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Rudmann L, Scholz D, Alt MT, Dieter A, Fiedler E, Moser T, Stieglitz T. Fabrication and Characterization of PDMS Waveguides for Flexible Optrodes. Adv Healthc Mater 2024; 13:e2304513. [PMID: 38608269 DOI: 10.1002/adhm.202304513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 04/08/2024] [Indexed: 04/14/2024]
Abstract
With the growth of optogenetic research, the demand for optical probes tailored to specific applications is ever rising. Specifically, for applications like the coiled cochlea of the inner ear, where planar, stiff, and nonconformable probes can hardly be used, transitioning from commonly used stiff glass fibers to flexible probes is required, especially for long-term use. Following this demand, polydimethylsiloxane (PDMS) with its lower Young's modulus compared to glass fibers can serve as material of choice. Hence, the long-term usability of PDMS as a waveguide material with respect to variations in transmission and refractive index over time is investigated. Different manufacturing methods for PDMS-based flexible waveguides are established and compared with the aim to minimize optical losses and thus maximize optical output power. Finally, the waveguides with lowest optical losses (-4.8 dB cm-1 ± 1.3 dB cm-1 at 472 nm) are successfully inserted into the optogenetically modified cochlea of a Mongolian gerbil (Meriones unguiculatus), where optical stimuli delivered by the waveguides evoked robust neuronal responses in the auditory pathway.
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Affiliation(s)
- Linda Rudmann
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, 79110, Freiburg, Germany
- BrainLinks BrainTools, University of Freiburg, 79110, Freiburg, Germany
| | - Daniel Scholz
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, 79110, Freiburg, Germany
| | - Marie T Alt
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, 79110, Freiburg, Germany
- BrainLinks BrainTools, University of Freiburg, 79110, Freiburg, Germany
| | - Alexander Dieter
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Eva Fiedler
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, 79110, Freiburg, Germany
- Bernstein Center Freiburg, University of Freiburg, 79104, Freiburg, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Thomas Stieglitz
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, 79110, Freiburg, Germany
- BrainLinks BrainTools, University of Freiburg, 79110, Freiburg, Germany
- Bernstein Center Freiburg, University of Freiburg, 79104, Freiburg, Germany
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McAlinden N, Reiche CF, Clark AM, Scharf R, Cheng Y, Sharma R, Rieth L, Dawson MD, Angelucci A, Mathieson K, Blair S. In vivo optogenetics using a Utah Optrode Array with enhanced light output and spatial selectivity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.18.585479. [PMID: 38562871 PMCID: PMC10983961 DOI: 10.1101/2024.03.18.585479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Optogenetics allows manipulation of neural circuits in vivo with high spatial and temporal precision. However, combining this precision with control over a significant portion of the brain is technologically challenging (especially in larger animal models). Here, we have developed, optimised, and tested in vivo, the Utah Optrode Array (UOA), an electrically addressable array of optical needles and interstitial sites illuminated by 181 µLEDs and used to optogenetically stimulate the brain. The device is specifically designed for non-human primate studies. Thinning the combined µLED and needle backplane of the device from 300 µm to 230 µm improved the efficiency of light delivery to tissue by 80%, allowing lower µLED drive currents, which improved power management and thermal performance. The spatial selectivity of each site was also improved by integrating an optical interposer to reduce stray light emission. These improvements were achieved using an innovative fabrication method to create an anodically bonded glass/silicon substrate with through-silicon vias etched, forming an optical interposer. Optical modelling was used to demonstrate that the tip structure of the device had a major influence on the illumination pattern. The thermal performance was evaluated through a combination of modelling and experiment, in order to ensure that cortical tissue temperatures did not rise by more than 1°C. The device was tested in vivo in the visual cortex of macaque expressing ChR2-tdTomato in cortical neurons. It was shown that the strongest optogenetic response occurred in the region surrounding the needle tips, and that the extent of the optogenetic response matched the predicted illumination profile based on optical modelling - demonstrating the improved spatial selectivity resulting from the optical interposer approach. Furthermore, different needle illumination sites generated different patterns of low-frequency potential (LFP) activity.
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Azees AA, Thompson AC, Thomas R, Zhou J, Ruther P, Wise AK, Ajay EA, Garrett DJ, Quigley A, Fallon JB, Richardson RT. Spread of activation and interaction between channels with multi-channel optogenetic stimulation in the mouse cochlea. Hear Res 2023; 440:108911. [PMID: 37977051 DOI: 10.1016/j.heares.2023.108911] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 10/19/2023] [Accepted: 11/02/2023] [Indexed: 11/19/2023]
Abstract
For individuals with severe to profound hearing loss resulting from irreversibly damaged hair cells, cochlear implants can be used to restore hearing by delivering electrical stimulation directly to the spiral ganglion neurons. However, current spread lowers the spatial resolution of neural activation. Since light can be easily confined, optogenetics is a technique that has the potential to improve the precision of neural activation, whereby visible light is used to stimulate neurons that are modified with light-sensitive opsins. This study compares the spread of neural activity across the inferior colliculus of the auditory midbrain during electrical and optical stimulation in the cochlea of acutely deafened mice with opsin-modified spiral ganglion neurons (H134R variant of the channelrhodopsin-2). Monopolar electrical stimulation was delivered via each of four 0.2 mm wide platinum electrode rings at 0.6 mm centre-to-centre spacing, whereas 453 nm wavelength light was delivered via each of five 0.22 × 0.27 mm micro-light emitting diodes (LEDs) at 0.52 mm centre-to-centre spacing. Channel interactions were also quantified by threshold changes during simultaneous stimulation by pairs of electrodes or micro-LEDs at different distances between the electrodes (0.6, 1.2 and 1.8 mm) or micro-LEDs (0.52, 1.04, 1.56 and 2.08 mm). The spread of activation resulting from single channel optical stimulation was approximately half that of monopolar electrical stimulation as measured at two levels of discrimination above threshold (p<0.001), whereas there was no significant difference between optical stimulation in opsin-modified deafened mice and pure tone acoustic stimulation in normal-hearing mice. During simultaneous micro-LED stimulation, there were minimal channel interactions for all micro-LED spacings tested. For neighbouring micro-LEDs/electrodes, the relative influence on threshold was 13-fold less for optical stimulation compared electrical stimulation (p<0.05). The outcomes of this study show that the higher spatial precision of optogenetic stimulation results in reduced channel interaction compared to electrical stimulation, which could increase the number of independent channels in a cochlear implant. Increased spatial resolution and the ability to activate more than one channel simultaneously could lead to better speech perception in cochlear implant recipients.
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Affiliation(s)
- Ajmal A Azees
- The Bionics Institute, East Melbourne, VIC 3002, Australia; Department of Electrical and Biomedical Engineering, RMIT University, Melbourne, VIC 3000, Australia
| | - Alex C Thompson
- The Bionics Institute, East Melbourne, VIC 3002, Australia; Medical Bionics Department, University of Melbourne, East Melbourne, VIC, Australia
| | - Ross Thomas
- The Bionics Institute, East Melbourne, VIC 3002, Australia
| | - Jenny Zhou
- The Bionics Institute, East Melbourne, VIC 3002, Australia
| | - Patrick Ruther
- Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg 79110, Germany; BrainLinks-BrainTools Center, University of Freiburg, Freiburg 79110, Germany
| | - Andrew K Wise
- The Bionics Institute, East Melbourne, VIC 3002, Australia; Department of Surgery (Otolaryngology), University of Melbourne, Melbourne, VIC 3002, Australia; Medical Bionics Department, University of Melbourne, East Melbourne, VIC, Australia
| | - Elise A Ajay
- The Bionics Institute, East Melbourne, VIC 3002, Australia; Faculty of Engineering and Information Technology, University of Melbourne, Melbourne, VIC, Australia
| | - David J Garrett
- Department of Electrical and Biomedical Engineering, RMIT University, Melbourne, VIC 3000, Australia
| | - Anita Quigley
- Department of Electrical and Biomedical Engineering, RMIT University, Melbourne, VIC 3000, Australia; Department of Medicine, University of Melbourne, St Vincent's Hospital, Melbourne, VIC 3065, Australia; The Aikenhead Centre for Medical Discovery, St Vincent's Hospital, Melbourne, VIC 3065, Australia
| | - James B Fallon
- The Bionics Institute, East Melbourne, VIC 3002, Australia; Department of Surgery (Otolaryngology), University of Melbourne, Melbourne, VIC 3002, Australia; Medical Bionics Department, University of Melbourne, East Melbourne, VIC, Australia
| | - Rachael T Richardson
- The Bionics Institute, East Melbourne, VIC 3002, Australia; Department of Surgery (Otolaryngology), University of Melbourne, Melbourne, VIC 3002, Australia; Medical Bionics Department, University of Melbourne, East Melbourne, VIC, Australia.
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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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Michael M, Wolf BJ, Klinge-Strahl A, Jeschke M, Moser T, Dieter A. Devising a framework of optogenetic coding in the auditory pathway: Insights from auditory midbrain recordings. Brain Stimul 2023; 16:1486-1500. [PMID: 37778456 DOI: 10.1016/j.brs.2023.09.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 09/19/2023] [Accepted: 09/21/2023] [Indexed: 10/03/2023] Open
Abstract
Cochlear implants (CIs) restore activity in the deafened auditory system via electrical stimulation of the auditory nerve. As the spread of electric current in biological tissues is rather broad, the spectral information provided by electrical CIs is limited. Optogenetic stimulation of the auditory nerve has been suggested for artificial sound coding with improved spectral selectivity, as light can be conveniently confined in space. Yet, the foundations for optogenetic sound coding strategies remain to be established. Here, we parametrized stimulus-response-relationships of the auditory pathway in gerbils for optogenetic stimulation. Upon activation of the auditory pathway by waveguide-based optogenetic stimulation of the spiral ganglion, we recorded neuronal activity of the auditory midbrain, in which neural representations of spectral, temporal, and intensity information can be found. Screening a wide range of optical stimuli and taking the properties of optical CI emitters into account, we aimed to optimize stimulus paradigms for potent and energy-efficient activation of the auditory pathway. We report that efficient optogenetic coding builds on neural integration of millisecond stimuli built from microsecond light pulses, which optimally accommodate power-efficient laser diode operation. Moreover, we performed an activity-level-dependent comparison of optogenetic and acoustic stimulation in order to estimate the dynamic range and the maximal stimulation intensity amenable to single channel optogenetic sound encoding, and indicate that it complies well with speech comprehension in a typical conversation (65 dB). Our results provide a first framework for the development of coding strategies for future optogenetic hearing restoration.
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Affiliation(s)
- Maria Michael
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Bettina Julia Wolf
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075, Göttingen, Germany; Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, 37077, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37075, Göttingen, Germany
| | - Astrid Klinge-Strahl
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075, Göttingen, Germany; Department of Otolaryngology, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Marcus Jeschke
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075, Göttingen, Germany; Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, 37077, Göttingen, Germany; Cognitive Hearing in Primates (CHiP) Group, German Primate Center, 37077, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075, Göttingen, Germany; Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, 37077, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37075, Göttingen, Germany; Auditory Neuroscience and Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Science, Göttingen, Germany.
| | - Alexander Dieter
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075, Göttingen, Germany; Göttingen Graduate Center for Neurosciences, Biophysic, and Molecular Biosciences, 37077, Göttingen, Germany; Department of Neurophysiology, MCTN, Medical Faculty Mannheim, Heidelberg University, 68167, Mannheim, Germany.
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Zhou Z, Wang X, Li X, Liao L. A bibliometric profile of optogenetics: quantitative and qualitative analyses. Front Neurosci 2023; 17:1221316. [PMID: 37424998 PMCID: PMC10323434 DOI: 10.3389/fnins.2023.1221316] [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] [Received: 05/12/2023] [Accepted: 06/05/2023] [Indexed: 07/11/2023] Open
Abstract
Introduction Optogenetics is a rapidly developing field combining optics and genetics, with promising applications in neuroscience and beyond. However, there is currently a lack of bibliometric analyses examining publications in this area. Method Publications on optogenetics were gathered from the Web of Science Core Collection Database. A quantitative analysis was conducted to gain insights into the annual scientific output, and distribution of authors, journals, subject categories, countries, and institutions. Additionally, qualitative analysis, such as co-occurrence network analysis, thematic analysis, and theme evolution, were performed to identify the main areas and trends of optogenetics articles. Results A total of 6,824 publications were included for analysis. The number of articles has rapidly grown since 2010, with an annual growth rate of 52.82%. Deisseroth K, Boyden ES, and Hegemann P were the most prolific contributors to the field. The United States contributed the most articles (3,051 articles), followed by China (623 articles). A majority of optogenetics-related articles are published in high-quality journals, including NATURE, SCIENCE, and CELL. These articles mainly belong to four subjects: neurosciences, biochemistry and molecular biology, neuroimaging, and materials science. Co-occurrence keyword network analysis identified three clusters: optogenetic components and techniques, optogenetics and neural circuitry, optogenetics and disease. Conclusion The results suggest that optogenetics research is flourishing, focusing on optogenetic techniques and their applications in neural circuitry exploration and disease intervention. Optogenetics is expected to remain a hot topic in various fields in the future.
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Affiliation(s)
- Zhonghan Zhou
- Shandong University, Jinan, Shandong, China
- Department of Urology, China Rehabilitation Research Center, Beijing, China
- University of Health and Rehabilitation Sciences, Qingdao, Shandong, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Xuesheng Wang
- Department of Urology, China Rehabilitation Research Center, Beijing, China
- University of Health and Rehabilitation Sciences, Qingdao, Shandong, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Xunhua Li
- Department of Urology, China Rehabilitation Research Center, Beijing, China
- University of Health and Rehabilitation Sciences, Qingdao, Shandong, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Limin Liao
- Shandong University, Jinan, Shandong, China
- Department of Urology, China Rehabilitation Research Center, Beijing, China
- University of Health and Rehabilitation Sciences, Qingdao, Shandong, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
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Helke C, Reinhardt M, Arnold M, Schwenzer F, Haase M, Wachs M, Goßler C, Götz J, Keppeler D, Wolf B, Schaeper J, Salditt T, Moser T, Schwarz UT, Reuter D. On the Fabrication and Characterization of Polymer-Based Waveguide Probes for Use in Future Optical Cochlear Implants. MATERIALS (BASEL, SWITZERLAND) 2022; 16:106. [PMID: 36614443 PMCID: PMC9821155 DOI: 10.3390/ma16010106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 06/17/2023]
Abstract
Improved hearing restoration by cochlear implants (CI) is expected by optical cochlear implants (oCI) exciting optogenetically modified spiral ganglion neurons (SGNs) via an optical pulse generated outside the cochlea. The pulse is guided to the SGNs inside the cochlea via flexible polymer-based waveguide probes. The fabrication of these waveguide probes is realized by using 6" wafer-level micromachining processes, including lithography processes such as spin-coating cladding layers and a waveguide layer in between and etch processes for structuring the waveguide layer. Further adhesion layers and metal layers for laser diode (LD) bonding and light-outcoupling structures are also integrated in this waveguide process flow. Optical microscope and SEM images revealed that the majority of the waveguides are sufficiently smooth to guide light with low intensity loss. By coupling light into the waveguides and detecting the outcoupled light from the waveguide, we distinguished intensity losses caused by bending the waveguide and outcoupling. The probes were used in first modules called single-beam guides (SBGs) based on a waveguide probe, a ball lens and an LD. Finally, these SBGs were tested in animal models for proof-of-concept implantation experiments.
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Affiliation(s)
- Christian Helke
- Fraunhofer Institute for Electronic Nanosystems ENAS, 09126 Chemnitz, Germany
- Center for Microtechnologies (ZfM), Technical University of Chemnitz, 09126 Chemnitz, Germany
| | - Markus Reinhardt
- Fraunhofer Institute for Electronic Nanosystems ENAS, 09126 Chemnitz, Germany
- Experimental Sensor Science, Technical University of Chemnitz, 09126 Chemnitz, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Goettingen, 37075 Goettingen, Germany
| | - Markus Arnold
- Center for Microtechnologies (ZfM), Technical University of Chemnitz, 09126 Chemnitz, Germany
| | - Falk Schwenzer
- Center for Microtechnologies (ZfM), Technical University of Chemnitz, 09126 Chemnitz, Germany
| | - Micha Haase
- Fraunhofer Institute for Electronic Nanosystems ENAS, 09126 Chemnitz, Germany
- Center for Microtechnologies (ZfM), Technical University of Chemnitz, 09126 Chemnitz, Germany
| | - Matthias Wachs
- Experimental Sensor Science, Technical University of Chemnitz, 09126 Chemnitz, Germany
| | - Christian Goßler
- Experimental Sensor Science, Technical University of Chemnitz, 09126 Chemnitz, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Goettingen, 37075 Goettingen, Germany
| | - Jonathan Götz
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Goettingen, 37075 Goettingen, Germany
| | - Daniel Keppeler
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Goettingen, 37075 Goettingen, Germany
| | - Bettina Wolf
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Goettingen, 37075 Goettingen, Germany
| | - Jannis Schaeper
- Institute for X-ray Physics, University of Goettingen, 37075 Goettingen, Germany
- Multiscale Bioimaging Cluster of Excellence, University Medical Center Goettingen, 37075 Goettingen, Germany
| | - Tim Salditt
- Institute for X-ray Physics, University of Goettingen, 37075 Goettingen, Germany
- Multiscale Bioimaging Cluster of Excellence, University Medical Center Goettingen, 37075 Goettingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Goettingen, 37075 Goettingen, Germany
- Multiscale Bioimaging Cluster of Excellence, University Medical Center Goettingen, 37075 Goettingen, Germany
| | | | - Danny Reuter
- Fraunhofer Institute for Electronic Nanosystems ENAS, 09126 Chemnitz, Germany
- Center for Microtechnologies (ZfM), Technical University of Chemnitz, 09126 Chemnitz, Germany
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Chen B, Luo W, Lv J, Lin S, Zheng B, Zhang H, Chen M. A universal strategy toward flame retardant epoxy resin with ultra-tough and transparent properties. Polym Degrad Stab 2022. [DOI: 10.1016/j.polymdegradstab.2022.110132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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9
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Yasunaga H, Takeuchi H, Mizuguchi K, Nishikawa A, Loesing A, Ishikawa M, Kamiyoshihara C, Setogawa S, Ohkawa N, Sekiguchi H. MicroLED neural probe for effective in vivo optogenetic stimulation. OPTICS EXPRESS 2022; 30:40292-40305. [PMID: 36298964 DOI: 10.1364/oe.470318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 10/05/2022] [Indexed: 06/16/2023]
Abstract
The MicroLED probe enables optogenetic control of neural activity in spatially separated brain regions. Understanding its heat generation characteristics is important. In this study, we investigated the temperature rise (ΔT) characteristics in the brain tissue using a MicroLED probe. The ΔT strongly depended on the surrounding environment of the probe, including the differences between the air and the brain, and the area touching the brain tissue. Through animal experiments, we suggest an in situ temperature monitoring method using temperature dependence on electrical characteristics of the MicroLED. Finally, optical stimulation by MicroLEDs proved effective in controlling optogenetic neural activity in animal models.
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Zhang H, Fang H, Liu D, Zhang Y, Adu-Amankwaah J, Yuan J, Tan R, Zhu J. Applications and challenges of rhodopsin-based optogenetics in biomedicine. Front Neurosci 2022; 16:966772. [PMID: 36213746 PMCID: PMC9537737 DOI: 10.3389/fnins.2022.966772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 09/05/2022] [Indexed: 11/24/2022] Open
Abstract
Optogenetics is an emerging bioengineering technology that has been rapidly developed in recent years by cross-integrating optics, genetic engineering, electrophysiology, software control, and other disciplines. Since the first demonstration of the millisecond neuromodulation ability of the channelrhodopsin-2 (ChR2), the application of optogenetic technology in basic life science research has been rapidly progressed, especially in neurobiology, which has driven the development of the discipline. As the optogenetic tool protein, microbial rhodopsins have been continuously explored, modified, and optimized, with many variants becoming available, with structural characteristics and functions that are highly diversified. Their applicability has been broadened, encouraging more researchers and clinicians to utilize optogenetics technology in research. In this review, we summarize the species and variant types of the most important class of tool proteins in optogenetic techniques, the microbial rhodopsins, and review the current applications of optogenetics based on rhodopsin qualitative light in biology and other fields. We also review the challenges facing this technology, to ultimately provide an in-depth technical reference to support the application of optogenetics in translational and clinical research.
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Affiliation(s)
- Hanci Zhang
- College of Life Sciences, Shandong Normal University, Jinan, China
| | - Hui Fang
- College of Life Sciences, Shandong Normal University, Jinan, China
| | - Deqiang Liu
- College of Life Sciences, Shandong Normal University, Jinan, China
| | - Yiming Zhang
- College of Life Sciences, Shandong Normal University, Jinan, China
| | - Joseph Adu-Amankwaah
- Department of Physiology, Basic Medical School, Xuzhou Medical University, Xuzhou, China
| | - Jinxiang Yuan
- College of Life Sciences, Shandong Normal University, Jinan, China
- Collaborative Innovation Center for Birth Defect Research and Transformation of Shandong Province, Jining Medical University, Jining, China
- Lin He’s Academician Workstation of New Medicine and Clinical Translation, Jining Medical University, Jining, China
- *Correspondence: Jinxiang Yuan,
| | - Rubin Tan
- Department of Physiology, Basic Medical School, Xuzhou Medical University, Xuzhou, China
- Rubin Tan,
| | - Jianping Zhu
- College of Life Sciences, Shandong Normal University, Jinan, China
- Jianping Zhu,
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Spagnolo B, Balena A, Peixoto RT, Pisanello M, Sileo L, Bianco M, Rizzo A, Pisano F, Qualtieri A, Lofrumento DD, De Nuccio F, Assad JA, Sabatini BL, De Vittorio M, Pisanello F. Tapered fibertrodes for optoelectrical neural interfacing in small brain volumes with reduced artefacts. NATURE MATERIALS 2022; 21:826-835. [PMID: 35668147 PMCID: PMC7612923 DOI: 10.1038/s41563-022-01272-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 04/27/2022] [Indexed: 06/02/2023]
Abstract
Deciphering the neural patterns underlying brain functions is essential to understanding how neurons are organized into networks. This deciphering has been greatly facilitated by optogenetics and its combination with optoelectronic devices to control neural activity with millisecond temporal resolution and cell type specificity. However, targeting small brain volumes causes photoelectric artefacts, in particular when light emission and recording sites are close to each other. We take advantage of the photonic properties of tapered fibres to develop integrated 'fibertrodes' able to optically activate small brain volumes with abated photoelectric noise. Electrodes are positioned very close to light emitting points by non-planar microfabrication, with angled light emission allowing the simultaneous optogenetic manipulation and electrical read-out of one to three neurons, with no photoelectric artefacts, in vivo. The unconventional implementation of two-photon polymerization on the curved taper edge enables the fabrication of recoding sites all around the implant, making fibertrodes a promising complement to planar microimplants.
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Affiliation(s)
| | | | - Rui T Peixoto
- Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, MA, USA
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | | | | | - Marco Bianco
- Istituto Italiano di Tecnologia, CBN, Lecce, Italy
- Dipartimento di Ingegneria dell'Innovazione, Università del Salento, Lecce, Italy
| | - Alessandro Rizzo
- Istituto Italiano di Tecnologia, CBN, Lecce, Italy
- Dipartimento di Ingegneria dell'Innovazione, Università del Salento, Lecce, Italy
| | | | | | - Dario Domenico Lofrumento
- DiSTeBA - Department of Biological and Environmental Sciences and Technologies, Università del Salento, Lecce, Italy
| | - Francesco De Nuccio
- DiSTeBA - Department of Biological and Environmental Sciences and Technologies, Università del Salento, Lecce, Italy
| | - John A Assad
- Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, MA, USA
- Istituto Italiano di Tecnologia, Genova, Italy
| | - Bernardo L Sabatini
- Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Massimo De Vittorio
- Istituto Italiano di Tecnologia, CBN, Lecce, Italy.
- Dipartimento di Ingegneria dell'Innovazione, Università del Salento, Lecce, Italy.
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12
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Eickenscheidt M, Herrmann T, Weisshap M, Mittnacht A, Rudmann L, Zeck G, Stieglitz T. An optoelectronic neural interface approach for precise superposition of optical and electrical stimulation in flexible array structures. Biosens Bioelectron 2022; 205:114090. [DOI: 10.1016/j.bios.2022.114090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 11/27/2022]
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13
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Abstract
INTRODUCTION More than 5% of the world's population have a disabling hearing loss which can be managed by hearing aids or implanted electrical devices. However, outcomes are highly variable, and the sound perceived by recipients is far from perfect. Sparked by the discovery of progenitor cells in the cochlea and rapid progress in drug delivery to the cochlea, biological and pharmaceutical therapies are currently in development to improve the function of the cochlear implant or eliminate the need for it altogether. AREAS COVERED This review highlights progress in emerging regenerative strategies to restore hearing and adjunct therapies to augment the cochlear implant. Novel approaches include the reprogramming of progenitor cells to restore the sensory hair cell population in the cochlea, gene therapy and gene editing to treat hereditary and acquired hearing loss. A detailed review of optogenetics is also presented as a technique that could enable optical stimulation of the spiral ganglion neurons, replacing or complementing electrical stimulation. EXPERT OPINION Increasing evidence of substantial reversal of hearing loss in animal models, alongside rapid advances in delivery strategies to the cochlea and learnings from clinical trials will amalgamate into a biological or pharmaceutical therapy to replace or complement the cochlear implant.
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Affiliation(s)
- Elise Ajay
- Bionics Institute, East Melbourne, Victoria, Australia.,University of Melbourne, Department of Engineering
| | | | - Rachael Richardson
- Bionics Institute, East Melbourne, Victoria, Australia.,University of Melbourne, Medical Bionics Department, Parkville, Victoria, Australia.,University of Melbourne, Department of Surgery (Otolaryngology), East Melbourne, Victoria, Australia
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14
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Kim H, Kim MJ, Kwon YW, Jeon S, Lee S, Kim C, Choi BT, Shin Y, Hong SW, Shin HK. Benefits of a Skull-Interfaced Flexible and Implantable Multilight Emitting Diode Array for Photobiomodulation in Ischemic Stroke. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2104629. [PMID: 35076161 PMCID: PMC9008794 DOI: 10.1002/advs.202104629] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 01/08/2022] [Indexed: 05/05/2023]
Abstract
Photobiomodulation (PBM) has received attention due to its potential for improving tissue function and enhancing regeneration in stroke. A lightweight, compact, and simple system of miniaturized electronic devices consisting of packaged light-emitting diodes (LEDs) that incorporates a flexible substrate for in vivo brain PBM in a mouse model is developed. Using this device platform, the preventive and therapeutic effects of PBM affixed to the exposed skull of mice in the photothrombosis and middle cerebral artery occlusion stroke model are evaluated. Among the wavelength range of 630, 850, and 940 nm LED array, the PBM with 630-nm LED array is proved to be the most effective for reducing the infarction volume and neurological impairment after ischemic stroke. Moreover, the PBM with 630 nm LED array remarkably improves the capability of spatial learning and memory in the chronic poststroke phase, attenuates AIM2 inflammasome activation and inflammasome-mediated pyroptosis, and modulates microglial polarization in the hippocampus and cortex 7 days following ischemic stroke. Thus, PBM may prevent tissue and functional damage in acute ischemic injury, thereby attenuating the development of cognitive impairment after stroke.
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Affiliation(s)
- Hyunha Kim
- Department of Korean Medical ScienceGraduate Training Program of Korean Medical Therapeutics for Healthy‐AgingSchool of Korean MedicinePusan National UniversityYangsan50612Republic of Korea
- Department of Pharmacology and NeuroscienceCreighton University School of MedicineOmahaNE68178USA
| | - Min Jae Kim
- Department of Korean Medical ScienceGraduate Training Program of Korean Medical Therapeutics for Healthy‐AgingSchool of Korean MedicinePusan National UniversityYangsan50612Republic of Korea
| | - Young Woo Kwon
- Department of Nano‐Fusion TechnologyCollege of Nanoscience & NanotechnologyPusan National UniversityBusan46241Republic of Korea
| | - Sangheon Jeon
- Department of Congo‐Mechatronics EngineeringDepartment of Optics and Mechatronics EngineeringCollege of Nanoscience & NanotechnologyPusan National UniversityBusan46241Republic of Korea
| | - Seo‐Yeon Lee
- Department of PharmacologyWonkwang University School of MedicineIksan54538Republic of Korea
| | - Chang‐Seok Kim
- Department of Congo‐Mechatronics EngineeringDepartment of Optics and Mechatronics EngineeringCollege of Nanoscience & NanotechnologyPusan National UniversityBusan46241Republic of Korea
| | - Byung Tae Choi
- Department of Korean Medical ScienceGraduate Training Program of Korean Medical Therapeutics for Healthy‐AgingSchool of Korean MedicinePusan National UniversityYangsan50612Republic of Korea
| | - Yong‐Il Shin
- Department of Rehabilitation MedicineSchool of MedicinePusan National UniversityYangsan50612Republic of Korea
| | - Suck Won Hong
- Department of Congo‐Mechatronics EngineeringDepartment of Optics and Mechatronics EngineeringCollege of Nanoscience & NanotechnologyPusan National UniversityBusan46241Republic of Korea
| | - Hwa Kyoung Shin
- Department of Korean Medical ScienceGraduate Training Program of Korean Medical Therapeutics for Healthy‐AgingSchool of Korean MedicinePusan National UniversityYangsan50612Republic of Korea
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15
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Vėbraitė I, Hanein Y. Soft Devices for High-Resolution Neuro-Stimulation: The Interplay Between Low-Rigidity and Resolution. FRONTIERS IN MEDICAL TECHNOLOGY 2022; 3:675744. [PMID: 35047928 PMCID: PMC8757739 DOI: 10.3389/fmedt.2021.675744] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 05/14/2021] [Indexed: 12/27/2022] Open
Abstract
The field of neurostimulation has evolved over the last few decades from a crude, low-resolution approach to a highly sophisticated methodology entailing the use of state-of-the-art technologies. Neurostimulation has been tested for a growing number of neurological applications, demonstrating great promise and attracting growing attention in both academia and industry. Despite tremendous progress, long-term stability of the implants, their large dimensions, their rigidity and the methods of their introduction and anchoring to sensitive neural tissue remain challenging. The purpose of this review is to provide a concise introduction to the field of high-resolution neurostimulation from a technological perspective and to focus on opportunities stemming from developments in materials sciences and engineering to reduce device rigidity while optimizing electrode small dimensions. We discuss how these factors may contribute to smaller, lighter, softer and higher electrode density devices.
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Affiliation(s)
- Ieva Vėbraitė
- School of Electrical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Yael Hanein
- School of Electrical Engineering, Tel Aviv University, Tel Aviv, Israel
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16
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Bansal A, Shikha S, Zhang Y. Towards translational optogenetics. Nat Biomed Eng 2022; 7:349-369. [PMID: 35027688 DOI: 10.1038/s41551-021-00829-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 10/21/2021] [Indexed: 02/07/2023]
Abstract
Optogenetics is widely used to interrogate the neural circuits underlying disease and has most recently been harnessed for therapeutic applications. The optogenetic toolkit consists of light-responsive proteins that modulate specific cellular functions, vectors for the delivery of the transgenes that encode the light-responsive proteins to targeted cellular populations, and devices for the delivery of light of suitable wavelengths at effective fluence rates. A refined toolkit with a focus towards translational uses would include efficient and safer viral and non-viral gene-delivery vectors, increasingly red-shifted photoresponsive proteins, nanomaterials that efficiently transduce near-infrared light deep into tissue, and wireless implantable light-delivery devices that allow for spatiotemporally precise interventions at clinically relevant tissue depths. In this Review, we examine the current optogenetics toolkit and the most notable preclinical and translational uses of optogenetics, and discuss future methodological and translational developments and bottlenecks.
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Affiliation(s)
- Akshaya Bansal
- Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore
| | - Swati Shikha
- Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore
| | - Yong Zhang
- Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore. .,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore. .,NUS Suzhou Research Institute, Suzhou, Jiangsu, P. R. China.
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17
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Ahmed Z, Reddy JW, Malekoshoaraie MH, Hassanzade V, Kimukin I, Jain V, Chamanzar M. Flexible optoelectric neural interfaces. Curr Opin Biotechnol 2021; 72:121-130. [PMID: 34826682 PMCID: PMC9741731 DOI: 10.1016/j.copbio.2021.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 10/30/2021] [Accepted: 11/02/2021] [Indexed: 12/14/2022]
Abstract
Understanding the neural basis of brain function and dysfunction and designing effective therapeutics require high resolution targeted stimulation and recording of neural activity. Optical methods have been recently developed for neural stimulation as well as functional and structural imaging. These methods call for implantable devices to deliver light into the neural tissue at depth with high spatiotemporal resolution. To address this need, rigid and flexible neurophotonic implants have been recently designed. This article reviews the state-of-the-art flexible passive and active penetrating optical neural probes developed for light delivery with minimal damage to the tissue. Passive and active flexible neurophotonic implants are compared and insights about future directions are provided.
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18
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Kilias A, Lee YT, Froriep UP, Sielaff C, Moser D, Holzhammer T, Egert U, Fang W, Paul O, Ruther P. Intracortical probe arrays with silicon backbone and microelectrodes on thin polyimide wings enable long-term stable recordings in vivo. J Neural Eng 2021; 18. [PMID: 34781276 DOI: 10.1088/1741-2552/ac39b7] [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: 04/28/2021] [Accepted: 11/15/2021] [Indexed: 11/12/2022]
Abstract
Objective.Recording and stimulating neuronal activity across different brain regions requires interfacing at multiple sites using dedicated tools while tissue reactions at the recording sites often prevent their successful long-term application. This implies the technological challenge of developing complex probe geometries while keeping the overall footprint minimal, and of selecting materials compatible with neural tissue. While the potential of soft materials in reducing tissue response is uncontested, the implantation of these materials is often limited to reliably target neuronal structures across large brain volumes.Approach.We report on the development of a new multi-electrode array exploiting the advantages of soft and stiff materials by combining 7-µm-thin polyimide wings carrying platinum electrodes with a silicon backbone enabling a safe probe implantation. The probe fabrication applies microsystems technologies in combination with a temporal wafer fixation method for rear side processing, i.e. grinding and deep reactive ion etching, of slender probe shanks and electrode wings. The wing-type neural probes are chronically implanted into the entorhinal-hippocampal formation in the mouse forin vivorecordings of freely behaving animals.Main results.Probes comprising the novel wing-type electrodes have been realized and characterized in view of their electrical performance and insertion capability. Chronic electrophysiologicalin vivorecordings of the entorhinal-hippocampal network in the mouse of up to 104 days demonstrated a stable yield of channels containing identifiable multi-unit and single-unit activity outperforming probes with electrodes residing on a Si backbone.Significance.The innovative fabrication process using a process compatible, temporary wafer bonding allowed to realize new Michigan-style probe arrays. The wing-type probe design enables a precise probe insertion into brain tissue and long-term stable recordings of unit activity due to the application of a stable backbone and 7-µm-thin probe wings provoking locally a minimal tissue response and protruding from the glial scare of the backbone.
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Affiliation(s)
- Antje Kilias
- Biomicrotechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
| | - Yu-Tao Lee
- Microsystem Materials Laboratory, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany.,Institute of NanoEngineering and Microsystems, National Tsing-Hua University, Hsinchu, Taiwan
| | - Ulrich P Froriep
- Biomicrotechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany.,Department of Implant Systems, Fraunhofer Institute for Toxicology and Experimental Medicine ITEM, Hannover, Germany
| | - Charlotte Sielaff
- Department of Implant Systems, Fraunhofer Institute for Toxicology and Experimental Medicine ITEM, Hannover, Germany
| | - Dominik Moser
- Microsystem Materials Laboratory, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany
| | - Tobias Holzhammer
- Microsystem Materials Laboratory, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany
| | - Ulrich Egert
- Biomicrotechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany.,Cluster of Excellence BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
| | - Weileun Fang
- Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu City, Taiwan
| | - Oliver Paul
- Microsystem Materials Laboratory, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany.,Cluster of Excellence BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
| | - Patrick Ruther
- Microsystem Materials Laboratory, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany.,Cluster of Excellence BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
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19
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Han Y, Zhao H, Chen L, Ran D, Chen J, Zhao J, Xu T. A bifunctional modifier endowing epoxy resin with outstanding flame retardancy and high impact strength. J Appl Polym Sci 2021. [DOI: 10.1002/app.50886] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yichen Han
- Department of Applied Chemistry College of Chemistry and Chemical Engineering, Northwestern Polytechnical University Xi'an Shanxi China
| | - Hui Zhao
- Department of Applied Chemistry College of Chemistry and Chemical Engineering, Northwestern Polytechnical University Xi'an Shanxi China
| | - Lixin Chen
- Department of Applied Chemistry College of Chemistry and Chemical Engineering, Northwestern Polytechnical University Xi'an Shanxi China
| | - Di Ran
- Department of Applied Chemistry College of Chemistry and Chemical Engineering, Northwestern Polytechnical University Xi'an Shanxi China
| | - Jichuan Chen
- Department of Applied Chemistry College of Chemistry and Chemical Engineering, Northwestern Polytechnical University Xi'an Shanxi China
| | - Jia Zhao
- Department of Applied Chemistry College of Chemistry and Chemical Engineering, Northwestern Polytechnical University Xi'an Shanxi China
| | - Tingting Xu
- Department of Applied Chemistry College of Chemistry and Chemical Engineering, Northwestern Polytechnical University Xi'an Shanxi China
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20
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Shin S, Ha Y, Choi G, Hyun J, Kim S, Oh SH, Min KS. Manufacturable 32-Channel Cochlear Electrode Array and Preliminary Assessment of Its Feasibility for Clinical Use. MICROMACHINES 2021; 12:mi12070778. [PMID: 34209329 PMCID: PMC8304779 DOI: 10.3390/mi12070778] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/11/2021] [Accepted: 06/16/2021] [Indexed: 11/20/2022]
Abstract
(1) Background: In this study, we introduce a manufacturable 32-channel cochlear electrode array. In contrast to conventional cochlear electrode arrays manufactured by manual processes that consist of electrode-wire welding, the placement of each electrode, and silicone molding over wired structures, the proposed cochlear electrode array is manufactured by semi-automated laser micro-structuring and a mass-produced layer-by-layer silicone deposition scheme similar to the semiconductor fabrication process. (2) Methods: The proposed 32-channel electrode array has 32 electrode contacts with a length of 24 mm and 0.75 mm spacing between contacts. The width of the electrode array is 0.45 mm at its apex and 0.8 mm at its base, and it has a three-layered arrangement consisting of a 32-channel electrode layer and two 16-lead wire layers. To assess its feasibility, we conducted an electrochemical evaluation, stiffness measurements, and insertion force measurements. (3) Results: The electrochemical impedance and charge storage capacity are 3.11 ± 0.89 kOhm at 1 kHz and 5.09 mC/cm2, respectively. The V/H ratio, which indicates how large the vertical stiffness is compared to the horizontal stiffness, is 1.26. The insertion force is 17.4 mN at 8 mm from the round window, and the maximum extraction force is 61.4 mN. (4) Conclusions: The results of the preliminary feasibility assessment of the proposed 32-channel cochlear electrode array are presented. After further assessments are performed, a 32-channel cochlear implant system consisting of the proposed 32-channel electrode array, 32-channel neural stimulation and recording IC, titanium-based hermetic package, and sound processor with wireless power and signal transmission coil will be completed.
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Affiliation(s)
- Soowon Shin
- TODOC Co., Ltd., Seoul 08394, Korea; (S.S.); (Y.H.); (G.C.); (J.H.); (S.K.)
| | - Yoonhee Ha
- TODOC Co., Ltd., Seoul 08394, Korea; (S.S.); (Y.H.); (G.C.); (J.H.); (S.K.)
| | - Gwangjin Choi
- TODOC Co., Ltd., Seoul 08394, Korea; (S.S.); (Y.H.); (G.C.); (J.H.); (S.K.)
| | - Junewoo Hyun
- TODOC Co., Ltd., Seoul 08394, Korea; (S.S.); (Y.H.); (G.C.); (J.H.); (S.K.)
| | - Sangwoo Kim
- TODOC Co., Ltd., Seoul 08394, Korea; (S.S.); (Y.H.); (G.C.); (J.H.); (S.K.)
| | - Seung-Ha Oh
- Department of Otorhinolaryngology, Seoul National University Hospital, Seoul 03080, Korea;
| | - Kyou-Sik Min
- TODOC Co., Ltd., Seoul 08394, Korea; (S.S.); (Y.H.); (G.C.); (J.H.); (S.K.)
- Correspondence:
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21
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Keppeler D, Schwaerzle M, Harczos T, Jablonski L, Dieter A, Wolf B, Ayub S, Vogl C, Wrobel C, Hoch G, Abdellatif K, Jeschke M, Rankovic V, Paul O, Ruther P, Moser T. Multichannel optogenetic stimulation of the auditory pathway using microfabricated LED cochlear implants in rodents. Sci Transl Med 2021; 12:12/553/eabb8086. [PMID: 32718992 DOI: 10.1126/scitranslmed.abb8086] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 06/03/2020] [Indexed: 12/28/2022]
Abstract
When hearing fails, electrical cochlear implants (eCIs) provide the brain with auditory information. One important bottleneck of CIs is the poor spectral selectivity that results from the wide current spread from each of the electrode contacts. Optical CIs (oCIs) promise to make better use of the tonotopic order of spiral ganglion neurons (SGNs) inside the cochlea by spatially confined stimulation. Here, we established multichannel oCIs based on light-emitting diode (LED) arrays and used them for optical stimulation of channelrhodopsin (ChR)-expressing SGNs in rodents. Power-efficient blue LED chips were integrated onto microfabricated 15-μm-thin polyimide-based carriers comprising interconnecting lines to address individual LEDs by a stationary or mobile driver circuitry. We extensively characterized the optoelectronic, thermal, and mechanical properties of the oCIs and demonstrated stability over weeks in vitro. We then implanted the oCIs into ChR-expressing rats and gerbils, and characterized multichannel optogenetic SGN stimulation by electrophysiological and behavioral experiments. Improved spectral selectivity was directly demonstrated by recordings from the auditory midbrain. Long-term experiments in deafened ChR-expressing rats and in nontreated control animals demonstrated specificity of optogenetic stimulation. Behavioral studies on animals carrying a wireless oCI sound processor revealed auditory percepts. This study demonstrates hearing restoration with improved spectral selectivity by an LED-based multichannel oCI system.
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Affiliation(s)
- Daniel Keppeler
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.,Göttingen Graduate Center for Neurosciences and Molecular Biosciences, University of Göttingen, 37075 Göttingen, Germany
| | - Michael Schwaerzle
- University of Freiburg, Department of Microsystems Engineering (IMTEK), 79110 Freiburg, Germany.,Cluster of Excellence BrainLinks-BrainTools, University of Freiburg, 79110 Freiburg, Germany
| | - Tamas Harczos
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
| | - Lukasz Jablonski
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
| | - Alexander Dieter
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.,Göttingen Graduate Center for Neurosciences and Molecular Biosciences, University of Göttingen, 37075 Göttingen, Germany
| | - Bettina Wolf
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
| | - Suleman Ayub
- University of Freiburg, Department of Microsystems Engineering (IMTEK), 79110 Freiburg, Germany.,Cluster of Excellence BrainLinks-BrainTools, University of Freiburg, 79110 Freiburg, Germany
| | - Christian Vogl
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, 37075 Göttingen, Germany
| | - Christian Wrobel
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.,Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center Göttingen, 37099 Göttingen, Germany
| | - Gerhard Hoch
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
| | - Khaled Abdellatif
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
| | - Marcus Jeschke
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
| | - Vladan Rankovic
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
| | - Oliver Paul
- University of Freiburg, Department of Microsystems Engineering (IMTEK), 79110 Freiburg, Germany.,Cluster of Excellence BrainLinks-BrainTools, University of Freiburg, 79110 Freiburg, Germany
| | - Patrick Ruther
- University of Freiburg, Department of Microsystems Engineering (IMTEK), 79110 Freiburg, Germany. .,Cluster of Excellence BrainLinks-BrainTools, University of Freiburg, 79110 Freiburg, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany. .,Göttingen Graduate Center for Neurosciences and Molecular Biosciences, University of Göttingen, 37075 Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, 37075 Göttingen, Germany.,Multiscale Bioimaging Cluster of Excellence, University Medical Center Göttingen, 37075 Göttingen, Germany.,MPI for Biophysical Chemistry, 37077 Göttingen, Germany
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22
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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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Abstract
The cochlea of our auditory system is an intricate structure deeply embedded in the temporal bone. Compared with other sensory organs such as the eye, the cochlea has remained poorly accessible for investigation, for example, by imaging. This limitation also concerns the further development of technology for restoring hearing in the case of cochlear dysfunction, which requires quantitative information on spatial dimensions and the sensorineural status of the cochlea. Here, we employed X-ray phase-contrast tomography and light-sheet fluorescence microscopy and their combination for multiscale and multimodal imaging of cochlear morphology in species that serve as established animal models for auditory research. We provide a systematic reference for morphological parameters relevant for cochlear implant development for rodent and nonhuman primate models. We simulate the spread of light from the emitters of the optical implants within the reconstructed nonhuman primate cochlea, which indicates a spatially narrow optogenetic excitation of spiral ganglion neurons.
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Abstract
Peripheral nerve interfaces (PNIs) record and/or modulate neural activity of nerves, which are responsible for conducting sensory-motor information to and from the central nervous system, and for regulating the activity of inner organs. PNIs are used both in neuroscience research and in therapeutical applications such as precise closed-loop control of neuroprosthetic limbs, treatment of neuropathic pain and restoration of vital functions (e.g. breathing and bladder management). Implantable interfaces represent an attractive solution to directly access peripheral nerves and provide enhanced selectivity both in recording and in stimulation, compared to their non-invasive counterparts. Nevertheless, the long-term functionality of implantable PNIs is limited by tissue damage, which occurs at the implant-tissue interface, and is thus highly dependent on material properties, biocompatibility and implant design. Current research focuses on the development of mechanically compliant PNIs, which adapt to the anatomy and dynamic movements of nerves in the body thereby limiting foreign body response. In this paper, we review recent progress in the development of flexible and implantable PNIs, highlighting promising solutions related to materials selection and their associated fabrication methods, and integrated functions. We report on the variety of available interface designs (intraneural, extraneural and regenerative) and different modulation techniques (electrical, optical, chemical) emphasizing the main challenges associated with integrating such systems on compliant substrates.
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Affiliation(s)
- Valentina Paggi
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Microengineering, Institute of Bioengineering, Centre for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1202 Geneva, Switzerland. Equally contributing authors
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Wrobel C, Zafeiriou MP, Moser T. Understanding and treating paediatric hearing impairment. EBioMedicine 2021; 63:103171. [PMID: 33422987 PMCID: PMC7808910 DOI: 10.1016/j.ebiom.2020.103171] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/20/2020] [Accepted: 12/01/2020] [Indexed: 12/26/2022] Open
Abstract
Sensorineural hearing impairment is the most frequent form of hearing impairment affecting 1-2 in 1000 newborns and another 1 in 1000 adolescents. More than 50% of congenital hearing impairment is of genetic origin and some forms of monogenic deafness are likely targets for future gene therapy. Good progress has been made in clinical phenotyping, genetic diagnostics, and counselling. Disease modelling, e.g. in transgenic mice, has helped elucidate disease mechanisms underlying genetic hearing impairment and informed clinical phenotyping in recent years. Clinical management of paediatric hearing impairment involves hearing aids, cochlear or brainstem implants, signal-to-noise improvement in educational settings, speech therapy, and sign language. Cochlear implants, for example, have much improved the situation of profoundly hearing impaired and deaf children. Nonetheless there remains a major unmet clinical need for improving hearing restoration. Preclinical studies promise that we will witness clinical trials on gene therapy and a next generation of cochlear implants during the coming decade. Moreover, progress in generating sensory hair cells and neurons from stem cells spurs disease modelling, drug screening, and regenerative approaches. This review briefly summarizes the pathophysiology of paediatric hearing impairment and provides an update on the current preclinical development of innovative approaches toward improved hearing restoration.
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Affiliation(s)
- Christian Wrobel
- Department of Otolaryngology and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany; Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Germany
| | - Maria-Patapia Zafeiriou
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Germany; Institute of Pharmacology and Toxicology, University Medical Center, 37075 Göttingen, Germany
| | - Tobias Moser
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Germany; Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany.
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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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Fekete Z, Horváth ÁC, Zátonyi A. Infrared neuromodulation:a neuroengineering perspective. J Neural Eng 2020; 17:051003. [PMID: 33055373 DOI: 10.1088/1741-2552/abb3b2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Infrared neuromodulation (INM) is a branch of photobiomodulation that offers direct or indirect control of cellular activity through elevation of temperature in a spatially confined region of the target tissue. Research on INM started about 15 ago and is gradually attracting the attention of the neuroscience community, as numerous experimental studies have provided firm evidence on the safe and reproducible excitation and inhibition of neuronal firing in both in vitro and in vivo conditions. However, its biophysical mechanism is not fully understood and several engineered interfaces have been created to investigate infrared stimulation in both the peripheral and central nervous system. In this review, recent applications and present knowledge on the effects of INM on cellular activity are summarized, and an overview of the technical approaches to deliver infrared light to cells and to interrogate the optically evoked response is provided. The micro- and nanoengineered interfaces used to investigate the influence of INM are described in detail.
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Affiliation(s)
- Z Fekete
- Research Group for Implantable Microsystems, Faculty of Information Technology & Bionics, Pázmány Péter Catholic University, Budapest 1083, Hungary. Author to whom any correspondence should be addressed
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Reddy JW, Lassiter M, Chamanzar M. Parylene photonics: a flexible, broadband optical waveguide platform with integrated micromirrors for biointerfaces. MICROSYSTEMS & NANOENGINEERING 2020; 6:85. [PMID: 34567695 PMCID: PMC8433189 DOI: 10.1038/s41378-020-00186-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 06/01/2020] [Accepted: 06/03/2020] [Indexed: 05/24/2023]
Abstract
Targeted light delivery into biological tissue is needed in applications such as optogenetic stimulation of the brain and in vivo functional or structural imaging of tissue. These applications require very compact, soft, and flexible implants that minimize damage to the tissue. Here, we demonstrate a novel implantable photonic platform based on a high-density, flexible array of ultracompact (30 μm × 5 μm), low-loss (3.2 dB/cm at λ = 680 nm, 4.1 dB/cm at λ = 633 nm, 4.9 dB/cm at λ = 532 nm, 6.1 dB/cm at λ = 450 nm) optical waveguides composed of biocompatible polymers Parylene C and polydimethylsiloxane (PDMS). This photonic platform features unique embedded input/output micromirrors that redirect light from the waveguides perpendicularly to the surface of the array for localized, patterned illumination in tissue. This architecture enables the design of a fully flexible, compact integrated photonic system for applications such as in vivo chronic optogenetic stimulation of brain activity.
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Affiliation(s)
- Jay W. Reddy
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA USA
| | - Maya Lassiter
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA USA
| | - Maysamreza Chamanzar
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA USA
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Ayub S, David F, Klein E, Borel M, Paul O, Gentet LJ, Ruther P. Compact Optical Neural Probes With Up to 20 Integrated Thin-Film $\mu$LEDs Applied in Acute Optogenetic Studies. IEEE Trans Biomed Eng 2020; 67:2603-2615. [DOI: 10.1109/tbme.2020.2966293] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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30
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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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Abstract
Electrical cochlear implants (CI) currently lack the frequency and intensity resolution to allow detection of complex sounds in background noise. The use of microscale optoelectronics in conjunction with optogenetics provides a promising direction in CI technology to allow improvements in spectral resolution, providing a richer soundscape for users. The present work offers the first instance of using multi-channel μLED-based optical CI to demonstrate optogenetic activation of auditory neurons.
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Affiliation(s)
- Siân R Kitcher
- Section on Neuronal CircuitryNational Institute on Deafness and Other Communication DisordersNIHBethesdaMDUSA
| | - Catherine JC Weisz
- Section on Neuronal CircuitryNational Institute on Deafness and Other Communication DisordersNIHBethesdaMDUSA
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Richardson RT, Ibbotson MR, Thompson AC, Wise AK, Fallon JB. Optical stimulation of neural tissue. Healthc Technol Lett 2020; 7:58-65. [PMID: 32754339 PMCID: PMC7353819 DOI: 10.1049/htl.2019.0114] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 05/08/2020] [Accepted: 05/15/2020] [Indexed: 12/23/2022] Open
Abstract
Electrical stimulation has been used for decades in devices such as pacemakers, cochlear implants and more recently for deep brain and retinal stimulation and electroceutical treatment of disease. However, current spread from the electrodes limits the precision of neural activation, leading to a low quality therapeutic outcome or undesired side-effects. Alternative methods of neural stimulation such as optical stimulation offer the potential to deliver higher spatial resolution of neural activation. Direct optical stimulation is possible with infrared light, while visible light can be used to activate neurons if the neural tissue is genetically modified with a light sensitive ion channel. Experimentally, both methods have resulted in highly precise stimulation with little spread of activation at least in the cochlea, each with advantages and disadvantages. Infrared neural stimulation does not require modification of the neural tissue, but has very high power requirements. Optogenetics can achieve precision of activation with lower power, but only in conjunction with targeted insertion of a light sensitive ion channel into the nervous system via gene therapy. This review will examine the advantages and limitations of optical stimulation of neural tissue, using the cochlea as an exemplary model and recent developments for retinal and deep brain stimulation.
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Affiliation(s)
- Rachael Theresa Richardson
- Bionics Institute, Melbourne 3002, Australia.,University of Melbourne, Medical Bionics Department, Melbourne, 3002, Australia.,University of Melbourne, Department of Surgery (Otolaryngology), Melbourne, 3002, Australia
| | - Michael R Ibbotson
- National Vision Research Institute, Australian College of Optometry, and Department of Optometry and Vision Science, University of Melbourne, Melbourne, Australia
| | | | - Andrew K Wise
- Bionics Institute, Melbourne 3002, Australia.,University of Melbourne, Medical Bionics Department, Melbourne, 3002, Australia.,University of Melbourne, Department of Surgery (Otolaryngology), Melbourne, 3002, Australia
| | - James B Fallon
- Bionics Institute, Melbourne 3002, Australia.,University of Melbourne, Medical Bionics Department, Melbourne, 3002, Australia.,University of Melbourne, Department of Surgery (Otolaryngology), Melbourne, 3002, Australia
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Moser T, Dieter A. Towards optogenetic approaches for hearing restoration. Biochem Biophys Res Commun 2020; 527:337-342. [DOI: 10.1016/j.bbrc.2019.12.126] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 12/23/2019] [Indexed: 01/06/2023]
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Gundelach LA, Hüser MA, Beutner D, Ruther P, Bruegmann T. Towards the clinical translation of optogenetic skeletal muscle stimulation. Pflugers Arch 2020; 472:527-545. [PMID: 32415463 PMCID: PMC7239821 DOI: 10.1007/s00424-020-02387-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/05/2020] [Accepted: 04/28/2020] [Indexed: 12/27/2022]
Abstract
Paralysis is a frequent phenomenon in many diseases, and to date, only functional electrical stimulation (FES) mediated via the innervating nerve can be employed to restore skeletal muscle function in patients. Despite recent progress, FES has several technical limitations and significant side effects. Optogenetic stimulation has been proposed as an alternative, as it may circumvent some of the disadvantages of FES enabling cell type–specific, spatially and temporally precise stimulation of cells expressing light-gated ion channels, commonly Channelrhodopsin2. Two distinct approaches for the restoration of skeletal muscle function with optogenetics have been demonstrated: indirect optogenetic stimulation through the innervating nerve similar to FES and direct optogenetic stimulation of the skeletal muscle. Although both approaches show great promise, both have their limitations and there are several general hurdles that need to be overcome for their translation into clinics. These include successful gene transfer, sustained optogenetic protein expression, and the creation of optically active implantable devices. Herein, a comprehensive summary of the underlying mechanisms of electrical and optogenetic approaches is provided. With this knowledge in mind, we substantiate a detailed discussion of the advantages and limitations of each method. Furthermore, the obstacles in the way of clinical translation of optogenetic stimulation are discussed, and suggestions on how they could be overcome are provided. Finally, four specific examples of pathologies demanding novel therapeutic measures are discussed with a focus on the likelihood of direct versus indirect optogenetic stimulation.
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Affiliation(s)
- Lili A Gundelach
- Institute of Cardiovascular Physiology, University Medical Center, Göttingen, Germany
| | - Marc A Hüser
- Institute of Cardiovascular Physiology, University Medical Center, Göttingen, Germany
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center, Göttingen, Germany
| | - Dirk Beutner
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center, Göttingen, Germany
| | - Patrick Ruther
- Microsystem Materials Laboratory, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany
- BrainLinks-BrainTools Cluster of Excellence at the University of Freiburg, Freiburg, Germany
| | - Tobias Bruegmann
- Institute of Cardiovascular Physiology, University Medical Center, Göttingen, Germany.
- DZHK e.V. (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany.
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35
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Recent Advances on Thermal Management of Flexible Inorganic Electronics. MICROMACHINES 2020; 11:mi11040390. [PMID: 32283609 PMCID: PMC7231351 DOI: 10.3390/mi11040390] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/27/2020] [Accepted: 04/05/2020] [Indexed: 12/16/2022]
Abstract
Flexible inorganic electronic devices (FIEDs) consisting of functional inorganic components on a soft polymer substrate have enabled many novel applications such as epidermal electronics and wearable electronics, which cannot be realized through conventional rigid electronics. The low thermal dissipation capacity of the soft polymer substrate of FIEDs demands proper thermal management to reduce the undesired thermal influences. The biointegrated applications of FIEDs pose even more stringent requirements on thermal management due to the sensitive nature of biological tissues to temperature. In this review, we take microscale inorganic light-emitting diodes (μ-ILEDs) as an example of functional components to summarize the recent advances on thermal management of FIEDs including thermal analysis, thermo-mechanical analysis and thermal designs of FIEDs with and without biological tissues. These results are very helpful to understand the underlying heat transfer mechanism and provide design guidelines to optimize FIEDs in practical applications.
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36
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Fallegger F, Schiavone G, Lacour SP. Conformable Hybrid Systems for Implantable Bioelectronic Interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1903904. [PMID: 31608508 DOI: 10.1002/adma.201903904] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 08/20/2019] [Indexed: 05/27/2023]
Abstract
Conformable bioelectronic systems are promising tools that may aid the understanding of diseases, alleviate pathological symptoms such as chronic pain, heart arrhythmia, and dysfunctions, and assist in reversing conditions such as deafness, blindness, and paralysis. Combining reduced invasiveness with advanced electronic functions, hybrid bioelectronic systems have evolved tremendously in the last decade, pushed by progress in materials science, micro- and nanofabrication, system assembly and packaging, and biomedical engineering. Hybrid integration refers here to a technological approach to embed within mechanically compliant carrier substrates electronic components and circuits prepared with traditional electronic materials. This combination leverages mechanical and electronic performance of polymer substrates and device materials, respectively, and offers many opportunities for man-made systems to communicate with the body with unmet precision. However, trade-offs between materials selection, manufacturing processes, resolution, electrical function, mechanical integrity, biointegration, and reliability should be considered. Herein, prominent trends in manufacturing conformable hybrid systems are analyzed and key design, function, and validation principles are outlined together with the remaining challenges to produce reliable conformable, hybrid bioelectronic systems.
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Affiliation(s)
- Florian Fallegger
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Microengineering, Institute of Bioengineering, Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, 1202, Geneva, Switzerland
| | - Giuseppe Schiavone
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Microengineering, Institute of Bioengineering, Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, 1202, Geneva, Switzerland
| | - Stéphanie P Lacour
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Microengineering, Institute of Bioengineering, Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, 1202, Geneva, Switzerland
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37
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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] [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 InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Göttingen Graduate School for Neurosciences, Biophysics and Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Daniel Keppeler
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center 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 Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
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Kleinlogel S, Vogl C, Jeschke M, Neef J, Moser T. Emerging approaches for restoration of hearing and vision. Physiol Rev 2020; 100:1467-1525. [DOI: 10.1152/physrev.00035.2019] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Impairments of vision and hearing are highly prevalent conditions limiting the quality of life and presenting a major socioeconomic burden. For long, retinal and cochlear disorders have remained intractable for causal therapies, with sensory rehabilitation limited to glasses, hearing aids, and electrical cochlear or retinal implants. Recently, the application of gene therapy and optogenetics to eye and ear has generated hope for a fundamental improvement of vision and hearing restoration. To date, one gene therapy for the restoration of vision has been approved and undergoing clinical trials will broaden its application including gene replacement, genome editing, and regenerative approaches. Moreover, optogenetics, i.e. controlling the activity of cells by light, offers a more general alternative strategy. Over little more than a decade, optogenetic approaches have been developed and applied to better understand the function of biological systems, while protein engineers have identified and designed new opsin variants with desired physiological features. Considering potential clinical applications of optogenetics, the spotlight is on the sensory systems. Multiple efforts have been undertaken to restore lost or hampered function in eye and ear. Optogenetic stimulation promises to overcome fundamental shortcomings of electrical stimulation, namely poor spatial resolution and cellular specificity, and accordingly to deliver more detailed sensory information. This review aims at providing a comprehensive reference on current gene therapeutic and optogenetic research relevant to the restoration of hearing and vision. We will introduce gene-therapeutic approaches and discuss the biotechnological and optoelectronic aspects of optogenetic hearing and vision restoration.
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Affiliation(s)
| | | | | | | | - Tobias Moser
- Institute for Auditory Neuroscience, University Medical Center Goettingen, Germany
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39
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Abstract
Monkeys are a premier model organism for neuroscience research. Activity in the central nervous systems of monkeys can be recorded and manipulated while they perform complex perceptual, motor, or cognitive tasks. Conventional techniques for manipulating neural activity in monkeys are too coarse to address many of the outstanding questions in primate neuroscience, but optogenetics holds the promise to overcome this hurdle. In this article, we review the progress that has been made in primate optogenetics over the past 5 years. We emphasize the use of gene regulatory sequences in viral vectors to target specific neuronal types, and we present data on vectors that we engineered to target parvalbumin-expressing neurons. We conclude with a discussion of the utility of optogenetics for treating sensorimotor hearing loss and Parkinson's disease, areas of translational neuroscience in which monkeys provide unique leverage for basic science and medicine.
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Zgierski-Johnston CM, Ayub S, Fernández MC, Rog-Zielinska EA, Barz F, Paul O, Kohl P, Ruther P. Cardiac pacing using transmural multi-LED probes in channelrhodopsin-expressing mouse hearts. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 154:51-61. [PMID: 31738979 PMCID: PMC7322525 DOI: 10.1016/j.pbiomolbio.2019.11.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 10/07/2019] [Accepted: 11/13/2019] [Indexed: 02/03/2023]
Abstract
Optogenetics enables cell-type specific monitoring and actuation via light-activated proteins. In cardiac research, expressing light-activated depolarising ion channels in cardiomyocytes allows optical pacing and defibrillation. Previous studies largely relied on epicardial illumination. Light penetration through the myocardium is however problematic when moving to larger animals and humans. To overcome this limitation, we assessed the utility of an implantable multi light-emitting diode (LED) optical probe (IMLOP) for intramural pacing of mouse hearts expressing cardiac-specific channelrhodopsin-2 (ChR2). Here we demonstrated that IMLOP insertion needs approximately 20 mN of force, limiting possible damage from excessive loads applied during implantation. Histological sections confirmed the confined nature of tissue damage during acute use. The temperature change of the surrounding tissue was below 1 K during LED operation, rendering the probe safe for use in situ. This was confirmed in control experiments where no effect on cardiac action potential conduction was observed even when using stimulation parameters twenty-fold greater than required for pacing. In situ experiments on ChR2-expressing mouse hearts demonstrated that optical stimulation is possible with light intensities as low as 700 μW/mm2; although stable pacing requires higher intensities. When pacing with a single LED, rheobase and chronaxie values were 13.3 mW/mm2 ± 0.9 mW/mm2 and 3 ms ± 0.6 ms, respectively. When doubling the stimulated volume the rheobase decreased significantly (6.5 mW/mm2 ± 0.9 mW/mm2). We have demonstrated IMLOP-based intramural optical pacing of the heart. Probes cause locally constrained tissue damage in the acute setting and require low light intensities for pacing. Further development is necessary to assess effects of chronic implantation.
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Affiliation(s)
- C M Zgierski-Johnston
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Medical Center, University of Freiburg, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - S Ayub
- Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany
| | - M C Fernández
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Medical Center, University of Freiburg, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - E A Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Medical Center, University of Freiburg, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - F Barz
- Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany
| | - O Paul
- Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany; Cluster of Excellence BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
| | - P Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Medical Center, University of Freiburg, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - P Ruther
- Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany; Cluster of Excellence BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
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Hu X, Yang H, Jiang Y, He H, Liu H, Huang H, Wan C. Facile synthesis of a novel transparent hyperbranched phosphorous/nitrogen-containing flame retardant and its application in reducing the fire hazard of epoxy resin. JOURNAL OF HAZARDOUS MATERIALS 2019; 379:120793. [PMID: 31252341 DOI: 10.1016/j.jhazmat.2019.120793] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 06/16/2019] [Accepted: 06/17/2019] [Indexed: 05/27/2023]
Abstract
In this study, a novel hyperbranched phosphorus/nitrogen-containing flame retardant (HPNFR) was facilely synthesized via the transesterification reaction of dimethyl methylphosphonate and tris (2-hydroxyethyl) isocyanurate and characterized successfully by 1H NMR and FTIR. The sample with 4 wt% HPNFR can achieve V-0 rating in UL-94 test and possess a LOI value as high as 34.5%. Conspicuous blowing-out effect was observed during the vertical burning test. TG results indicated that the presence of HPNFR significantly improved the thermal stability of EP thermosets. From cone test, THR, p-HRR, p-SPR and TSP values of HPNFR/EP composites were decreased in comparison to those of pure EP, revealing the reduced fire hazard of EP composites with HPNFR. SEM images of EP thermoset with 4 wt% of HPNFR after cone test exhibited compact and continuous char layers, while those of pure EP are fragmentary and broken. From TG-IR test, the yield of toxic CO and other pyrolysis products was significantly reduced, indicating a decrease in toxicity. Phosphorus-containing compounds were detected in gas phase, which verified the gaseous phase flame retardant effect of HPNFR. Besides, HPNFR would not significantly damage the transparence of EP thermosets, consequently reserved it's application value in some special fields.
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Affiliation(s)
- Xin Hu
- College of Materials Science and Engineering, Chongqing University, 174 Shazhengjie, Chongqing 400044, PR China
| | - Hongyu Yang
- College of Materials Science and Engineering, Chongqing University, 174 Shazhengjie, Chongqing 400044, PR China; Chongqing Key Laboratory of New Building Materials and Engineering, Chongqing University, 174 Shazhengjie, Chongqing 400044, PR China.
| | - Yuping Jiang
- College of Materials Science and Engineering, Chongqing University, 174 Shazhengjie, Chongqing 400044, PR China
| | - Hualing He
- College of Materials Science and Engineering, Chongqing University, 174 Shazhengjie, Chongqing 400044, PR China
| | - Hongyin Liu
- College of Materials Science and Engineering, Chongqing University, 174 Shazhengjie, Chongqing 400044, PR China
| | - Hao Huang
- College of Materials Science and Engineering, Chongqing University, 174 Shazhengjie, Chongqing 400044, PR China
| | - Chaojun Wan
- College of Materials Science and Engineering, Chongqing University, 174 Shazhengjie, Chongqing 400044, PR China
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Choi J, Taal AJ, Pollmann EH, Lee C, Kim K, Moreaux LC, Roukes ML, Shepard KL. A 512-Pixel, 51-kHz-Frame-Rate, Dual-Shank, Lens-less, Filter-less Single Photon Avalanche Diode CMOS Neural Imaging Probe. IEEE JOURNAL OF SOLID-STATE CIRCUITS 2019; 54:2957-2968. [PMID: 31798187 PMCID: PMC6886722 DOI: 10.1109/jssc.2019.2941529] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We present an implantable single photon shank-based imager, monolithically integrated onto a single CMOS IC. The imager comprises of 512 single photon avalanche diodes distributed along two shanks, with a 6-bit depth in-pixel memory and an on-chip digital-to-time converter. To scale down the system to a minimally invasive form factor, we substitute optical filtering and focusing elements with a time-gated, angle-sensitive detection system. The imager computationally reconstructs the position of fluorescent sources within a three-dimensional volume of 3.4 mm × 600 µm × 400 µm.
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Affiliation(s)
- Jaebin Choi
- Electrical Engineering Department, Columbia University, New York, NY, USA
| | - Adriaan J Taal
- Electrical Engineering Department, Columbia University, New York, NY, USA
| | - Eric H Pollmann
- Electrical Engineering Department, Columbia University, New York, NY, USA
| | - Changhyuk Lee
- Brain Science Institute, Korea Institute of Science and Technology, Seoul, South Korea
| | - Kukjoo Kim
- Electronics and Telecommunications Research Institute, Daejeon, South Korea
| | | | | | - Kenneth L Shepard
- Bioelectronic Systems Laboratories, Columbia University, New York, NY, USA
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Reddy JW, Kimukin I, Stewart LT, Ahmed Z, Barth AL, Towe E, Chamanzar M. High Density, Double-Sided, Flexible Optoelectronic Neural Probes With Embedded μLEDs. Front Neurosci 2019; 13:745. [PMID: 31456654 PMCID: PMC6699515 DOI: 10.3389/fnins.2019.00745] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 07/05/2019] [Indexed: 01/09/2023] Open
Abstract
Optical stimulation and imaging of neurons deep in the brain require implantable optical neural probes. External optical access to deeper regions of the brain is limited by scattering and absorption of light as it propagates through tissue. Implantable optoelectronic probes capable of high-resolution light delivery and high-density neural recording are needed for closed-loop manipulation of neural circuits. Micro-light-emitting diodes (μLEDs) have been used for optical stimulation, but predominantly on rigid silicon or sapphire substrates. Flexible polymer neural probes would be preferable for chronic applications since they cause less damage to brain tissue. Flexible μLED neural probes have been recently implemented by flip-chip bonding of commercially available μLED chips onto flexible substrates. Here, we demonstrate a monolithic design for flexible optoelectronic neural interfaces with embedded gallium nitride μLEDs that can be microfabricated at wafer-scale. Parylene C is used as the substrate and insulator due to its biocompatibility, compliance, and optical transparency. We demonstrate one-dimensional and two-dimensional individually-addressable μLED arrays. Our μLEDs have sizes as small as 22 × 22 μm in arrays of up to 32 μLEDs per probe shank. These devices emit blue light at a wavelength of 445 nm, suitable for stimulation of channelrhodopsin-2, with output powers greater than 200 μW at 2 mA. Our flexible optoelectronic probes are double-sided and can illuminate brain tissue from both sides. Recording electrodes are co-fabricated with μLEDs on the front- and backside of the optoelectronic probes for electrophysiology recording of neuronal activity from the volumes of tissue on the front- and backside simultaneously with bi-directional optical stimulation.
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Affiliation(s)
- Jay W. Reddy
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Ibrahim Kimukin
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Luke T. Stewart
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Zabir Ahmed
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Alison L. Barth
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States
- Carnegie Mellon Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Elias Towe
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Maysamreza Chamanzar
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, United States
- Carnegie Mellon Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA, United States
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Abstract
Neural recording electrode technologies have contributed considerably to neuroscience by enabling the extracellular detection of low-frequency local field potential oscillations and high-frequency action potentials of single units. Nevertheless, several long-standing limitations exist, including low multiplexity, deleterious chronic immune responses and long-term recording instability. Driven by initiatives encouraging the generation of novel neurotechnologies and the maturation of technologies to fabricate high-density electronics, novel electrode technologies are emerging. Here, we provide an overview of recently developed neural recording electrode technologies with high spatial integration, long-term stability and multiple functionalities. We describe how these emergent neurotechnologies can approach the ultimate goal of illuminating chronic brain activity with minimal disruption of the neural environment, thereby providing unprecedented opportunities for neuroscience research in the future.
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Affiliation(s)
- Guosong Hong
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, USA
| | - Charles M Lieber
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
- Center for Brain Science, Harvard University, Cambridge, MA, USA.
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
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