioning of the otolith organs. Submitted on January 20, 1959

Sympathetic nerve activity during natural stimulation of horizontal semicircular canals in humans

1998 ◽  
Vol 275 (4) ◽  
pp. R1274-R1278 ◽  
Author(s):  
Chester A. Ray ◽  
Keith M. Hume ◽  
Samuel L. Steele
Keyword(s):  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Semicircular Canals ◽  
Head Rotation ◽  
Otolith Organs ◽  
Nerve Activity ◽  
Natural Stimulation ◽  
Vascular Beds ◽  
Static Head ◽  
Stimulation Of

We have shown that static head-down neck flexion elicits increases in muscle (MSNA) but not skin sympathetic nerve activity (SSNA) in humans. These findings suggest that stimulation of the otolith organs causes differential sympathetic outflow to vascular beds. The purpose of the present study was to determine whether yaw head rotation (YHR), which stimulates the horizontal semicircular canals, elicits sympathetic nerve responses. To test this question, we recorded MSNA ( n = 33) and SSNA ( n = 25) before and during 3 min of sinusoidal YHR performed at 0.1, 0.6, and 1.0 Hz. At all frequencies, YHR elicited no significant changes in heart rate and mean arterial pressure. Likewise, YHR did not significantly change either MSNA or SSNA at all frequencies. Our results indicate that stimulation of the horizontal semicircular canals by YHR does not alter SNA to either muscle or skin. Moreover, these results provide evidence to support the concept that the otolith organs but not the horizontal semicircular canals participate in the regulation of SNA in humans.

Neural Processing of Gravito-Inertial Cues in Humans. I. Influence of the Semicircular Canals Following Post-Rotatory Tilt

2000 ◽  
Vol 84 (4) ◽  
pp. 2001-2015 ◽  
Author(s):  
L. H. Zupan ◽  
R. J. Peterka ◽  
D. M. Merfeld
Keyword(s):  
Eye Movements ◽  
Information Integration ◽  
Constant Velocity ◽  
Gravitational Force ◽  
Inertial Force ◽  
Semicircular Canals ◽  
Linear Acceleration ◽  
Head Orientation ◽  
Otolith Organs ◽  
Sensory Cues

Sensory systems often provide ambiguous information. Integration of various sensory cues is required for the CNS to resolve sensory ambiguity and elicit appropriate responses. The vestibular system includes two types of sensors: the semicircular canals, which measure head rotation, and the otolith organs, which measure gravito-inertial force (GIF), the sum of gravitational force and inertial force due to linear acceleration. According to Einstein's equivalence principle, gravitational force is indistinguishable from inertial force due to linear acceleration. As a consequence, otolith measurements must be supplemented with other sensory information for the CNS to distinguish tilt from translation. The GIF resolution hypothesis states that the CNS estimates gravity and linear acceleration, so that the difference between estimates of gravity and linear acceleration matches the measured GIF. Both otolith and semicircular canal cues influence this estimation of gravity and linear acceleration. The GIF resolution hypothesis predicts that inaccurate estimates of both gravity and linear acceleration can occur due to central interactions of sensory cues. The existence of specific patterns of vestibuloocular reflexes (VOR) related to these inaccurate estimates can be used to test the GIF resolution hypothesis. To investigate this hypothesis, we measured eye movements during two different protocols. In one experiment, eight subjects were rotated at a constant velocity about an earth-vertical axis and then tilted 90° in darkness to one of eight different evenly spaced final orientations, a so-called “dumping” protocol. Three speeds (200, 100, and 50°/s) and two directions, clockwise (CW) and counterclockwise (CCW), of rotation were tested. In another experiment, four subjects were rotated at a constant velocity (200°/s, CW and CCW) about an earth-horizontal axis and stopped in two different final orientations (nose-up and nose-down), a so-called “barbecue” protocol. The GIF resolution hypothesis predicts that post-rotatory horizontal VOR eye movements for both protocols should include an “induced” VOR component, compensatory to an interaural estimate of linear acceleration, even though no true interaural linear acceleration is present. The GIF resolution hypothesis accurately predicted VOR and induced VOR dependence on rotation direction, rotation speed, and head orientation. Alternative hypotheses stating that frequency segregation may discriminate tilt from translation or that the post-rotatory VOR time constant is dependent on head orientation with respect to the GIF direction did not predict the observed VOR for either experimental protocol.

scholarly journals Head Roll-Tilt Subjective Visual Vertical Test in the Diagnosis of Persistent Postural-Perceptual Dizziness

2021 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Chihiro Yagi ◽  
Yuka Morita ◽  
Meiko Kitazawa ◽  
Yoriko Nonomura ◽  
Tatsuya Yamagishi ◽  
...  
Keyword(s):  
Subjective Visual Vertical ◽  
Visual Vertical ◽  
Head Roll ◽  
Vertical Test ◽  
Roll Tilt

scholarly journals Time course of the subjective visual vertical during sustained optokinetic and galvanic vestibular stimulation

2019 ◽  
Vol 122 (2) ◽  
pp. 788-796
Author(s):  
Nynke Niehof ◽  
Florian Perdreau ◽  
Mathieu Koppen ◽  
W. Pieter Medendorp
Keyword(s):  
Time Course ◽  
Head Tilt ◽  
Inertial Force ◽  
Vestibular Stimulation ◽  
Galvanic Vestibular Stimulation ◽  
Constant Current ◽  
Subjective Visual Vertical ◽  
Time Constants ◽  
Visual Vertical ◽  
Over Time

The brain is thought to use rotation cues from both the vestibular and optokinetic system to disambiguate the gravito-inertial force, as measured by the otoliths, into components of linear acceleration and gravity direction relative to the head. Hence, when the head is stationary and upright, an erroneous percept of tilt arises during optokinetic roll stimulation (OKS) or when an artificial canal-like signal is delivered by means of galvanic vestibular stimulation (GVS). It is still unknown how this percept is affected by the combined presence of both cues or how it develops over time. Here, we measured the time course of the subjective visual vertical (SVV), as a proxy of perceived head tilt, in human participants ( n = 16) exposed to constant-current GVS (1 and 2 mA, cathodal and anodal) and constant-velocity OKS (30°/s clockwise and counterclockwise) or their combination. In each trial, participants continuously adjusted the orientation of a visual line, which drifted randomly, to Earth vertical. We found that both GVS and OKS evoke an exponential time course of the SVV. These time courses have different amplitudes and different time constants, 4 and 7 s respectively, and combine linearly when the two stimulations are presented together. We discuss these results in the framework of observer theory and Bayesian state estimation. NEW & NOTEWORTHY While it is known that both roll optokinetic stimuli and galvanic vestibular stimulation affect the percept of vertical, how their effects combine and develop over time is still unclear. Here we show that both effects combined linearly but are characterized by different time constants, which we discuss from a probabilistic perspective.

scholarly journals Subjective Visual Vertical during Caloric Stimulation in Healthy Subjects: Implications to Research and Neurorehabilitation

2015 ◽  
Vol 2015 ◽  
pp. 1-4 ◽  
Author(s):  
Martha Funabashi ◽  
Aline I. Flores ◽  
Amanda Vicentino ◽  
Camila G. C. Barros ◽  
Octavio M. Pontes-Neto ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Cognitive Strategies ◽  
Semicircular Canals ◽  
Subjective Visual Vertical ◽  
Caloric Stimulation ◽  
Neurologic Disorders ◽  
Significant Difference ◽  
Sensitive Tool ◽  
Visual Vertical ◽  
The Mean

Background. The subjective visual vertical (SVV) is a perception often impaired in patients with neurologic disorders and is considered a sensitive tool to detect otolithic dysfunctions. However, it remains unclear whether the semicircular canals (SCCs) are also involved in the visual vertical perception.Objective. The aim of this study was to analyze the influence of horizontal SCCs on SVV by caloric stimulation in healthy subjects.Methods. SVV was performed before and during the ice-cold caloric stimulation (4°C, right ear) in 30 healthy subjects.Results. The mean SVV tilts before and during the caloric stimulation were 0.31° ± 0.39 and −0.28° ± 0.40, respectively. There was no significant difference between the mean SVV tilts before and during stimulationp=0.113.Conclusion. These results suggest that horizontal SCCs do not influence SVV. Therefore, investigations and rehabilitation approaches for SVV misperceptions should be focused on otolithic and cognitive strategies.

scholarly journals Head roll dependent variability of subjective visual vertical and ocular counterroll

2009 ◽  
Vol 195 (4) ◽  
pp. 621-626 ◽  
Author(s):  
Alexander A. Tarnutzer ◽  
Christopher J. Bockisch ◽  
Dominik Straumann
Keyword(s):  
Subjective Visual Vertical ◽  
Ocular Counterroll ◽  
Visual Vertical ◽  
Head Roll

scholarly journals The neural basis of motion sickness

2019 ◽  
Vol 121 (3) ◽  
pp. 973-982 ◽  
Author(s):  
Bernard Cohen ◽  
Mingjia Dai ◽  
Sergei B. Yakushin ◽  
Catherine Cho
Keyword(s):  
Motion Sickness ◽  
Semicircular Canals ◽  
Signs And Symptoms ◽  
Vestibular Nuclei ◽  
The Body ◽  
Velocity Storage ◽  
Otolith Organs ◽  
Neural Basis ◽  
Sense Orientation ◽  
Roll Tilt

Although motion of the head and body has been suspected or known as the provocative cause for the production of motion sickness for centuries, it is only within the last 20 yr that the source of the signal generating motion sickness and its neural basis has been firmly established. Here, we briefly review the source of the conflicts that cause the body to generate the autonomic signs and symptoms that constitute motion sickness and provide a summary of the experimental data that have led to an understanding of how motion sickness is generated and can be controlled. Activity and structures that produce motion sickness include vestibular input through the semicircular canals, the otolith organs, and the velocity storage integrator in the vestibular nuclei. Velocity storage is produced through activity of vestibular-only (VO) neurons under control of neural structures in the nodulus of the vestibulo-cerebellum. Separate groups of nodular neurons sense orientation to gravity, roll/tilt, and translation, which provide strong inhibitory control of the VO neurons. Additionally, there are acetylcholinergic projections from the nodulus to the stomach, which along with other serotonergic inputs from the vestibular nuclei, could induce nausea and vomiting. Major inhibition is produced by the GABAB receptors, which modulate and suppress activity in the velocity storage integrator. Ingestion of the GABAB agonist baclofen causes suppression of motion sickness. Hopefully, a better understanding of the source of sensory conflict will lead to better ways to avoid and treat the autonomic signs and symptoms that constitute the syndrome.

Chronic unilateral loss of otolith function revealed by the subjective visual vertical during off center yaw rotation

1999 ◽  
Vol 9 (6) ◽  
pp. 413-422
Author(s):  
Andreas Böhmer ◽  
Fred Mast
Keyword(s):  
Rotation Axis ◽  
Inertial Force ◽  
Normal Subjects ◽  
Clinical Test ◽  
Subjective Visual Vertical ◽  
Eccentric Rotation ◽  
Midsagittal Plane ◽  
Vestibular Loss ◽  
Visual Vertical ◽  
Set Up

Assessing the subjective visual vertical, SVV, in a static upright position is an easy clinical test in which a deviation of some 10 ∘ from true vertical indicates an acute loss of unilateral (otolithic) vestibular function on the side to which the SVV is tilted. Because this deviation of the SVV is compensated during the following months, patients with chronic unilateral vestibular loss do no longer differ from normal subjects. This study presents an experimental set-up that allows for clear detection of compensated chronic loss of unilateral otolithic function by testing the SVV. 21 normals and 17 unilaterally vestibular deafferentiated (UVD) patients (vestibular neurectomies) were first rotated on a human centrifuge about an earth vertical yaw axis through the midsagittal plane of the head ( 240 ∘ /s). This induced tilts of the gravito-inertial force (GIF) vectors, which differed at the two inner ears by 8 ∘ . During constant velocity rotation, the subjects were moved in pseudo-randomized steps laterally up to 16 cm apart from the rotation axis, inducing roll tilts of the GIF vectors up to 16 ∘ . Normal subjects set their SVV to pre-centrifugation values at positions with the midsagittal plane of their head close to the rotation axis, while chronic UVD patients indicated pre-centrifugation values during positions with the rotation axis 5.9 ± 2.5 cm paramedian on the side of the intact ear. Tilts of the GIF vectors shifted the SVV with a gain of 0.70 in normals and only 0.32 in UVD patients. Roll gains for laterally directed GIF vectors relative to the intact inner ear did not differ from medially directed roll gains in the UVD patients. The roll gains observed in this experimental set-up were lower than those observed with static body tilts or during eccentric rotation with a larger radius, which might be at least partially due to conflicting stimulation between otolithic and extra-vestibular cues.

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