Dynamic Effects on the Subjective Visual Vertical After Roll Rotation

We investigated in normal human subjects how semicircular canal and otolith signals interact in the estimation of the subjective visual vertical after constant velocity or constant acceleration roll tilt. In the constant velocity paradigm, subjects were rotated in darkness at ±60°/s for five complete cycles before being stopped in one of seven orientations ranging from 0 to ±90° (right/left ear down). In the constant acceleration paradigm, subjects were rotated with an acceleration of +30 or −30°/s2 to the same seven end positions between −90 and +90°, by way of passing once through the upside-down position. The subjective visual vertical was assessed by measuring the setting of a luminous line that appeared at different test delays after stop rotation in otherwise complete darkness. The data suggest that gravitational jerk signals generated by otolith–semicircular canal interactions and/or carried by phasic otolith signals are responsible for the observed transient bias in the estimation of the subjective visual vertical. This transient bias depended on both rotation and tilt direction after constant velocity rotations, but was almost abolished following constant acceleration rotations.

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

Journal of Neurophysiology ◽

10.1152/jn.00704.2007 ◽

2008 ◽

Vol 99 (5) ◽

pp. 2264-2280 ◽

Cited By ~ 23

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.

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Gravity dependence of the effect of optokinetic stimulation on the subjective visual vertical

Journal of Neurophysiology ◽

10.1152/jn.00303.2016 ◽

2017 ◽

Vol 117 (5) ◽

pp. 1948-1958 ◽

Cited By ~ 11

Author(s):

Bryan K. Ward ◽

Christopher J. Bockisch ◽

Nicoletta Caramia ◽

Giovanni Bertolini ◽

Alexander Andrea Tarnutzer

Keyword(s):

Bayesian Theory ◽

Roll Angle ◽

Whole Body ◽

Optokinetic Stimulation ◽

Subjective Visual Vertical ◽

Vestibular Input ◽

Stimulus Velocity ◽

Visual Vertical ◽

Observer Model ◽

Roll Tilt

Accurate and precise estimates of direction of gravity are essential for spatial orientation. According to Bayesian theory, multisensory vestibular, visual, and proprioceptive input is centrally integrated in a weighted fashion based on the reliability of the component sensory signals. For otolithic input, a decreasing signal-to-noise ratio was demonstrated with increasing roll angle. We hypothesized that the weights of vestibular (otolithic) and extravestibular (visual/proprioceptive) sensors are roll-angle dependent and predicted an increased weight of extravestibular cues with increasing roll angle, potentially following the Bayesian hypothesis. To probe this concept, the subjective visual vertical (SVV) was assessed in different roll positions (≤ ± 120°, steps = 30°, n = 10) with/without presenting an optokinetic stimulus (velocity = ± 60°/s). The optokinetic stimulus biased the SVV toward the direction of stimulus rotation for roll angles ≥ ± 30° ( P < 0.005). Offsets grew from 3.9 ± 1.8° (upright) to 22.1 ± 11.8° (±120° roll tilt, P < 0.001). Trial-to-trial variability increased with roll angle, demonstrating a nonsignificant increase when providing optokinetic stimulation. Variability and optokinetic bias were correlated ( R2 = 0.71, slope = 0.71, 95% confidence interval = 0.57–0.86). An optimal-observer model combining an optokinetic bias with vestibular input reproduced measured errors closely. These findings support the hypothesis of a weighted multisensory integration when estimating direction of gravity with optokinetic stimulation. Visual input was weighted more when vestibular input became less reliable, i.e., at larger roll-tilt angles. However, according to Bayesian theory, the variability of combined cues is always lower than the variability of each source cue. If the observed increase in variability, although nonsignificant, is true, either it must depend on an additional source of variability, added after SVV computation, or it would conflict with the Bayesian hypothesis. NEW & NOTEWORTHY Applying a rotating optokinetic stimulus while recording the subjective visual vertical in different whole body roll angles, we noted the optokinetic-induced bias to correlate with the roll angle. These findings allow the hypothesis that the established optimal weighting of single-sensory cues depending on their reliability to estimate direction of gravity could be extended to a bias caused by visual self-motion stimuli.

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Interpretation of a Discontinuity in the Sense of Verticality at Large Body Tilt

Journal of Neurophysiology ◽

10.1152/jn.00804.2003 ◽

2004 ◽

Vol 91 (5) ◽

pp. 2205-2214 ◽

Cited By ~ 61

Author(s):

Ronald G. Kaptein ◽

Jan A. M. Van Gisbergen

Keyword(s):

Spatial Orientation ◽

Human Subjects ◽

Large Body ◽

Body Tilt ◽

Head Orientation ◽

Subjective Visual Vertical ◽

Egocentric Bias ◽

Visual Vertical ◽

Series Of Experiments ◽

Tilt Signal

Results of earlier spatial-orientation studies focusing on the sense of verticality have emphasized an intriguing paradox. Despite evidence that nearly veridical signals for gravicentric head orientation and egocentric visual stimulus orientation are available, roll-tilted subjects err in the direction of the long body axis when adjusting a visual line to vertical in darkness (Aubert effect). This has led to the suggestion that a central egocentric bias signal with fixed strength and direction acts to pull the perceived vertical to the subjects' zenith (M-model). In the present study, the subjective visual vertical (SVV) was tested in six human subjects, across the entire 360° range. For comparison, body-tilt estimates from four subjects where collected in a separate series of experiments. For absolute tilts up to ∼135°, SVV responses showed a gradually increasing Aubert effect that could not be attributed to errors in perceived body tilt but was nicely in line with the M-model. At larger absolute tilts, SVV errors abruptly reversed sign, now showing a pattern concordant with errors in body-tilt estimates but incompatible with the M-model. These results suggest that, in the normal working range, the perception of external space and the perception of body posture are based on different processing of body-tilt signals. Beyond this range, both spatial-orientation tasks seem to rely mainly on a common tilt signal.

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

Otology & Neurotology ◽

10.1097/mao.0000000000003340 ◽

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

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Static roll-tilt over 5 minutes locally distorts the internal estimate of direction of gravity

Journal of Neurophysiology ◽

10.1152/jn.00540.2014 ◽

2014 ◽

Vol 112 (11) ◽

pp. 2672-2679 ◽

Cited By ~ 6

Author(s):

A. A. Tarnutzer ◽

C. J. Bockisch ◽

D. Straumann ◽

S. Marti ◽

G. Bertolini

Keyword(s):

Human Subjects ◽

Healthy Human ◽

Healthy Human Subjects ◽

Short Term Adaptation ◽

Body Roll ◽

Visual Vertical ◽

Head Roll ◽

Global Bias ◽

Mixture Of Gaussian ◽

Roll Tilt

The subjective visual vertical (SVV) indicates perceived direction of gravity. Even in healthy human subjects, roll angle-dependent misestimations, roll overcompensation (A-effect, head-roll > 60° and <135°) and undercompensation (E-effect, head-roll < 60°), occur. Previously, we demonstrated that, after prolonged roll-tilt, SVV estimates when upright are biased toward the preceding roll position, which indicates that perceived vertical (PV) is shifted by the prior tilt (Tarnutzer AA, Bertolini G, Bockisch CJ, Straumann D, Marti S. PLoS One 8: e78079, 2013). Hypothetically, PV in any roll position could be biased toward the previous roll position. We asked whether such a “global” bias occurs or whether the bias is “local”. The SVV of healthy human subjects ( N = 9) was measured in nine roll positions (−120° to +120°, steps = 30°) after 5 min of roll-tilt in one of two adaptation positions (±90°) and compared with control trials without adaptation. After adapting, adjustments were shifted significantly ( P < 0.05) toward the previous adaptation position for nearby roll-tilted positions (±30°, ±60°) and upright only. We computationally simulated errors based on the sum of a monotonically increasing function (producing roll undercompensation) and a mixture of Gaussian functions (representing roll overcompensation centered around PV). In combination, the pattern of A- and E-effects could be generated. By shifting the function representing local overcompensation toward the adaptation position, the experimental postadaptation data could be fitted successfully. We conclude that prolonged roll-tilt locally distorts PV rather than globally shifting it. Short-term adaptation of roll overcompensation may explain these shifts and could reflect the brain's strategy to optimize SVV estimates around recent roll positions. Thus postural stability can be improved by visually-mediated compensatory responses at any sustained body-roll orientation.

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