The Vestibulo-ocular Reflex During Active Head Motion in Chiari II Malformation

Background:Chiari type II malformation (CII) is a developmental anomaly of the cerebellum and brainstem, which are important structures for processing the vestibulo-ocular reflex (VOR). We investigated the effects of the deformity of CII on the angular VOR during active head motion.Methods:Eye and head movements were recorded using an infrared eye tracker and magnetic head tracker in 20 participants with CII [11 males, age range 8-19 years, mean (SD) 14.4 (3.2) years]. Thirty-eight age-matched healthy children and adolescents (21 males) constituted the control group. Participants were instructed to ‘look’ in darkness at the position of their thumb, placed 25 cm away, while they made horizontal and vertical sinusoidal head rotations at frequencies of about 0.5 Hz and 2 Hz. Parametric and non-parametric tests were used to compare the two groups.Results:The VOR gains, the ratio of eye to head velocities, were abnormally low in two participants with CII and abnormally high in one participant with CII.Conclusion:The majority of participants with CII had normal VOR performance in this investigation. However, the deformity of CII can impair the active angular VOR in some patients with CII. Low gain is attributed to brainstem damage and high gain to cerebellar dysfunction.

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Cervico-ocular Reflex Is Increased in People With Nonspecific Neck Pain

Physical Therapy ◽

10.2522/ptj.20150211 ◽

2016 ◽

Vol 96 (8) ◽

pp. 1190-1195 ◽

Cited By ~ 11

Author(s):

Jurryt de Vries ◽

Britta K. Ischebeck ◽

Lennard P. Voogt ◽

Malou Janssen ◽

Maarten A. Frens ◽

...

Keyword(s):

Neck Pain ◽

Head Movements ◽

Control Group ◽

Pain Group ◽

Cross Sectional ◽

Ocular Reflex ◽

Afferent Information ◽

Vestibulo Ocular Reflex ◽

Cross Sectional Design ◽

Tracking Device

Abstract Background Neck pain is a widespread complaint. People experiencing neck pain often present an altered timing in contraction of cervical muscles. This altered afferent information elicits the cervico-ocular reflex (COR), which stabilizes the eye in response to trunk-to-head movements. The vestibulo-ocular reflex (VOR) elicited by the vestibulum is thought to be unaffected by afferent information from the cervical spine. Objective The aim of the study was to measure the COR and VOR in people with nonspecific neck pain. Design This study utilized a cross-sectional design in accordance with the STROBE statement. Methods An infrared eye-tracking device was used to record the COR and the VOR while the participant was sitting on a rotating chair in darkness. Eye velocity was calculated by taking the derivative of the horizontal eye position. Parametric statistics were performed. Results The mean COR gain in the control group (n=30) was 0.26 (SD=0.15) compared with 0.38 (SD=0.16) in the nonspecific neck pain group (n=37). Analyses of covariance were performed to analyze differences in COR and VOR gains, with age and sex as covariates. Analyses of covariance showed a significantly increased COR in participants with neck pain. The VOR between the control group, with a mean VOR of 0.67 (SD=0.17), and the nonspecific neck pain group, with a mean VOR of 0.66 (SD=0.22), was not significantly different. Limitations Measuring eye movements while the participant is sitting on a rotating chair in complete darkness is technically complicated. Conclusions This study suggests that people with nonspecific neck pain have an increased COR. The COR is an objective, nonvoluntary eye reflex and an unaltered VOR. This study shows that an increased COR is not restricted to patients with traumatic neck pain.

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Vestibular adaptation to centrifugation does not transfer across planes of head rotation

Journal of Vestibular Research ◽

10.3233/ves-2008-18103 ◽

2008 ◽

Vol 18 (1) ◽

pp. 25-37

Author(s):

Ian Garrick-Bethell ◽

Thomas Jarchow ◽

Heiko Hecht ◽

Laurence R. Young

Keyword(s):

Sagittal Plane ◽

Head Rotation ◽

Head Movements ◽

Control Group ◽

Illusory Motion ◽

Ocular Reflex ◽

Before And After ◽

Out Of Plane ◽

Vestibulo Ocular Reflex ◽

Axis Rotation

Out-of-plane head movements performed during fast rotation produce non-compensatory nystagmus, sensations of illusory motion, and often motion sickness. Adaptation to this cross-coupled Coriolis stimulus has previously been demonstrated for head turns made in the yaw (transverse) plane of motion, during supine head-on-axis rotation. An open question, however, is if adaptation to head movements in one plane of motion transfers to head movements performed in a new, unpracticed plane of motion. Evidence of transfer would imply the brain builds up a generalized model of the vestibular sensory-motor system, instead of learning a variety of individual input/output relations separately. To investigate, over two days 9 subjects performed pitch head turns (sagittal plane) while rotating, before and after a series of yaw head turns while rotating. A Control Group of 10 subjects performed only the pitch movements. The vestibulo-ocular reflex (VOR) and sensations of illusory motion were recorded in the dark for all movements. Upon comparing the two groups we failed to find any evidence of transfer from the yaw plane to the pitch plane, suggesting that adaptation to cross-coupled stimuli is specific to the particular plane of head movement. The findings have applications for the use of centrifugation as a possible countermeasure for long duration spaceflight. Adapting astronauts to unconstrained head movements while rotating will likely require exposure to head movements in all planes and directions.

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The Vestibular and Optokinetic Systems

Eye Movement Disorders ◽

10.1093/oso/9780195324266.003.0009 ◽

2008 ◽

Author(s):

Agnes Wong

Keyword(s):

Visual Information ◽

Brain Structures ◽

Head Movements ◽

Head Motion ◽

Ocular Reflex ◽

Vestibulo Ocular Reflex ◽

Position And Orientation ◽

Change Position ◽

Direction Information ◽

Eye Velocity

The vestibulo-ocular and optokinetic reflexes are the earliest eye movements to appear phylogenetically. The vestibulo-ocular reflex (VOR) stabilizes retinal images during head motion by counter-rotating the eyes at the same speed as the head but in the opposite direction. Information about head motion passes from the vestibular sensors in the inner ear to the VOR circuitry within the brainstem, which computes an appropriate eye velocity command. The eyes, confined in their bony orbits, normally do not change position, and their motion relative to the head is restricted to a change in orientation. However, the head can both change position and orientation relative to space. Thus, the function of the VOR is to generate eye orientation that best compensates for changes in position and orientation of the head. Because the drive for this reflex is vestibular rather than visual, it operates even in darkness. To appreciate the benefits of having our eyes under vestibular and not just visual control, hold a page of text in front of you, and oscillate it back and forth horizontally at a rate of about two cycles per second. You will find that the text is blurred. However, if you hold the page still and instead oscillate your head at the same rate, you will be able to read the text clearly. This is because when the page moves, only visual information is available. Visual information normally takes about 100 msec to travel from the visual cortices, through a series of brain structures, to the ocular motoneurons that move the eyes. This delay is simply too long for the eyes to keep up with the oscillating page. However, when the head moves, both vestibular and visual information are available. Vestibular information takes only about 7–15 msec to travel from the vestibular sensors, through the brainstem, to the ocular motoneurons. With this short latency, the eyes can easily compensate for the rapid oscillation of the head. Thus, damages to the vestibular system often cause oscillopsia, an illusion of motion in the stationary environment, especially during head movements.

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The vertical vestibulo-ocular reflex, and its interaction with vision during active head motion: Effects of aging

Journal of Vestibular Research ◽

10.3233/ves-2001-11102 ◽

2001 ◽

Vol 11 (1) ◽

pp. 3-12

Author(s):

Ji Soo Kim ◽

James A. Sharpe

Keyword(s):

Smooth Pursuit ◽

Low Frequency ◽

The Elderly ◽

Head Motion ◽

Head Tracking ◽

Elderly Age ◽

Ocular Reflex ◽

Visual Enhancement ◽

Vestibulo Ocular Reflex ◽

Effects Of Aging

The effects of aging on the vertical vestibulo-ocular reflex (VOR), and its interactions with vision during active head motion had not been investigated. We measured smooth pursuit, combined eye-head tracking, the VOR, and its visual enhancement and cancellation during active head motion in pitch using a magnetic search coil technique in 21 younger (age < 65) and 10 elderly (age ⩾ 65) subjects. With the head immobile, subjects pursued a target moving sinusoidally with a frequency range of 0.125 to 2.0 Hz, and with peak target accelerations (PTAs) ranging from 12 to 789Âř/s 2 . Combined eye-head tracking, the VOR in darkness, and its visual enhancement during fixation of an earth-fixed target (VVOR) were measured during active sinusoidal head motion with a peak-to-peak amplitude of 20Âř at frequencies of 0.25, 0.5, 1.0 and 2.0 Hz. The efficacy of VOR cancellation was determined from VOR gains during combined eye-head tracking. VOR and VVOR gains were symmetrical in both directions and did not change with aging, except for reduced gains of the downward VOR and VVOR at low frequency (0.25 Hz). However, in the elderly, smooth pursuit, and combined eye-head tracking gains and the efficacy of cancellation of the VOR were significantly lower than in younger subjects. In both the young and elderly groups, VOR gain in darkness did not vary with the frequency of active head motion while the gains of smooth pursuit, combined eye-head tracking, and VVOR declined with increasing target frequency. VOR and VVOR performance in the elderly implicates relative preservation of neural structures subserving vertical vestibular smooth eye motion in senescence.

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Active head movements facilitate compensation for effects of prism displacement on dynamic gait12

Journal of Vestibular Research ◽

10.3233/ves-2006-161-203 ◽

2006 ◽

Vol 16 (1-2) ◽

pp. 29-33

Author(s):

Kim R. Gottshall ◽

Michael E. Hoffer ◽

Helen S. Cohen ◽

Robert J. Moore

Keyword(s):

Head Movement ◽

Sensory Modality ◽

Normal Subjects ◽

The Body ◽

Head Movements ◽

Head Motion ◽

Control Group ◽

Entire Body ◽

Group 3 ◽

Group 2

Study design: Four groups, between-subjects study. Objectives: To investigate the effects of exercise on adaptation of normal subjects who had been artificially spatially disoriented. Background: Many patients referred for rehabilitation experience sensory changes, due to age or disease processes, and these changes affect motor skill. The best way to train patients to adapt to these changes and to improve their sensorimotor skills is unclear. Using normal subjects, we tested the hypothesis that active, planned head movement is needed to adapt to modified visual input. Methods and measures: Eighty male and female subjects who had normal balance on computerized dynamic posturography (CDP) and the dynamic gait index (DGI), were randomly assigned to four groups. All groups donned diagonally shift lenses and were again assessed with CDP and DGI. The four groups were then treated for 20 min. Group 1 (control group) viewed a video, Group 2 performed exercise that involved translating the entire body through space, but without separate, volitional head movement, Group 3 performed exercises which all incorporated volitional, planned head rotations, and Group 4 performed exercises that involved translating the body (as in Group 2) and incorporated volitional, planned head motion (as in Group 3). All subjects were post-tested with CDP and DGI, lenses were removed, and subjects were retested again with CDP and DGI. Results: The groups did not differ significantly on CDP scores but Groups 3 and 4 had significantly better DGI scores than Groups 1 and 2. Conclusions: Active head movement that is specifically planned as part of the exercise is more effective than passive attention or head movements that are not consciously planned, for adapting to sensorimotor change when it incorporates active use of the changed sensory modality, in this case head motion.

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

Audiology and Neurotology ◽

10.1159/000493845 ◽

2018 ◽

Vol 23 (5) ◽

pp. 285-289 ◽

Cited By ~ 2

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.

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Evaluation of depression and self-esteem in children with monosymptomatic nocturnal enuresis: A controlled trial

Archivio Italiano di Urologia e Andrologia ◽

10.4081/aiua.2014.3.212 ◽

2014 ◽

Vol 86 (3) ◽

pp. 212 ◽

Cited By ~ 7

Author(s):

Orhan Koca ◽

Mehmet Akyüz ◽

Bilal Karaman ◽

Zeynep Yesim Özcan ◽

Metin Öztürk ◽

...

Keyword(s):

Children And Adolescents ◽

Nocturnal Enuresis ◽

Depression Scale ◽

Self Esteem ◽

Control Group ◽

Case Group ◽

Healthy Children ◽

Significant Difference ◽

Monosymptomatic Nocturnal Enuresis ◽

Age Range

Objectives: Nocturnal enuresis (NE) is very common and is one of the most common causes for patients to be admitted to urology, pediatrics, child psychiatry and child surgery departments. We aimed to investigate the effect on depression and self-esteem of this disorder that can cause problems on person's social development and human relations. Material and methods: 90 patients who were admitted to our clinic with complaints of nocturnal enuresis were enrolled. Investigations to rule out organic causes were performed in this group of patients. Out of them 38 children and adolescents (age range 8-18 years) with primary monosymptomatic nocturnal enuresis (PMNE) agreed to participate in the study In the same period 46 healthy children and adolescents with a similar age range without bed wetting complaint were included in the study as a control group. The age of the family, educational and socioeconomic level were questioned and Piers-Harris Children's Self-Concept Scale (PHCSCS) and Children's Depression Inventory (CDI) forms were filled out. Results: Mean age of the cases (18 females or 47.4% and 20 males or 52.6%) was 10.76 ± 3.82 years whereas mean age of controls (26 females or 56.5% and 20 males or 43.5%) was 10.89 ± 3.11 years. Depression scale was significantly higher (p = 0.001) in the case group than in the control group (10.42 ± 4.31 vs 7.09 ± 4.35). In both groups there was no statistically significant difference by age and sex in terms of depression scale (p > 0.05). Conclusion: NE is widely seen as in the community and is a source of stresses either for children and for their families. When patients were admitted to physicians for treatment, a multidisciplinary approach should be offered and the necessary psychological support should be provided jointly by child psychiatrists and psychologists.

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

Journal of Vestibular Research ◽

10.3233/ves-1991-1207 ◽

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.

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