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Wu X, Yu S, Shen S, Liu W. Quantitative analysis of the biomechanical response of semicircular canals and nystagmus under different head positions. Hear Res 2021; 407:108282. [PMID: 34130038 DOI: 10.1016/j.heares.2021.108282] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 05/20/2021] [Accepted: 05/26/2021] [Indexed: 01/11/2023]
Abstract
The semicircular canals (SCCs) in the vestibular system can sense angular motion of the head, which performs a crucial role in maintaining the human's sense of balance. The different spatial orientations of the head affect the response of human SCCs to rotational movement. In this study, we combined the numerical model of bilateral human SCCs with vestibulo-ocular reflex experiments, and quantitatively investigated the responses of SCCs to constant angular acceleration when the head was in different left-leaning positions, including the head tilted 0°, 15°, 30°, 45°, 60°, 70°, 80°, and 90° to the left. The results showed that the vertical nystagmus slow-phase velocity (SPV) and the corresponding maximal cupula shear strain at the crista surface rose with an increase in the left-leaning angle of the head, reached a maximum at the position of the head tilted approximately 70° to the left, and then decreased gradually. Both the horizontal nystagmus SPV and the corresponding maximal cupula shear strain at the crista surface were the largest under the position of the head tilted 0° to the left, and decreased gradually as the left-leaning angle of the head increased. The numerical results of cupula shear strain at the crista surface in bilateral SCCs can quantitatively explain the combined effects of each SCC's excitation or inhibition on volunteers' nystagmus SPV under different head positions. In addition, a fluid-structure interaction investigation revealed that different left-leaning head positions changed the endolymphatic pressure gradient distribution in SCCs, which determined the transcupular pressure, cupula shear strain at the crista surface, and nystagmus SPV.
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Affiliation(s)
- Xiang Wu
- School of Information and Communication Engineering, Dalian University of Technology, Dalian 116024, China
| | - Shen Yu
- State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China
| | - Shuang Shen
- School of Rehabilitation Medicine, Binzhou Medical University, Yantai 264003, China
| | - Wenlong Liu
- School of Information and Communication Engineering, Dalian University of Technology, Dalian 116024, China.
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Exploring the biomechanical responses of human cupula by numerical analysis of temperature experiments. Sci Rep 2021; 11:8208. [PMID: 33859270 PMCID: PMC8050243 DOI: 10.1038/s41598-021-87730-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Accepted: 03/30/2021] [Indexed: 11/09/2022] Open
Abstract
The vestibular receptor of cupula acts an important role in maintaining body balance. However, the cupula buried in the semicircular canals (SCCs) will be destroyed if it is detached from the relevant environment. The mechanical properties of human cupula still remain ambiguous. In this paper, we explored the cupula responses changing with temperature by experiments and numerical simulation of SCCs model. We obtained 3 volunteers’ nystagmus induced by constant angular acceleration when the temperature of volunteers’ SCCs was 36 °C and 37 °C respectively. The slow-phase velocity of 3 volunteers decreased by approximately 3°/s when the temperature of SCCs reduced by 1 °C, which corresponded to the reduction of cupula deformation by 0.3–0.8 μm in the numerical model. Furthermore, we investigated the effects of the variation of endolymphatic properties induced by temperature reduction on cupula deformation through numerical simulation. We found that the decrease of cupula deformation was not caused by the change of endolymphatic properties, but probably by the increase of cupula’s elastic modulus. With the temperature reducing by 1 °C, the cupula’s elastic modulus may increase by 6–20%, suggesting that the stiffness of cupula is enhanced. This exploration of temperature characteristic of human cupula promotes the research of alleviating vestibular diseases.
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Rucker JC, Rizzo JR, Hudson TE, Horn AKE, Buettner-Ennever JA, Leigh RJ, Optican LM. Dysfunctional mode switching between fixation and saccades: collaborative insights into two unusual clinical disorders. J Comput Neurosci 2021; 49:283-293. [PMID: 33839988 DOI: 10.1007/s10827-021-00785-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/01/2021] [Accepted: 02/24/2021] [Indexed: 11/28/2022]
Abstract
Voluntary rapid eye movements (saccades) redirect the fovea toward objects of visual interest. The saccadic system can be considered as a dual-mode system: in one mode the eye is fixating, in the other it is making a saccade. In this review, we consider two examples of dysfunctional saccades, interrupted saccades in late-onset Tay-Sachs disease and gaze-position dependent opsoclonus after concussion, which fail to properly shift between fixation and saccade modes. Insights and benefits gained from bi-directional collaborative exchange between clinical and basic scientists are emphasized. In the case of interrupted saccades, existing mathematical models were sufficiently detailed to provide support for the cause of interrupted saccades. In the case of gaze-position dependent opsoclonus, existing models could not explain the behavior, but further development provided a reasonable hypothesis for the mechanism underlying the behavior. Collaboration between clinical and basic science is a rich source of progress for developing biologically plausible models and understanding neurological disease. Approaching a clinical problem with a specific hypothesis (model) in mind often prompts new experimental tests and provides insights into basic mechanisms.
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Affiliation(s)
- Janet C Rucker
- Departments of Neurology, New York University Grossman School of Medicine, New York, NY, USA. .,Departments of Ophthalmology, New York University Grossman School of Medicine, New York, NY, USA.
| | - John-Ross Rizzo
- Departments of Neurology, New York University Grossman School of Medicine, New York, NY, USA.,Departments of Rehabilitation Medicine, New York University Grossman School of Medicine, New York, NY, USA.,Departments of Biomedical Engineering, New York University Tandon School of Engineering, New York, NY, USA.,Departments of Mechanical and Aerospace Engineering, New York University Tandon School of Engineering, New York, NY, USA
| | - Todd E Hudson
- Departments of Neurology, New York University Grossman School of Medicine, New York, NY, USA.,Departments of Rehabilitation Medicine, New York University Grossman School of Medicine, New York, NY, USA
| | - Anja K E Horn
- Department of Anatomy and Cell Biology I, Ludwig-Maximilians University, Munich, Germany
| | | | - R John Leigh
- Department of Neurology, Case Western Reserve University, Cleveland, OH, USA
| | - Lance M Optican
- Laboratory of Sensorimotor Research, NEI, NIH, DHHS, Bethesda, MD, USA
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Lädrach C, Zee DS, Wyss T, Wimmer W, Korda A, Salmina C, Caversaccio MD, Mantokoudis G. Alexander's Law During High-Speed, Yaw-Axis Rotation: Adaptation or Saturation? Front Neurol 2020; 11:604502. [PMID: 33329363 PMCID: PMC7719745 DOI: 10.3389/fneur.2020.604502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 10/02/2020] [Indexed: 11/13/2022] Open
Abstract
Objective: Alexander's law (AL) states the intensity of nystagmus increases when gaze is toward the direction of the quick phase. What might be its cause? A gaze-holding neural integrator (NI) that becomes imperfect as the result of an adaptive process, or saturation in the discharge of neurons in the vestibular nuclei? Methods: We induced nystagmus in normal subjects using a rapid chair acceleration around the yaw (vertical) axis to a constant velocity of 200°/second [s] and then, 90 s later, a sudden stop to induce post-rotatory nystagmus (PRN). Subjects alternated gaze every 2 s between flashing LEDs (right/left or up/down). We calculated the change in slow-phase velocity (ΔSPV) between right and left gaze when the lateral semicircular canals (SCC) were primarily stimulated (head upright) or, with the head tilted to the side, stimulating the vertical and lateral SCC together. Results: During PRN AL occurred for horizontal eye movements with the head upright and for both horizontal and vertical components of eye movements with the head tilted. AL was apparent within just a few seconds of the chair stopping when peak SPV of PRN was reached. When slow-phase velocity of PRN faded into the range of 6-18°/s AL could no longer be demonstrated. Conclusions: Our results support the idea that AL is produced by asymmetrical responses within the vestibular nuclei impairing the NI, and not by an adaptive response that develops over time. AL was related to the predicted plane of eye rotations in the orbit based on the pattern of SCC activation.
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Affiliation(s)
- Claudia Lädrach
- Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital Bern, Bern, Switzerland
| | - David S Zee
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Thomas Wyss
- Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital Bern, Bern, Switzerland
| | - Wilhelm Wimmer
- Hearing Research Laboratory, ARTORG Center, University of Bern, Bern, Switzerland
| | - Athanasia Korda
- Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital Bern, Bern, Switzerland
| | - Cinzia Salmina
- Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital Bern, Bern, Switzerland
| | - Marco D Caversaccio
- Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital Bern, Bern, Switzerland
| | - Georgios Mantokoudis
- Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital Bern, Bern, Switzerland
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Wu X, Yu S, Liu W, Shen S. Numerical modeling and verification by nystagmus slow-phase velocity of the function of semicircular canals. Biomech Model Mechanobiol 2020; 19:2343-2356. [DOI: 10.1007/s10237-020-01343-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 05/12/2020] [Indexed: 01/09/2023]
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Abstract
Opsoclonus/flutter (O/F) is a rare disorder of the saccadic system. Previously, we modeled O/F that developed in a patient following abuse of anabolic steroids. That model, as in all models of the saccadic system, generates commands to make a change in eye position. Recently, we saw a patient who developed a unique form of opsoclonus following a concussion. The patient had postsaccadic ocular flutter in both directions of gaze, and opsoclonus during fixation and pursuit in the left hemifield. A new model of the saccadic system is needed to account for this gaze-position dependent O/F. We started with our prior model, which contains two key elements, mutual inhibition between inhibitory burst neurons on both sides and a prolonged reactivation time of the omnipause neurons (OPNs). We included new inputs to the OPNs from the nucleus prepositus hypoglossi and the frontal eye fields, which contain position-dependent neurons. This provides a mechanism for delaying OPN reactivation, and creating a gaze-position dependence. A simplified pursuit system was also added, the output of which inhibits the OPNs, providing a mechanism for gaze-dependence during pursuit. The rest of the model continues to generate a command to change eye position.
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Kim SH, Zee DS, du Lac S, Kim HJ, Kim JS. Nucleus prepositus hypoglossi lesions produce a unique ocular motor syndrome. Neurology 2016; 87:2026-2033. [PMID: 27733568 DOI: 10.1212/wnl.0000000000003316] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 07/27/2016] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To describe the ocular motor abnormalities in 9 patients with a lesion involving the nucleus prepositus hypoglossi (NPH), a key constituent of a vestibular-cerebellar-brainstem neural network that ensures that the eyes are held steady in all positions of gaze. METHODS We recorded eye movements, including the vestibulo-ocular reflex during head impulses, in patients with vertigo and a lesion involving the NPH. RESULTS Our patients showed an ipsilesional-beating spontaneous nystagmus, horizontal gaze-evoked nystagmus more intense on looking toward the ipsilesional side, impaired pursuit more to the ipsilesional side, central patterns of head-shaking nystagmus, contralateral eye deviation, and decreased vestibulo-ocular reflex gain during contralesionally directed head impulses. CONCLUSIONS We attribute these findings to an imbalance in the NPH-inferior olive-flocculus-vestibular nucleus loop, and the ocular motor abnormalities provide a new brainstem localization for patients with acute vertigo.
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Affiliation(s)
- Sung-Hee Kim
- From the Department of Neurology (S.-H.K.), Kyungpook National University School of Medicine, Daegu, Korea; Departments of Neurology, Ophthalmology, Otolaryngology-Head and Neck Surgery, and Neuroscience (D.S.Z., S.d.L.), Johns Hopkins University School of Medicine, Baltimore, MD; Department of Biomedical Laboratory Science (H.J.K.), Kyungdong University, Goseong-Gun, Gangwon-do; and Department of Neurology (J.-S.K.), Seoul National University College of Medicine, Seoul National University Bundang Hospital, Korea
| | - David S Zee
- From the Department of Neurology (S.-H.K.), Kyungpook National University School of Medicine, Daegu, Korea; Departments of Neurology, Ophthalmology, Otolaryngology-Head and Neck Surgery, and Neuroscience (D.S.Z., S.d.L.), Johns Hopkins University School of Medicine, Baltimore, MD; Department of Biomedical Laboratory Science (H.J.K.), Kyungdong University, Goseong-Gun, Gangwon-do; and Department of Neurology (J.-S.K.), Seoul National University College of Medicine, Seoul National University Bundang Hospital, Korea
| | - Sascha du Lac
- From the Department of Neurology (S.-H.K.), Kyungpook National University School of Medicine, Daegu, Korea; Departments of Neurology, Ophthalmology, Otolaryngology-Head and Neck Surgery, and Neuroscience (D.S.Z., S.d.L.), Johns Hopkins University School of Medicine, Baltimore, MD; Department of Biomedical Laboratory Science (H.J.K.), Kyungdong University, Goseong-Gun, Gangwon-do; and Department of Neurology (J.-S.K.), Seoul National University College of Medicine, Seoul National University Bundang Hospital, Korea
| | - Hyo Jung Kim
- From the Department of Neurology (S.-H.K.), Kyungpook National University School of Medicine, Daegu, Korea; Departments of Neurology, Ophthalmology, Otolaryngology-Head and Neck Surgery, and Neuroscience (D.S.Z., S.d.L.), Johns Hopkins University School of Medicine, Baltimore, MD; Department of Biomedical Laboratory Science (H.J.K.), Kyungdong University, Goseong-Gun, Gangwon-do; and Department of Neurology (J.-S.K.), Seoul National University College of Medicine, Seoul National University Bundang Hospital, Korea
| | - Ji-Soo Kim
- From the Department of Neurology (S.-H.K.), Kyungpook National University School of Medicine, Daegu, Korea; Departments of Neurology, Ophthalmology, Otolaryngology-Head and Neck Surgery, and Neuroscience (D.S.Z., S.d.L.), Johns Hopkins University School of Medicine, Baltimore, MD; Department of Biomedical Laboratory Science (H.J.K.), Kyungdong University, Goseong-Gun, Gangwon-do; and Department of Neurology (J.-S.K.), Seoul National University College of Medicine, Seoul National University Bundang Hospital, Korea.
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Boselli F, Kleiser L, Bockisch C, Hegemann S, Obrist D. Quantitative analysis of benign paroxysmal positional vertigo fatigue under canalithiasis conditions. J Biomech 2014; 47:1853-60. [DOI: 10.1016/j.jbiomech.2014.03.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 03/08/2014] [Accepted: 03/11/2014] [Indexed: 11/26/2022]
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