Active Head Rotation Research Articles

頭部に対する振子様回転の視運動性眼振に及ぼす影響

The influence of pendular head rotation on optokinetic nystagmus was studied with the use of a pendular rotating chair and an optic cylinder operated independently. Healthy subjects and patients with unilateral loss of vestibular function were examined.The pendular rotation and optokinetic stimuli were applied in both horizontal and vertical directions. The optokinetic stimuli consisted of 12 stripes rotating with applied uniform velocity of 90°/sec. The pendular rotation was applied at a frequency of 0.1 Hz and a peak angular velocity of 30°/sec.In healthy subjects, horizontal optokinetic nystagmus was promoted when the head rotated to the direction opposite to the optic cylinder rotation. On the other hand, when the head and optic cylinder rotated in the same direction, optokinetic nystagmus was inhibited.In patients with unilateral loss of vestibular function, a difference in response to ampullopetal and amupullofugal stimulation of the remaining intact labyrinth was seen. However, this difference gradually disappeared with compensation.In healthy subjects, vertical pendular rotation promoted and inhibited vertical optokinetic nystagmus.In patients with unilateral loss of vestibular function, promotion by vertical pendular rotation of vertical optokinetic nystagmus was the same as that in healthy subjects.The influence of active pendular head rotation on optokinetic nystagmus was studied with an optic cylinder fixed to the head. Inhibition of nystagmus during active pendular head rotation was weaker than that during passive pendular head rotation, but the effect on promotion was almost the same.

Headshake versus whole‐body rotation testing of the vestibulo‐ocular reflex

The vestibulo-ocular reflex (VOR) is usually evaluated by whole-body rotary chair oscillation in darkness, but is limited to ambulatory patients. In order to develop a portable method of VOR assessment, eye movements from 10 normal subjects were studied under three conditions: 1. whole-body rotary chair oscillation in the dark and in the light with a head mounted blank field, 2. passive head-on-body rotation in the light with a blank field, and 3. active head-on-body rotation in the light with a blank field. The influence of visual fixation, neck rotation, and volition on VOR gain was to be assessed. Head oscillations were maintained at 0.5 and 1.0 Hz, 50 degrees/s peak velocity. Mean VOR gains with blank field testing were indistinguishable from those obtained in darkness during whole-body rotation. In addition, there were no significant differences in the mean gain between whole-body, passive head rotation or active head rotation. Two vestibulopathic patients (absent calorics bilaterally and oscillopsia) were also studied to illustrate potential clinical utility of the methods. Rotations under all conditions revealed low but variable gains. The evaluation of the VOR in the light with a blank visual surround and passive or active head rotation is a potentially useful clinical method of bedside assessment of the VOR.

Cervico-ocular function in patients with spasmodic torticollis.

The cervico-ocular (COR) and active and passive vestibulo-ocular reflexes (VOR) were measured in seven patients with spasmodic torticollis (ST) and six normal controls. The COR was found to be weak or absent in both groups. The VOR gain was similar in the two groups but five patients had a significant asymmetry of the response. There was no evidence of abnormal cervico-vestibular interaction during active head rotation. The study suggests that the VOR asymmetry frequently found in ST cannot be explained on the basis of an abnormal cervical input.

Instability of gaze during locomotion in patients with deficient vestibular function

We measured the stability of gaze in the horizontal and vertical planes, in 2 patients with bilaterally deficient vestibular function while they sat, stood still, walked in place, and made active horizontal and vertical head rotations. During sitting and standing, gaze was equally as stable as that in normal subjects. During walking in place, however, gaze velocity was double that of normal subjects. Thus, our patients' complaints of impaired vision and oscillopsia during walking could be ascribed to excessive motion of images on their retinas. Eye movements compensated for head rotations more effectively (higher gain) during active head rotations than during locomotion; this difference may be due to the predictable nature of active head movements. We conclude that testing of patients with vestibular symptoms should include stimuli corresponding to the rotational head perturbations that occur during locomotion; such head rotations have nonpredictable characteristics and a frequency range of 0.5 to 5.0 Hz.

Visual issues in the use of a head-mounted monocular display

A miniature display device, recently available commercially, is aimed at providing a portable, inexpensive means of visual information communication. The display is head mounted in front of one eye with the other eye's view of the environment unobstructed. Various visual phenomena are associated with this design. The consequences of these phenomena for visual safety, comfort, and efficiency of the user were evaluated: (1) The monocular, partially occluded mode ofoperation interrupts binocular vision. Presenting disparate images to each eye results in binocular rivalry. Most observers can use the display comfortably in this rivalrous mode. In many cases, it is easier to use the display in a peripheral position, slightly above or below the line of sight, thus permitting normal binocular vision of the environment. (2) As a head-mounted device, the displayed image is perceived to move during head movements due to the response of the vestibulo-ocular reflex. These movements affect the visibility of small letters during active head rotations and sharp accelerations. Adaptation is likely to reduce this perceived image motion. No evidence for postural instability or motion sickness was noted as a result of these conflicts between visual and vestibular inputs. (3) Small displacements of the image are noted even without head motion, resulting from eye movements and the virtual lack of display persistence. These movements are noticed spontaneously by few observers and are unlikely to interfere with the display use in most tasks.

Visual cancellation of the torsional vestibulo-ocular reflex in humans.

Using the eye-coil/magnetic field method, we measured the torsional vestibulo-ocular reflex (VOR) in ten subjects during active head rotations in roll at about 0.5 Hz. In the dark, regardless of instructions or mental effort, the gains (eye velocity/head velocity) had a mean value of around 0.61. When they viewed a visual display that was stationary, gains rose to 0.72. When viewing a visual display that moved in roll with their heads, subjects could decrease their gains to a mean of 0.46. Separate experiments showed that, as expected at this frequency, the optokinetic system made only a weak contribution. It has been proposed that the horizontal VOR is cancelled by the smooth pursuit system. Since there is no torsional pursuit system, some other mechanism must be used to augment or partially cancel the torsional VOR. Attempts to show that imagination could change this gain showed only weak effects. When asked to imagine an earth-fixed scene, gains were around 0.63; when asked to imagine a subject-fixed scene, gains decreased to only 0.60. When allowed to use a tactile contribution to aid the imagination in cancelling the VOR, the gain dropped further but only to 0.57. We conclude that mental effort in the dark has little influence on the torsional VOR but vision does by a mechanism that is not optokinetic or pursuit.

Secondary vestibular and neck position signals in the vestibular nuclei of alert rhesus monkeys performing active head movements

Rhesus monkeys were trained to track a visual target with head and eye movements in order to study central vestibular neurons under natural conditions. Single unit recordings of cells in the vestibular nuclei were obtained during active head rotations in the horizontal plane, and also during passive copies of these self-induced movements. Most cells exhibited secondary responses immediately following the primary vestibular responses to active or passive rapid head movements. They were of opposite polarity to the primary responses, and generally rate enhancements of secondary responses were of greater amplitude than rate suppressions. In addition, vestibular nuclei cells also encoded tonic neck position. The corresponding signal consisted of a variation in the basal discharge rate as a function of neck, and thus head, position. These observations prove for the first time that dynamic and static response characteristics recorded earlier from lesioned brains and under anaesthesia are, at least qualitatively, representative for the normally behaving vestibulomotor system in primates.

Comparison of smooth pursuit and combined eye-head tracking in human subjects with deficient labyrinthine function.

The effects of deficient labyrinthine function on smooth visual tracking with the eyes and head were investigated in ten patients with bilateral peripheral vestibular disease. Ten normal subjects served as controls. In the patients active, combined eye-head tracking (EHT) was significantly better than smooth pursuit (SP) with the eyes alone with a target frequency of 1.0 Hz. Normal subjects pursued equally well with SP and with active EHT. The gain of compensatory eye movements during active head rotation in darkness was also measured. Compensatory eye movements in labyrinthine-deficient patients (attributable to residual vestibulo-ocular reflex (VOR), cervico-ocular reflex (COR) and pre-programmed eye movements) were always less than in normal subjects. These data were used to examine current hypotheses that postulate central cancellation of the VOR (or compensatory eye movements) during EHT. A model that proposes summation of an internal smooth pursuit command and VOR/compensatory eye movements accounted for the findings in normal subjects and labyrinthine-deficient patients. In seven labyrinthine-deficient patients and nine normal subjects, passive EHT was measured during en bloc rotation while they viewed a head-fixed target. With a target frequency of 1.0 Hz, both subjects and patients showed significantly better tracking during passive EHT than during SP. Normal subjects also showed superior tracking during passive EHT compared with active EHT. These findings support the notion that during passive EHT, parametric gain changes contribute to modulation of the VOR.

高頻度頭部運動における前庭眼反射と固視

Gaze stabilizing function during active head rotations at high frequencies was investigated in 12 normal adults. Head rotation amplitude decreased as the frequency increased, from 31° at 2 Hz to 11° at 5 Hz on average ; the corresponding maximum head velocity and acceleration amounted to about 170-200°/sec and 2500-5000°/sec2, respectively. At the frequencies higher than 2 Hz, the amplitude of compensatory eye movement exceeded head rotation amplitude ; the mean ratio of the former to the latter increased linearly from 1.19 at 2 Hz to 1.80 at 5 Hz.The present study indicated that the compensation for head rotation by the vestibulo-ocular reflex, which is adapted in daily experienced head movements, deteriorates quickly as head oscillates over this functional range.

Compensatory eye movements during active head rotation for near targets: effects of imagination, rapid head oscillation and vergence.

Because the center of natural head rotation lies some distance behind the centers of eye rotation, the VOR has to operate with a gain substantially above 1 for there to be stable fixation of targets lying near the head. In humans, VOR gain was increased inversely proportional to fixation distance and changed with the angle of the head for very near targets. These effects were also evident when the subject imagined the target. However, this "high-gain" VOR was found to deteriorate substantially at frequencies beyond ca 2.5 Hz. In conditions without visual feedback, the VOR gain enhancement due to near fixation was disrupted by monocular viewing. When the subjects wore lenses to relax or increase accommodation, the lenses were found to have no effect on VOR gain. On the other hand, prisms of equivalent power to the lenses had a large effect whereby gain was adjusted according to the vergence state of the eyes. This suggests that VOR gain modulation is under the direct control of convergence.

SUBJECTIVE VERGENCE ERROR AT NEAR DURING ACTIVE HEAD ROTATION

There exists some controversy regarding the effects of active horizontal head rotation on vergence error. We used a conventional, Ogle-type, subjective fixation disparity apparatus to measure vergence error at near over a full range of horizontal head-rotation frequencies. Change in vergence error rarely exceeded 10 min arc. This finding demonstrates the adequacy of the vergence system to maintain relatively accurate bifixation at near and to allow for continuous maintenance of binocular sensory-motor integrative ability, even in the presence of system perturbations.

Subjective vergence error at near during active head rotation

Abstract— There exists some controversy regarding the effects of active horizontal head rotation on vergence error. We used a conventional, Ogle-type, subjective fixation disparity apparatus to measure vergence error at near over a full range of horizontal head-rotation frequencies. Change in vergence error rarely exceeded 10 min arc. This finding demonstrates the adequacy of the vergence system to maintain relatively accurate bifixation at near and to allow for continuous maintenance of binocular sensorymotor integrative ability, even in the presence of system perturbations.

Stereopsis during continuous head motion

This study investigated the degree to which the processing of stereoscopic information is degraded by side-to-side head rotations of amplitudes and frequencies known to disrupt binocular correspondence. Forced-choice recognition thresholds were obtained for a briefly presented stereoscopic test stimulus, formed from a dynamic random-element stereogram, under conditions of active head rotation. Thresholds were not impaired by such head movements, a result consistent with the hypothesis that precise binocular correspondence is not essential for the processing of stereoscopic information.

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The conditions required for a new rotation test were defined as (1) to obtain findings not detectable by other tests, especially caloric tests, (2) to reflect the most important function of the vestibulo-ocular reflex and (3) to have specificity and sensitivity as a clinical test.The active head rotation test is a new test in which the vestibulo-ocular reflex and smooth pursuit can be demonstrated by measuring the abilities of spatial fixation and fixation suppression during daily experienced fast head rotations in the light. The findings and clinical application of this test are described.

Compensatory eye movement and gaze fixation upon passive head- and body rotation and active head rotation

To detect differences in compensatory eye movement and gaze fixation, normal subjects and patients with bilateral loss of labyrinthine functions were subjected to passive head-and-body rotation and performed active head rotation. In normal subjects, there was no difference between passive and active rotation with respect to compensatory eye movement in the dark and spatial gaze fixation; on the other hand, the ability to gaze fixedly on a head-fixed target was better during passive than active rotation. In our patients, the findings obtained upon passive rotation resembled those already reported for active rotation, indicating that observing compensatory eye movements and gaze fixation during passive rotation is useful in the detection of disorders of the vestibulo-ocular reflex.

Compensatory Eye Movement and Gaze Fixation During Active Head Rotation and Passive Head-and-Body Rotation

Compensatory Eye Movement and Gaze Fixation During Active Head Rotation and Passive Head-and-Body Rotation

Assessment of retinal image displacement during head movement using an afterimage method

An afterimage method has been used to measure retinal image displacement during binocular fixation with active head rotation about a vertical axis. The results confirm previously published reports that fixation accuracy in the horizontal direction deteriorates as a result of a head rotation. However, both retinal image displacements and fixation disparities were found to remain much smaller (by a factor of 3 and 8 respectively) than the values previously reported in the literature for similar head rotations (peak-to-peak amplitude: 20°, frequency: 0.66 Hz). Moreover, our results show that fixation accuracy fell not only in the horizontal direction, but also in the vertical direction by about the same factor. It is concluded that eye-movement compensation of active head rotation may be much better than previously reported in the literature, and good enough to prevent deterioration of vision.

Active head rotations and eye-head coordination.

Annals of the New York Academy of SciencesVolume 374, Issue 1 p. 540-559 ACTIVE HEAD ROTATIONS AND EYE-HEAD COORDINATION* Wolfgang H. Zangemeister, Wolfgang H. Zangemeister Departments of Physiological Optics, Neurology, and Bioengineering University of California Berkeley, California 94720 On leave from the University of Hamburg. Address correspondence to the Neurological University Clinic (UKE), University of Hamburg, Martinistr. 52, D-2000 Hamburg 20, Federal Republic of Germany. Supported by Deutsche Forschungsgemeinschaft, Bonn, F.R.G.Search for more papers by this authorLawrence Stark, Lawrence Stark Departments of Physiological Optics, Neurology, and Bioengineering University of California Berkeley, California 94720Search for more papers by this author Wolfgang H. Zangemeister, Wolfgang H. Zangemeister Departments of Physiological Optics, Neurology, and Bioengineering University of California Berkeley, California 94720 On leave from the University of Hamburg. Address correspondence to the Neurological University Clinic (UKE), University of Hamburg, Martinistr. 52, D-2000 Hamburg 20, Federal Republic of Germany. Supported by Deutsche Forschungsgemeinschaft, Bonn, F.R.G.Search for more papers by this authorLawrence Stark, Lawrence Stark Departments of Physiological Optics, Neurology, and Bioengineering University of California Berkeley, California 94720Search for more papers by this author First published: November 1981 https://doi.org/10.1111/j.1749-6632.1981.tb30899.xCitations: 52 * The authors are pleased to acknowledge support from the NCC 2-86 Cooperative Agreement, NASA-Ames Research Center. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume374, Issue1Vestibular and Oculomotor Physiology: International Meeting of the Barany SocietyNovember 1981Pages 540-559 RelatedInformation

The behavior of the vestibulo-ocular reflex at high velocities of head rotation

The behavior of the vestibulo-ocular reflex (VOR) during both passive and active, high-velocity head movements was recorded in three normal subjects. We found that the VOR is compensatory for head velocities up to at least 350 deg·s −1, during both active and passive head rotation provided there is an attempt to visualize a real (or imagined) stationary object in space. Slow phase velocities, however, could reach values as high as 500 deg·s −1. Furthermore, during passive rotation at high velocities, the quick phase trajectory is modified — indicating an interaction between the slow phase and quick phase eye velocity commands.

Compensatory eye movement and gaze fixation during active head rotation in patients with labyrinthine disorders.

Compensatory eye movement and gaze fixation during active head rotation were studied in patients with unilateral and bilateral loss of vestibular function. Patients with bilateral lesions were asked to perform mental arithmetic tasks in the dark. Although compensatory eye movements of these patients corresponded to 38-46% of compensatory movements in normal subjects, the ability of patients with lesions to visually fix on a stationary target was markedly impaired. Visual fixation on moving targets attached to the head (head-fixed targets) was also measured and found to be good. For patients with unilateral lesions, in the early stages of the disease, findings during rotations to the intact side resembled those for normal subjects, while results of rotations to the affected side resembled those for patients with bilateral lesions.