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Abstract
PURPOSE OF REVIEW Electrical stimulation of the peripheral and central vestibular system using noninvasive (galvanic vestibular stimulation, GVS) or invasive (intracranial electrical brain stimulation, iEBS) approaches have a long history of use in studying self-motion perception and balance control. The aim of this review is to summarize recent electrophysiological studies of the effects of GVS, and functional mapping of the central vestibular system using iEBS in awake patients. RECENT FINDINGS The use of GVS has become increasingly common in the assessment and treatment of a wide range of clinical disorders including vestibulopathy and Parkinson's disease. The results of recent single unit recording studies have provided new insight into the neural mechanisms underlying GVS-evoked improvements in perceptual and motor responses. Furthermore, the application of iEBS in patients with epilepsy or during awake brain surgery has provided causal evidence of vestibular information processing in mostly the middle cingulate cortex, posterior insula, inferior parietal lobule, amygdala, precuneus, and superior temporal gyrus. SUMMARY Recent studies have established that GVS evokes robust and parallel activation of both canal and otolith afferents that is significantly different from that evoked by natural head motion stimulation. Furthermore, there is evidence that GVS can induce beneficial neural plasticity in the central pathways of patients with vestibular loss. In addition, iEBS studies highlighted an underestimated contribution of areas in the medial part of the cerebral hemispheres to the cortical vestibular network.
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Affiliation(s)
- Christophe Lopez
- Aix Marseille Univ, CNRS, Laboratory of Cognitive Neuroscience (LNC), FR3C, Marseille, France
| | - Kathleen E. Cullen
- Department of Biomedical Engineering, Johns Hopkins University
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University
- Department of Neuroscience, Johns Hopkins University
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore 21205 MD, USA
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2
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Chow MR, Fernandez Brillet C, Hageman KN, Roberts DC, Ayiotis AI, Haque RM, Della Santina CC. Binocular 3-D otolith-ocular reflexes: responses of chinchillas to natural and prosthetic stimulation after ototoxic injury and vestibular implantation. J Neurophysiol 2023; 129:1157-1176. [PMID: 37018758 PMCID: PMC10151050 DOI: 10.1152/jn.00445.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 03/29/2023] [Accepted: 03/29/2023] [Indexed: 04/07/2023] Open
Abstract
The otolith end organs inform the brain about gravitational and linear accelerations, driving the otolith-ocular reflex (OOR) to stabilize the eyes during translational motion (e.g., moving forward without rotating) and head tilt with respect to gravity. We previously characterized OOR responses of normal chinchillas to whole body tilt and translation and to prosthetic electrical stimulation targeting the utricle and saccule via electrodes implanted in otherwise normal ears. Here we extend that work to examine OOR responses to tilt and translation stimuli after unilateral intratympanic gentamicin injection and to natural/mechanical and prosthetic/electrical stimulation delivered separately or in combination to animals with bilateral vestibular hypofunction after right ear intratympanic gentamicin injection followed by surgical disruption of the left labyrinth at the time of electrode implantation. Unilateral intratympanic gentamicin injection decreased natural OOR response magnitude to about half of normal, without markedly changing OOR response direction or symmetry. Subsequent surgical disruption of the contralateral labyrinth at the time of electrode implantation surgery further decreased OOR magnitude during natural stimulation, consistent with bimodal-bilateral otolith end organ hypofunction (ototoxic on the right ear, surgical on the left ear). Delivery of pulse frequency- or pulse amplitude-modulated prosthetic/electrical stimulation targeting the left utricle and saccule in phase with whole body tilt and translation motion stimuli yielded responses closer to normal than the deficient OOR responses of those same animals in response to head tilt and translation alone.NEW & NOTEWORTHY Previous studies to expand the scope of prosthetic stimulation of the otolith end organs showed that selective stimulation of the utricle and saccule is possible. This article further defines those possibilities by characterizing a diseased animal model and subsequently studying its responses to electrical stimulation alone and in combination with mechanical motion. We show that we can partially restore responses to tilt and translation in animals with unilateral gentamicin ototoxic injury and contralateral surgical disruption.
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Affiliation(s)
- Margaret R Chow
- Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Celia Fernandez Brillet
- Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Kristin N Hageman
- Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Dale C Roberts
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Andrianna I Ayiotis
- Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Razi M Haque
- Lawrence Livermore National Laboratory, Livermore, California, United States
| | - Charles C Della Santina
- Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
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3
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Fritzsch B, Kersigo J, Rejent K, Gherman W, Frank PW, Giovannucci DR, Maklad A. Hair cell morphological patterns and polarity organization in the sea lamprey vestibular cristae. Anat Rec (Hoboken) 2023. [PMID: 36651665 DOI: 10.1002/ar.25164] [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: 07/11/2022] [Revised: 12/19/2022] [Accepted: 12/23/2022] [Indexed: 01/19/2023]
Abstract
The inner ear of the sea lamprey was examined by scanning electron microscopy, antibody labeling with tubulin, Myo7a, Spectrin, and Phalloidin stain to elucidate the canal cristae organization and the morphology and polarity of the hair cells. We characterized the hair cell stereocilia bundles and their morphological polarity with respect to the kinocilia. We identified three types of hair cells. In Type 1 hair cells, the kinocilia were slightly longer than the tallest stereocilia. This type was located along the medial bank of the crista and their polarity, based on kinocilia location, was uniformly pointed ampullipetally. Type 2 hair cells that had kinocilia that were much longer than the stereocilia, were most abundant in the central region of the crista. This type of hair cell displayed variable polarity. Type 3 hair cells had extremely long kinocilia (~40-50 μm long) and with extremely short stereocilia. They were mostly located in the lateral zone crista and displayed ampullipetal polarity. Myo7a and tubulin antibodies revealed that hair cells and vestibular afferents are distributed across the canal cristae in the lamprey, covering the area of cruciate eminence; a feature that is absent in more derived vertebrates. Spectrin shows hair cells of varying polarities in the central zone. In this zone, some cells followed the main polarity vector (lateral) like those in medial and lateral zones, whereas other cells displayed polarities that carried up to 40° from the main polarity vector.
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Affiliation(s)
- Bernd Fritzsch
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, Iowa, USA
| | - Jennifer Kersigo
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, Iowa, USA
| | - Kassidy Rejent
- Department of Neurosciences, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA
| | - Wesley Gherman
- Department of Neurosciences, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA
| | - Patrick W Frank
- Department of Neurosciences, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA.,Department of Medical Education, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA
| | - David R Giovannucci
- Department of Neurosciences, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA.,Department of Medical Education, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA
| | - Adel Maklad
- Department of Neurosciences, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA.,Department of Medical Education, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA
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4
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Babaee S, Shaabani M, Vahedi M. Comparison of verticality perception and postural sway induced by double temple-mastoidal and bipolar binaural 20 Hz sinusoidal galvanic vestibular stimulation. J Vestib Res 2022; 32:407-421. [PMID: 34957979 DOI: 10.3233/ves-210112] [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: 12/29/2022]
Abstract
BACKGROUND Galvanic vestibular stimulation (GVS) is believed to be one of the most valuable tools for studying the vestibular system. In our opinion, its combined effect on posture and perception needs to be examined more. OBJECTIVE The present study was conducted to investigate the effect of a 20 Hz sinusoidal Galvanic Vestibular Stimulation (sGVS) on the body sway and subjective visual vertical (SVV) deviation through two sets of electrode montages (bipolar binaural and double temple-mastoidal stimulation) during a three-stage experiment (baseline, threshold, and supra-threshold levels). METHODS While the individuals (32 normal individuals, 10 males, the mean age of 25.37±3.00 years) were standing on a posturography device and SVV goggles were put on, the parameters of the body sway and SVV deviation were measured simultaneously. Following the baseline stage (measuring without stimulation), the parameters were investigated during the threshold and supra-threshold stages (1 mA above the threshold) for 20 seconds. This was done separately for each electrode montage. Then, the results were compared between the three experimental stages and the two electrode montages. RESULTS In both electrode montages, "the maximum amplitude" of the mediolateral (ML) and anteroposterior (AP) body sway decreased and increased in the threshold and supra-threshold stages, respectively, compared to the baseline stage. Comparison of the amount of "amplitude change" caused by each electrode montages showed that the double temple-mastoidal stimulation induced a significantly greater amplitude change in body sway during both threshold and supra-threshold stages (relative to the baseline stage).The absolute mean values of the SVV deviation were significantly different between the baseline and supra-threshold levels in both electrode montages. The SVV deviation in double temple-mastoidal stimulation was a bit greater than that in the bipolar binaural stimulation. CONCLUSION Double temple-mastoidal stimulation has induced greater amount of change in the body sway and SVV deviation. This may be due to the more effective stimulation of the otoliths than semicircular canals.
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Affiliation(s)
- Samar Babaee
- Department of Student Research Committee, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Moslem Shaabani
- Department of Audiology, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Mohsen Vahedi
- Department of Biostatistics, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
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Nam GS, Nguyen TT, Kang JJ, Han GC, Oh SY. Effects of Galvanic Vestibular Stimulation on Vestibular Compensation in Unilaterally Labyrinthectomized Mice. Front Neurol 2021; 12:736849. [PMID: 34539564 PMCID: PMC8446527 DOI: 10.3389/fneur.2021.736849] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 08/02/2021] [Indexed: 12/01/2022] Open
Abstract
Objectives: To investigate the ameliorating effects of sinusoidal galvanic vestibular stimulation (GVS) on vestibular compensation from unilateral vestibular deafferentation (UVD) using a mouse model of unilateral labyrinthectomy (UL). Methods: Sixteen male C57BL/6 mice were allocated into two groups that comprise UL groups with GVS (GVS group, n = 9) and without GVS intervention (non-GVS group, n = 7). In the experimental groups, we assessed vestibulo-ocular reflex (VOR) recovery before (baseline) and at 3, 7, and 14 days after surgical unilateral labyrinthectomy. In the GVS group, stimulation was applied for 30 min daily from postoperative days (PODs) 0–4 via electrodes inserted subcutaneously next to both bony labyrinths. Results: Locomotion and VOR were significantly impaired in the non-GVS group compared to baseline. The mean VOR gain of the non-GVS group was attenuated to 0.23 at POD 3 and recovered continuously to the value of 0.54 at POD 14, but did not reach the baseline values at any frequency. GVS intervention significantly accelerated recovery of locomotion, as assessed by the amount of circling and total path length in the open field tasks compared to the non-GVS groups on PODs 3 (p < 0.001 in both amount of circling and total path length) and 7 (p < 0.01 in amount of circling and p < 0.001 in total path length, Mann–Whitney U-test). GVS also significantly improved VOR gain compared to the non-GVS groups at PODs 3 (p < 0.001), 7 (p < 0.001), and 14 (p < 0.001, independent t-tests) during sinusoidal rotations. In addition, the recovery of the phase responses and asymmetry of the VOR was significantly better in the GVS group than in the non-GVS group until 2 weeks after UVD (phase, p = 0.001; symmetry, p < 0.001 at POD 14). Conclusion: Recoveries for UVD-induced locomotion and VOR deficits were accelerated by an early intervention with GVS, which implies that GVS has the potential to improve vestibular compensation in patients with acute unilateral vestibular failure.
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Affiliation(s)
- Gi-Sung Nam
- Jeonbuk National University College of Medicine, Jeonju, South Korea.,Department of Otorhinolaryngology-Head and Neck Surgery, Chosun University College of Medicine, Gwangju, South Korea
| | - Thanh Tin Nguyen
- Jeonbuk National University College of Medicine, Jeonju, South Korea.,Department of Neurology, Jeonbuk National University Hospital & School of Medicine, Jeonju, South Korea.,Department of Pharmacology, Hue University of Medicine and Pharmacy, Hue University, Hue, Vietnam
| | - Jin-Ju Kang
- Jeonbuk National University College of Medicine, Jeonju, South Korea.,Department of Neurology, Jeonbuk National University Hospital & School of Medicine, Jeonju, South Korea.,Research Institute of Clinical Medicine of Jeonbuk National University-Jeonbuk National University Hospital, Jeonju, South Korea
| | - Gyu Cheol Han
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Gachon University of Medicine and Science, Incheon, South Korea
| | - Sun-Young Oh
- Jeonbuk National University College of Medicine, Jeonju, South Korea.,Department of Neurology, Jeonbuk National University Hospital & School of Medicine, Jeonju, South Korea.,Research Institute of Clinical Medicine of Jeonbuk National University-Jeonbuk National University Hospital, Jeonju, South Korea
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6
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Steinhardt CR, Fridman GY. Direct current effects on afferent and hair cell to elicit natural firing patterns. iScience 2021; 24:102205. [PMID: 33748701 PMCID: PMC7967006 DOI: 10.1016/j.isci.2021.102205] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 12/17/2020] [Accepted: 02/16/2021] [Indexed: 12/13/2022] Open
Abstract
In contrast to the conventional pulsatile neuromodulation that excites neurons, galvanic or direct current stimulation can excite, inhibit, or sensitize neurons. The vestibular system presents an excellent system for studying galvanic neural interface due to the spontaneously firing afferent activity that needs to be either suppressed or excited to convey head motion sensation. We determine the cellular mechanisms underlying the beneficial properties of galvanic vestibular stimulation (GVS) by creating a computational model of the vestibular end organ that elicits all experimentally observed response characteristics to GVS simultaneously. When GVS was modeled to affect the axon alone, the complete experimental data could not be replicated. We found that if GVS affects hair cell vesicle release and axonal excitability simultaneously, our modeling results matched all experimental observations. We conclude that contrary to the conventional belief that GVS affects only axons, the hair cells are likely also affected by this stimulation paradigm. Galvanic vestibular stimulation was shown to evoke naturalistic neural responses Conventional understanding maintains that it affects only afferent axons In contrast, our work suggests that it affects both hair cells and afferents Our work further explains the likely underlying mechanisms of these effects
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Affiliation(s)
- Cynthia R Steinhardt
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21217, USA
| | - Gene Y Fridman
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21217, USA.,Department of Otolaryngology Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.,Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21217, USA
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7
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Sayyid ZN, Wang T, Chen L, Jones SM, Cheng AG. Atoh1 Directs Regeneration and Functional Recovery of the Mature Mouse Vestibular System. Cell Rep 2020; 28:312-324.e4. [PMID: 31291569 PMCID: PMC6659123 DOI: 10.1016/j.celrep.2019.06.028] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 02/13/2019] [Accepted: 06/06/2019] [Indexed: 12/02/2022] Open
Abstract
Utricular hair cells (HCs) are mechanoreceptors required for vestibular function. After damage, regeneration of mammalian utricular HCs is limited and regenerated HCs appear immature. Thus, loss of vestibular function is presumed irreversible. Here, we found partial HC replacement and functional recovery in the mature mouse utricle, both enhanced by overexpressing the transcription factor Atoh1. Following damage, long-term fate mapping revealed that support cells non-mitotically and modestly regenerated HCs displaying no or immature bundles. By contrast, Atoh1 overexpression stimulated proliferation and widespread regeneration of HCs exhibiting elongated bundles, patent mechanotransduction channels, and synaptic connections. Finally, although damage without Atoh1 overexpression failed to initiate or sustain a spontaneous functional recovery, Atoh1 overexpression significantly enhanced both the degree and percentage of animals exhibiting sustained functional recovery. Therefore, the mature, damaged utricle has an Atoh1-responsive regenerative program leading to functional recovery, underscoring the potential of a reprogramming approach to sensory regeneration. The mature mouse utricle, which detects linear acceleration, displays limited regeneration, but whether function returns is unknown. Sayyid et al. show that regenerated hair cells appear and mature over months, resulting in a limited, unsustained functional recovery. Atoh1 overexpression enhances regeneration and leads to a sustained recovery of vestibular function.
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Affiliation(s)
- Zahra N Sayyid
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Tian Wang
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Leon Chen
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Sherri M Jones
- Department of Special Education and Communication Disorders, College of Education and Human Sciences, University of Nebraska, Lincoln, NE 68583, USA
| | - Alan G Cheng
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
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Kim G, Lee S, Kim KS. Dominant parameter of galvanic vestibular stimulation for the non-associative learning processes. Med Biol Eng Comput 2020; 58:701-708. [PMID: 31953797 DOI: 10.1007/s11517-019-02117-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 12/28/2019] [Indexed: 12/22/2022]
Abstract
Electrical stimulus is one of the common stimulating methods, and Galvanic vestibular stimulation (GVS) is the oldest form as an electrical stimulation. Nevertheless, GVS is still considered as a secondary stimulating tool for the medical purposes. Even though some unarguable findings have made using GVS, its use has been limited because of its ambiguity as an input source. For better understanding, many previous studies mainly focused on its functional effects, like the ocular reflexes. However, its fundamental effects on the neural activities are still elusive, such as the dominant influences by different parameters of GVS. Here we compared the effects on the neuronal responses by applying two different parameters, strength and rate, of GVS. To assess the dominance on the neuronal responses to these parameters, we designed three independent stimuli. Those stimuli were multiply applied to obtain the responding slopes based on the mechanism of non-associative learning processes, and the effects on the neurons were calculated as an inner angle between two responding slopes. Out of 23 neurons, 15 (65.2%) units were affected more by the strength with a statistical significance (p = 0.047). The ranges of the inner angles also implied the strength (- 3.354°~2.063°) mainly modulated by the neuronal responses comparing with those by the rate (- 2.001°~1.975°). The dominance of the parameters was closely related with the neuronal sensitivity to stimulation (SE) (p = 0.018), while there were few relations with the neuronal regularity, directional preference (DP), and the physiological response (PR) (p > 0.059). Thus, the neural information related with the dominance was delivered by the irregular neurons, and these types of neurons should be the targets for the stimulation. Graphical abstract.
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Affiliation(s)
- Gyutae Kim
- Research Institute for Aerospace Medicine, Inha University, High-Tech center #303, 100 Inharo, Namgu, InCheon, 402-751, South Korea.
- Institute for Information and Electronics Research, Inha University, High-Tech center #716, 100 Inharo, Namgu, InCheon, 402-751, South Korea.
| | - Sangmin Lee
- Institute for Information and Electronics Research, Inha University, High-Tech center #716, 100 Inharo, Namgu, InCheon, 402-751, South Korea
- Department of Electronic Engineering, Inha University, High-Tech center #704, 100 Inharo, Namgu, InCheon, 402-751, South Korea
| | - Kyu-Sung Kim
- Research Institute for Aerospace Medicine, Inha University, High-Tech center #303, 100 Inharo, Namgu, InCheon, 402-751, South Korea
- Department of Otolaryngology Head & Neck Surg., Inha University Hospital, 27 Inhang-ro, Jung-Gu, Incheon, 400-711, South Korea
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9
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Ono K, Keller J, López Ramírez O, González Garrido A, Zobeiri OA, Chang HHV, Vijayakumar S, Ayiotis A, Duester G, Della Santina CC, Jones SM, Cullen KE, Eatock RA, Wu DK. Retinoic acid degradation shapes zonal development of vestibular organs and sensitivity to transient linear accelerations. Nat Commun 2020; 11:63. [PMID: 31896743 PMCID: PMC6940366 DOI: 10.1038/s41467-019-13710-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 11/21/2019] [Indexed: 01/18/2023] Open
Abstract
Each vestibular sensory epithelium in the inner ear is divided morphologically and physiologically into two zones, called the striola and extrastriola in otolith organ maculae, and the central and peripheral zones in semicircular canal cristae. We found that formation of striolar/central zones during embryogenesis requires Cytochrome P450 26b1 (Cyp26b1)-mediated degradation of retinoic acid (RA). In Cyp26b1 conditional knockout mice, formation of striolar/central zones is compromised, such that they resemble extrastriolar/peripheral zones in multiple features. Mutants have deficient vestibular evoked potential (VsEP) responses to jerk stimuli, head tremor and deficits in balance beam tests that are consistent with abnormal vestibular input, but normal vestibulo-ocular reflexes and apparently normal motor performance during swimming. Thus, degradation of RA during embryogenesis is required for formation of highly specialized regions of the vestibular sensory epithelia with specific functions in detecting head motions.
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Affiliation(s)
- Kazuya Ono
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA
| | - James Keller
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA
- Qiagen Sciences Inc., Germantown, MD, 20874, USA
| | - Omar López Ramírez
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA
| | | | - Omid A Zobeiri
- Department of Physiology McGill University, Montreal, QC, Canada, H3G 1Y6
| | | | - Sarath Vijayakumar
- Department of Special Education and Communication Disorders, 301 Barkley Memorial Center, University of Nebraska-Lincoln, Lincoln, NE, 68583-0738, USA
| | - Andrianna Ayiotis
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Gregg Duester
- Neuroscience and Aging Research Center, Stanford Burnham Prebys Medical Discovery Institutes, Stanford, CA, 92037, USA
| | - Charles C Della Santina
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Sherri M Jones
- Department of Special Education and Communication Disorders, 301 Barkley Memorial Center, University of Nebraska-Lincoln, Lincoln, NE, 68583-0738, USA
| | - Kathleen E Cullen
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Ruth Anne Eatock
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA
| | - Doris K Wu
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA.
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10
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Manca M, Glowatzki E, Roberts DC, Fridman GY, Aplin FP. Ionic direct current modulation evokes spike-rate adaptation in the vestibular periphery. Sci Rep 2019; 9:18924. [PMID: 31831760 PMCID: PMC6908704 DOI: 10.1038/s41598-019-55045-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 11/20/2019] [Indexed: 12/28/2022] Open
Abstract
Recent studies have shown that ionic direct current (iDC) can modulate the vestibular system in-vivo, with potential benefits over conventional pulsed stimulation. In this study, the effects of iDC stimulation on vestibular nerve fiber firing rate was investigated using loose-patch nerve fiber recordings in the acutely excised mouse crista ampullaris of the semicircular canals. Cathodic and anodic iDC steps instantaneously reduced and increased afferent spike rate, with the polarity of this effect dependent on the position of the stimulating electrode. A sustained constant anodic or cathodic current resulted in an adaptation to the stimulus and a return to spontaneous spike rate. Post-adaptation spike rate responses to iDC steps were similar to pre-adaptation controls. At high intensities spike rate response sensitivities were modified by the presence of an adaptation step. Benefits previously observed in behavioral responses to iDC steps delivered after sustained current may be due to post-adaptation changes in afferent sensitivity. These results contribute to an understanding of peripheral spike rate relationships for iDC vestibular stimulation and validate an ex-vivo model for future investigation of cellular mechanisms. In conjunction with previous in-vivo studies, these data help to characterize iDC stimulation as a potential therapy to restore vestibular function after bilateral vestibulopathy.
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Affiliation(s)
- Marco Manca
- Department of Otolaryngology Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, 21205, United States
| | - Elisabeth Glowatzki
- Department of Otolaryngology Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, 21205, United States.,Department of Neuroscience, Johns Hopkins University, Baltimore, Maryland, 21205, United States
| | - Dale C Roberts
- Department of Otolaryngology Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, 21205, United States
| | - Gene Y Fridman
- Department of Otolaryngology Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, 21205, United States. .,Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland, 21205, United States. .,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, 21205, United States.
| | - Felix P Aplin
- Department of Otolaryngology Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, 21205, United States
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11
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Wang T, Niwa M, Sayyid ZN, Hosseini DK, Pham N, Jones SM, Ricci AJ, Cheng AG. Uncoordinated maturation of developing and regenerating postnatal mammalian vestibular hair cells. PLoS Biol 2019; 17:e3000326. [PMID: 31260439 PMCID: PMC6602158 DOI: 10.1371/journal.pbio.3000326] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Accepted: 05/30/2019] [Indexed: 11/18/2022] Open
Abstract
Sensory hair cells are mechanoreceptors required for hearing and balance functions. From embryonic development, hair cells acquire apical stereociliary bundles for mechanosensation, basolateral ion channels that shape receptor potential, and synaptic contacts for conveying information centrally. These key maturation steps are sequential and presumed coupled; however, whether hair cells emerging postnatally mature similarly is unknown. Here, we show that in vivo postnatally generated and regenerated hair cells in the utricle, a vestibular organ detecting linear acceleration, acquired some mature somatic features but hair bundles appeared nonfunctional and short. The utricle consists of two hair cell subtypes with distinct morphological, electrophysiological and synaptic features. In both the undamaged and damaged utricle, fate-mapping and electrophysiology experiments showed that Plp1+ supporting cells took on type II hair cell properties based on molecular markers, basolateral conductances and synaptic properties yet stereociliary bundles were absent, or small and nonfunctional. By contrast, Lgr5+ supporting cells regenerated hair cells with type I and II properties, representing a distinct hair cell precursor subtype. Lastly, direct physiological measurements showed that utricular function abolished by damage was partially regained during regeneration. Together, our data reveal a previously unrecognized aberrant maturation program for hair cells generated and regenerated postnatally and may have broad implications for inner ear regenerative therapies. During development, sensory hair cells undergo a series of critical maturation steps that are sequential and presumed coupled, but whether regenerated hair cells mature similarly is unknown. This study shows that regenerated vestibular hair cells acquired some mature somatic features, but the apical bundles remained immature.
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Affiliation(s)
- Tian Wang
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Otolaryngology-Head and Neck Surgery, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Mamiko Niwa
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California, United States of America
| | - Zahra N. Sayyid
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California, United States of America
| | - Davood K. Hosseini
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California, United States of America
| | - Nicole Pham
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California, United States of America
| | - Sherri M. Jones
- Department of Special Education and Communication Disorders, College of Education and Human Sciences, University of Nebraska, Lincoln, Nebraska, United States of America
| | - Anthony J. Ricci
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail: (AGC); (AJR)
| | - Alan G. Cheng
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail: (AGC); (AJR)
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12
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Dlugaiczyk J, Gensberger KD, Straka H. Galvanic vestibular stimulation: from basic concepts to clinical applications. J Neurophysiol 2019; 121:2237-2255. [DOI: 10.1152/jn.00035.2019] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Galvanic vestibular stimulation (GVS) plays an important role in the quest to understand sensory signal processing in the vestibular system under normal and pathological conditions. It has become a highly relevant tool to probe neuronal computations and to assist in the differentiation and treatment of vestibular syndromes. Following its accidental discovery, GVS became a diagnostic tool that generates eye movements in the absence of head/body motion. With the possibility to record extracellular and intracellular spikes, GVS became an indispensable method to activate or block the discharge in vestibular nerve fibers by cathodal and anodal currents, respectively. Bernie Cohen, in his attempt to decipher vestibular signal processing, has used this method in a number of hallmark studies that have added to our present knowledge, such as the link between selective electrical stimulation of semicircular canal nerves and the generation of directionally corresponding eye movements. His achievements paved the way for other major milestones including the differential recruitment order of vestibular fibers for cathodal and anodal currents, pronounced discharge adaptation of irregularly firing afferents, potential activation of hair cells, and fiber type-specific activation of central circuits. Previous disputes about the structural substrate for GVS are resolved by integrating knowledge of ion channel-related response dynamics of afferents, fiber type-specific innervation patterns, and central convergence and integration of semicircular canal and otolith signals. On the basis of solid knowledge of the methodology, specific waveforms of GVS are currently used in clinical diagnosis and patient treatment, such as vestibular implants and noisy galvanic stimulation.
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Affiliation(s)
- Julia Dlugaiczyk
- German Center for Vertigo and Balance Disorders, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
- Department of Neurology, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | | | - Hans Straka
- Department Biology II, Ludwig-Maximilians-Universität München, Planegg, Germany
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13
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Arntz AI, van der Putte DAM, Jonker ZD, Hauwert CM, Frens MA, Forbes PA. The Vestibular Drive for Balance Control Is Dependent on Multiple Sensory Cues of Gravity. Front Physiol 2019; 10:476. [PMID: 31114504 PMCID: PMC6503156 DOI: 10.3389/fphys.2019.00476] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 04/04/2019] [Indexed: 11/24/2022] Open
Abstract
Vestibular signals, which encode head movement in space as well as orientation relative to gravity, contribute to the ongoing muscle activity required to stand. The strength of this vestibular contribution changes with the presence and quality of sensory cues of balance. Here we investigate whether the vestibular drive for standing balance also depends on different sensory cues of gravity by examining vestibular-evoked muscle responses when independently varying load and gravity conditions. Standing subjects were braced by a backboard structure that limited whole-body sway to the sagittal plane while load and vestibular cues of gravity were manipulated by: (a) loading the body downward at 1.5 and 2 times body weight (i.e., load cues), and/or (b) exposing subjects to brief periods (20 s) of micro- (<0.05 g) and hyper-gravity (∼1.8 g) during parabolic flights (i.e., vestibular cues). A stochastic electrical vestibular stimulus (0–25 Hz) delivered during these tasks evoked a vestibular-error signal and corrective muscles responses that were used to assess the vestibular drive to standing balance. With additional load, the magnitude of the vestibular-evoked muscle responses progressively increased, however, when these responses were normalized by the ongoing muscle activity, they decreased and plateaued at 1.5 times body weight. This demonstrates that the increased muscle activity necessary to stand with additional load is accompanied a proportionally smaller increase in vestibular input. This reduction in the relative vestibular contribution to balance was also observed when we varied the vestibular cues of gravity, but only during an absence (<0.05 g) and not an excess (∼1.8 g) of gravity when compared to conditions with normal 1 g gravity signals and equivalent load signals. Despite these changes, vestibular-evoked responses were observed in all conditions, indicating that vestibular cues of balance contribute to upright standing even in the near absence of a vestibular signal of gravity (i.e., micro-gravity). Overall, these experiments provide evidence that both load and vestibular cues of gravity influence the vestibular signal processing for the control of standing balance.
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Affiliation(s)
- Anne I Arntz
- Department of Neuroscience, Erasmus MC, Erasmus University Medical Center, Rotterdam, Netherlands.,Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, Netherlands
| | - Daphne A M van der Putte
- Department of Neuroscience, Erasmus MC, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Zeb D Jonker
- Department of Neuroscience, Erasmus MC, Erasmus University Medical Center, Rotterdam, Netherlands.,Department of Rehabilitation Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, Netherlands.,Rijndam Rehabilitation Centre, Rotterdam, Netherlands
| | - Christopher M Hauwert
- Department of Neuroscience, Erasmus MC, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Maarten A Frens
- Department of Neuroscience, Erasmus MC, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Patrick A Forbes
- Department of Neuroscience, Erasmus MC, Erasmus University Medical Center, Rotterdam, Netherlands.,Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, Netherlands
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14
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Kwan A, Forbes PA, Mitchell DE, Blouin JS, Cullen KE. Neural substrates, dynamics and thresholds of galvanic vestibular stimulation in the behaving primate. Nat Commun 2019; 10:1904. [PMID: 31015434 PMCID: PMC6478681 DOI: 10.1038/s41467-019-09738-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/21/2019] [Indexed: 11/09/2022] Open
Abstract
Galvanic vestibular stimulation (GVS) uses the external application of electrical current to selectively target the vestibular system in humans. Despite its recent popularity for the assessment/treatment of clinical conditions, exactly how this non-invasive tool activates the vestibular system remains an open question. Here we directly investigate single vestibular afferent responses to GVS applied to the mastoid processes of awake-behaving monkeys. Transmastoid GVS produces robust and parallel activation of both canal and otolith afferents. Notably, afferent activation increases with intrinsic neuronal variability resulting in constant GVS-evoked neuronal detection thresholds across all afferents. Additionally, afferent tuning differs for GVS versus natural self-motion stimulation. Using a stochastic model of repetitive activity in afferents, we largely explain the main features of GVS-evoked vestibular afferent dynamics. Taken together, our results reveal the neural substrate underlying transmastoid GVS-evoked perceptual, ocular and postural responses-information that is essential to advance GVS applicability for biomedical uses in humans.
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Affiliation(s)
- Annie Kwan
- Department of Biomedical Engineering, McGill University, Montreal, QC, H3G 1Y6, Canada
| | - Patrick A Forbes
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, 3000 CA, The Netherlands.,Department of BioMechanical Engineering, Delft University of Technology, Delft, 2628 CD, The Netherlands.,School of Kinesiology, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - Diana E Mitchell
- Department of Physiology, McGill University, Montreal, QC, H3G 1Y6, Canada
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - Kathleen E Cullen
- Department of Physiology, McGill University, Montreal, QC, H3G 1Y6, Canada. .,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, 21205, MD, USA.
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15
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Rabbitt RD. Semicircular canal biomechanics in health and disease. J Neurophysiol 2019; 121:732-755. [PMID: 30565972 PMCID: PMC6520623 DOI: 10.1152/jn.00708.2018] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 12/11/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022] Open
Abstract
The semicircular canals are responsible for sensing angular head motion in three-dimensional space and for providing neural inputs to the central nervous system (CNS) essential for agile mobility, stable vision, and autonomic control of the cardiovascular and other gravity-sensitive systems. Sensation relies on fluid mechanics within the labyrinth to selectively convert angular head acceleration into sensory hair bundle displacements in each of three inner ear sensory organs. Canal afferent neurons encode the direction and time course of head movements over a broad range of movement frequencies and amplitudes. Disorders altering canal mechanics result in pathological inputs to the CNS, often leading to debilitating symptoms. Vestibular disorders and conditions with mechanical substrates include benign paroxysmal positional nystagmus, direction-changing positional nystagmus, alcohol positional nystagmus, caloric nystagmus, Tullio phenomena, and others. Here, the mechanics of angular motion transduction and how it contributes to neural encoding by the semicircular canals is reviewed in both health and disease.
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Affiliation(s)
- R. D. Rabbitt
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah
- Otolaryngology-Head Neck Surgery, University of Utah, Salt Lake City, Utah
- Neuroscience Program, University of Utah, Salt Lake City, Utah
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16
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Rasman BG, Forbes PA, Tisserand R, Blouin JS. Sensorimotor Manipulations of the Balance Control Loop-Beyond Imposed External Perturbations. Front Neurol 2018; 9:899. [PMID: 30416481 PMCID: PMC6212554 DOI: 10.3389/fneur.2018.00899] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/03/2018] [Indexed: 12/22/2022] Open
Abstract
Standing balance relies on the integration of multiple sensory inputs to generate the motor commands required to stand. Mechanical and sensory perturbations elicit compensatory postural responses that are interpreted as a window into the sensorimotor processing involved in balance control. Popular methods involve imposed external perturbations that disrupt the control of quiet stance. Although these approaches provide critical information on how the balance system responds to external disturbances, the control mechanisms involved in correcting for these errors may differ from those responsible for the regulation of quiet standing. Alternative approaches use manipulations of the balance control loop to alter the relationship between sensory and motor cues. Coupled with imposed perturbations, these manipulations of the balance control loop provide unique opportunities to reveal how sensory and motor signals are integrated to control the upright body. In this review, we first explore imposed perturbation approaches that have been used to investigate the neural control of standing balance. We emphasize imposed perturbations that only elicit balance responses when the disturbing stimuli are relevant to the balance task. Next, we highlight manipulations of the balance control loop that, when carefully implemented, replicate and/or alter the sensorimotor dynamics of quiet standing. We further describe how manipulations of the balance control loop can be used in combination with imposed perturbations to characterize mechanistic principles underlying the control of standing balance. We propose that recent developments in the use of robotics and sensory manipulations will continue to enable new possibilities for simulating and/or altering the sensorimotor control of standing beyond compensatory responses to imposed external perturbations.
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Affiliation(s)
- Brandon G. Rasman
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Patrick A. Forbes
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, Netherlands
| | - Romain Tisserand
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
- Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, BC, Canada
- Institute for Computing, Information and Cognitive Systems, University of British Columbia, Vancouver, BC, Canada
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17
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Tamás LT, Lundberg YW, Büki B. Vergence increases the gain of the human angular vestibulo-ocular reflex during peripheral hyposensitivity elicited by cold thermal irrigation. J Vestib Res 2018; 27:265-270. [PMID: 29400687 DOI: 10.3233/ves-170629] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND When viewing a far target, the gain of the horizontal vestibulo-ocular reflex (VOR) is around 1.0, but when viewing a near target there is an increased response. It has been shown that while this convergence-mediated modulation is unaffected by canal plugging and clinically practical transmastoid galvanic stimulation, it is eliminated by a partial peripheral gentamicin lesion. OBJECTIVE The aim of this study was to determine if convergence increases the gain during peripheral hyposensitivity elicited by cold thermal irrigation. METHODS The high frequency VOR gain was measured using video head impulse testing immediately after the cold caloric stimulus in 9 healthy human subjects with the lateral semicircular canals oriented approximately earth-vertical. RESULTS Before caloric irrigation, near viewing (15 cm) increased the average VOR gain by 28% (from 1 to 1.28). Cold (24°C) water irrigation of the right ear decreased the gain to 0.66 (far viewing) and 0.82 (near viewing) (22% difference). Although vergence also increased the gain for impulses to the left to the same degree before caloric stimulus, the caloric irrigation itself (applied to the right ear) did not influence the gain for contralateral impulses. CONCLUSION In our experiments vergence increased the gain of the human angular VOR during peripheral hyposensitivity elicited by cold thermal irrigation. These results suggest that cold irrigation does not abolish the function of the nonlinear/phasic vestibular afferent pathway.
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Affiliation(s)
- László T Tamás
- Department of Otolaryngology, Petz Aladár Teaching Hospital, 9023 Győr, Vasváry Pál u. 2-4., Hungary
| | - Yunxia W Lundberg
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, NE, USA
| | - Béla Büki
- Department of Otolaryngology, Karl Landsteiner University Hospital Krems, Krems an der Donau, Austria
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18
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Galvanic Vestibular Stimulation: Cellular Substrates and Response Patterns of Neurons in the Vestibulo-Ocular Network. J Neurosci 2017; 36:9097-110. [PMID: 27581452 DOI: 10.1523/jneurosci.4239-15.2016] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 07/14/2016] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED Galvanic vestibular stimulation (GVS) uses modulated currents to evoke neuronal activity in vestibular endorgans in the absence of head motion. GVS is typically used for a characterization of vestibular pathologies; for studies on the vestibular influence of gaze, posture, and locomotion; and for deciphering the sensory-motor transformation underlying these behaviors. At variance with the widespread use of this method, basic aspects such as the activated cellular substrate at the sensory periphery or the comparability to motion-induced neuronal activity patterns are still disputed. Using semi-intact preparations of Xenopus laevis tadpoles, we determined the cellular substrate and the spatiotemporal specificity of GVS-evoked responses and compared sinusoidal GVS-induced activity patterns with motion-induced responses in all neuronal elements along the vestibulo-ocular pathway. As main result, we found that, despite the pharmacological block of glutamatergic hair cell transmission by combined bath-application of NMDA (7-chloro-kynurenic acid) and AMPA (CNQX) receptor blockers, GVS-induced afferent spike activity persisted. However, the amplitude modulation was reduced by ∼30%, suggesting that both hair cells and vestibular afferent fibers are normally recruited by GVS. Systematic alterations of electrode placement with respect to bilateral semicircular canal pairs or alterations of the bipolar stimulus phase timing yielded unique activity patterns in extraocular motor nerves, compatible with a spatially and temporally specific activation of vestibulo-ocular reflexes in distinct planes. Despite the different GVS electrode placement in semi-intact X. laevis preparations and humans and the more global activation of vestibular endorgans by the latter approach, this method is suitable to imitate head/body motion in both circumstances. SIGNIFICANCE STATEMENT Galvanic vestibular stimulation is used frequently in clinical practice to test the functionality of the sense of balance. The outcome of the test that relies on the activation of eye movements by electrical stimulation of vestibular organs in the inner ear helps to dissociate vestibular impairments that cause vertigo and imbalance in patients. This study uses an amphibian model to investigate at the cellular level the underlying mechanism on which this method depends. The outcome of this translational research unequivocally revealed the cellular substrate at the vestibular sensory periphery that is activated by electrical currents, as well as the spatiotemporal specificity of the evoked eye movements, thus facilitating the interpretation of clinical test results.
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19
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Curthoys IS, MacDougall HG, Vidal PP, de Waele C. Sustained and Transient Vestibular Systems: A Physiological Basis for Interpreting Vestibular Function. Front Neurol 2017; 8:117. [PMID: 28424655 PMCID: PMC5371610 DOI: 10.3389/fneur.2017.00117] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 03/14/2017] [Indexed: 01/17/2023] Open
Abstract
Otolithic afferents with regular resting discharge respond to gravity or low-frequency linear accelerations, and we term these the static or sustained otolithic system. However, in the otolithic sense organs, there is anatomical differentiation across the maculae and corresponding physiological differentiation. A specialized band of receptors called the striola consists of mainly type I receptors whose hair bundles are weakly tethered to the overlying otolithic membrane. The afferent neurons, which form calyx synapses on type I striolar receptors, have irregular resting discharge and have low thresholds to high frequency (e.g., 500 Hz) bone-conducted vibration and air-conducted sound. High-frequency sound and vibration likely causes fluid displacement which deflects the weakly tethered hair bundles of the very fast type I receptors. Irregular vestibular afferents show phase locking, similar to cochlear afferents, up to stimulus frequencies of kilohertz. We term these irregular afferents the transient system signaling dynamic otolithic stimulation. A 500-Hz vibration preferentially activates the otolith irregular afferents, since regular afferents are not activated at intensities used in clinical testing, whereas irregular afferents have low thresholds. We show how this sustained and transient distinction applies at the vestibular nuclei. The two systems have differential responses to vibration and sound, to ototoxic antibiotics, to galvanic stimulation, and to natural linear acceleration, and such differential sensitivity allows probing of the two systems. A 500-Hz vibration that selectively activates irregular otolithic afferents results in stimulus-locked eye movements in animals and humans. The preparatory myogenic potentials for these eye movements are measured in the new clinical test of otolith function—ocular vestibular-evoked myogenic potentials. We suggest 500-Hz vibration may identify the contribution of the transient system to vestibular controlled responses, such as vestibulo-ocular, vestibulo-spinal, and vestibulo-sympathetic responses. The prospect of particular treatments targeting one or the other of the transient or sustained systems is now being realized in the clinic by the use of intratympanic gentamicin which preferentially attacks type I receptors. We suggest that it is valuable to view vestibular responses by this sustained-transient distinction.
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Affiliation(s)
- Ian S Curthoys
- Vestibular Research Laboratory, School of Psychology, The University of Sydney, Sydney, NSW, Australia
| | - Hamish G MacDougall
- Vestibular Research Laboratory, School of Psychology, The University of Sydney, Sydney, NSW, Australia
| | - Pierre-Paul Vidal
- Cognition and Action Group, CNRS UMR8257, Centre Universitaire des Saints-Pères, University Paris Descartes, Paris, France
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20
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Peters RM, Rasman BG, Inglis JT, Blouin JS. Gain and phase of perceived virtual rotation evoked by electrical vestibular stimuli. J Neurophysiol 2015; 114:264-73. [PMID: 25925318 DOI: 10.1152/jn.00114.2015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 04/28/2015] [Indexed: 11/22/2022] Open
Abstract
Galvanic vestibular stimulation (GVS) evokes a perception of rotation; however, very few quantitative data exist on the matter. We performed psychophysical experiments on virtual rotations experienced when binaural bipolar electrical stimulation is applied over the mastoids. We also performed analogous real whole body yaw rotation experiments, allowing us to compare the frequency response of vestibular perception with (real) and without (virtual) natural mechanical stimulation of the semicircular canals. To estimate the gain of vestibular perception, we measured direction discrimination thresholds for virtual and real rotations. Real direction discrimination thresholds decreased at higher frequencies, confirming multiple previous studies. Conversely, virtual direction discrimination thresholds increased at higher frequencies, implying low-pass filtering of the virtual perception process occurring potentially anywhere between afferent transduction and cortical responses. To estimate the phase of vestibular perception, participants manually tracked their perceived position during sinusoidal virtual and real kinetic stimulation. For real rotations, perceived velocity was approximately in phase with actual velocity across all frequencies. Perceived virtual velocity was in phase with the GVS waveform at low frequencies (0.05 and 0.1 Hz). As frequency was increased to 1 Hz, the phase of perceived velocity advanced relative to the GVS waveform. Therefore, at low frequencies GVS is interpreted as an angular velocity signal and at higher frequencies GVS becomes interpreted increasingly as an angular position signal. These estimated gain and phase spectra for vestibular perception are a first step toward generating well-controlled virtual vestibular percepts, an endeavor that may reveal the usefulness of GVS in the areas of clinical assessment, neuroprosthetics, and virtual reality.
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Affiliation(s)
- Ryan M Peters
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Brandon G Rasman
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - J Timothy Inglis
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada; International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada; and
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada; Institute for Computing, Information, and Cognitive Systems, University of British Columbia, Vancouver, British Columbia, Canada
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21
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van de Berg R, Guinand N, Nguyen TAK, Ranieri M, Cavuscens S, Guyot JP, Stokroos R, Kingma H, Perez-Fornos A. The vestibular implant: frequency-dependency of the electrically evoked vestibulo-ocular reflex in humans. Front Syst Neurosci 2015; 8:255. [PMID: 25653601 PMCID: PMC4299437 DOI: 10.3389/fnsys.2014.00255] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 12/29/2014] [Indexed: 12/05/2022] Open
Abstract
The vestibulo-ocular reflex (VOR) shows frequency-dependent behavior. This study investigated whether the characteristics of the electrically evoked VOR (eVOR) elicited by a vestibular implant, showed the same frequency-dependency. Twelve vestibular electrodes implanted in seven patients with bilateral vestibular hypofunction (BVH) were tested. Stimuli consisted of amplitude-modulated electrical stimulation with a sinusoidal profile at frequencies of 0.5, 1, and 2 Hz. The main characteristics of the eVOR were evaluated and compared to the “natural” VOR characteristics measured in a group of age-matched healthy volunteers who were subjected to horizontal whole body rotations with equivalent sinusoidal velocity profiles at the same frequencies. A strong and significant effect of frequency was observed in the total peak eye velocity of the eVOR. This effect was similar to that observed in the “natural” VOR. Other characteristics of the (e)VOR (angle, habituation-index, and asymmetry) showed no significant frequency-dependent effect. In conclusion, this study demonstrates that, at least at the specific (limited) frequency range tested, responses elicited by a vestibular implant closely mimic the frequency-dependency of the “normal” vestibular system.
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Affiliation(s)
- Raymond van de Berg
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Faculty of Health Medicine and Life Sciences, School for Mental Health and Neuroscience, Maastricht University Medical Center Maastricht, Netherlands ; Faculty of Physics, Tomsk State University Tomsk, Russia
| | - Nils Guinand
- Service of Otorhinolaryngology and Head and Neck Surgery, Department of Clinical Neurosciences, Geneva University Hospitals Geneva, Switzerland
| | - T A Khoa Nguyen
- Translational Neural Engineering Lab, Center for Neuroprosthetics, Interfaculty Institute of Bioengineering, École Polytechnique Fédérale de Lausanne Lausanne, Switzerland
| | - Maurizio Ranieri
- Service of Otorhinolaryngology and Head and Neck Surgery, Department of Clinical Neurosciences, Geneva University Hospitals Geneva, Switzerland
| | - Samuel Cavuscens
- Service of Otorhinolaryngology and Head and Neck Surgery, Department of Clinical Neurosciences, Geneva University Hospitals Geneva, Switzerland
| | - Jean-Philippe Guyot
- Service of Otorhinolaryngology and Head and Neck Surgery, Department of Clinical Neurosciences, Geneva University Hospitals Geneva, Switzerland
| | - Robert Stokroos
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Faculty of Health Medicine and Life Sciences, School for Mental Health and Neuroscience, Maastricht University Medical Center Maastricht, Netherlands
| | - Herman Kingma
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Faculty of Health Medicine and Life Sciences, School for Mental Health and Neuroscience, Maastricht University Medical Center Maastricht, Netherlands ; Faculty of Physics, Tomsk State University Tomsk, Russia
| | - Angelica Perez-Fornos
- Service of Otorhinolaryngology and Head and Neck Surgery, Department of Clinical Neurosciences, Geneva University Hospitals Geneva, Switzerland
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22
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Forbes PA, Dakin CJ, Vardy AN, Happee R, Siegmund GP, Schouten AC, Blouin JS. Frequency response of vestibular reflexes in neck, back, and lower limb muscles. J Neurophysiol 2013; 110:1869-81. [DOI: 10.1152/jn.00196.2013] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Vestibular pathways form short-latency disynaptic connections with neck motoneurons, whereas they form longer-latency disynaptic and polysynaptic connections with lower limb motoneurons. We quantified frequency responses of vestibular reflexes in neck, back, and lower limb muscles to explain between-muscle differences. Two hypotheses were evaluated: 1) that muscle-specific motor-unit properties influence the bandwidth of vestibular reflexes; and 2) that frequency responses of vestibular reflexes differ between neck, back, and lower limb muscles because of neural filtering. Subjects were exposed to electrical vestibular stimuli over bandwidths of 0–25 and 0–75 Hz while recording activity in sternocleidomastoid, splenius capitis, erector spinae, soleus, and medial gastrocnemius muscles. Coherence between stimulus and muscle activity revealed markedly larger vestibular reflex bandwidths in neck muscles (0–70 Hz) than back (0–15 Hz) or lower limb muscles (0–20 Hz). In addition, vestibular reflexes in back and lower limb muscles undergo low-pass filtering compared with neck-muscle responses, which span a broader dynamic range. These results suggest that the wider bandwidth of head-neck biomechanics requires a vestibular influence on neck-muscle activation across a larger dynamic range than lower limb muscles. A computational model of vestibular afferents and a motoneuron pool indicates that motor-unit properties are not primary contributors to the bandwidth filtering of vestibular reflexes in different muscles. Instead, our experimental findings suggest that pathway-dependent neural filtering, not captured in our model, contributes to these muscle-specific responses. Furthermore, gain-phase discontinuities in the neck-muscle vestibular reflexes provide evidence of destructive interaction between different reflex components, likely via indirect vestibular-motor pathways.
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Affiliation(s)
- Patrick A. Forbes
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands
| | - Christopher J. Dakin
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alistair N. Vardy
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands
| | - Riender Happee
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands
| | - Gunter P. Siegmund
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
- MEA Forensic Engineers & Scientists, Richmond, British Columbia, Canada
| | - Alfred C. Schouten
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands
- Laboratory of Biomechanical Engineering, Institute for Biomedical Technology and Technical Medicine (MIRA), University of Twente, Enschede, The Netherlands
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
- Brain Research Center, University of British Columbia, Vancouver, British Columbia, Canada
- Institute for Computing, Information and Cognitive Systems, University of British Columbia, Vancouver, British Columbia, Canada; and
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Goldberg JM, Holt JC. Discharge regularity in the turtle posterior crista: comparisons between experiment and theory. J Neurophysiol 2013; 110:2830-48. [PMID: 24004525 DOI: 10.1152/jn.00195.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Intra-axonal recordings were made from bouton fibers near their termination in the turtle posterior crista. Spike discharge, miniature excitatory postsynaptic potentials (mEPSPs), and afterhyperpolarizations (AHPs) were monitored during resting activity in both regularly and irregularly discharging units. Quantal size (qsize) and quantal rate (qrate) were estimated by shot-noise theory. Theoretically, the ratio, σV/(dμV/dt), between synaptic noise (σV) and the slope of the mean voltage trajectory (dμV/dt) near threshold crossing should determine discharge regularity. AHPs are deeper and more prolonged in regular units; as a result, dμV/dt is larger, the more regular the discharge. The qsize is larger and qrate smaller in irregular units; these oppositely directed trends lead to little variation in σV with discharge regularity. Of the two variables, dμV/dt is much more influential than the nearly constant σV in determining regularity. Sinusoidal canal-duct indentations at 0.3 Hz led to modulations in spike discharge and synaptic voltage. Gain, the ratio between the amplitudes of the two modulations, and phase leads re indentation of both modulations are larger in irregular units. Gain variations parallel the sensitivity of the postsynaptic spike encoder, the set of conductances that converts synaptic input into spike discharge. Phase variations reflect both synaptic inputs to the encoder and postsynaptic processes. Experimental data were interpreted using a stochastic integrate-and-fire model. Advantages of an irregular discharge include an enhanced encoder gain and the prevention of nonlinear phase locking. Regular and irregular units are more efficient, respectively, in the encoding of low- and high-frequency head rotations, respectively.
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Affiliation(s)
- Jay M Goldberg
- Department of Pharmacological and Physiological Sciences, University of Chicago, Chicago, Illinois
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