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Cheng Y, Zhang Y, Chen F, Chen Z, Xue T, Zhang Q, Xu M. Virtual reality for the measurement of SVV and SVH during static head tilt in healthy adults: a novel vestibular test. Acta Otolaryngol 2022; 142:291-297. [PMID: 35382691 DOI: 10.1080/00016489.2022.2058082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
BACKGROUND AND OBJECTIVE Few previous studies have used virtual-reality (VR) technology to measure subjective visual vertical (SVV) and subjective visual horizontal (SVH) during static head tilt (0°, 30°, 45°, 60° and 90°). We propose a novel vestibular test for measuring the normal range of SVV and SVH during static head tilt in healthy adults. METHODS Eighty healthy adults were included in the study. SVV and SVH were calculated in nine head positions. RESULTS With head tilt 90° to the right, SVV skewed to the right, and SVH skewed upward. With head tilt 90° to the left, SVV skewed to the left, and SVH skewed downward. SVV was asymmetrical only at a head tilt of 90°. SVV and SVH were similar at all degrees of head tilt, except for 30° to the right, 45° to the left, and 0°. CONCLUSIONS VR measurements showed that SVV and SVH differed at various degrees of static head tilt. The standardized protocol proposed here may be used to establish a reference range for utricle function when evaluating acute, unilateral vestibular lesions.
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Affiliation(s)
- Ying Cheng
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi’an, China
| | - Yuzhong Zhang
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi’an, China
| | - Feiyun Chen
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi’an, China
| | - Zichen Chen
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi’an, China
| | - Tingting Xue
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi’an, China
| | - Qing Zhang
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi’an, China
- Xinhua Hospital of Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Min Xu
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi’an, China
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2
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Jung Kim M, Otero-Millan J, Tian J, Kheradmand A. Psychophysical Haptic Measurement of Vertical Perception: Elucidating a Hand Sensory Bias. Neuroscience 2022; 481:21-29. [PMID: 34848259 PMCID: PMC8817686 DOI: 10.1016/j.neuroscience.2021.11.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 01/17/2023]
Abstract
The primary sensory modality for probing spatial perception can vary among psychophysical paradigms. In the subjective visual vertical (SVV) task, the brain must account for the position of the eye within the orbit to generate an estimate of a visual line orientation, whereas in the subjective haptic vertical (SHV) task, the position of the hand is used to sense the orientation of a haptic bar. Here we investigated whether a hand sensory bias can affect SHV measurement. We measured SHV in 12 subjects (6 left-handed and 6 right-handed) with a forced-choice paradigm using their left and right hands separately. The SHV measurement was less accurate than the SVV measurements (-0.6 ± 0.7) and it was biased in the direction of the hand used in the task but was not affected by handedness; SHV left hand -6.8 ± 2.1° (left-handed -7.9 ± 3.6°, right-handed -5.8 ± 2.5°) and right hand 9.8 ± 1.5° (left-handed 7.4 ± 2.2°, right-handed 12.3 ± 1.8°). SHV measurement with the same hand was also affected by the haptic bar placement on the left or right side versus midline, showing a side effect (left vs midline -2.0 ± 1.3°, right vs midline 3.8 ± 1.7°). Midline SHV measures using the left and right hands were different, confirming a laterality effect (left hand -4.5 ± 1.7°, right hand 6.4 ± 2.0°). These results demonstrate a sensory bias in SHV measurement related to the effects of both hand-in-body (i.e., right vs left hand) and hand-in-space positions. Such modality-specific bias may result in disparity between SHV and SVV measurements, and therefore cannot be generalized to vertical or spatial perception.
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Affiliation(s)
- Min Jung Kim
- Department of Neurology, The Johns Hopkins University, Baltimore, MD, USA,Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD, USA
| | - Jorge Otero-Millan
- Department of Neurology, The Johns Hopkins University, Baltimore, MD, USA,School of Optometry, University of California, Berkeley, Berkeley, CA
| | - Jing Tian
- Department of Neurology, The Johns Hopkins University, Baltimore, MD, USA
| | - Amir Kheradmand
- Department of Neurology, The Johns Hopkins University, Baltimore, MD, USA,Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University, Baltimore, MD, USA,Department of Neuroscience, The Johns Hopkins University, Baltimore, MD, USA,Laboratory for Computational Sensing and Robotics (LCSR), The Johns Hopkins University, Baltimore, MD, USA
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3
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Wedtgrube A, Bockisch C, Tarnutzer A. Effects of prolonged roll-tilt on the subjective visual and haptic vertical in healthy human subjects. J Vestib Res 2020; 30:1-16. [DOI: 10.3233/ves-200690] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- A. Wedtgrube
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
| | - C.J. Bockisch
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
- Department of Otorhinolaryngology, University Hospital Zurich, Zurich, Switzerland
- Department of Ophthalmology, University Hospital Zurich, Zurich, Switzerland
- Faculty of Medicine, University of Zurich, Switzerland
- Center of Clinical Neurosciences, University Hospital Zurich, Switzerland
| | - A.A. Tarnutzer
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
- Faculty of Medicine, University of Zurich, Switzerland
- Center of Clinical Neurosciences, University Hospital Zurich, Switzerland
- Cantonal Hospital of Baden, Baden, Switzerland
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4
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Dockheer KM, Bockisch CJ, Tarnutzer AA. Effects of Optokinetic Stimulation on Verticality Perception Are Much Larger for Vision-Based Paradigms Than for Vision-Independent Paradigms. Front Neurol 2018; 9:323. [PMID: 29867732 PMCID: PMC5954029 DOI: 10.3389/fneur.2018.00323] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 04/24/2018] [Indexed: 01/08/2023] Open
Abstract
Introduction Verticality perception as assessed by the subjective visual vertical (SVV) is significantly biased by a rotating optokinetic stimulus. The underlying mechanisms of this effect remain open. Potentially, the optokinetic stimulus induces a shift of the internal estimate of the direction of gravity. This hypothesis predicts a shift of perceived vertical using other, non-vision dependent, paradigms as well. Alternatively, an optokinetic stimulus may only induce a shift of visual orientation, and so would be task specific. Methods To test this prediction, both vision-dependent SVV and vision-independent [subjective haptic vertical (SHV)] paradigms were applied. In 12 healthy human subjects, perceived vertical was measured in different whole-body roll positions (up to ±120°, steps = 30°) while watching a clockwise or counterclockwise rotating optokinetic stimulus. For comparison, baseline trials were collected in darkness. A generalized linear model was applied for statistical analysis. Results A significant main effect for optokinetic stimulation was noted both for the SVV paradigm (p < 0.001) and the SHV paradigm (p = 0.013). However, while pairwise comparisons demonstrated significant optokinetic-induced shifts (p ≤ 0.035) compared to baseline in all roll-tilted orientations except 30° and 60° left-ear-down position and counterclockwise optokinetic stimulation for the SVV paradigm, significant shifts were found in only 1 of the 18 test conditions (120° left-ear-down roll orientation, counterclockwise optokinetic stimulation) for the SHV paradigm. Compared to the SHV, the SVV showed significantly (p < 0.001) larger shifts of perceived vertical when presenting a clockwise (15.3 ± 16.0° vs. 1.1 ± 5.2°, mean ± 1 SD) or counterclockwise (−12.6 ± 7.7° vs. −2.6 ± 5.4°) rotating optokinetic stimulus. Conclusion Comparing the effect of optokinetic stimulation on verticality perception in both vision-dependent and vision-independent paradigms, we demonstrated distinct patterns. While significant large and roll-angle dependent shifts were noted for the SVV, offsets were minor and reached significance only in one test condition for the SHV. These results suggest that optokinetic stimulation predominately affects vision-related mechanisms, possibly due to induced torsional eye displacements, and that any shifts of the internal estimate of the direction of gravity are relatively minor.
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Affiliation(s)
- Katja M Dockheer
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
| | - Christopher J Bockisch
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland.,Department of Otorhinolaryngology, University Hospital Zurich, Zurich, Switzerland.,Department of Ophthalmology, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Alexander A Tarnutzer
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
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5
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Precision of perceived direction of gravity in partial bilateral vestibulopathy correlates with residual utricular function. Clin Neurophysiol 2018; 129:934-945. [DOI: 10.1016/j.clinph.2018.02.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 01/05/2018] [Accepted: 02/09/2018] [Indexed: 11/16/2022]
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6
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Otero-Millan J, Winnick A, Kheradmand A. Exploring the Role of Temporoparietal Cortex in Upright Perception and the Link With Torsional Eye Position. Front Neurol 2018; 9:192. [PMID: 29681880 PMCID: PMC5897546 DOI: 10.3389/fneur.2018.00192] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 03/12/2018] [Indexed: 11/13/2022] Open
Abstract
Upright perception is a key aspect of orientation constancy, as we maintain a stable perception of the world despite continuous movements of our eyes, head, and body. Torsional position of the eyes can impact perception of upright by changing orientation of the images on the retina relative to gravity. Here, we investigated the role of temporoparietal cortex in upright perception with respect to ocular torsion, by means of the inhibitory effect of continuous theta burst transcranial magnetic stimulation (TMS). We used a subjective visual vertical (SVV) paradigm to track changes in upright perception, and a custom video method to track ocular torsion simultaneously. Twelve participants were tested during a lateral head tilt of 20° to the left. TMS at the posterior aspect of the supramarginal gyrus (SMGp) resulted in an average SVV shift in the opposite direction of the head tilt compared to a sham stimulation (1.8°). Ocular torsion following TMS at SMGp showed no significant change compared to the sham stimulation (-0.1°). Thus, changes in upright perception at SMGp were dissociated from ocular torsion. This finding suggests that perception of upright at SMGp is primarily related to sensory processing for spatial orientation, as opposed to subcortical regions that have direct influence on ocular torsion.
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Affiliation(s)
- Jorge Otero-Millan
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Ariel Winnick
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Amir Kheradmand
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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7
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Kheradmand A, Winnick A. Perception of Upright: Multisensory Convergence and the Role of Temporo-Parietal Cortex. Front Neurol 2017; 8:552. [PMID: 29118736 PMCID: PMC5660972 DOI: 10.3389/fneur.2017.00552] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/28/2017] [Indexed: 12/18/2022] Open
Abstract
We inherently maintain a stable perception of the world despite frequent changes in the head, eye, and body positions. Such "orientation constancy" is a prerequisite for coherent spatial perception and sensorimotor planning. As a multimodal sensory reference, perception of upright represents neural processes that subserve orientation constancy through integration of sensory information encoding the eye, head, and body positions. Although perception of upright is distinct from perception of body orientation, they share similar neural substrates within the cerebral cortical networks involved in perception of spatial orientation. These cortical networks, mainly within the temporo-parietal junction, are crucial for multisensory processing and integration that generate sensory reference frames for coherent perception of self-position and extrapersonal space transformations. In this review, we focus on these neural mechanisms and discuss (i) neurobehavioral aspects of orientation constancy, (ii) sensory models that address the neurophysiology underlying perception of upright, and (iii) the current evidence for the role of cerebral cortex in perception of upright and orientation constancy, including findings from the neurological disorders that affect cortical function.
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Affiliation(s)
- Amir Kheradmand
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Department of Otolaryngology – Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Ariel Winnick
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
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8
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Ward BK, Bockisch CJ, Caramia N, Bertolini G, Tarnutzer AA. Gravity dependence of the effect of optokinetic stimulation on the subjective visual vertical. J Neurophysiol 2017; 117:1948-1958. [PMID: 28148642 DOI: 10.1152/jn.00303.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 12/17/2022] Open
Abstract
Accurate and precise estimates of direction of gravity are essential for spatial orientation. According to Bayesian theory, multisensory vestibular, visual, and proprioceptive input is centrally integrated in a weighted fashion based on the reliability of the component sensory signals. For otolithic input, a decreasing signal-to-noise ratio was demonstrated with increasing roll angle. We hypothesized that the weights of vestibular (otolithic) and extravestibular (visual/proprioceptive) sensors are roll-angle dependent and predicted an increased weight of extravestibular cues with increasing roll angle, potentially following the Bayesian hypothesis. To probe this concept, the subjective visual vertical (SVV) was assessed in different roll positions (≤ ± 120°, steps = 30°, n = 10) with/without presenting an optokinetic stimulus (velocity = ± 60°/s). The optokinetic stimulus biased the SVV toward the direction of stimulus rotation for roll angles ≥ ± 30° (P < 0.005). Offsets grew from 3.9 ± 1.8° (upright) to 22.1 ± 11.8° (±120° roll tilt, P < 0.001). Trial-to-trial variability increased with roll angle, demonstrating a nonsignificant increase when providing optokinetic stimulation. Variability and optokinetic bias were correlated (R2 = 0.71, slope = 0.71, 95% confidence interval = 0.57-0.86). An optimal-observer model combining an optokinetic bias with vestibular input reproduced measured errors closely. These findings support the hypothesis of a weighted multisensory integration when estimating direction of gravity with optokinetic stimulation. Visual input was weighted more when vestibular input became less reliable, i.e., at larger roll-tilt angles. However, according to Bayesian theory, the variability of combined cues is always lower than the variability of each source cue. If the observed increase in variability, although nonsignificant, is true, either it must depend on an additional source of variability, added after SVV computation, or it would conflict with the Bayesian hypothesis.NEW & NOTEWORTHY Applying a rotating optokinetic stimulus while recording the subjective visual vertical in different whole body roll angles, we noted the optokinetic-induced bias to correlate with the roll angle. These findings allow the hypothesis that the established optimal weighting of single-sensory cues depending on their reliability to estimate direction of gravity could be extended to a bias caused by visual self-motion stimuli.
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Affiliation(s)
- Bryan K Ward
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland.,Department of Neurology, University Hospital Zurich and University of Zurich, Switzerland
| | - Christopher J Bockisch
- Department of Neurology, University Hospital Zurich and University of Zurich, Switzerland.,Department of Otorhinolaryngology, University Hospital Zurich and University of Zurich, Switzerland; and.,Department of Ophthalmology, University Hospital Zurich and University of Zurich, Switzerland
| | - Nicoletta Caramia
- Department of Neurology, University Hospital Zurich and University of Zurich, Switzerland
| | - Giovanni Bertolini
- Department of Neurology, University Hospital Zurich and University of Zurich, Switzerland
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9
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Kheradmand A, Gonzalez G, Otero-Millan J, Lasker A. Visual perception of upright: Head tilt, visual errors and viewing eye. J Vestib Res 2016; 25:201-9. [PMID: 26890421 DOI: 10.3233/ves-160565] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Perception of upright is often assessed by aligning a luminous line to the subjective visual vertical (SVV). OBJECTIVE Here we investigated the effects of visual line rotation and viewing eye on SVV responses and whether there was any change with head tilt. METHODS SVV was measured using a forced-choice paradigm and by combining the following conditions in 22 healthy subjects: head position (20° left tilt, upright and 20° right tilt), viewing eye (left eye, both eyes and right eye) and direction of visual line rotation (clockwise [CW] and counter clockwise [CCW]). RESULTS The accuracy and precision of SVV responses were not different between the viewing eye conditions in all head positions (P> 0.05, Kruskal-Wallis test). The accuracy of SVV responses was % significantly different between the CW and CCW line rotations (p ≈ 0.0001; Kruskal-Wallis test) and SVV was tilted in the same direction as the line rotation. This effect of line rotation was however not consistent across head tilts and was only present in the upright and right tilt head positions. The accuracy of SVV responses showed a higher variability among subjects in the left head tilt position with no significant difference between the CW and CCW line rotations (P> 0.05; post-hoc Dunn's test). CONCLUSIONS In spite of the challenges to the estimate of upright with head tilt, normal subjects did remarkably well irrespective of the viewing eye. The physiological significance of the asymmetry in the effect of line rotation between the head tilt positions is unclear but it %may suggest suggests a lateralizing effect of head tilt on the visual perception of upright.
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Affiliation(s)
- Amir Kheradmand
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Grisel Gonzalez
- Department of Ophthalmology, National Institute of Neurology and Neurosurgery, National Autonomous University of México, México City, México
| | - Jorge Otero-Millan
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Adrian Lasker
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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10
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Spatial orientation in patients with chronic unilateral vestibular hypofunction is ipsilesionally distorted. Clin Neurophysiol 2016; 127:3243-51. [DOI: 10.1016/j.clinph.2016.07.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/22/2016] [Accepted: 07/21/2016] [Indexed: 11/22/2022]
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11
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Piscicelli C, Nadeau S, Barra J, Pérennou D. Assessing the visual vertical: how many trials are required? BMC Neurol 2015; 15:215. [PMID: 26492863 PMCID: PMC4619006 DOI: 10.1186/s12883-015-0462-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Accepted: 10/06/2015] [Indexed: 11/26/2022] Open
Abstract
Background The visual vertical (VV) consists of repeated adjustments of a luminous rod to the earth vertical. How many trials are required to reach consistency in this measure? This question has never been addressed despite the widespread clinical use of the measurement in stroke rehabilitation. Methods VV perception was assessed (10 trials) in 117 patients undergoing rehabilitation after a first hemisphere stroke. The intraclass correlation coefficient (ICC) and standard error of measurement (SEM) were calculated for each patient category: with contralesional VV bias (n = 48), ipsilesional VV bias (n = 17) and normal VV (n = 52). Results For patients with VV biases, 6 trials were required to reach high inter-trial reliability (contralesional: ICC = 0.9, SEM = 1.36°; ipsilesional: ICC = 0.896, SEM = 0.96°). For patients with normal VV, a minimum of 10 trials was required (ICC = 0.728, SEM = 1.13°). A set of 6 trials correctly classified 96 % of patients. Conclusions In the literature, 10 is the most frequently used number of trials used to assess VV orientation. Our study shows that 10 trials are required to adequately measure VV orientation in non-selected subacute stroke patients. For complex protocols imposing a decrease in the number of trials in each condition, 6 trials are needed to identify VV biases in most patients.
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Affiliation(s)
- C Piscicelli
- Département de Rééducation Neurologique, Centre Hospitalier Universitaire de Grenoble, Grenoble, France. .,Laboratoire de Psychologie et Neurocognition CNRS UMR 5105, Grenoble Université, Grenoble, France.
| | - S Nadeau
- École de réadaptation, Université de Montréal and Centre de recherche interdisciplinaire en réadaptation (CRIR), Québec, Canada.
| | - J Barra
- Laboratoire Vision, Action, Cognition, Université Paris Descartes, Paris, EA7326, France.
| | - D Pérennou
- Département de Rééducation Neurologique, Centre Hospitalier Universitaire de Grenoble, Grenoble, France. .,Laboratoire de Psychologie et Neurocognition CNRS UMR 5105, Grenoble Université, Grenoble, France.
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Schwarz AJ, Straumann D, Tarnutzer AA. Diurnal Fluctuations of Verticality Perception - Lesser Precision Immediately after Waking up in the Morning. Front Neurol 2015; 6:195. [PMID: 26388837 PMCID: PMC4557077 DOI: 10.3389/fneur.2015.00195] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 08/20/2015] [Indexed: 11/30/2022] Open
Abstract
Internal estimates of direction of gravity are continuously updated by integrating vestibular, visual and proprioceptive input, and prior experience about upright position. Prolonged static roll-tilt biases perceived direction of gravity by adaptation of peripheral sensors and central structures. We hypothesized that in the morning after sleep, estimates of direction of gravity [assessed by the subjective visual vertical (SVV)] are less precise than in the evening because of adaptation to horizontal body position and lack of prior knowledge about upright position. Using a mobile SVV-measuring device, verticality perception was assessed in seven healthy human subjects on 7 days in the morning immediately after waking up and in the evening while sitting upright. Paired t-tests were applied to analyze diurnal changes in SVV trial-to-trial variability. Average SVV variability in the morning was significantly larger than in the evening (1.9 ± 0.6° vs. 0.9 ± 0.3°, p = 0.002). SVV accuracy was not significantly different (−1.2 ± 0.9° vs. −0.4 ± 0.4°, morning vs. evening, p = 0.058) and was within normal range (±2.3°) in all but one subject. A good night’s sleep has a profound effect on the brain’s ability to estimate direction of gravity. Resulting variability was significantly worse after waking up reaching values more than twice as large as in the evening while there was no significant impact on SVV accuracy. We hypothesize that lacking prior knowledge, adaptation of peripheral sensors, and lower levels of arousal and cerebral metabolism contribute to such impoverished estimates. Our observations have considerable clinical impact as they indicate an increased risk for falls and fall-related injuries in the morning.
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Affiliation(s)
| | - Dominik Straumann
- Department of Neurology, University Hospital Zurich, University of Zurich , Zurich , Switzerland
| | - Alexander A Tarnutzer
- Department of Neurology, University Hospital Zurich, University of Zurich , Zurich , Switzerland
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13
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Subjective Visual Vertical during Caloric Stimulation in Healthy Subjects: Implications to Research and Neurorehabilitation. Rehabil Res Pract 2015; 2015:367695. [PMID: 26161271 PMCID: PMC4460243 DOI: 10.1155/2015/367695] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 05/13/2015] [Indexed: 11/17/2022] Open
Abstract
Background. The subjective visual vertical (SVV) is a perception often impaired in patients with neurologic disorders and is considered a sensitive tool to detect otolithic dysfunctions. However, it remains unclear whether the semicircular canals (SCCs) are also involved in the visual vertical perception. Objective. The aim of this study was to analyze the influence of horizontal SCCs on SVV by caloric stimulation in healthy subjects. Methods. SVV was performed before and during the ice-cold caloric stimulation (4°C, right ear) in 30 healthy subjects. Results. The mean SVV tilts before and during the caloric stimulation were 0.31° ± 0.39 and −0.28° ± 0.40, respectively. There was no significant difference between the mean SVV tilts before and during stimulation (p = 0.113). Conclusion. These results suggest that horizontal SCCs do not influence SVV. Therefore, investigations and rehabilitation approaches for SVV misperceptions should be focused on otolithic and cognitive strategies.
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14
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Tarnutzer AA, Bockisch CJ, Straumann D, Marti S, Bertolini G. Static roll-tilt over 5 minutes locally distorts the internal estimate of direction of gravity. J Neurophysiol 2014; 112:2672-9. [PMID: 25185812 DOI: 10.1152/jn.00540.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The subjective visual vertical (SVV) indicates perceived direction of gravity. Even in healthy human subjects, roll angle-dependent misestimations, roll overcompensation (A-effect, head-roll > 60° and <135°) and undercompensation (E-effect, head-roll < 60°), occur. Previously, we demonstrated that, after prolonged roll-tilt, SVV estimates when upright are biased toward the preceding roll position, which indicates that perceived vertical (PV) is shifted by the prior tilt (Tarnutzer AA, Bertolini G, Bockisch CJ, Straumann D, Marti S. PLoS One 8: e78079, 2013). Hypothetically, PV in any roll position could be biased toward the previous roll position. We asked whether such a "global" bias occurs or whether the bias is "local". The SVV of healthy human subjects (N = 9) was measured in nine roll positions (-120° to +120°, steps = 30°) after 5 min of roll-tilt in one of two adaptation positions (±90°) and compared with control trials without adaptation. After adapting, adjustments were shifted significantly (P < 0.05) toward the previous adaptation position for nearby roll-tilted positions (±30°, ±60°) and upright only. We computationally simulated errors based on the sum of a monotonically increasing function (producing roll undercompensation) and a mixture of Gaussian functions (representing roll overcompensation centered around PV). In combination, the pattern of A- and E-effects could be generated. By shifting the function representing local overcompensation toward the adaptation position, the experimental postadaptation data could be fitted successfully. We conclude that prolonged roll-tilt locally distorts PV rather than globally shifting it. Short-term adaptation of roll overcompensation may explain these shifts and could reflect the brain's strategy to optimize SVV estimates around recent roll positions. Thus postural stability can be improved by visually-mediated compensatory responses at any sustained body-roll orientation.
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Affiliation(s)
- A A Tarnutzer
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland;
| | - C J Bockisch
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland; Department of Otorhinolaryngology, University Hospital Zurich, Zurich, Switzerland; and Department of Ophthalmology, University Hospital Zurich, Zurich, Switzerland
| | - D Straumann
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
| | - S Marti
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
| | - G Bertolini
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
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Tarnutzer AA, Bertolini G, Bockisch CJ, Straumann D, Marti S. Modulation of internal estimates of gravity during and after prolonged roll-tilts. PLoS One 2013; 8:e78079. [PMID: 24205099 PMCID: PMC3815095 DOI: 10.1371/journal.pone.0078079] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 09/16/2013] [Indexed: 11/18/2022] Open
Abstract
Perceived direction of gravity, as assessed by the subjective visual vertical (SVV), shows roll-angle dependent errors that drift over time and a bias upon return to upright. According to Bayesian observer theory, the estimated direction of gravity is derived from the posterior probability distribution by combining sensory input and prior knowledge about earth-vertical in a statistically optimal fashion. Here we aimed to further characterize the stability of SVV during and after prolonged roll-tilts. Specifically we asked whether the post-tilt bias is related to the drift pattern while roll-tilted. Twenty-nine healthy human subjects (23-56 yo) repetitively adjusted a luminous arrow to the SVV over periods of 5 min while upright, roll-tilted (± 45°, ± 90°), and immediately after returning to upright. Significant (p<0.05) drifts (median absolute drift-amplitude: 10°/5 min) were found in 71% (± 45°) and 78% (± 90°) of runs. At ± 90° roll-tilt significant increases in absolute adjustment errors were more likely (76%), whereas significant increases (56%) and decreases (44%) were about equally frequent at ± 45°. When returning to upright, an initial bias towards the previous roll-position followed by significant exponential decay (median time-constant: 71 sec) was noted in 47% of all runs (all subjects pooled). No significant correlations were found between the drift pattern during and immediately after prolonged roll-tilt. We conclude that the SVV is not stable during and after prolonged roll-tilt and that the direction and magnitude of drift are individually distinct and roll-angle-dependent. Likely sensory and central adaptation and random-walk processes contribute to drift while roll-tilted. Lack of correlation between the drift and the post-tilt bias suggests that it is not the inaccuracy of the SVV estimate while tilted that determines post-tilt bias, but rather the previous head-roll orientation relative to gravity. We therefore favor central adaptation, most likely a shift in prior knowledge towards the previous roll orientation, to explain the post-tilt bias.
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Affiliation(s)
| | - Giovanni Bertolini
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
| | - Christopher J. Bockisch
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
- Department of Otorhinolaryngology, University Hospital Zurich, Zurich, Switzerland
- Department of Ophthalmology, University Hospital Zurich, Zurich, Switzerland
| | - Dominik Straumann
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
| | - Sarah Marti
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
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Kheradmand A, Lasker A, Zee DS. Transcranial magnetic stimulation (TMS) of the supramarginal gyrus: a window to perception of upright. Cereb Cortex 2013; 25:765-71. [PMID: 24084127 DOI: 10.1093/cercor/bht267] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Although the pull of gravity, primarily detected by the labyrinth, is the fundamental input for our sense of upright, vision and proprioception must also be integrated with vestibular information into a coherent perception of spatial orientation. Here, we used transcranial magnetic stimulation (TMS) to probe the role of the cortex at the temporal parietal junction (TPJ) of the right cerebral hemisphere in the perception of upright. We measured the perceived vertical orientation of a visual line; that is, the subjective visual vertical (SVV), after a short period of continuous theta burst stimulation (cTBS) with the head upright. cTBS over the posterior aspect of the supramarginal gyrus (SMGp) in 8 right-handed subjects consistently tilted the perception of upright when tested with the head tilted 20° to either shoulder (right: 3.6°, left: 2.7°). The tilt of SVV was always in the direction opposite to the head tilt. On the other hand, there was no significant tilt after sham stimulation or after cTBS of nearby areas. These findings suggest that a small area of cerebral cortex--SMGp--has a role in processing information from different sensory modalities into an accurate perception of upright.
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Affiliation(s)
- Amir Kheradmand
- Department of Neurology Department of Otolaryngology-Head and Neck Surgery
| | | | - David S Zee
- Department of Neurology Department of Otolaryngology-Head and Neck Surgery Department of Ophthalmology Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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Bjasch D, Bockisch CJ, Straumann D, Tarnutzer AA. Differential effects of visual feedback on subjective visual vertical accuracy and precision. PLoS One 2012; 7:e49311. [PMID: 23152894 PMCID: PMC3495913 DOI: 10.1371/journal.pone.0049311] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 10/08/2012] [Indexed: 11/19/2022] Open
Abstract
The brain constructs an internal estimate of the gravitational vertical by integrating multiple sensory signals. In darkness, systematic head-roll dependent errors in verticality estimates, as measured by the subjective visual vertical (SVV), occur. We hypothesized that visual feedback after each trial results in increased accuracy, as physiological adjustment errors (A-/E-effect) are likely based on central computational mechanisms and investigated whether such improvements were related to adaptational shifts of perceived vertical or to a higher cognitive strategy. We asked 12 healthy human subjects to adjust a luminous arrow to vertical in various head-roll positions (0 to 120deg right-ear down, 15deg steps). After each adjustment visual feedback was provided (lights on, display of previous adjustment and of an earth-vertical cross). Control trials consisted of SVV adjustments without feedback. At head-roll angles with the largest A-effect (90, 105, and 120deg), errors were reduced significantly (p<0.001) by visual feedback, i.e. roll under-compensation decreased, while precision of SVV was not significantly (p>0.05) influenced. In seven subjects an additional session with two consecutive blocks (first with, then without visual feedback) was completed at 90, 105 and 120deg head-roll. In these positions the error-reduction by the previous visual feedback block remained significant over the consecutive 18-24 min (post-feedback block), i.e., was still significantly (p<0.002) different from the control trials. Eleven out of 12 subjects reported having consciously added a bias to their perceived vertical based on visual feedback in order to minimize errors. We conclude that improvements of SVV accuracy by visual feedback, which remained effective after removal of feedback for ≥18 min, rather resulted from a cognitive strategy than by adapting the internal estimate of the gravitational vertical. The mechanisms behind the SVV therefore, remained stable, which is also supported by the fact that SVV precision - depending mostly on otolith input - was not affected by visual feedback.
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Affiliation(s)
- Daniel Bjasch
- Department of Neurology, Zurich University Hospital, Zurich, Switzerland
| | - Christopher J. Bockisch
- Department of Neurology, Zurich University Hospital, Zurich, Switzerland
- Department of Otorhinolaryngology, Zurich University Hospital, Zurich, Switzerland
- Department of Ophthalmology, Zurich University Hospital, Zurich, Switzerland
| | - Dominik Straumann
- Department of Neurology, Zurich University Hospital, Zurich, Switzerland
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Tarnutzer AA, Fernando DP, Lasker AG, Zee DS. How stable is perceived direction of gravity over extended periods in darkness? Exp Brain Res 2012; 222:427-36. [PMID: 23053369 DOI: 10.1007/s00221-012-3230-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 08/11/2012] [Indexed: 11/24/2022]
Abstract
Previous studies reported linear drift of perceived vertical for brief (≤10 min) observation periods. Here, we repeated estimates of direction of gravity up to 60 min to evaluate whether the drift is sustained, shows saturation or even reverses over time. Fifteen healthy human subjects repetitively adjusted a luminous line along subjective visual vertical (SVV) and horizontal (SVH) over periods of 5 min (constituting one block). We obtained seven blocks within 60 min in each subject for SVV and SVH. In between the first six blocks, subjects remained in darkness for 5 min each, whereas the lights were briefly turned on before block 7. We noted significantly (p < 0.05) increased errors in perceived direction of gravity by block 2 (SVV) and 3 (SVH). These increases disappeared after turning on the lights before block 7. Focusing on blocks 2-6, significant drift started from similar offset positions and pointed to the same direction in a majority of runs in 9/15 (SVV) and 11/15 (SVH) subjects. When pooling data from all blocks, orthogonality of errors was lost in all subjects. Trial-to-trial variability remained stable over the seven runs for SVV and SVH. Only when pooling all runs, precision was significantly (p < 0.05) higher for the SVH. Our findings suggest that perceived direction of gravity continues to fluctuate over extended recording periods with individuals showing unique patterns of direction-specific drift while variability remains stable. As subjects were upright during the entire experiment and as drift persisted over several blocks, sensory adaptation seems unlikely. We therefore favor a central origin of this kind of drift.
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Affiliation(s)
- A A Tarnutzer
- Department of Neurology, The Johns Hopkins University School of Medicine, Path 2-210, 600 N. Wolfe St., Baltimore, MD 21201, USA.
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