Vision and vestibular adaptation

1998 ◽  
Vol 119 (1) ◽  
pp. 78-88 ◽  
Author(s):  
Joseph L. Demer ◽  
Benjamin T. Crane
Keyword(s):  
Visual Tracking ◽  
Head Movements ◽  
Whole Body ◽  
Elderly Subjects ◽  
Normal Vision ◽  
Gaze Stabilization ◽  
Linear Interaction ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Visible Target

This article summarizes six recent degree-of-freedom studies of visual-vestibular interaction during natural activities and relates the findings to canalotolith interactions evaluated during eccentric axis rotations. Magnetic search coils were used to measure angular eye and head movements of young and elderly subjects. A flux gate magnetometer was used to measure three-dimensional head translation. Three activities were studied: standing quietly, walking in place, and running in place. Each activity was evaluated with three viewing conditions: a visible target viewed normally, a remembered target in darkness, and a visible target viewed with x2 binocular telescopic spectacles. Canal-otolith interaction was assessed with passive, whole-body, transient, and steady-state rotations in pitch and yaw at multiple frequencies about axes that were either oculocentric or eccentric to the eyes. For each rotational axis, subjects regarded visible and remembered targets located at various distances. Horizontal and vertical angular vestibulo-ocular reflexes were demonstrable in all subjects during standing, walking, and running. When only angular gains were considered, gains in both darkness and during normal vision were less than 1.0 and were generally lower in elderly than in young subjects. Magnified vision with x2 telescopic spectacles produced only small gain increases as compared with normal vision. During walking and running all subjects exhibited significant mediolateral and dorsoventral head translations that were antiphase locked to yaw and pitch head movements, respectively. These head translations and rotations have mutually compensating effects on gaze in a target plane for typical viewing distances and allow angular vestibulo-ocular reflex gains of less than 1.0 to be optimal for gaze stabilization during natural activities. During passive, whole-body eccentric pitch and yaw head rotations, vestibulo-ocular reflex gain was modulated as appropriate to stabilize gaze on targets at the distances used. This modulation was evident within the first 80 msec of onset of head movement, too early to be caused by immediate visual tracking. Modeling suggests a linear interaction between canal signals and otolith signals scaled by the inverse of target distance. Vestibulo-ocular reflex performance appears to be adapted to stabilize gaze during translational and rotational perturbations that occur during natural activities, as is appropriate for relevant target distances. Although immediate visual tracking contributes little to gaze stabilization during natural activities, visual requirements determine the performance of vestibulo-ocular reflexes arising from both canals and otoliths. (Otolaryngol Head Neck Surg 1998;119:78-88.)

Viewing Target Distance Influences the Vestibulo-Ocular Reflex Gain when Assessed Using the Video Head Impulse Test

2018 ◽  
Vol 23 (5) ◽  
pp. 285-289 ◽  
Author(s):  
Patricia Castro ◽  
Sara Sena Esteves ◽  
Florencia Lerchundi ◽  
David Buckwell ◽  
Michael A. Gresty ◽  
...  
Keyword(s):  
Head Movements ◽  
Target Distance ◽  
Head Impulse Test ◽  
Video Head Impulse Test ◽  
Gaze Stabilization ◽  
Head Impulse ◽  
Ocular Reflex ◽  
Significant Difference ◽  
Vestibulo Ocular Reflex ◽  
Reflex Gain

Gaze stabilization during head movements is provided by the vestibulo-ocular reflex (VOR). Clinical assessment of this reflex is performed using the video Head Impulse Test (vHIT). To date, the influence of different fixation distances on VOR gain using the vHIT has not been explored. We assessed the effect of target proximity on the horizontal VOR using the vHIT. Firstly, we assessed the VOR gain in 18 healthy subjects with 5 viewing target distances (150, 40, 30, 20, and 10 cm). The gain increased significantly as the viewing target distance decreased. A second experiment on 10 subjects was performed in darkness whilst the subjects were imagining targets at different distances. There were significant inverse relationships between gain and distance for both the real and the imaginary targets. There was a statistically significant difference between light and dark gains for the 20- and 40-cm distances, but not for the 150-cm distance. Theoretical VOR gains for different target distances were calculated and compared with those found in light and darkness. The increase in gain observed for near targets was lower than predicted by geometrical calculations, implying a physiological ceiling effect on the VOR. The VOR gain in the dark, as assessed with the vHIT, demonstrates an enhancement associated with a reduced target distance.

Predictive Mechanisms of Head-Eye Coordination and Vestibulo-Ocular Reflex Suppression in Humans

1992 ◽  
Vol 2 (3) ◽  
pp. 193-212 ◽  
Author(s):  
G.R. Barnes ◽  
M.A. Grealy
Keyword(s):  
Peak Velocity ◽  
Human Subjects ◽  
Head Movements ◽  
Whole Body ◽  
Head Velocity ◽  
The Gaze ◽  
Ocular Reflex ◽  
Sinusoidal Motion ◽  
Smooth Component ◽  
Vestibulo Ocular Reflex

Head and eye movements of human subjects have been recorded during head-free pursuit in the horizontal plane of a target executing sinusoidal motion at a frequency of 0.26 to 0.78 Hz and a peak velocity of ±96∘/s. The target was not presented continuously but was exposed for brief durations of 120 to 320 ms as it passed through the centre of the visual field at peak velocity. This technique allowed the timing of each response to be assessed in relation to the onset of target appearance. During the first 3 to 4 target presentations, there was a progressive buildup of both head velocity and the smooth component of gaze velocity, while, simultaneously, the responses became more phase-advanced with respect to target onset. In the steady state, similar temporal response trajectories were observed for head and gaze velocity, which were initiated approximately 500 ms prior to target on-set, rose to a peak that increased with the duration of target exposure, and then decayed with a time constant of 0.5 to 1 s. Whenever the target failed to appear as expected, the gaze and head velocity trajectories continued to be made, indicating that predictive suppression of the vestibulo-ocular reflex (VOR) was taking place in darkness. In a further experiment, subjects attempted to suppress the VOR during whole body oscillation at 0.2 or 0.4 Hz on a turntable by fixating, a head-fixed target that appeared for 10 to 160 ms at the time of peak head velocity. Again, VOR suppression was initiated prior to target appearance in the same manner as for natural head movements, and when the target suddenly disappeared but rotation continued, predictive VOR suppression was observed in darkness. The similarity of these predictive effects to those obtained previously for head-fixed pursuit provides further support for the hypothesis that both pursuit and visual suppression of the VOR are controlled primarily by identical visual feedback mechanisms.

Adaptation of the vestibulo-ocular reflex, subjective tilt, and motion sickness to head movements during short-radius centrifugation

2003 ◽  
Vol 13 (2-3) ◽  
pp. 65-77
Author(s):  
Laurence R. Young ◽  
Kathleen H. Sienko ◽  
Lisette E. Lyne ◽  
Heiko Hecht ◽  
Alan Natapoff
Keyword(s):  
Motion Sickness ◽  
Body Position ◽  
Rest Period ◽  
Vertical Axis ◽  
Head Movements ◽  
Whole Body ◽  
Slow Phase ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Angular Velocities

Head movements made while the whole body is rotating at unusually high angular velocities (here with supine body position about an earth-vertical axis) result in inappropriate eye movements, sensory illusions, disorientation, and frequently motion sickness. We investigated the acquisition and retention of sensory adaptation to cross-coupled components of the vestibulo-ocular reflex (VOR) by asking eight subjects to make headturns while being rotated at 23 rpm on two consecutive days, and again a week later. The dependent measures were inappropriate vertical VOR, subjective tilt, and motion sickness in response to 90° yaw out-of-plane head movements. Motion sickness was evaluated during and following exposure to rotation. Significant adaptation effects were found for the slow phase velocity of vertical nystagmus, the reported magnitude of the subjective tilt experienced during head turns, and motion-sickness scores. Retention of adaptation over a six-day rest period without rotation occurred, but was not complete for all measures. Adaptation of VOR was fully maintained while subjective tilt was only partially maintained and motion-sickness scores continued to decrease. Practical implications of these findings are discussed with particular emphasis on artificial gravity, which could be produced in weightlessness by means of a short-radius (2 m) rotator.

scholarly journals Galvanic stimulation of the vestibular periphery in guinea pigs during passive whole body rotation and self-generated head movement

2012 ◽  
Vol 107 (8) ◽  
pp. 2260-2270 ◽  
Author(s):  
N. Shanidze ◽  
K. Lim ◽  
J. Dye ◽  
W. M. King
Keyword(s):  
Guinea Pigs ◽  
Head Movements ◽  
Whole Body ◽  
Body Rotation ◽  
Galvanic Stimulation ◽  
Ocular Reflex ◽  
Anticipatory Eye Movements ◽  
Vestibulo Ocular Reflex ◽  
Vestibulospinal Neurons ◽  
Stimulation Of

Irregular vestibular afferents exhibit significant phase leads with respect to angular velocity of the head in space. This characteristic and their connectivity with vestibulospinal neurons suggest a functionally important role for these afferents in producing the vestibulo-collic reflex (VCR). A goal of these experiments was to test this hypothesis with the use of weak galvanic stimulation of the vestibular periphery (GVS) to selectively activate or suppress irregular afferents during passive whole body rotation of guinea pigs that could freely move their heads. Both inhibitory and excitatory GVS had significant effects on compensatory head movements during sinusoidal and transient whole body rotations. Unexpectedly, GVS also strongly affected the vestibulo-ocular reflex (VOR) during passive whole body rotation. The effect of GVS on the VOR was comparable in light and darkness and whether the head was restrained or unrestrained. Significantly, there was no effect of GVS on compensatory eye and head movements during volitional head motion, a confirmation of our previous study that demonstrated the extravestibular nature of anticipatory eye movements that compensate for voluntary head movements.

Human Horizontal Vestibulo-Ocular Reflex Initiation: Effects of Acceleration, Target Distance, and Unilateral Deafferentation

1998 ◽  
Vol 80 (3) ◽  
pp. 1151-1166 ◽  
Author(s):  
Benjamin T. Crane ◽  
Joseph L. Demer
Keyword(s):  
Semicircular Canals ◽  
Linear Acceleration ◽  
Head Rotation ◽  
Target Distance ◽  
Whole Body ◽  
Viewing Distance ◽  
Gaze Stabilization ◽  
Ocular Reflex ◽  
Acceleration Period ◽  
Vestibulo Ocular Reflex

Crane, Benjamin T. and Joseph L. Demer. Human horizontal vestibulo-ocular reflex initiation: effects of acceleration, target distance, and unilateral deafferentation. J. Neurophysiol. 80: 1151–1166, 1998. The vestibulo-ocular reflex (VOR) generates compensatory eye movements in response to angular and linear acceleration sensed by semicircular canals and otoliths respectively. Gaze stabilization demands that responses to linear acceleration be adjusted for viewing distance. This study in humans determined the transient dynamics of VOR initiation during angular and linear acceleration, modification of the VOR by viewing distance, and the effect of unilateral deafferentation. Combinations of unpredictable transient angular and linear head rotation were created by whole body yaw rotation about eccentric axes: 10 cm anterior to eyes, centered between eyes, centered between otoliths, and 20 cm posterior to eyes. Subjects viewed a target 500, 30, or 15 cm away that was extinguished immediately before rotation. There were four stimulus intensities up to a maximum peak acceleration of 2,800°/s2. The normal initial VOR response began 7–10 ms after onset of head rotation. Response gain (eye velocity/head velocity) for near as compared with distant targets was increased as early as 1–11 ms after onset of eye movement; this initial effect was independent of linear acceleration. An otolith mediated effect modified VOR gain depending on both linear acceleration and target distance beginning 25–90 ms after onset of head rotation. For rotational axes anterior to the otoliths, VOR gain for the nearest target was initially higher but later became less than that for the far target. There was no gain correction for the physical separation between the eyes and otoliths. With lower acceleration, there was a nonlinear reduction in the early gain increase with close targets although later otolith-mediated effects were not affected. In subjects with unilateral vestibular deafferentation, the initial VOR was quantitatively normal for rotation toward the intact side. When rotating toward the deafferented side, VOR gain remained less than half of normal for at least the initial 55 ms when head acceleration was highest and was not modulated by target distance. After this initial high acceleration period, gain increased to a degree depending on target distance and axis eccentricity. This behavior suggests that the commissural VOR pathways are not modulated by target distance. These results suggest that the VOR is initially driven by short latency ipsilateral target distance dependent and bilateral target-distance independent canal pathways. After 25 ms, otolith inputs contribute to the target distance dependent pathway. The otolith input later grows to eventually dominate the target distance mediated effect. When otolith input is unavailable the target distance mediated canal component persists. Modulation of canal mediated responses by target distance is a nonlinear effect, most evident for high head accelerations.

Effects of adaptation of vestibulo-ocular reflex function on manual target localization

2000 ◽  
Vol 10 (2) ◽  
pp. 75-86 ◽  
Author(s):  
Jacob J. Bloomberg ◽  
Lauren A. Merkle ◽  
Susan R. Barry ◽  
William P. Huebner ◽  
Helen S. Cohen ◽  
...  
Keyword(s):  
Adaptive Modulation ◽  
Normal Subjects ◽  
Target Localization ◽  
Whole Body ◽  
Spatial Coding ◽  
Ocular Reflex ◽  
Manual Responses ◽  
Vestibular Cues ◽  
Before And After ◽  
Vestibulo Ocular Reflex

The goal of the present study was to determine if adaptive modulation of vestibulo-ocular reflex (VOR) function is associated with commensurate alterations in manual target localization. To measure the effects of adapted VOR on manual responses we developed the Vestibular-Contingent Pointing Test (VCP). In the VCP test, subjects pointed to a remembered target following passive whole body rotation in the dark. In the first experiment, subjects performed VCP before and after wearing 0.5X minifying lenses that adaptively attenuate horizontal VOR gain. Results showed that adaptive reduction in horizontal VOR gain was accompanied by a commensurate change in VCP performance. In the second experiment, bilaterally labyrinthine deficient (LD) subjects were tested to confirm that vestibular cues were central to the spatial coding of both eye and hand movements during VCP. LD subjects performed significantly worse than normal subjects. These results demonstrate that adaptive change in VOR can lead to alterations in manual target localization.

Torsional vestibulo-ocular reflex during whole-body oscillation in the upright and the supine position: II. Responses in patients after vestibular neuritis

2004 ◽  
Vol 14 (4) ◽  
pp. 353-359
Author(s):  
A. Schmid-Priscoveanu ◽  
A.A. Kori ◽  
D. Straumann
Keyword(s):  
Supine Position ◽  
Semicircular Canal ◽  
Low Frequency ◽  
Phase Changes ◽  
Vestibular Neuritis ◽  
Whole Body ◽  
Healthy Human ◽  
Phase Lead ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex

In a recent study we demonstrated that otolith input modifies the torsional angular vestibulo-ocular reflex (torVOR) of healthy human subjects: Compared to turntable oscillations in supine position, oscillations in upright position increased the gain of torVOR by 0.1 and cancelled the phase lead originating from low-frequency semicircular canal signals. We asked whether these otolith-related changes of torVOR are still present in patients after vestibular neuritis (VN). Eight patients were sinusoidally oscillated about their naso-occipital axis in supine (canal-only stimulation) and upright (canal-and-otolith stimulation) position. Three-dimensional eye movements were recorded with dual search coils. The patients showed similar otolith-related gain and phase changes of the torVOR as healthy subjects: the gain increased by about 0.1 (p < 0.05) and the low-frequency phase lead from semicircular canal signals was abolished. These results indicate that otolith function after VN is still sufficient to interact with semicircular canal signals to optimize torsional gaze stabilization when the head is upright.

Eye-Head Movement Coordination: Vestibulo-Ocular Reflex Suppression with Head-Fixed Target Fixation1

1991 ◽  
Vol 1 (2) ◽  
pp. 161-170
Author(s):  
Jean-Louis Vercher ◽  
Gabriel M. Gauthier
Keyword(s):  
Eye Movements ◽  
Time Course ◽  
Mental Arithmetic ◽  
Visual Space ◽  
Head Movements ◽  
Total Darkness ◽  
Fixed Target ◽  
Ocular Reflex ◽  
Optokinetic Reflex ◽  
Vestibulo Ocular Reflex

To maintain clear vision, the images on the retina must remain reasonably stable. Head movements are generally dealt with successfully by counter-rotation of the eyes induced by the combined actions of the vestibulo-ocular reflex (VOR) and the optokinetic reflex. A problem of importance relates to the value of the so-called intrinsic gain of the VOR (VORG) in man, and how this gain is modulated to provide appropriate eye movements. We have studied these problems in two situations: 1. fixation of a stationary object of the visual space while the head moves; 2. fixation of an object moving with the head. These two situations were compared to a basic condition in which no visual target was allowed in order to induce “pure” VOR. Eye movements were recorded in seated subjects during stationary sinusoidal and transient rotations around the vertical axis. Subjects were in total darkness (DARK condition) and involved in mental arithmetic. Alternatively, they were provided with a small foveal target, either fixed with respect to earth (earth-fixed target: EFT condition), or moving with them (chair-fixed-target: CFT condition). The stationary rotation experiment was used as baseline for the ensuing experiment and yielded control data in agreement with the literature. In all 3 visual conditions, typical responses to transient rotations were rigorously identical during the first 200 ms. They showed, sequentially, a 16-ms delay of the eye behind the head and a rapid increase in eye velocity during 75 to 80 ms, after which the average VORG was 0.9 ± 0.15. During the following 50 to 100 ms, the gain remained around 0.9 in all three conditions. Beyond 200 ms, the VORG remained around 0.9 in DARK and increased slowly towards 1 or decreased towards zero in the EFT and CFT conditions, respectively. The time-course of the later events suggests that visual tracking mechanisms came into play to reduce retinal slip through smooth pursuit, and position error through saccades. Our data also show that in total darkness VORG is set to 0.9 in man. Lower values reported in the literature essentially reflect predictive properties of the vestibulo-ocular mechanism, particularly evident when the input signal is a sinewave.

Modification of compensatory saccades after aVOR gain recovery

2007 ◽  
Vol 16 (6) ◽  
pp. 285-291
Author(s):  
Michael C. Schubert ◽  
Americo A. Migliaccio ◽  
Charles C. Della Santina
Keyword(s):  
Head Rotation ◽  
Rehabilitation Program ◽  
Inverse Dynamic ◽  
Gaze Stabilization ◽  
Ocular Reflex ◽  
Dynamic Relationship ◽  
Vestibulo Ocular Reflex ◽  
Functional Relevance ◽  
Vestibular Neuronitis ◽  
Eye Velocity

The recruitment of extra-vestibular mechanisms to assist a deficient angular vestibulo-ocular reflex (aVOR) during ipsilesional head rotations is well established and includes saccades of reduced latency that occur in the direction of the lesioned aVOR, termed compensatory saccades (CS). Less well known is the functional relevance of these unique saccades. Here we report a 42 y.o. male diagnosed with right unilateral vestibular hypofunction due to vestibular neuronitis who underwent a vestibular rehabilitation program including gaze stabilization exercises. After three weeks, he had a significant improvement in his ability to see clearly during head rotation. Our data show a reduction in the recruitment and magnitude of CS as well as improved peripheral aVOR gain (eye velocity/head velocity) and retinal eye velocity. Our data suggest an inverse, dynamic relationship between the recruitment of CS and the gain of the aVOR.

Sign in / Sign up

Export Citation Format

Share Document