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Sander MY, Zhu X. Infrared neuromodulation-a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:066701. [PMID: 38701769 DOI: 10.1088/1361-6633/ad4729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 05/03/2024] [Indexed: 05/05/2024]
Abstract
Infrared (IR) neuromodulation (INM) is an emerging light-based neuromodulation approach that can reversibly control neuronal and muscular activities through the transient and localized deposition of pulsed IR light without requiring any chemical or genetic pre-treatment of the target cells. Though the efficacy and short-term safety of INM have been widely demonstrated in both peripheral and central nervous systems, the investigations of the detailed cellular and biological processes and the underlying biophysical mechanisms are still ongoing. In this review, we discuss the current research progress in the INM field with a focus on the more recently discovered IR nerve inhibition. Major biophysical mechanisms associated with IR nerve stimulation are summarized. As the INM effects are primarily attributed to the spatiotemporal thermal transients induced by water and tissue absorption of pulsed IR light, temperature monitoring techniques and simulation models adopted in INM studies are discussed. Potential translational applications, current limitations, and challenges of the field are elucidated to provide guidance for future INM research and advancement.
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Affiliation(s)
- Michelle Y Sander
- Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, Boston, MA 02215, United States of America
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA 02215, United States of America
- Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Brookline, MA 02446, United States of America
- Photonics Center, Boston University, 8 Saint Mary's Street, Boston, MA 02215, United States of America
- Neurophotonics Center, Boston University, 24 Cummington Mall, Boston, MA 02215, United States of America
| | - Xuedong Zhu
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA 02215, United States of America
- Photonics Center, Boston University, 8 Saint Mary's Street, Boston, MA 02215, United States of America
- Neurophotonics Center, Boston University, 24 Cummington Mall, Boston, MA 02215, United States of America
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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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Almasri RM, Ladouceur F, Mawad D, Esrafilzadeh D, Firth J, Lehmann T, Poole-Warren LA, Lovell NH, Al Abed A. Emerging trends in the development of flexible optrode arrays for electrophysiology. APL Bioeng 2023; 7:031503. [PMID: 37692375 PMCID: PMC10491464 DOI: 10.1063/5.0153753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 08/08/2023] [Indexed: 09/12/2023] Open
Abstract
Optical-electrode (optrode) arrays use light to modulate excitable biological tissues and/or transduce bioelectrical signals into the optical domain. Light offers several advantages over electrical wiring, including the ability to encode multiple data channels within a single beam. This approach is at the forefront of innovation aimed at increasing spatial resolution and channel count in multichannel electrophysiology systems. This review presents an overview of devices and material systems that utilize light for electrophysiology recording and stimulation. The work focuses on the current and emerging methods and their applications, and provides a detailed discussion of the design and fabrication of flexible arrayed devices. Optrode arrays feature components non-existent in conventional multi-electrode arrays, such as waveguides, optical circuitry, light-emitting diodes, and optoelectronic and light-sensitive functional materials, packaged in planar, penetrating, or endoscopic forms. Often these are combined with dielectric and conductive structures and, less frequently, with multi-functional sensors. While creating flexible optrode arrays is feasible and necessary to minimize tissue-device mechanical mismatch, key factors must be considered for regulatory approval and clinical use. These include the biocompatibility of optical and photonic components. Additionally, material selection should match the operating wavelength of the specific electrophysiology application, minimizing light scattering and optical losses under physiologically induced stresses and strains. Flexible and soft variants of traditionally rigid photonic circuitry for passive optical multiplexing should be developed to advance the field. We evaluate fabrication techniques against these requirements. We foresee a future whereby established telecommunications techniques are engineered into flexible optrode arrays to enable unprecedented large-scale high-resolution electrophysiology systems.
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Affiliation(s)
- Reem M. Almasri
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
| | | | - Damia Mawad
- School of Materials Science and Engineering, UNSW, Sydney, NSW 2052, Australia
| | - Dorna Esrafilzadeh
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
| | - Josiah Firth
- Australian National Fabrication Facility, UNSW, Sydney, NSW 2052, Australia
| | - Torsten Lehmann
- School of Electrical Engineering and Telecommunications, UNSW, Sydney, NSW 2052, Australia
| | | | | | - Amr Al Abed
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
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Ping A, Pan L, Zhang J, Xu K, Schriver KE, Zhu J, Roe AW. Targeted Optical Neural Stimulation: A New Era for Personalized Medicine. Neuroscientist 2023; 29:202-220. [PMID: 34865559 DOI: 10.1177/10738584211057047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Targeted optical neural stimulation comprises infrared neural stimulation and optogenetics, which affect the nervous system through induced thermal transients and activation of light-sensitive proteins, respectively. The main advantage of this pair of optical tools is high functional selectivity, which conventional electrical stimulation lacks. Over the past 15 years, the mechanism, safety, and feasibility of optical stimulation techniques have undergone continuous investigation and development. When combined with other methods like optical imaging and high-field functional magnetic resonance imaging, the translation of optical stimulation to clinical practice adds high value. We review the theoretical foundations and current state of optical stimulation, with a particular focus on infrared neural stimulation as a potential bridge linking optical stimulation to personalized medicine.
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Affiliation(s)
- An Ping
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Li Pan
- Qiushi Academy for Advanced Studies (QAAS), Key Laboratory of Biomedical Engineering of Education Ministry & Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jianmin Zhang
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Kedi Xu
- Qiushi Academy for Advanced Studies (QAAS), Key Laboratory of Biomedical Engineering of Education Ministry & Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, Zhejiang, China.,Zhejiang Lab, Hangzhou, Zhejiang, China
| | - Kenneth E Schriver
- Zhejiang University Interdisciplinary Institute of Neuroscience and Technology (ZIINT), School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Junming Zhu
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Anna Wang Roe
- Zhejiang University Interdisciplinary Institute of Neuroscience and Technology (ZIINT), School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang, China
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