Apparent head position as a basis for a visual aftereffect of prolonged head tilt

N. J. Wade; R. H. Day

doi:10.3758/bf03212477

Gravity-Specific Adaptation of the Angular Vestibuloocular Reflex: Dependence on Head Orientation With Regard to Gravity

Journal of Neurophysiology ◽

10.1152/jn.00287.2002 ◽

2003 ◽

Vol 89 (1) ◽

pp. 571-586 ◽

Cited By ~ 27

Author(s):

Sergei B. Yakushin ◽

Theodore Raphan ◽

Bernard Cohen

Keyword(s):

Head Tilt ◽

Vertical Axis ◽

Continuous Functions ◽

Head Position ◽

Head Orientation ◽

Vestibuloocular Reflex ◽

Specific Adaptation ◽

Gain Adaptation ◽

Bias Level ◽

Single State

The gain of the vertical angular vestibuloocular reflex (aVOR) was adaptively altered by visual-vestibular mismatch during rotation about an interaural axis, using steps of velocity in three head orientations: upright, left-side down, and right-side down. Gains were decreased by rotating the animal and visual surround in the same direction and increased by visual and surround rotation in opposite directions. Gains were adapted in one head position (single-state adaptation) or decreased with one side down and increased with the other side down (dual-state adaptation). Animals were tested in darkness using sinusoidal rotation at 0.5 Hz about an interaural axis that was tilted from horizontal to vertical. They were also sinusoidally oscillated from 0.5 to 4 Hz about a spatial vertical axis in static tilt positions from yaw to pitch. After both single- and dual-state adaptation, gain changes were maximal when the monkeys were in the position in which the gain had been adapted, and the gain changes progressively declined as the head was tilted away from that position. We call this gravity-specific aVOR gain adaptation. The spatial distribution of the specific aVOR gain changes could be represented by a cosine function that was superimposed on a bias level, which we called gravity-independent gain adaptation. Maximal gravity-specific gain changes were produced by 2–4 h of adaptation for both single- and dual-state adaptations, and changes in gain were similar at all test frequencies. When adapted while upright, the magnitude and distribution of the gravity-specific adaptation was comparable to that when animals were adapted in side-down positions. Single-state adaptation also produced gain changes that were independent of head position re gravity particularly in association with gain reduction. There was no bias after dual-state adaptation. With this difference, fits to data obtained by altering the gain in separate sessions predicted the modulations in gain obtained from dual-state adaptations. These data show that the vertical aVOR gain changes dependent on head position with regard to gravity are continuous functions of head tilt, whose spatial phase depends on the position in which the gain was adapted. From their different characteristics, it is likely that gravity-specific and gravity-independent adaptive changes in gain are produced by separate neural processes. These data demonstrate that head orientation to gravity plays an important role in both orienting and tuning the gain of the vertical aVOR.

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An Interdisciplinary Approach to Improve Head Tilt in Pediatric Torticollis Patients with the Use of Prism Glasses

Vision Development & Rehabilitation ◽

10.31707/vdr2021.7.4.p235 ◽

2021 ◽

pp. 235-244

Keyword(s):

Physical Therapy ◽

Manual Therapy ◽

Motor Development ◽

Depth Perception ◽

Physical Therapists ◽

Physical Therapist ◽

Treatment Options ◽

Head Tilt ◽

Head Position ◽

Full Time

Background: Infants with head tilts are most often diagnosed with torticollis and are referred to a pediatric physical therapist for evaluation and treatment. Determining if the head position is muscular or non-muscular when assessing these infants is key in making the appropriate referrals to other specialists and determining the best treatment approach. Most pediatric physical therapists treat patients with head tilts with manual therapy (i.e. massage, myofascial release, and passive/active range of motion). Many physical therapists only consider a visual etiology as a possibility after other treatment options have been exhausted and the head tilt persists. Although the incidence of torticollis has increased, based on the author’s experience, the number of cases of non-muscular etiology has also increased. There is a lack of current research on the use of prism glasses for treating head tilts in young children and infants carrying a diagnosis of torticollis, especially those presenting without any active/passive motion limitations. Traditionally, these patients undergo years of treatment without resolution of the head tilt. Case Report: A two-year-old patient initially presented with a diagnosis of torticollis with an intermittent and alternating head tilt for physical therapy. After several months of manual therapy, with little improvement in her head posture, the patient’s physical therapist referred her to a behavioral optometrist for a comprehensive vision examination and to pursue alternative treatment options. The optometric evaluation revealed ocular misalignment causing poor depth perception skills and prism glasses were prescribed full-time with the recommendation of continuing physical therapy for gross motor development. Conclusion: Prism glasses are an appropriate treatment consideration for some pediatric patients with persistent head tilts because they can provide immediate improvement in head position and depth perception. It is important to include optometrists in the multi-disciplinary team when working with patients with head tilts. Pediatric physical therapists would benefit from training on how to properly screen visual skills when evaluating children with head tilts. With such training, an appropriate optometric referral could be initiated early on in treatment.

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Comparative analysis of head-tilt and forward head position during laptop use between females with postural induced headache and healthy controls

Journal of Bodywork and Movement Therapies ◽

10.1016/j.jbmt.2015.11.015 ◽

2016 ◽

Vol 20 (3) ◽

pp. 533-541 ◽

Cited By ~ 6

Author(s):

Sarah Mingels ◽

Wim Dankaerts ◽

Ludo van Etten ◽

Herbert Thijs ◽

Marita Granitzer

Keyword(s):

Comparative Analysis ◽

Head Tilt ◽

Head Position ◽

Healthy Controls

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Spatial Distribution of Gravity-Dependent Gain Changes in the Vestibuloocular Reflex

Journal of Neurophysiology ◽

10.1152/jn.01269.2004 ◽

2005 ◽

Vol 93 (6) ◽

pp. 3693-3698 ◽

Cited By ~ 15

Author(s):

Sergei B. Yakushin ◽

Yongqing Xiang ◽

Theodore Raphan ◽

Bernard Cohen

Keyword(s):

Dimensional Space ◽

Three Dimensional ◽

Head Tilt ◽

Fundamental Property ◽

Head Position ◽

Three Dimensions ◽

Vestibuloocular Reflex ◽

Gain Adaptation ◽

The Stability ◽

Three Dimensional Space

This study determined whether dependence of angular vestibuloocular reflex (aVOR) gain adaptation on gravity is a fundamental property in three dimensions. Horizontal aVOR gains were adaptively increased or decreased in two cynomolgus monkeys in upright, side down, prone, and supine positions, and aVOR gains were tested in darkness by yaw rotation with the head in a wide variety of orientations. Horizontal aVOR gain changes peaked at the head position in which the adaptation took place and gradually decreased as the head moved away from this position in any direction. The gain changes were plotted as a function of head tilt and fit with a sinusoid plus a bias to obtain the gravity-dependent (amplitude) and gravity-independent (bias) components. Peak-to-peak gravity-dependent gain changes in planes containing the position of adaptation and the magnitude of the gravity-independent components were both ∼25%. We assumed that gain changes over three-dimensional space could be described by a sinusoid the amplitude of which also varied sinusoidally. Using gain changes obtained from the head position in which the gains were adapted, a three-dimensional surface was generated that was qualitatively similar to a surface obtained from the experimental data. This extends previous findings on vertical aVOR gain adaptation in one plane and introduces a conceptual framework for understanding plasticity in three dimensions: aVOR gain changes are composed of two components, one of which depends on head position relative to gravity. It is likely that this gravitational dependence optimizes the stability of retinal images during movement in three-dimensional space.

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Head Position Identification

Journal of Speech and Hearing Research ◽

10.1044/jshr.1003.438 ◽

1967 ◽

Vol 10 (3) ◽

pp. 438-448

Author(s):

H. N. Wright

Keyword(s):

Roc Curve ◽

Head Position ◽

Hearing Impaired ◽

Type Ii ◽

Experimental Conditions ◽

Partial Explanation ◽

Complex Sounds ◽

Binaural Cues ◽

Criterion Behavior ◽

Stimulus Degradation

A binaural recording of traffic sounds that reached an artificial head oriented in five different positions was presented to five subjects, each of whom responded under four different criteria. The results showed that it is possible to examine the ability of listeners to localize sound while listening through earphones and that the criterion adopted by an individual listener is independent of his performance. For the experimental conditions used, the Type II ROC curve generated by manipulating criterion behavior was linear and consistent with a guessing model. Further experiments involving different degrees of stimulus degradation suggested a partial explanation for this finding and illustrated the various types of monaural and binaural cues used by normal and hearing-impaired listeners to localize complex sounds.

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