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Sander MY, Zhu X. Infrared neuromodulation-a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:066701. [PMID: 38701769 DOI: 10.1088/1361-6633/ad4729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 05/03/2024] [Indexed: 05/05/2024]
Abstract
Infrared (IR) neuromodulation (INM) is an emerging light-based neuromodulation approach that can reversibly control neuronal and muscular activities through the transient and localized deposition of pulsed IR light without requiring any chemical or genetic pre-treatment of the target cells. Though the efficacy and short-term safety of INM have been widely demonstrated in both peripheral and central nervous systems, the investigations of the detailed cellular and biological processes and the underlying biophysical mechanisms are still ongoing. In this review, we discuss the current research progress in the INM field with a focus on the more recently discovered IR nerve inhibition. Major biophysical mechanisms associated with IR nerve stimulation are summarized. As the INM effects are primarily attributed to the spatiotemporal thermal transients induced by water and tissue absorption of pulsed IR light, temperature monitoring techniques and simulation models adopted in INM studies are discussed. Potential translational applications, current limitations, and challenges of the field are elucidated to provide guidance for future INM research and advancement.
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Affiliation(s)
- Michelle Y Sander
- Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, Boston, MA 02215, United States of America
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA 02215, United States of America
- Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Brookline, MA 02446, United States of America
- Photonics Center, Boston University, 8 Saint Mary's Street, Boston, MA 02215, United States of America
- Neurophotonics Center, Boston University, 24 Cummington Mall, Boston, MA 02215, United States of America
| | - Xuedong Zhu
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA 02215, United States of America
- Photonics Center, Boston University, 8 Saint Mary's Street, Boston, MA 02215, United States of America
- Neurophotonics Center, Boston University, 24 Cummington Mall, Boston, MA 02215, United States of America
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2
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Khurana L, Harczos T, Moser T, Jablonski L. En route to sound coding strategies for optical cochlear implants. iScience 2023; 26:107725. [PMID: 37720089 PMCID: PMC10502376 DOI: 10.1016/j.isci.2023.107725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2023] Open
Abstract
Hearing loss is the most common human sensory deficit. Severe-to-complete sensorineural hearing loss is often treated by electrical cochlear implants (eCIs) bypassing dysfunctional or lost hair cells by direct stimulation of the auditory nerve. The wide current spread from each intracochlear electrode array contact activates large sets of tonotopically organized neurons limiting spectral selectivity of sound coding. Despite many efforts, an increase in the number of independent eCI stimulation channels seems impossible to achieve. Light, which can be better confined in space than electric current may help optical cochlear implants (oCIs) to overcome eCI shortcomings. In this review, we present the current state of the optogenetic sound encoding. We highlight optical sound coding strategy development capitalizing on the optical stimulation that requires fine-grained, fast, and power-efficient real-time sound processing controlling dozens of microscale optical emitters as an emerging research area.
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Affiliation(s)
- Lakshay Khurana
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
- Auditory Neuroscience and Synaptic Nanophysiology Group, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
- Junior Research Group “Computational Neuroscience and Neuroengineering”, Göttingen, Germany
- The Doctoral Program “Sensory and Motor Neuroscience”, Göttingen Graduate Center for Neurosciences, Biophysics, and Molecular Biosciences (GGNB), Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Tamas Harczos
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
- Auditory Neuroscience and Synaptic Nanophysiology Group, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
| | - Lukasz Jablonski
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
- Junior Research Group “Computational Neuroscience and Neuroengineering”, Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
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3
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Ismaiel E, Fiáth R, Szabó Á, Horváth ÁC, Fekete Z. Thermal neuromodulation using pulsed and continuous infrared illumination in a penicillin-induced acute epilepsy model. Sci Rep 2023; 13:14460. [PMID: 37660232 PMCID: PMC10475096 DOI: 10.1038/s41598-023-41552-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 08/28/2023] [Indexed: 09/04/2023] Open
Abstract
Infrared neuromodulation (INM) is a promising neuromodulation tool that utilizes pulsed or continuous-wave near-infrared (NIR) laser light to produce an elevation of the background temperature of the neural tissue. The INM-based cortical heating has been proven as an effective modality to induce changes in neuronal activities. In this paper, we investigate the effect of INM-based cortical heating on the characteristics of interictal epileptiform discharges (IEDs) induced by penicillin in anesthetized rats. Cortical heating was conducted using a NIR laser light guided through a needle-like silicon-based waveguide probe. We detected penicillin-induced cortical IEDs from preprocessed micro-electrocorticography ([Formula: see text]ECoG) recordings, then we assessed changes in various temporal and spectral features of IEDs due to INM. Our findings show that the fast cortical heating phase obtained with continuous-wave NIR light is highly associated with a reduction of IED amplitudes, small but significant changes in the negative amplitude of IEDs compared with the baseline, and a proportional increase in the power of frequency bands related to delta/theta (2-8 Hz) and gamma (28-80 Hz) oscillations. Furthermore, a low rate of cortical heating with pulsed NIR illumination has a more inhibitory impact on the sharp negative polarity of IEDs. Our findings do not indicate a clear reduction in the frequency of IEDs in anesthetized rodents. In contrast, 2-4 min of continuous laser illumination leads to a notable increase in IED frequency. This effect of INM could potentially restrict its use in therapeutic applications related to epilepsy. However, the thermal effect of INM on cortical neurons induces changes in other characteristics of IEDs, which could prove beneficial for future applications.
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Affiliation(s)
- Ebrahim Ismaiel
- Research Group for Implantable Microsystems, Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Richárd Fiáth
- Research Centre for Natural Sciences, Institute of Cognitive Neuroscience and Psychology, Magyar tudósok körútja 2, Budapest, 1117, Hungary
- Integrative Neuroscience Research Group, Faculty of Information Technology & Bionics, Pazmany Peter Catholic University, Budapest, Hungary
| | - Ágnes Szabó
- Research Group for Implantable Microsystems, Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Ágoston Csaba Horváth
- Research Group for Implantable Microsystems, Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Zoltán Fekete
- Research Group for Implantable Microsystems, Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary.
- Research Centre for Natural Sciences, Institute of Cognitive Neuroscience and Psychology, Magyar tudósok körútja 2, Budapest, 1117, Hungary.
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4
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Almasri RM, Ladouceur F, Mawad D, Esrafilzadeh D, Firth J, Lehmann T, Poole-Warren LA, Lovell NH, Al Abed A. Emerging trends in the development of flexible optrode arrays for electrophysiology. APL Bioeng 2023; 7:031503. [PMID: 37692375 PMCID: PMC10491464 DOI: 10.1063/5.0153753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 08/08/2023] [Indexed: 09/12/2023] Open
Abstract
Optical-electrode (optrode) arrays use light to modulate excitable biological tissues and/or transduce bioelectrical signals into the optical domain. Light offers several advantages over electrical wiring, including the ability to encode multiple data channels within a single beam. This approach is at the forefront of innovation aimed at increasing spatial resolution and channel count in multichannel electrophysiology systems. This review presents an overview of devices and material systems that utilize light for electrophysiology recording and stimulation. The work focuses on the current and emerging methods and their applications, and provides a detailed discussion of the design and fabrication of flexible arrayed devices. Optrode arrays feature components non-existent in conventional multi-electrode arrays, such as waveguides, optical circuitry, light-emitting diodes, and optoelectronic and light-sensitive functional materials, packaged in planar, penetrating, or endoscopic forms. Often these are combined with dielectric and conductive structures and, less frequently, with multi-functional sensors. While creating flexible optrode arrays is feasible and necessary to minimize tissue-device mechanical mismatch, key factors must be considered for regulatory approval and clinical use. These include the biocompatibility of optical and photonic components. Additionally, material selection should match the operating wavelength of the specific electrophysiology application, minimizing light scattering and optical losses under physiologically induced stresses and strains. Flexible and soft variants of traditionally rigid photonic circuitry for passive optical multiplexing should be developed to advance the field. We evaluate fabrication techniques against these requirements. We foresee a future whereby established telecommunications techniques are engineered into flexible optrode arrays to enable unprecedented large-scale high-resolution electrophysiology systems.
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Affiliation(s)
- Reem M. Almasri
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
| | | | - Damia Mawad
- School of Materials Science and Engineering, UNSW, Sydney, NSW 2052, Australia
| | - Dorna Esrafilzadeh
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
| | - Josiah Firth
- Australian National Fabrication Facility, UNSW, Sydney, NSW 2052, Australia
| | - Torsten Lehmann
- School of Electrical Engineering and Telecommunications, UNSW, Sydney, NSW 2052, Australia
| | | | | | - Amr Al Abed
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
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Montazeri K, Farhadi M, Akbarnejad Z, Asadpour A, Majdabadi A, Fekrazad R, Mahmoudian S. Acoustic and optoacoustic stimulations in auditory brainstem response test in salicylate induced tinnitus. Sci Rep 2023; 13:11930. [PMID: 37488197 PMCID: PMC10366222 DOI: 10.1038/s41598-023-39033-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 07/19/2023] [Indexed: 07/26/2023] Open
Abstract
As a common debilitating disorder worldwide, tinnitus requires objective assessment. In the auditory brainstem response (ABR) test, auditory potentials can be evoked by acoustic or optoacoustic (induced by laser light) stimulations. In order to use the ABR test in the objective assessment of tinnitus, in this study, acoustic ABR (aABR) and optoacoustic ABR (oABR) were compared in the control and tinnitus groups to determine the changes caused by sodium salicylate (SS)-induced tinnitus in rat. In both aABR and oABR, wave II was the most prominent waveform, and the amplitude of wave II evoked by oABR was significantly higher than that of aABR. Brainstem transmission time (BTT), which represents the time required for a neural stimulation to progress from the auditory nerve ending to the inferior colliculus, was significantly shorter in oABR. In the tinnitus group, there was a significant increase in the threshold of both ABRs and a significant decrease in the amplitude of wave II only in the oABR. Based on our findings, the ABR test has the potential to be used in the assessment of SS-induced tinnitus, but oABR has the advantages of producing more prominent waveforms and significantly reducing the amplitude of wave II in tinnitus.
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Affiliation(s)
- Katayoon Montazeri
- ENT and Head and Neck Research Center, The Five Senses Health Institute, School of Medicine, Hazrate Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, 1445613131, Iran
| | - Mohammad Farhadi
- ENT and Head and Neck Research Center, The Five Senses Health Institute, School of Medicine, Hazrate Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, 1445613131, Iran
| | - Zeinab Akbarnejad
- ENT and Head and Neck Research Center, The Five Senses Health Institute, School of Medicine, Hazrate Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, 1445613131, Iran
| | - Abdoreza Asadpour
- Intelligent Systems Research Centre, Ulster University, Derry Campus, Derry~Londonderry, Northern Ireland, UK
| | - Abbas Majdabadi
- Laser Research Center of Dentistry, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Reza Fekrazad
- Radiation Sciences Research Center, Laser Research Center in Medical Sciences, AJA University of Medical Sciences, Tehran, Iran
| | - Saeid Mahmoudian
- ENT and Head and Neck Research Center, The Five Senses Health Institute, School of Medicine, Hazrate Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, 1445613131, Iran.
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6
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Ping A, Pan L, Zhang J, Xu K, Schriver KE, Zhu J, Roe AW. Targeted Optical Neural Stimulation: A New Era for Personalized Medicine. Neuroscientist 2023; 29:202-220. [PMID: 34865559 DOI: 10.1177/10738584211057047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Targeted optical neural stimulation comprises infrared neural stimulation and optogenetics, which affect the nervous system through induced thermal transients and activation of light-sensitive proteins, respectively. The main advantage of this pair of optical tools is high functional selectivity, which conventional electrical stimulation lacks. Over the past 15 years, the mechanism, safety, and feasibility of optical stimulation techniques have undergone continuous investigation and development. When combined with other methods like optical imaging and high-field functional magnetic resonance imaging, the translation of optical stimulation to clinical practice adds high value. We review the theoretical foundations and current state of optical stimulation, with a particular focus on infrared neural stimulation as a potential bridge linking optical stimulation to personalized medicine.
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Affiliation(s)
- An Ping
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Li Pan
- Qiushi Academy for Advanced Studies (QAAS), Key Laboratory of Biomedical Engineering of Education Ministry & Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jianmin Zhang
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Kedi Xu
- Qiushi Academy for Advanced Studies (QAAS), Key Laboratory of Biomedical Engineering of Education Ministry & Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, Zhejiang, China.,Zhejiang Lab, Hangzhou, Zhejiang, China
| | - Kenneth E Schriver
- Zhejiang University Interdisciplinary Institute of Neuroscience and Technology (ZIINT), School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Junming Zhu
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Anna Wang Roe
- Zhejiang University Interdisciplinary Institute of Neuroscience and Technology (ZIINT), School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang, China
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7
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Uenaka M, Nagamura H, Okamoto A, Hiryu S, Kobayasi KI, Tamai Y. Feasibility evaluation of transtympanic laser stimulation of the cochlea from the outer ear. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 152:1850. [PMID: 36182303 DOI: 10.1121/10.0014241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 09/06/2022] [Indexed: 06/16/2023]
Abstract
Infrared laser stimulation has been studied as an alternative approach to auditory prostheses. This study evaluated the feasibility of infrared laser stimulation of the cochlea from the outer ear, bypassing the middle ear function. An optic fiber was inserted into the ear canal, and a laser was used to irradiate the cochlea through the tympanic membrane in Mongolian gerbils. A pulsed infrared laser (6.9 mJ/cm2) and clicking sound (70 peak-to-peak equivalent sound pressure level) were presented to the animals. The amplitude of the laser-evoked cochlear response was systematically decreased following insertion of a filter between the tympanic membrane and cochlea; however, the auditory-evoked cochlear response did not decrease. The filter was removed, and the laser-evoked response returned to around the original level. The amplitude ratio and the relative change in response amplitude before and during filter insertion significantly decreased as the absorbance of the infrared filter increased. These results indicate that laser irradiation could bypass the function of the middle ear and directly activate the cochlea. Therefore, laser irradiation from the outer ear is a possible alternative for stimulating the cochlea, circumventing the middle ear.
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Affiliation(s)
- Miku Uenaka
- Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Hidekazu Nagamura
- Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Aya Okamoto
- Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Shizuko Hiryu
- Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Kohta I Kobayasi
- Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Yuta Tamai
- Organization for Research Initiatives and Development, Doshisha University, Kyotanabe, Kyoto, Japan
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Wolf BJ, Kusch K, Hunniford V, Vona B, Kühler R, Keppeler D, Strenzke N, Moser T. Is there an unmet medical need for improved hearing restoration? EMBO Mol Med 2022; 14:e15798. [PMID: 35833443 PMCID: PMC9358394 DOI: 10.15252/emmm.202215798] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 05/12/2022] [Accepted: 06/02/2022] [Indexed: 12/26/2022] Open
Abstract
Hearing impairment, the most prevalent sensory deficit, affects more than 466 million people worldwide (WHO). We presently lack causative treatment for the most common form, sensorineural hearing impairment; hearing aids and cochlear implants (CI) remain the only means of hearing restoration. We engaged with CI users to learn about their expectations and their willingness to collaborate with health care professionals on establishing novel therapies. We summarize upcoming CI innovations, gene therapies, and regenerative approaches and evaluate the chances for clinical translation of these novel strategies. We conclude that there remains an unmet medical need for improving hearing restoration and that we are likely to witness the clinical translation of gene therapy and major CI innovations within this decade.
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Affiliation(s)
- Bettina Julia Wolf
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany.,Auditory Neuroscience & Synaptic Nanophysiology Group, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Kathrin Kusch
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Functional Auditory Genomics Group, Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
| | - Victoria Hunniford
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Sensory and Motor Neuroscience PhD Program, Göttingen Graduate Center for Neurosciences, Biophysics, and Molecular Biosciences, Göttingen, Germany
| | - Barbara Vona
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany
| | - Robert Kühler
- Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany
| | - Daniel Keppeler
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Auditory Neuroscience & Synaptic Nanophysiology Group, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Nicola Strenzke
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany.,Auditory Neuroscience & Synaptic Nanophysiology Group, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
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Brant JA, Adewole DO, Vitale F, Cullen DK. Bioengineering applications for hearing restoration: emerging biologically inspired and biointegrated designs. Curr Opin Biotechnol 2021; 72:131-138. [PMID: 34826683 DOI: 10.1016/j.copbio.2021.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 10/29/2021] [Accepted: 11/08/2021] [Indexed: 12/21/2022]
Abstract
Cochlear implantation has become the standard of care for hearing loss not amenable to amplification by bypassing the structures of the cochlea and stimulating the spiral ganglion neurons directly. Since the first single channel electrodes were implanted, significant advancements have been made: multi-channel arrays are now standard, they are softer to avoid damage to the cochlea and pre-curved to better position the electrode array adjacent to the nerve, and surgical and stimulation techniques have helped to conform to the anatomy and physiology of the cochlea. However, even with these advances the experience does not approach that of normal hearing. In order to make significant advances in performance, the next generation of implants will require novel interface technology. Advances in regenerative techniques, optogenetics, piezoelectric materials, and bioengineered living scaffolds hold the promise for the next generation of implantable hearing devices, and hope for the restoration of natural hearing.
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Affiliation(s)
- Jason A Brant
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104, USA; Center for Brain Injury & Repair, Department of Neurosurgery, University of Pennsylvania, 240 S. 33rd St., 301 Hayden Hall, Philadelphia, PA 19104, USA
| | - Dayo O Adewole
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104, USA; Center for Brain Injury & Repair, Department of Neurosurgery, University of Pennsylvania, 240 S. 33rd St., 301 Hayden Hall, Philadelphia, PA 19104, USA; Department of Bioengineering, School of Engineering and Applied, Science, University of Pennsylvania, 220 S 33rd St., Philadelphia, PA 19104, USA; Center for Brain Injury & Repair, Department of Neurosurgery, University of Pennsylvania, 3320 Smith Walk, 105 Hayden Hall, Philadelphia, PA 19104, USA; Center for Neuroengineering & Therapeutics, University of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104, USA
| | - Flavia Vitale
- Center for Brain Injury & Repair, Department of Neurosurgery, University of Pennsylvania, 240 S. 33rd St., 301 Hayden Hall, Philadelphia, PA 19104, USA; Department of Bioengineering, School of Engineering and Applied, Science, University of Pennsylvania, 220 S 33rd St., Philadelphia, PA 19104, USA; Department of Neurology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104, USA; Department of Physical Medicine & Rehabilitation, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104, USA; Center for Neuroengineering & Therapeutics, University of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104, USA
| | - Daniel K Cullen
- Center for Brain Injury & Repair, Department of Neurosurgery, University of Pennsylvania, 240 S. 33rd St., 301 Hayden Hall, Philadelphia, PA 19104, USA; Department of Bioengineering, School of Engineering and Applied, Science, University of Pennsylvania, 220 S 33rd St., Philadelphia, PA 19104, USA; Center for Brain Injury & Repair, Department of Neurosurgery, University of Pennsylvania, 3320 Smith Walk, 105 Hayden Hall, Philadelphia, PA 19104, USA; Center for Neuroengineering & Therapeutics, University of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104, USA.
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10
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Viral-mediated transduction of auditory neurons with opsins for optical and hybrid activation. Sci Rep 2021; 11:11229. [PMID: 34045604 PMCID: PMC8160204 DOI: 10.1038/s41598-021-90764-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 05/13/2021] [Indexed: 12/15/2022] Open
Abstract
Optical stimulation is a paradigm-shifting approach to modulating neural activity that has the potential to overcome the issue of current spread that occurs with electrical stimulation by providing focused stimuli. But optical stimulation either requires high power infrared light or genetic modification of neurons to make them responsive to lower power visible light. This work examines optical activation of auditory neurons following optogenetic modification via AAV injection in two species (mouse and guinea pig). An Anc80 viral vector was used to express the channelrhodopsin variant ChR2-H134R fused to a fluorescent reporter gene under the control of the human synapsin-1 promoter. The AAV was administered directly to the cochlea (n = 33) or posterior semi-circular canal of C57BL/6 mice (n = 4) or to guinea pig cochleae (n = 6). Light (488 nm), electrical stimuli or the combination of these (hybrid stimulation) was delivered to the cochlea via a laser-coupled optical fibre and co-located platinum wire. Activation thresholds, spread of activation and stimulus interactions were obtained from multi-unit recordings from the central nucleus of the inferior colliculus of injected mice, as well as ChR2-H134R transgenic mice (n = 4). Expression of ChR2-H134R was examined by histology. In the mouse, transduction of auditory neurons by the Anc80 viral vector was most successful when injected at a neonatal age with up to 89% of neurons transduced. Auditory neuron transductions were not successful in guinea pigs. Inferior colliculus responses to optical stimuli were detected in a cochleotopic manner in all mice with ChR2-H134R expression. There was a significant correlation between lower activation thresholds in mice and higher proportions of transduced neurons. There was no difference in spread of activation between optical stimulation and electrical stimulation provided by the light/electrical delivery system used here (optical fibre with bonded 25 µm platinum/iridium wire). Hybrid stimulation, comprised of sub-threshold optical stimulation to 'prime' or raise the excitability of the neurons, lowered the threshold for electrical activation in most cases, but the impact on excitation width was more variable compared to transgenic mice. This study demonstrates the impact of opsin expression levels and expression pattern on optical and hybrid stimulation when considering optical or hybrid stimulation techniques for neuromodulation.
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11
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Littlefield PD, Richter C. Near-infrared stimulation of the auditory nerve: A decade of progress toward an optical cochlear implant. Laryngoscope Investig Otolaryngol 2021; 6:310-319. [PMID: 33869763 PMCID: PMC8035937 DOI: 10.1002/lio2.541] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 12/14/2020] [Accepted: 02/12/2021] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVES We provide an appraisal of recent research on stimulation of the auditory system with light. In particular, we discuss direct infrared stimulation and ongoing controversies regarding the feasibility of this modality. We also discuss advancements and barriers to the development of an optical cochlear implant. METHODS This is a review article that covers relevant animal studies. RESULTS The auditory system has been stimulated with infrared light, and in a much more spatially selective manner than with electrical stimulation. However, there are experiments from other labs that have not been able to reproduce these results. This has resulted in an ongoing controversy regarding the feasibility of infrared stimulation, and the reasons for these experimental differences still require explanation. The neural response characteristics also appear to be much different than with electrical stimulation. The electrical stimulation paradigms used for modern cochlear implants do not apply well to optical stimulation and new coding strategies are under development. Stimulation with infrared light brings the risk of heat accumulation in the tissue at high pulse repetition rates, so optimal pulse shapes and combined optical/electrical stimulation are being investigated to mitigate this. Optogenetics is another promising technique, which makes neurons more sensitive to light stimulation by inserting light sensitive ion channels via viral vectors. Challenges of optogenetics include the expression of light sensitive channels in sufficient density in the target neurons, and the risk of damaging neurons by the expression of a foreign protein. CONCLUSION Optical stimulation of the nervous system is a promising new field, and there has been progress toward the development of a cochlear implant that takes advantage of the benefits of optical stimulation. There are barriers, and controversies, but so far none that seem intractable. LEVEL OF EVIDENCE NA (animal studies and basic research).
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Affiliation(s)
| | - Claus‐Peter Richter
- Department of OtolaryngologyNorthwestern UniversityChicagoIllinoisUSA
- Department of Communication Sciences and DisordersNorthwestern UniversityEvanstonIllinoisUSA
- Department of Biomedical EngineeringNorthwestern UniversityEvanstonIllinoisUSA
- The Hugh Knowles Center, Department of Communication Sciences and DisordersNorthwestern UniversityEvanstonIllinoisUSA
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12
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Brown WGA, Needham K, Begeng JM, Thompson AC, Nayagam BA, Kameneva T, Stoddart PR. Response of primary auditory neurons to stimulation with infrared light in vitro. J Neural Eng 2021; 18:046003. [PMID: 33724234 DOI: 10.1088/1741-2552/abe7b8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Infrared light can be used to modulate the activity of neuronal cells through thermally-evoked capacitive currents and thermosensitive ion channel modulation. The infrared power threshold for action potentials has previously been found to be far lower in the in vivo cochlea when compared with other neuronal targets, implicating spiral ganglion neurons (SGNs) as a potential target for infrared auditory prostheses. However, conflicting experimental evidence suggests that this low threshold may arise from an intermediary mechanism other than direct SGN stimulation, potentially involving residual hair cell activity. APPROACH Patch-clamp recordings from cultured SGNs were used to explicitly quantify the capacitive and ion channel currents in an environment devoid of hair cells. Neurons were irradiated by a 1870 nm laser with pulse durations of 0.2-5.0 ms and powers up to 1.5 W. A Hodgkin-Huxley-type model was established by first characterising the voltage dependent currents, and then incorporating laser-evoked currents separated into temperature-dependent and temperature-gradient-dependent components. This model was found to accurately simulate neuronal responses and allowed the results to be extrapolated to stimulation parameter spaces not accessible during this study. MAIN RESULTS The previously-reported low in vivo SGN stimulation threshold was not observed, and only subthreshold depolarisation was achieved, even at high light exposures. Extrapolating these results with our Hodgkin-Huxley-type model predicts an action potential threshold which does not deviate significantly from other neuronal types. SIGNIFICANCE This suggests that the low-threshold response that is commonly reported in vivo may arise from an alternative mechanism, and calls into question the potential usefulness of the effect for auditory prostheses. The step-wise approach to modelling optically-evoked currents described here may prove useful for analysing a wider range of cell types where capacitive currents and conductance modulation are dominant.
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Affiliation(s)
- William G A Brown
- Faculty of Science, Engineering and Technology, Swinburne University of Technology, John Street, Hawthorn VIC 3122, Australia
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13
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Agarwal A, Tan X, Xu Y, Richter CP. Channel Interaction During Infrared Light Stimulation in the Cochlea. Lasers Surg Med 2021; 53:986-997. [PMID: 33476051 DOI: 10.1002/lsm.23360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 10/21/2020] [Accepted: 11/07/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND AND OBJECTIVES The number of perceptually independent channels to encode acoustic information is limited in contemporary cochlear implants (CIs) because of the current spread in the tissue. It has been suggested that neighboring electrodes have to be separated in humans by a distance of more than 2 mm to eliminate significant overlap of the electric current fields and subsequent interaction between the channels. It has also been argued that an increase in the number of independent channels could improve CI user performance in challenging listening environments, such as speech in noise, tonal languages, or music perception. Optical stimulation has been suggested as an alternative modality for neural stimulation because it is spatially selective. This study reports the results of experiments designed to quantify the interaction between neighboring optical sources in the cochlea during stimulation with infrared radiation. STUDY DESIGN/MATERIALS AND METHODS In seven adult albino guinea pigs, a forward masking method was used to quantify the interaction between two neighboring optical sources during stimulation. Two optical fibers were placed through cochleostomies into the scala tympani of the basal cochlear turn. The radiation beams were directed towards different neuron populations along the spiral ganglion. Optically evoked compound action potentials were recorded for different radiant energies and distances between the optical fibers. The outcome measure was the radiant energy of a masker pulse delivered 3 milliseconds before a probe pulse to reduce the response evoked by the probe pulse by 3 dB. Results were compared for different distances between the fibers placed along the cochlea. RESULTS The energy required to reduce the probe's response by 3 dB increased by 20.4 dB/mm and by 26.0 dB/octave. The inhibition was symmetrical for the masker placed basal to the probe (base-to-apex) and the masker placed apical to the probe (apex-to-base). CONCLUSION The interaction between neighboring optical sources during infrared laser stimulation is less than the interaction between neighboring electrical contacts during electrical stimulation. Previously published data for electrical stimulation reported an average current spread in human and cat cochleae of 2.8 dB/mm. With the increased number of independent channels for optical stimulation, it is anticipated that speech and music performance will improve. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.
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Affiliation(s)
- Aditi Agarwal
- Department of Otolaryngology, Feinberg School of Medicine, Northwestern University, 320 E. Superior Street, Searle 12-561, Chicago, Illinois, 60611
| | - Xiaodong Tan
- Department of Otolaryngology, Feinberg School of Medicine, Northwestern University, 320 E. Superior Street, Searle 12-561, Chicago, Illinois, 60611
| | - Yingyue Xu
- Department of Otolaryngology, Feinberg School of Medicine, Northwestern University, 320 E. Superior Street, Searle 12-561, Chicago, Illinois, 60611
| | - Claus-Peter Richter
- Department of Otolaryngology, Feinberg School of Medicine, Northwestern University, 320 E. Superior Street, Searle 12-561, Chicago, Illinois, 60611.,Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Tech E310, Evanston, Illinois, 60208.,Department of Communication Sciences and Disorders, Northwestern University, Evanston, Illinois, 60208.,Department of Communication Sciences and Disorders, The Hugh Knowles Center, Northwestern University, Evanston, Illinois, 60208
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14
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Thompson AC, Wise AK, Hart WL, Needham K, Fallon JB, Gunewardene N, Stoddart PR, Richardson RT. Hybrid optogenetic and electrical stimulation for greater spatial resolution and temporal fidelity of cochlear activation. J Neural Eng 2020; 17:056046. [PMID: 33036009 DOI: 10.1088/1741-2552/abbff0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Compared to electrical stimulation, optogenetic stimulation has the potential to improve the spatial precision of neural activation in neuroprostheses, but it requires intense light and has relatively poor temporal kinetics. We tested the effect of hybrid stimulation, which is the combination of subthreshold optical and electrical stimuli, on spectral and temporal fidelity in the cochlea by recording multiunit activity in the inferior colliculus of channelrhodopsin (H134R variant) transgenic mice. APPROACH Pulsed light or biphasic electrical pulses were delivered to cochlear spiral ganglion neurons of acutely deafened mice, either as individual stimuli or as hybrid stimuli for which the timing of the electrical pulse had a varied delay relative to the start of the optical pulse. Response thresholds, spread of activation and entrainment data were obtained from multi-unit recordings from the auditory midbrain. MAIN RESULTS Facilitation occurred when subthreshold electrical stimuli were applied at the end of, or up to 3.75 ms after subthreshold optical pulses. The spread of activation resulting from hybrid stimulation was significantly narrower than electrical-only and optical-only stimulation (p < 0.01), measured at equivalent suprathreshold levels of loudness that are relevant to cochlear implant users. Furthermore, temporal fidelity, measured as maximum following rates to 300 ms pulse trains bursts up to 240 Hz, was 2.4-fold greater than optical-only stimulation (p < 0.05). SIGNIFICANCE By significantly improving spectral resolution of electrical- and optical-only stimulation and the temporal fidelity of optical-only stimulation, hybrid stimulation has the potential to increase the number of perceptually independent stimulating channels in a cochlear implant.
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15
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Raufer S, Gamm UA, Grossöhmichen M, Lenarz T, Maier H. Middle Ear Actuator Performance Determined From Intracochlear Pressure Measurements in a Single Cochlear Scala. Otol Neurotol 2020; 42:e86-e93. [PMID: 33044336 DOI: 10.1097/mao.0000000000002836] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Intracochlear pressure measurements in one cochlear scala are sufficient as reference to determine the output of an active middle ear implant (AMEI) in terms of "equivalent sound pressure level" (eqSPL). BACKGROUND The performance of AMEIs is commonly calculated from stapes velocities or intracochlear pressure differences (PDiff). However, there are scenarios where measuring stapes velocities or PDiff may not be feasible, for example when access to the stapes or one of the scalae is impractical. METHODS We reanalyzed data from a previous study of our group that investigated the performance of an AMEI coupled to the incus in 10 human temporal bones. We calculated eqSPL based on stapes velocities according to the ASTM standard F2504-05 and based on intracochlear pressures in scala vestibuli, scala tympani, and PDiff. RESULTS The AMEI produced eqSPL of ∼100 to 120 dB at 1 Vrms. No significant differences were found between using intracochlear pressures in scala vestibuli, scala tympani, or PDiff as a reference. The actuator performance calculated from stapes displacements predicted slightly higher eqSPLs at frequencies above 1000 Hz, but these differences were not statistically significant. CONCLUSION Our findings show that pressure measurements in one scala can be sufficient to evaluate the performance of an AMEI coupled to the incus. The method may be extended to other stimulation modalities of the middle ear or cochlea when access to the stapes or one of the scalae is not possible.
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Affiliation(s)
- Stefan Raufer
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover.,DFG Cluster of Excellence, Hearing4all
| | - Ute A Gamm
- Cochlear Deutschland GmbH & Co. KG, Hannover, Germany
| | - Martin Grossöhmichen
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover.,DFG Cluster of Excellence, Hearing4all
| | - Thomas Lenarz
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover.,DFG Cluster of Excellence, Hearing4all
| | - Hannes Maier
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover.,DFG Cluster of Excellence, Hearing4all
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16
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Dieter A, Klein E, Keppeler D, Jablonski L, Harczos T, Hoch G, Rankovic V, Paul O, Jeschke M, Ruther P, Moser T. μLED-based optical cochlear implants for spectrally selective activation of the auditory nerve. EMBO Mol Med 2020; 12:e12387. [PMID: 32596983 PMCID: PMC7411546 DOI: 10.15252/emmm.202012387] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 05/23/2020] [Accepted: 06/02/2020] [Indexed: 01/19/2023] Open
Abstract
Electrical cochlear implants (eCIs) partially restore hearing and enable speech comprehension to more than half a million users, thereby re-connecting deaf patients to the auditory scene surrounding them. Yet, eCIs suffer from limited spectral selectivity, resulting from current spread around each electrode contact and causing poor speech recognition in the presence of background noise. Optogenetic stimulation of the auditory nerve might overcome this limitation as light can be conveniently confined in space. Here, we combined virus-mediated optogenetic manipulation of cochlear spiral ganglion neurons (SGNs) and microsystems engineering to establish acute multi-channel optical cochlear implant (oCI) stimulation in adult Mongolian gerbils. oCIs based on 16 microscale thin-film light-emitting diodes (μLEDs) evoked tonotopic activation of the auditory pathway with high spectral selectivity and modest power requirements in hearing and deaf gerbils. These results prove the feasibility of μLED-based oCIs for spectrally selective activation of the auditory nerve.
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Affiliation(s)
- Alexander Dieter
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Göttingen Graduate School for Neurosciences and Molecular BiosciencesUniversity of GöttingenGöttingenGermany
- Present address:
Synaptic Wiring LabCenter for Molecular Neurobiology HamburgUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Eric Klein
- Department of Microsystems Engineering (IMTEK)University of FreiburgFreiburgGermany
| | - Daniel Keppeler
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
| | - Lukasz Jablonski
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
| | - Tamas Harczos
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
| | - Gerhard Hoch
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
| | - Vladan Rankovic
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
- Restorative Cochlear Genomics GroupAuditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
| | - Oliver Paul
- Department of Microsystems Engineering (IMTEK)University of FreiburgFreiburgGermany
- BrainLinks‐BrainToolsCluster of ExcellenceUniversity of FreiburgFreiburgGermany
| | - Marcus Jeschke
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
- Cognitive Hearing in Primates GroupAuditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
| | - Patrick Ruther
- Department of Microsystems Engineering (IMTEK)University of FreiburgFreiburgGermany
- BrainLinks‐BrainToolsCluster of ExcellenceUniversity of FreiburgFreiburgGermany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Göttingen Graduate School for Neurosciences and Molecular BiosciencesUniversity of GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
- Auditory Neuroscience GroupMax Planck Institute for Experimental MedicineGöttingenGermany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC)University of GoettingenGoettingenGermany
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17
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Dieter A, Keppeler D, Moser T. Towards the optical cochlear implant: optogenetic approaches for hearing restoration. EMBO Mol Med 2020; 12:e11618. [PMID: 32227585 PMCID: PMC7136966 DOI: 10.15252/emmm.201911618] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 01/08/2020] [Accepted: 01/28/2020] [Indexed: 12/30/2022] Open
Abstract
Cochlear implants (CIs) are considered the most successful neuroprosthesis as they enable speech comprehension in the majority of half a million CI users suffering from sensorineural hearing loss. By electrically stimulating the auditory nerve, CIs constitute an interface re-connecting the brain and the auditory scene, providing the patient with information regarding the latter. However, since electric current is hard to focus in conductive environments such as the cochlea, the precision of electrical sound encoding-and thus quality of artificial hearing-is limited. Recently, optogenetic stimulation of the cochlea has been suggested as an alternative approach for hearing restoration. Cochlear optogenetics promises increased spectral selectivity of artificial sound encoding, hence improved hearing, as light can conveniently be confined in space to activate the auditory nerve within smaller tonotopic ranges. In this review, we discuss the latest experimental and technological developments of cochlear optogenetics and outline the remaining challenges on the way to clinical translation.
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Affiliation(s)
- Alexander Dieter
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Göttingen Graduate School for NeurosciencesBiophysics and Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Daniel Keppeler
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
- Auditory Neuroscience GroupMax Planck Institute of Experimental MedicineGöttingenGermany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC)University of GöttingenGöttingenGermany
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