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Kartal Özcan A, Satici S, Akbulut AA, Kiliç M, Çankaya S, Polat Z. Investigation of Video Ocular Counter-Roll Findings According to Head and Body Tilt Positions in Healthy Subjects. Ear Hear 2024:00003446-990000000-00333. [PMID: 39175112 DOI: 10.1097/aud.0000000000001563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2024]
Abstract
OBJECTIVES A vestibulo-ocular reflex called the ocular counter-roll can be used to assess how well the otolith organs are functioning. The video ocular counter-roll (vOCR) test is a recent addition to the videonystagmography test battery that allows for video recording and quantitative ocular counter-roll analysis. The purpose of this study is to investigate potential discrepancies in vOCR measurements obtained from a 30° lateral head tilt in the roll plane versus measurements obtained from a 30° tilt of the head and body. DESIGN Thirty otologically, and neurologically healthy subjects aged 18 to 30 (M = 23.32 years, SD = 2.66 years; 8 men, 22 women) participated in this study. Pure-tone audiometry, oculomotor tests, and vOCR evaluation were performed for all participants. The vOCR assessment was performed in 2 positions, 30° lateral head tilt, and 30° body tilt position. The degree of static vOCR eye position and vOCR asymmetry in both positions were calculated and compared. RESULTS There was no statistically significant difference between the vOCR findings obtained in the right and left 30° lateral head tilt (p = 0.546) and body tilt (p = 0.114). vOCR asymmetry was determined as median (interquartile range) 0.08 (0.07) in lateral head tilt position and 0.09 (0.06) in body tilt position. The degree of static vOCR (8.75° [1.91]) detected during body tilt was statistically greater than the static vOCR (6.62 [1.69]) detected during head tilt (p < 0.001). There was no statistically significant difference in terms of ocular counter-roll asymmetry detected between head tilt and body tilt (p = 0.918). CONCLUSIONS Our study shows a significant difference in the vOCR responses during head tilt and body tilt, a finding that should be considered during clinical evaluation of vestibular function. There was no significant asymmetry between the responses with either head or body tilt.
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Affiliation(s)
- Ahsen Kartal Özcan
- Department of Audiology, Hamidiye Faculty of Health Sciences, University of Health Sciences, Istanbul, Türkiye
- Audiology and Language Disorders PhD Program, Department of Otorhinolaryngology, Institute of Health Sciences, Marmara University, Istanbul, Türkiye
| | - Sema Satici
- Department of Audiology, Hamidiye Faculty of Health Sciences, University of Health Sciences, Istanbul, Türkiye
- Audiology and Language Disorders PhD Program, Department of Otorhinolaryngology, Institute of Health Sciences, Marmara University, Istanbul, Türkiye
| | - Ahmet Alperen Akbulut
- Department of Audiology, Hamidiye Faculty of Health Sciences, University of Health Sciences, Istanbul, Türkiye
- Audiology and Language Disorders PhD Program, Department of Otorhinolaryngology, Institute of Health Sciences, Marmara University, Istanbul, Türkiye
| | - Mert Kiliç
- Department of Audiology, Hamidiye Faculty of Health Sciences, University of Health Sciences, Istanbul, Türkiye
| | - Sare Çankaya
- Department of Audiology, Hamidiye Faculty of Health Sciences, University of Health Sciences, Istanbul, Türkiye
| | - Zahra Polat
- Department of Audiology, Hamidiye Faculty of Health Sciences, University of Health Sciences, Istanbul, Türkiye
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Wibble T, Pansell T. Human proprioceptive gaze stabilization during passive body rotations underneath a fixed head. Sci Rep 2024; 14:17355. [PMID: 39075206 PMCID: PMC11286784 DOI: 10.1038/s41598-024-68116-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Accepted: 07/19/2024] [Indexed: 07/31/2024] Open
Abstract
The present study explored the presence of torsional gaze-stabilization to proprioceptive neck activation in humans. Thirteen healthy subjects (6 female, mean age 25) were exposed to passive body rotations while maintaining a head-fixed, gravitationally upright, position. Participants were seated in a mechanical sled, their heads placed in a chin rest embedded in a wooden beam while wearing an eye tracker attached to the beam using strong rubber bands to ensure head stability. The body was passively rotated underneath the head both in darkness and while viewing a projected visual scene. Static torsional gaze positions were compared between the baseline position prior to the stimulation, and immediately after the final body tilt had been reached. Results showed that passive neck flexion produced ocular torsion when combined with a visual background. The eyes exhibited rotations in the opposite direction of the neck's extension, matching a hypothetical head tilt in the same direction as the sled. This corresponded with a predicted head rotation aimed at straightening the head in relation to the body. No such response was seen during trials in darkness. Altogether, these findings suggest that proprioception may produce a predictive gaze-stabilizing response in humans.
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Affiliation(s)
- Tobias Wibble
- Division of Eye and Vision, Department of Clinical Neuroscience, Marianne Bernadotte Centrum, St. Erik's Eye Hospital, Karolinska Institutet, Stockholm, Sweden.
| | - Tony Pansell
- Division of Eye and Vision, Department of Clinical Neuroscience, Marianne Bernadotte Centrum, St. Erik's Eye Hospital, Karolinska Institutet, Stockholm, Sweden
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Yang Y, Tian J, Otero-Millan J, Schubert MC, Kheradmand A. Video Ocular Counter-Roll (vOCR): Otolith-Ocular Function and Compensatory Effect of the Neck Following Vestibular Loss. Otolaryngol Head Neck Surg 2023; 169:669-678. [PMID: 36861848 PMCID: PMC10474240 DOI: 10.1002/ohn.304] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 02/02/2023] [Accepted: 02/04/2023] [Indexed: 03/03/2023]
Abstract
OBJECTIVE Assessment of recovery following vestibular loss has been limited by the lack of bedside measures in clinical settings. Here, we used the video ocular counter-roll (vOCR) test to study otolith-ocular function and compensatory effect of neck proprioception in patients at different stages of vestibular loss. STUDY DESIGN Case-control study. SETTING Tertiary care center. METHODS Fifty-six subjects were recruited including patients with acute (9 ± 2 days [mean ± standard error of mean]), subacute (61 ± 11 days), and chronic (1009 ± 266 days) unilateral loss of vestibular function, as well as a group of healthy controls. We used a video-oculography method based on tracking the iris for vOCR measurement. To examine the effect of neck inputs, vOCR was recorded during two simple tilt maneuvers in all subjects while seated: 30° head-on-body tilt and 30° head-and-body tilt. RESULTS The vOCR responses evolved at different stages following vestibular loss with improvement of the gains in the chronic stage. The deficit was more pronounced when the whole body was tilted (acute: 0.08 ± 0.01, subacute: 0.11 ± 0.01, chronic: 0.13 ± 0.02, healthy control: 0.18 ± 0.01), and the gain of vOCR improved when the head was tilted on the body (acute: 0.11 ± 0.01, subacute: 0.14 ± 0.01, chronic: 0.13 ± 0.02, healthy control: 0.17 ± 0.01). The time course of vOCR response was affected as well with reduced amplitude and slower response in the acute stage of vestibular loss. CONCLUSION The vOCR test can be valuable as a clinical marker to measure vestibular recovery and compensatory effect of neck proprioception in patients at different stages following loss of vestibular function.
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Affiliation(s)
- Yuchen Yang
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Otolaryngology–Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jing Tian
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jorge Otero-Millan
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, California, USA
| | - Michael C. Schubert
- Department of Otolaryngology–Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Physical Medicine and Rehabilitation, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Amir Kheradmand
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Otolaryngology–Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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McCarthy J, Castro P, Cottier R, Buttell J, Arshad Q, Kheradmand A, Kaski D. Multisensory contribution in visuospatial orientation: an interaction between neck and trunk proprioception. Exp Brain Res 2021; 239:2501-2508. [PMID: 34120203 PMCID: PMC8354892 DOI: 10.1007/s00221-021-06146-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 05/29/2021] [Indexed: 10/28/2022]
Abstract
A coherent perception of spatial orientation is key in maintaining postural control. To achieve this the brain must access sensory inputs encoding both the body and the head position and integrate them with incoming visual information. Here we isolated the contribution of proprioception to verticality perception and further investigated whether changing the body position without moving the head can modulate visual dependence-the extent to which an individual relies on visual cues for spatial orientation. Spatial orientation was measured in ten healthy individuals [6 female; 25-47 years (SD 7.8 years)] using a virtual reality based subjective visual vertical (SVV) task. Individuals aligned an arrow to their perceived gravitational vertical, initially against a static black background (10 trials), and then in other conditions with clockwise and counterclockwise background rotations (each 10 trials). In all conditions, subjects were seated first in the upright position, then with trunk tilted 20° to the right, followed by 20° to the left while the head was always aligned vertically. The SVV error was modulated by the trunk position, and it was greater when the trunk was tilted to the left compared to right or upright trunk positions (p < 0.001). Likewise, background rotation had an effect on SVV errors as these were greater with counterclockwise visual rotation compared to static background and clockwise roll motion (p < 0.001). Our results show that the interaction between neck and trunk proprioception can modulate how visual inputs affect spatial orientation.
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Affiliation(s)
- Jason McCarthy
- Regional Neurological Rehabilitation Unit, Homerton University Hospital, London, UK
| | - Patricia Castro
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, London, UK.,Department of Clinical and Movement Neurosciences, Centre for Vestibular and Behavioural Neuroscience, University College London, London, UK.,Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Rachael Cottier
- Regional Neurological Rehabilitation Unit, Homerton University Hospital, London, UK
| | - Joseph Buttell
- Regional Neurological Rehabilitation Unit, Homerton University Hospital, London, UK
| | - Qadeer Arshad
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, London, UK.,inAmind Laboratory, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK
| | - Amir Kheradmand
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, USA
| | - Diego Kaski
- Department of Clinical and Movement Neurosciences, Centre for Vestibular and Behavioural Neuroscience, University College London, London, UK.
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Douglas SB, Clément G, Denise P, Wood SJ. Ocular Reflex Phase during Off-Vertical Axis Rotation in Humans is Modified by Head-Turn-On-Trunk Position. Sci Rep 2017; 7:42071. [PMID: 28176802 PMCID: PMC5296736 DOI: 10.1038/srep42071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 01/03/2017] [Indexed: 11/23/2022] Open
Abstract
Constant velocity Off-Vertical Axis Rotation (OVAR) imposes a continuously varying orientation of the head and body relative to gravity, which generates a modulation of horizontal (conjugate and vergence), vertical, and torsional eye movements. We introduced the head-turn-on-trunk paradigm during OVAR to examine the extent to whether the modulation of these ocular reflexes is mediated by graviceptors in the head, i.e., otoliths, versus other body graviceptors. Ten human subjects were rotated in darkness about their longitudinal axis 20° off-vertical at a constant velocity of 45 and 180°/s, corresponding to 0.125 and 0.5 Hz. Binocular responses were obtained with the head and trunk aligned, and then with the head turned relative to the trunk 40° to the right or left of center. The modulation of vertical and torsional eye position was greater at 0.125 Hz while the modulation of horizontal and vergence slow phase velocity was greater at 0.5 Hz. The amplitude modulation was not significantly altered by head-on-trunk position, but the phases shifted towards alignment with the head. These results are consistent with the modulation of ocular reflexes during OVAR being primarily mediated by the otoliths in response to the sinusoidally varying linear acceleration along the interaural and naso-occipital head axis.
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Affiliation(s)
| | - Gilles Clément
- Lyon Neuroscience Research Center, CNRS UMR5292 - INSERM U1028 - University of Lyon, Impact Team, Bron, France
| | - Pierre Denise
- University of Caen Normandy, INSERM COMETE, Caen, France
| | - Scott J Wood
- Department of Psychology, Azusa Pacific University, Azusa CA, USA
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Guerraz M, Caudron S, Thomassin N, Blouin J. Influence of head orientation on visually and memory-guided arm movements. Acta Psychol (Amst) 2011; 136:390-8. [PMID: 21292227 DOI: 10.1016/j.actpsy.2011.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 01/04/2011] [Accepted: 01/04/2011] [Indexed: 12/25/2022] Open
Abstract
In the absence of visual supervision, tilting the head sideways gives rise to deviations in spatially defined arm movements. The purpose of this study was to determine whether these deviations are restricted to situations with impoverished visual information. Two experiments were conducted in which participants were positioned supine and reproduced with their unseen index finger a 2 dimensional figure either under visual supervision or from memory (eyes closed). In the former condition, the figure remained visible (using a mirror). In the latter condition, the figure was first observed and then reproduced from memory. Participants' head was either aligned with the trunk or tilted 30° towards the left or right shoulder. In experiment 1, participants observed first the figure with the head straight and then reproduced it with the head either aligned or tilted sideways. In Experiment 2, participants observed the figure with the head in the position in which the figure was later reproduced. Results of Experiment 1 and 2 showed deviations of the motor reproduction in the direction opposite to the head in both the memory and visually-guided conditions. However, the deviations decreased significantly under visual supervision when the head was tilted left. In Experiment 1, the perceptual visual bias induced by head tilt was evaluated. Participants were required to align the figure parallel to their median trunk axis. Results revealed that the figure was perceived as parallel with the trunk when it was actually tilted in the direction of the head. Perceptual and motor responses did not correlate. Therefore, as long as visual feedback of the arm is prevented, an internal bias, likely originating from head/trunk representation, alters hand-motor production irrespectively of whether visual feedback of the figure is available or not.
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Affiliation(s)
- Michel Guerraz
- Laboratory of Psychology and NeuroCognition, UMR 5105 CNRS - University of Savoie, BP 1104, 73011 Chambéry Cedex, France.
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Farshadmanesh F, Klier EM, Chang P, Wang H, Crawford JD. Three-Dimensional Eye–Head Coordination After Injection of Muscimol Into the Interstitial Nucleus of Cajal (INC). J Neurophysiol 2007; 97:2322-38. [PMID: 17229829 DOI: 10.1152/jn.00752.2006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The interstitial nucleus of Cajal (INC) is thought to be the “neural integrator” for torsional/vertical eye position and head posture. Here, we investigated the coordination of eye and head movements after reversible INC inactivation. Three-dimensional (3-D) eye–head movements were recorded in three head-unrestrained monkeys using search coils. INC sites were identified by unit recording/electrical stimulation and then reversibly inactivated by 0.3 μl of 0.05% muscimol injection into 26 INC sites. After muscimol injection, the eye and head 1) began to drift (an inability to maintain stable fixation) torsionally: clockwise (CW)/counterclockwise (CCW) after left/right INC inactivation respectively. 2) The eye and head tilted torsionally CW/CCW after left/right INC inactivation, respectively. Horizontal gaze/head drifts were inconsistently present and did not result in considerable position offsets. Vertical eye drift was dependent on both vertical eye position and the magnitude of the previous vertical saccade, as in head-fixed condition. This correlation was smaller for gaze and head drift, suggesting that the gaze and head deficits could not be explained by a first-order integrator model. Ocular counterroll (OC) was completely disrupted. The gain of torsional vestibuloocular reflex (VOR) during spontaneous eye and head movements was reduced by 22% in both CW/CCW directions after either left or right INC inactivation. Our results suggest a complex interdependence of eye and head deficits after INC inactivation during fixation, gaze shifts, and VOR. Some of our results resemble the symptoms of spasmodic torticollis (ST).
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Affiliation(s)
- Farshad Farshadmanesh
- York Center for Vision Research, Canadian Institutes of Health Research Group for Action and Perception, Departments of Psychology, Biology, and Kinesiology and Health Sciences York University, Toronto, Ontario, Canada
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Hamasaki I, Hasebe S, Ohtsuki H. Static Ocular Counterroll: Video-based Analysis After Minimizing the False-Torsion Factors. Jpn J Ophthalmol 2005; 49:497-504. [PMID: 16365796 DOI: 10.1007/s10384-005-0254-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Accepted: 03/04/2005] [Indexed: 10/25/2022]
Abstract
PURPOSE To determine the validity and usefulness of a newly developed measurement method of static ocular counterrolling (s-OCR) that eliminates false-torsion factors and to test the Jampel hypothesis that s-OCR does not exist. METHODS A lightweight measurement device, consisting of a video camera, a coaxial light source, and a laser pointer projecting a fixation target on the wall, was fixed to a subject's head by means of a mouthpiece. In 11 healthy adults (mean age: 30 +/- 15 years), digital images of the right eye were captured while the subject kept his head tilted at a randomly selected angle ranging from 0 degrees to 50 degrees . By a frame-by-frame analysis of movements of the corneal light reflex and the iris patterns, OCR was evaluated. RESULTS Torsional eye movement in the opposite direction to head tilt was found in all subjects. The amount of torsion continuously increased until the head-tilt angle reached 40 degrees. The average (+/- SD) amplitude of a fitted sine curve was 7.6 +/- 3.2 degrees (range: 4.3 degrees-10.3 degrees), and the individual amplitude was significantly larger than the test-retest repeatability of the measurement (+/-1.7 degrees). CONCLUSIONS The measurement method used in this study provided good test-retest repeatability and ease of application. The characteristics of torsional eye movements that we observed after minimizing the false-torsion factors agree with previous reports supporting the existence of s-OCR.
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Affiliation(s)
- Ichiro Hamasaki
- Department of Ophthalmology, Okayama University, Graduate School of Medicine and Dentistry, Okayama, Japan
| | - Satoshi Hasebe
- Department of Ophthalmology, Okayama University, Graduate School of Medicine and Dentistry, Okayama, Japan.
| | - Hiroshi Ohtsuki
- Department of Ophthalmology, Okayama University, Graduate School of Medicine and Dentistry, Okayama, Japan
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Aoyagi M, Kimura M, Yagi T. The effect of gravity on the stability of human eye orientation. Auris Nasus Larynx 2004; 30:363-7. [PMID: 14656561 DOI: 10.1016/j.anl.2003.07.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The stabilization of both the horizontal (H) and vertical (V) eye movements during voluntary fixation is believed to depend upon the visual feedback system in the upright position. However, ocular stability in the tilted position has been less well investigated. Therefore, in the present study, we examined the gaze stability of healthy human subjects in the three dimensions in the tilted position using a video image analysis system (VIAS). METHODS In 10 healthy human subjects, the eye movements were recorded after fixating the eye on a target in an upright position and also in the tilted position. The standard deviations of the eye movements in the three dimensions were calculated to evaluate the stability of the movements. RESULTS In the tilted position, there were no significant changes in the horizontal and vertical eye movements as compared those in the upright position. However, the standard deviation of the torsional (T) segment was significantly larger in the tilted position, compared to that in the upright position. CONCLUSION From these results, we speculate that, a combination of otolith and somatosensory inputs play a major role in maintaining the stability of eye movements.
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Affiliation(s)
- Mio Aoyagi
- Department of Otolaryngology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, 113-8603, Tokyo, Japan
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Crawford JD, Tweed DB, Vilis T. Static ocular counterroll is implemented through the 3-D neural integrator. J Neurophysiol 2004; 90:2777-84. [PMID: 14534281 DOI: 10.1152/jn.00231.2003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Static head roll about the naso-occipital axis is known to produce an opposite ocular counterroll with a gain of approximately 10%, but the purpose and neural mechanism of this response remain obscure. In theory counterroll could be maintained either by direct tonic vestibular inputs to motoneurons, or by a neurally integrated pulse, as observed in the saccade generator and vestibulo-ocular reflex. When simulated together with ocular drift related to torsional integrator failure, the direct tonic input model predicted that the pattern of drift would shift torsionally as in ordinary counterroll, but the integrated pulse model predicted that the equilibrium position of torsional drift would be unaffected by head roll. This was tested experimentally by measuring ocular counterroll in 2 monkeys after injection of muscimol into the mesencephalic interstitial nucleus of Cajal. Whereas 90 degrees head roll produced a mean ocular counterroll of 8.5 degrees (+/-0.7 degrees SE) in control experiments, the torsional equilibrium position observed during integrator failure failed to counterroll, showing a torsional shift of only 0.3 degrees (+/-0.6 degrees SE). This result contradicted the direct tonic input model, but was consistent with models that implement counterroll by a neurally integrated pulse.
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Affiliation(s)
- J Douglas Crawford
- Canadian Institutes for Health Research Group for Action and Perception, York University, Toronto, Ontario M3J 1P3, Canada.
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Abstract
The coordination of head tilt, ocular counter-roll and vertical vergence is maintained by adaptive mechanisms; the desired outcome being clear single vision. A disruption or imbalance in otolith-ocular pathways may result in diplopia which stimulates these adaptive processes. In the present experiment, dove prisms were used to create cyclodisparities that varied with head tilt about a naso-occipital axis (roll). A stimulus for incyclovergence was presented with the head rolled 45 degrees to one side and a stimulus for an excyclovergence was presented with the head rolled 45 degrees to the other side. At the end of 1 h of training, all subjects demonstrated a change in open-loop cyclovergence that would help to correct for the cyclodisparities experienced during the closed-loop training period. The change appeared to be a simple gain change in the ocular counter-roll of one or both eyes.
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Affiliation(s)
- J S Maxwell
- Vision Science Group, School of Optometry, University of California at Berkeley 94720-2020, USA
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Abstract
When the head is inclined sideways, the eyes are counter-rotated with respect to the head (ocular-counterroll, OCR). In man, the gain of OCR in static body tilts is limited to about 10% of the angle of roll tilt, which suggests that its function is vestigial. However, it is still unclear how the residual OCR is related to the perceived orientation of visual stimuli. Wade and Curthoys (1997) claim that the brain does not “take into account” the OCR, so that the eye position directly interferes with perception of visual orientation. Alternately, it has been argued that OCR is partly compensated by an extraretinal eye-position information such as, e.g., an efference copy ( Haustein, 1992 ; Haustein & Mittelstaedt, 1990 ). The two experiments reported in this study are targeted towards critically examining this inter-relation between OCR and perceived visual orientation. The latter was assessed via the subjective visual vertical, SVV, which is determined when a subject judges the orientation of an indicator (e.g., a short line segment) as apparently vertical. The OCR was measured by using a video-oculographic system. In Experiment 1, a human centrifuge was used to test the effect of an increase of the gravito-inertial force (GIF) on SVV and OCR. Experiment 2 was inspired by the fact that OCR can also be elicited during “barbecue rotation”. Again, it was the aim to compare OCR and SVV in different body positions, such as pure roll and barbecue rotated tilts. The present study provides convincing experimental evidence that SVV is widely uninfluenced by the course of OCR. Increasing the GIF in Experiment 1 had a divergent effect on SVV and OCR; the gain of OCR increases whereas the SVV changed differently, at obtuse tilt angles even in the opposite direction. OCR and SVV were again found to dissociate in Experiment 2, which emphasizes the fact that the SVV and OCR are not controlled by the same neural mechanism, but rather use different spatial reference information.
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Abstract
Binocular visual feedback is used to continually calibrate binocular eye alignment so that the retinal images of the two eyes remain in correspondence. Past experiments have shown that vertical eye alignment (measured as vertical phoria) can be altered by training to disparities that vary as a function of orbital eye position. The present experiments demonstrate that vertical eye alignment can also be trained to differ with head position when eye position (with respect to the orbit) is held constant. Changes in head position were about either an earth-vertical or earth-horizontal axis to distinguish otolith-ocular related adaptation from cervical-ocular related adaptation. Changes in head position were implemented by either by rotating the whole body (WB) or by rotating the head with the body stationary (HO). Following training, adaptation of eye alignment was observed in all cases of rotation about an earth-horizontal axis and for HO pitch rotations about an earth-vertical axis. The results illustrate the ability of the oculomotor system to compensate for imbalances in otolith-ocular pathways.
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Affiliation(s)
- J S Maxwell
- University of California, Berkeley 94720-2020, USA
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Seidman SH, Leigh RJ, Tomsak RL, Grant MP, Dell'Osso LF. Dynamic properties of the human vestibulo-ocular reflex during head rotations in roll. Vision Res 1995; 35:679-89. [PMID: 7900306 DOI: 10.1016/0042-6989(94)00151-b] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We investigated the dynamic properties of the human vestibulo-ocular reflex (VOR) during roll head rotations in three human subjects using the magnetic search coil technique. In the first of two experiments, we quantify the behavior of the ocular motor plant in the torsional plane. The subject's eye was mechanically displaced into intorsion, extorsion or abduction, and the dynamic course of return of the eye to its resting position was measured. The mean predominant time constants of return were 210 msec from intorsion, 83 msec from extorsion, and 217 msec from abduction, although there was considerable variability of results from different trials and subjects. In the second experiment, we quantify the efficacy of velocity-to-position integration of the vestibular signal. Position-step stimuli were used to test the torsional or horizontal VOR, being applied with subjects heads erect or supine. After a torsional position-step, the eye drifted back to its resting position, but after a horizontal position-step the eye held its new horizontal position. To interpret these responses we used a simple model of the VOR with parameters of the ocular motor plant set to values determined during Exp 1. The time constant of the velocity-to-position neural integrator was smaller (typically 2 sec) in the torsional plane than in the horizontal plane (> 20 sec). No disconjugacy of torsional eye movements was observed. Thus, the dynamic properties of the VOR in roll differ significantly from those of the VOR in yaw, reflecting different visual demands placed on this reflex in these two planes.
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Affiliation(s)
- S H Seidman
- Department of Biomedical Engineering, Department of Veterans Affairs Medical Center, Cleveland, Ohio
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