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Dorrian RM, Leonard AV, Lauto A. Millimetric devices for nerve stimulation: a promising path towards miniaturization. Neural Regen Res 2024; 19:1702-1706. [PMID: 38103235 PMCID: PMC10960286 DOI: 10.4103/1673-5374.389627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/21/2023] [Accepted: 10/19/2023] [Indexed: 12/18/2023] Open
Abstract
Nerve stimulation is a rapidly developing field, demonstrating positive outcomes across several conditions. Despite potential benefits, current nerve stimulation devices are large, complicated, and are powered via implanted pulse generators. These factors necessitate invasive surgical implantation and limit potential applications. Reducing nerve stimulation devices to millimetric sizes would make these interventions less invasive and facilitate broader therapeutic applications. However, device miniaturization presents a serious engineering challenge. This review presents significant advancements from several groups that have overcome this challenge and developed millimetric-sized nerve stimulation devices. These are based on antennas, mini-coils, magneto-electric and opto-electronic materials, or receive ultrasound power. We highlight key design elements, findings from pilot studies, and present several considerations for future applications of these devices.
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Affiliation(s)
- Ryan M. Dorrian
- Spinal Cord Injury Research Group, School of Biomedicine, The University of Adelaide, Adelaide, SA, Australia
| | - Anna V. Leonard
- Spinal Cord Injury Research Group, School of Biomedicine, The University of Adelaide, Adelaide, SA, Australia
| | - Antonio Lauto
- School of Science, Western Sydney University, Penrith, NSW, Australia
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2
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Zheng Y, Liu Q, Zhao Y, Qi Y, Dong L. Design of a 1 × 4 micro-magnetic stimulation device and its targeted, coordinated regulation on LTP of Schaffer-CA1 in the hippocampus of rats. Methods 2024; 229:49-60. [PMID: 38880432 DOI: 10.1016/j.ymeth.2024.06.004] [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: 02/20/2024] [Revised: 05/29/2024] [Accepted: 06/12/2024] [Indexed: 06/18/2024] Open
Abstract
Magnetic technology has been a hotspot of neuromodulation research in recent years. However, magnetic coil is limited by their size, and it is impossible to realize precise targeted magnetic stimulation to the target area at the cellular scale. To this end, this study designs a 1 × 4 array micro-magnetic stimulation (μMS) device with four sub-millimeter-sized elements, enabling precise magnetic stimulation of the CA1-CA3-DG tri-synaptic positions in the rat hippocampal region. First, it is determined that 70 KHz/2 mT/1 min magnetic stimulation parameter has a modulatory effect on the long-term potentiation (LTP) of Schaffer-CA1 in rat hippocampus. Then, a 1 × 4 array μMS device is used to perform magnetic stimulation at 70 KHz/2 mT/1 min, targeting the CA1, CA3, and DG regions individually with single-point magnetic stimulation; and multi-region magnetic stimulation is applied to the double-point targeting regions of CA1-CA3, CA1-DG, and CA3-DG, as well as the triple-point targeting region of CA1-CA3-DG, so as to investigate the regulation of LTP by single-region magnetic stimulation and multi-region magnetic stimulation. The experimental results indicate that, in the case of single-region magnetic stimulation, the magnitude of the increase in LTP in the CA1 region is the greatest, followed by the CA3 region, while the effect of magnetic stimulation on the DG region is less pronounced. In multi-region magnetic stimulation, synergistic magnetic stimulation of the three-point CA1-CA3-DG results in a greater increase in LTP compared to stimulation of two individual areas, and the enhancement of LTP induction with multi-region magnetic stimulation surpasses that of single-region stimulation. This study has implications for the collaborative targeted magnetic stimulation application of arrayed micro-magnetic devices.
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Affiliation(s)
- Yu Zheng
- School of Life Sciences, Tiangong University, Tianjin, China.
| | - Qiwen Liu
- School of Control Science and Engineering, Tiangong University, Tianjin, China
| | - Yuhang Zhao
- School of Life Sciences, Tiangong University, Tianjin, China
| | - Yenan Qi
- School of Life Sciences, Tiangong University, Tianjin, China
| | - Lei Dong
- School of Life Sciences, Tiangong University, Tianjin, China; Precision Instrument and Opto-Electronics Engineering, Tianjin University, Tianjin, China.
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3
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Saha R, Van Helden D, Hopper MS, Low WC, Netoff TI, Osborn J, Wang JP. Impact of anesthesia on micromagnetic stimulation ( μMS) of the vagus nerve. Biomed Phys Eng Express 2024; 10:035028. [PMID: 38565093 DOI: 10.1088/2057-1976/ad3968] [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: 11/27/2023] [Accepted: 04/02/2024] [Indexed: 04/04/2024]
Abstract
To treat diseases associated with vagal nerve control of peripheral organs, it is necessary to selectively activate efferent and afferent fibers in the vagus. As a result of the nerve's complex anatomy, fiber-specific activation proves challenging. Spatially selective neuromodulation using micromagnetic stimulation(μMS) is showing incredible promise. This neuromodulation technique uses microcoils(μcoils) to generate magnetic fields by powering them with a time-varying current. Following the principles of Faraday's law of induction, a highly directional electric field is induced in the nerve from the magnetic field. In this study on rodent cervical vagus, a solenoidalμcoil was oriented at an angle to left and right branches of the nerve. The aim of this study was to measure changes in the mean arterial pressure (MAP) and heart rate (HR) followingμMS of the vagus. Theμcoils were powered by a single-cycle sinusoidal current varying in pulse widths(PW = 100, 500, and 1000μsec) at a frequency of 20 Hz. Under the influence of isoflurane,μMS of the left vagus at 1000μsec PW led to an average drop in MAP of 16.75 mmHg(n = 7). In contrast,μMS of the right vagus under isoflurane resulted in an average drop of 11.93 mmHg in the MAP(n = 7). Surprisingly, there were no changes in HR to either right or left vagalμMS suggesting the drop in MAP associated with vagusμMS was the result of stimulation of afferent, but not efferent fibers. In urethane anesthetized rats, no changes in either MAP or HR were observed uponμMS of the right or left vagus(n = 3). These findings suggest the choice of anesthesia plays a key role in determining the efficacy ofμMS on the vagal nerve. Absence of HR modulation uponμMS could offer alternative treatment options using VNS with fewer heart-related side-effects.
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Affiliation(s)
- Renata Saha
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States of America
| | - Dusty Van Helden
- Department of Surgery, University of Minnesota, Minneapolis, MN, United States of America
| | - Matthew S Hopper
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States of America
| | - Walter C Low
- Department of Neurosurgery, University of Minnesota, Minneapolis, MN, United States of America
| | - Theoden I Netoff
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States of America
| | - John Osborn
- Department of Surgery, University of Minnesota, Minneapolis, MN, United States of America
| | - Jian-Ping Wang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States of America
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4
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Bok I, Ashtiani A, Gokhale Y, Phillips J, Zhu T, Hai A. Nanofabricated high turn-density spiral coils for on-chip electromagneto-optical conversion. MICROSYSTEMS & NANOENGINEERING 2024; 10:44. [PMID: 38529010 PMCID: PMC10961313 DOI: 10.1038/s41378-024-00674-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 12/19/2023] [Accepted: 01/11/2024] [Indexed: 03/27/2024]
Abstract
Circuit-integrated electromagnets are fundamental building blocks for on-chip signal transduction, modulation, and tunability, with specific applications in environmental and biomedical micromagnetometry. A primary challenge for improving performance is pushing quality limitations while minimizing size and fabrication complexity and retaining spatial capabilities. Recent efforts have exploited highly involved three-dimensional synthesis, advanced insulation, and exotic material compositions. Here, we present a rapid nanofabrication process that employs electron beam dose control for high-turn-density diamond-embedded flat spiral coils; these coils achieve efficient on-chip electromagnetic-to-optical signal conversion. Our fabrication process relies on fast 12.3 s direct writing on standard poly(methyl methacrylate) as a basis for the metal lift-off process. Prototypes with 70 micrometer overall diameters and 49-470 nm interturn spacings with corresponding inductances of 12.3-12.8 nH are developed. We utilize optical micromagnetometry to demonstrate that magnetic field generation at the center of the structure effectively correlates with finite element modeling predictions. Further designs based on our process can be integrated with photolithography to broadly enable optical magnetic sensing and spin-based computation.
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Affiliation(s)
- Ilhan Bok
- Department of Biomedical Engineering, University of Wisconsin–Madison, Madison, WI USA
- Department of Electrical and Computer Engineering, University of Wisconsin–Madison, Madison, WI USA
- Wisconsin Institute for Translational Neuroengineering (WITNe), University of Wisconsin–Madison, Madison, WI USA
| | - Alireza Ashtiani
- Department of Biomedical Engineering, University of Wisconsin–Madison, Madison, WI USA
| | - Yash Gokhale
- Department of Biomedical Engineering, University of Wisconsin–Madison, Madison, WI USA
| | - Jack Phillips
- Department of Biomedical Engineering, University of Wisconsin–Madison, Madison, WI USA
| | - Tianxiang Zhu
- Department of Biomedical Engineering, University of Wisconsin–Madison, Madison, WI USA
| | - Aviad Hai
- Department of Biomedical Engineering, University of Wisconsin–Madison, Madison, WI USA
- Department of Electrical and Computer Engineering, University of Wisconsin–Madison, Madison, WI USA
- Wisconsin Institute for Translational Neuroengineering (WITNe), University of Wisconsin–Madison, Madison, WI USA
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5
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Stoddart PR, Begeng JM, Tong W, Ibbotson MR, Kameneva T. Nanoparticle-based optical interfaces for retinal neuromodulation: a review. Front Cell Neurosci 2024; 18:1360870. [PMID: 38572073 PMCID: PMC10987880 DOI: 10.3389/fncel.2024.1360870] [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: 12/24/2023] [Accepted: 03/04/2024] [Indexed: 04/05/2024] Open
Abstract
Degeneration of photoreceptors in the retina is a leading cause of blindness, but commonly leaves the retinal ganglion cells (RGCs) and/or bipolar cells extant. Consequently, these cells are an attractive target for the invasive electrical implants colloquially known as "bionic eyes." However, after more than two decades of concerted effort, interfaces based on conventional electrical stimulation approaches have delivered limited efficacy, primarily due to the current spread in retinal tissue, which precludes high-acuity vision. The ideal prosthetic solution would be less invasive, provide single-cell resolution and an ability to differentiate between different cell types. Nanoparticle-mediated approaches can address some of these requirements, with particular attention being directed at light-sensitive nanoparticles that can be accessed via the intrinsic optics of the eye. Here we survey the available known nanoparticle-based optical transduction mechanisms that can be exploited for neuromodulation. We review the rapid progress in the field, together with outstanding challenges that must be addressed to translate these techniques to clinical practice. In particular, successful translation will likely require efficient delivery of nanoparticles to stable and precisely defined locations in the retinal tissues. Therefore, we also emphasize the current literature relating to the pharmacokinetics of nanoparticles in the eye. While considerable challenges remain to be overcome, progress to date shows great potential for nanoparticle-based interfaces to revolutionize the field of visual prostheses.
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Affiliation(s)
- Paul R. Stoddart
- School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, VIC, Australia
| | - James M. Begeng
- School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, VIC, Australia
- Department of Biomedical Engineering, Faculty of Engineering & Information Technology, The University of Melbourne, Melbourne, VIC, Australia
| | - Wei Tong
- Department of Biomedical Engineering, Faculty of Engineering & Information Technology, The University of Melbourne, Melbourne, VIC, Australia
- School of Physics, The University of Melbourne, Melbourne, VIC, Australia
| | - Michael R. Ibbotson
- Department of Biomedical Engineering, Faculty of Engineering & Information Technology, The University of Melbourne, Melbourne, VIC, Australia
| | - Tatiana Kameneva
- School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, VIC, Australia
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Ye H, Dima M, Hall V, Hendee J. Cellular mechanisms underlying carry-over effects after magnetic stimulation. Sci Rep 2024; 14:5167. [PMID: 38431662 PMCID: PMC10908793 DOI: 10.1038/s41598-024-55915-8] [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: 06/03/2023] [Accepted: 02/28/2024] [Indexed: 03/05/2024] Open
Abstract
Magnetic fields are widely used for neuromodulation in clinical settings. The intended effect of magnetic stimulation is that neural activity resumes its pre-stimulation state right after stimulation. Many theoretical and experimental works have focused on the cellular and molecular basis of the acute neural response to magnetic field. However, effects of magnetic stimulation can still last after the termination of the magnetic stimulation (named "carry-over effects"), which could generate profound effects to the outcome of the stimulation. However, the cellular and molecular mechanisms of carry-over effects are largely unknown, which renders the neural modulation practice using magnetic stimulation unpredictable. Here, we investigated carry-over effects at the cellular level, using the combination of micro-magnetic stimulation (µMS), electrophysiology, and computation modeling. We found that high frequency magnetic stimulation could lead to immediate neural inhibition in ganglion neurons from Aplysia californica, as well as persistent, carry-over inhibition after withdrawing the magnetic stimulus. Carry-over effects were found in the neurons that fired action potentials under a variety of conditions. The carry-over effects were also observed in the neurons when the magnetic field was applied across the ganglion sheath. The state of the neuron, specifically synaptic input and membrane potential fluctuation, plays a significant role in generating the carry-over effects after magnetic stimulation. To elucidate the cellular mechanisms of such carry-over effects under magnetic stimulation, we simulated a single neuron under magnetic stimulation with multi-compartment modeling. The model successfully replicated the carry-over effects in the neuron, and revealed that the carry-over effect was due to the dysfunction of the ion channel dynamics that were responsible for the initiation and sustaining of membrane excitability. A virtual voltage-clamp experiment revealed a compromised Na conductance and enhanced K conductance post magnetic stimulation, rendering the neurons incapable of generating action potentials and, therefore, leading to the carry over effects. Finally, both simulation and experimental results demonstrated that the carry-over effects could be controlled by disturbing the membrane potential during the post-stimulus inhibition period. Delineating the cellular and ion channel mechanisms underlying carry-over effects could provide insights to the clinical outcomes in brain stimulation using TMS and other modalities. This research incentivizes the development of novel neural engineering or pharmacological approaches to better control the carry-over effects for optimized clinical outcomes.
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Affiliation(s)
- Hui Ye
- Department of Biology, Loyola University Chicago, Quinlan Life Sciences Education and Research Center, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA.
| | - Maria Dima
- Department of Biology, Loyola University Chicago, Quinlan Life Sciences Education and Research Center, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA
| | - Vincent Hall
- Department of Biology, Loyola University Chicago, Quinlan Life Sciences Education and Research Center, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA
| | - Jenna Hendee
- Department of Biology, Loyola University Chicago, Quinlan Life Sciences Education and Research Center, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA
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7
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Kumari P, Wunderlich H, Milojkovic A, López JE, Fossati A, Jahanshahi A, Kozielski K. Multiscale Modeling of Magnetoelectric Nanoparticles for the Analysis of Spatially Selective Neural Stimulation. Adv Healthc Mater 2024:e2302871. [PMID: 38262344 DOI: 10.1002/adhm.202302871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 01/17/2024] [Indexed: 01/25/2024]
Abstract
The growing field of nanoscale neural stimulators offers a potential alternative to larger scale electrodes for brain stimulation. Nanoelectrodes made of magnetoelectric nanoparticles (MENPs) can provide an alternative to invasive electrodes for brain stimulation via magnetic-to-electric signal transduction. However, the magnetoelectric effect is a complex phenomenon and challenging to probe experimentally. Consequently, quantifying the stimulation voltage provided by MENPs is difficult, hindering precise regulation and control of neural stimulation and limiting their practical implementation as wireless nanoelectrodes. The work herein develops an approach to determine the stimulation voltage for MENPs in a finite element analysis (FEA) model. This model is informed by atomistic material properties from ab initio Density Functional Theory (DFT) calculations and supplemented by experimentally obtainable nanoscale parameters. This process overcomes the need for experimentally inaccessible characteristics for magnetoelectricity, and offers insights into the effect of the more manageable variables, such as the driving magnetic field. The model's voltage is compared to in vivo experimental data to assess its validity. With this, a predictable and controllable stimulation is simulated by MENPs, computationally substantiating their spatial selectivity. This work proposes a generalizable and accessible method for evaluating the stimulation capability of magnetoelectric nanostructures, facilitating their realization as wireless neural stimulators in the future.
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Affiliation(s)
- Prachi Kumari
- Professorship of Neuroengineering Materials, School of Computation, Information and Technology, Technical University of Munich, 80333, Munich, Germany
| | - Hannah Wunderlich
- Professorship of Neuroengineering Materials, School of Computation, Information and Technology, Technical University of Munich, 80333, Munich, Germany
| | - Aleksandra Milojkovic
- Professorship of Neuroengineering Materials, School of Computation, Information and Technology, Technical University of Munich, 80333, Munich, Germany
| | - Jorge Estudillo López
- Professorship of Neuroengineering Materials, School of Computation, Information and Technology, Technical University of Munich, 80333, Munich, Germany
| | - Arianna Fossati
- Department of Electronics and Information, Politecnico di Milano, Milano, 20133, Italy
| | - Ali Jahanshahi
- Department of Neurosurgery, Maastricht University Medical Center, Maastricht, 6229, Netherlands
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, 1105, Netherlands
| | - Kristen Kozielski
- Professorship of Neuroengineering Materials, School of Computation, Information and Technology, Technical University of Munich, 80333, Munich, Germany
- Munich Institute of Biomedical Engineering, Technical University of Munich, 85748, Garching, Germany
- Munich Institute of Robotics and Machine Intelligence, Technical University of Munich, 80992, Munich, Germany
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8
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Song L, Wang H, Peng R. Advances in the Regulation of Neural Function by Infrared Light. Int J Mol Sci 2024; 25:928. [PMID: 38256001 PMCID: PMC10815576 DOI: 10.3390/ijms25020928] [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: 12/19/2023] [Revised: 01/02/2024] [Accepted: 01/10/2024] [Indexed: 01/24/2024] Open
Abstract
In recent years, with the rapid development of optical technology, infrared light has been increasingly used in biomedical fields. Research has shown that infrared light could play roles in light stimulation and biological regulation. Infrared light has been used to regulate neural function due to its high spatial resolution, safety and neural sensitivity and has been considered a useful method to replace traditional neural regulation approaches. Infrared neuromodulation methods have been used for neural activation, central nervous system disorder treatment and cognitive enhancement. Research on the regulation of neural function by infrared light stimulation began only recently, and the underlying mechanism remains unclear. This article reviews the characteristics of infrared light, the advantages and disadvantages of infrared neuromodulation, its effects on improving individual health, and its mechanism. This article aims to provide a reference for future research on the use of infrared neural regulation to treat neuropsychological disorders.
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Affiliation(s)
| | - Hui Wang
- Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Ruiyun Peng
- Beijing Institute of Radiation Medicine, Beijing 100850, China
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Alzahrani M, Roth BJ. The Electric Field Induced by a Microcoil During Magnetic Stimulation. IEEE Trans Biomed Eng 2023; 70:3260-3262. [PMID: 37167044 DOI: 10.1109/tbme.2023.3275098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
OBJECTIVE The purpose of this study is to calculate the electric field produced by an implanted microcoil during magnetic stimulation of the brain. METHODS The electric field of a microcoil was calculated numerically. RESULTS The maximum value of the induced electric field is approximately 0.000026 V/m for a 1 mA, 3 kHz current passed through the coil. CONCLUSION This electric field value is too small to cause neural stimulation. SIGNIFICANCE Previous studies reporting magnetic stimulation using a microcoil must have been exciting neurons by some other mechanism.
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Tian H, Zhu H, Gao C, Shi M, Yang D, Jin M, Wang F, Sui X. System-level biological effects of extremely low-frequency electromagnetic fields: an in vivo experimental review. Front Neurosci 2023; 17:1247021. [PMID: 37869515 PMCID: PMC10590107 DOI: 10.3389/fnins.2023.1247021] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 09/12/2023] [Indexed: 10/24/2023] Open
Abstract
During the past decades, the potential effects of extremely low-frequency electromagnetic fields (ELF-EMFs) on human health have gained great interest all around the world. Though the International Commission on Non-Ionizing Radiation Protection recommended a 100 μT, and then a 200 μT magnetic field limit, the long-term effects of ELF-EMFs on organisms and systems need to be further investigated. It was reported that both electrotherapy and possible effects on human health could be induced under ELF-EM radiation with varied EM frequencies and fields. This present article intends to systematically review the in vivo experimental outcome and the corresponding mechanisms to shed some light on the safety considerations of ELF-EMFs. This will further advance the subsequent application of electrotherapy in human health.
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Affiliation(s)
- Haoyang Tian
- Electric Power Research Institute, State Grid Shanghai Municipal Electric Power Company, Shanghai, China
| | - Haozheng Zhu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Chenhao Gao
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Mingxia Shi
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Dekun Yang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Mingyu Jin
- State Grid Shanghai Municipal Electric Power Company, Shanghai, China
| | - Fenghua Wang
- Department of Electrical Engineering, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaohong Sui
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
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Saha R, Goyal A, Yuen J, Oh Y, Bloom RP, Benally OJ, Wu K, Netoff TI, Low WC, Bennet KE, Lee KH, Shin H, Wang JP. Micromagnetic Stimulation (μMS) Controls Dopamine Release: An in vivo Study Using WINCS Harmoni. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.25.542334. [PMID: 37292985 PMCID: PMC10246005 DOI: 10.1101/2023.05.25.542334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Objective Research into the role of neurotransmitters in regulating normal and pathologic brain functions has made significant progress. Yet, clinical trials that aim to improve therapeutic interventions do not take advantage of the in vivo changes in the neurochemistry that occur in real time during disease progression, drug interactions or response to pharmacological, cognitive, behavioral, and neuromodulation therapies. In this work, we used the WINCS Harmoni tool to study the real time in vivo changes in dopamine release in rodent brains for the micromagnetic neuromodulation therapy. Approach Although still in its infancy, micromagnetic stimulation (µMS) using micro-meter sized coils or microcoils (μcoils) has shown incredible promise in spatially selective, galvanic contact free and highly focal neuromodulation. These μcoils are powered by a time-varying current which generates a magnetic field. As per Faraday's Laws of Electromagnetic Induction, this magnetic field induces an electric field in a conducting medium (here, the brain tissues). We used a solenoidal-shaped μcoil to stimulate the medial forebrain bundle (MFB) of the rodent brain in vivo. The evoked in vivo dopamine releases in the striatum were tracked in real time by carbon fiber microelectrodes (CFM) using fast scan cyclic voltammetry (FSCV). Results Our experiments report that μcoils can successfully activate the MFB in rodent brains, triggering dopamine release in vivo. We further show that the successful release of dopamine upon micromagnetic stimulation is dependent on the orientation of the μcoil. Furthermore, varied intensities of µMS can control the concentration of dopamine releases in the striatum. Significance This work helps us better understand the brain and its conditions arising from a new therapeutic intervention, like µMS, at the level of neurotransmitter release. Despite its early stage, this study potentially paves the path for µMS to enter the clinical world as a precisely controlled and optimized neuromodulation therapy.
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Affiliation(s)
- Renata Saha
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Abhinav Goyal
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
- Medical Scientist Training Program, Mayo Clinic, Rochester, MN, United States
| | - Jason Yuen
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
- Deakin University, IMPACT – the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong VIC 3216, Australia
| | - Yoonbae Oh
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
- Department of Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
| | - Robert P. Bloom
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Onri J. Benally
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Kai Wu
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Theoden I. Netoff
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Walter C. Low
- Department of Neurosurgery, University of Minnesota, Minneapolis, MN, United States
| | - Kevin E. Bennet
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
- Division of Engineering, Mayo Clinic, Rochester, MN, United States
| | - Kendall H. Lee
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
- Department of Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
| | - Hojin Shin
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
- Department of Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
| | - Jian-Ping Wang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States
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12
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Sung K, Jo S, Lee J, Park JH, Park YH, Moon J, Kim SJ, Jeong J, Lee J, Eom K. Computational analysis of multichannel magnetothermal neural stimulation using magnetic resonator array. Biomed Eng Lett 2023; 13:209-219. [PMID: 37124115 PMCID: PMC10130299 DOI: 10.1007/s13534-023-00267-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 01/24/2023] [Accepted: 02/01/2023] [Indexed: 02/12/2023] Open
Abstract
Heating nanoparticles with a magnetic field could facilitate selective remote control of neural activity in deep tissue. However, current magnetothermal stimulation approaches are limited to single-channel stimulation. Here, we investigated various designs for multichannel magnetothermal stimulation based on an array of resonant coils that are driven by a single loop coil. Using a tuning capacitor that allows resonant coils to resonate at the operating frequency, each coil's ON and OFF resonance can be controlled, enabling us to select stimulation channels. We found that smaller inner diameters of resonant coils produce more localized magnetic fields while larger coils produce magnetic fields over a longer distance. The constructed multichannel resonant coil arrays can provide a high enough magnetic field intensity to raise the temperature of nanoparticles by 8 °C when we apply 35.2 W into the loop coil that is spaced 1 mm from the target neurons. This multichannel stimulation using a simple resonant circuit approach would be useful for clinical applications of magnetothermal neural stimulation.
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Affiliation(s)
- Kyungmo Sung
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
| | - Seonghoon Jo
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
| | - Jaewook Lee
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
| | - Jeong Hoan Park
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583 Singapore
| | - Young Hoon Park
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
| | - Jeongjoo Moon
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
| | - Sung June Kim
- School of Electrical and Computer Engineering, Seoul National University, Seoul, 08826 Republic of Korea
| | - Joonsoo Jeong
- School of Biomedical Convergence Engineering, Pusan National University, Yangsan, 50612 Republic of Korea
| | - Jonghwan Lee
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI 02912 USA
- Carney Institute for Brain Science, Brown University, Providence, RI 02912 USA
| | - Kyungsik Eom
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
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13
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Liu X, Whalen AJ, Ryu SB, Lee SW, Fried SI, Kim K, Cai C, Lauritzen M, Bertram N, Chang B, Yu T, Han A. MEMS micro-coils for magnetic neurostimulation. Biosens Bioelectron 2023; 227:115143. [PMID: 36805270 DOI: 10.1016/j.bios.2023.115143] [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: 12/12/2022] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 02/12/2023]
Abstract
Micro-coil magnetic stimulation of brain tissue presents new challenges for MEMS micro-coil probe fabrication. The main challenges are threefold; (i) low coil resistance for high power efficiency, (ii) low leak current from the probe into the in vitro experimental set-up, (iii) adaptive MEMS process technology because of the dynamic research area, which requires agile design changes. Taking on these challenges, we present a MEMS fabrication process that has three main features; (i) multilayer resist lift-off process to pattern up to 1800-nm-thick metal films, and special care is taken to obtain high conductivity thin-films by physical vapor deposition, and (ii) all micro-coil Al wires are encapsulated in at least 200 nm of ALD alumina and 6-μm-thick parylene C such the leak resistance is high (>210 GΩ), (iii) combining a multi-step DRIE process and maskless photolithography for adaptive design and device fabrication. The entire process requires four lithography steps. Because we avoided SOI wafers and lithography mask fabrication, the design-to-device time is shortened significantly. The resulting probes are 4-mm-long, 60-μm-thick, and down to 150 μm-wide. Selected MEMS coil devices were validated in vivo using mice and compared to previous work.
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Affiliation(s)
- Xiyuan Liu
- Department of Civil and Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark; Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Andrew J Whalen
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Neurosurgery, Yale School of Medicine, New Haven, CT, USA
| | - Sang Baek Ryu
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Seung Woo Lee
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Brain and Cognitive Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Shelley I Fried
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Boston VA Healthcare System, Boston, MA, USA
| | - Kayeon Kim
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Changsi Cai
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Martin Lauritzen
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark
| | - Nicolas Bertram
- Department of Civil and Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark; Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Bingdong Chang
- Department of Civil and Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Tianbo Yu
- Department of Civil and Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Anpan Han
- Department of Civil and Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark.
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14
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Momi D, Wang Z, Griffiths JD. TMS-evoked responses are driven by recurrent large-scale network dynamics. eLife 2023; 12:83232. [PMID: 37083491 PMCID: PMC10121222 DOI: 10.7554/elife.83232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 04/03/2023] [Indexed: 04/22/2023] Open
Abstract
A compelling way to disentangle the complexity of the brain is to measure the effects of spatially and temporally synchronized systematic perturbations. In humans, this can be non-invasively achieved by combining transcranial magnetic stimulation (TMS) and electroencephalography (EEG). Spatiotemporally complex and long-lasting TMS-EEG evoked potential (TEP) waveforms are believed to result from recurrent, re-entrant activity that propagates broadly across multiple cortical and subcortical regions, dispersing from and later re-converging on, the primary stimulation site. However, if we loosely understand the TEP of a TMS-stimulated region as the impulse response function of a noisy underdamped harmonic oscillator, then multiple later activity components (waveform peaks) should be expected even for an isolated network node in the complete absence of recurrent inputs. Thus emerges a critically important question for basic and clinical research on human brain dynamics: what parts of the TEP are due to purely local dynamics, what parts are due to reverberant, re-entrant network activity, and how can we distinguish between the two? To disentangle this, we used source-localized TMS-EEG analyses and whole-brain connectome-based computational modelling. Results indicated that recurrent network feedback begins to drive TEP responses from 100 ms post-stimulation, with earlier TEP components being attributable to local reverberatory activity within the stimulated region. Subject-specific estimation of neurophysiological parameters additionally indicated an important role for inhibitory GABAergic neural populations in scaling cortical excitability levels, as reflected in TEP waveform characteristics. The novel discoveries and new software technologies introduced here should be of broad utility in basic and clinical neuroscience research.
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Affiliation(s)
- Davide Momi
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, Canada
| | - Zheng Wang
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, Canada
| | - John D Griffiths
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, Canada
- Department of Psychiatry, University of Toronto, Toronto, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Canada
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15
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Cehajic-Kapetanovic J, Singh MS, Zrenner E, MacLaren RE. Bioengineering strategies for restoring vision. Nat Biomed Eng 2023; 7:387-404. [PMID: 35102278 DOI: 10.1038/s41551-021-00836-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 11/30/2021] [Indexed: 12/15/2022]
Abstract
Late-stage retinal degenerative disease involving photoreceptor loss can be treated by optogenetic therapy, cell transplantation and retinal prostheses. These approaches aim to restore light sensitivity to the retina as well as visual perception by integrating neuronal responses for transmission to the cortex. In age-related macular degeneration, some cell-based therapies also aim to restore photoreceptor-supporting tissue to prevent complete photoreceptor loss. In the earlier stages of degeneration, gene-replacement therapy could attenuate retinal-disease progression and reverse loss of function. And gene-editing strategies aim to correct the underlying genetic defects. In this Review, we highlight the most promising gene therapies, cell therapies and retinal prostheses for the treatment of retinal disease, discuss the benefits and drawbacks of each treatment strategy and the factors influencing whether functional tissue is reconstructed and repaired or replaced with an electronic device, and summarize upcoming technologies for enhancing the restoration of vision.
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Affiliation(s)
- Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, UK.
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.
| | | | - Eberhart Zrenner
- Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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16
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Ye H, Hall V, Hendee J. Improving focality and consistency in micromagnetic stimulation. Front Comput Neurosci 2023; 17:1105505. [PMID: 36817316 PMCID: PMC9932264 DOI: 10.3389/fncom.2023.1105505] [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: 11/22/2022] [Accepted: 01/17/2023] [Indexed: 02/05/2023] Open
Abstract
The novel micromagnetic stimulation (μMS) technology aims to provide high resolution on neuronal targets. However, consistency of neural activation could be compromised by a lack of surgical accuracy, biological variation, and human errors in operation. We have recently modeled the activation of an unmyelinated axon by a circular micro-coil. Although the coil could activate the axon, its performance sometimes lacked focality and consistency. The site of axonal activation could shift by several experimental factors, including the reversal of the coil current, displacement of the coil, and changes in the intensity of the stimulation. Current clinical practice with transcranial magnetic stimulation (TMS) has suggested that figure-eight coils could provide better performance in magnetic stimulation than circular coils. Here, we estimate the performance of μMS by a figure-eight micro-coil, by exploring the impact of the same experimental factors on its focality and consistency in axonal activation. We derived the analytical expression of the electric field and activating function generated by the figure-eight micro-coil, and estimated the location of axonal activation. Using NEURON modeling of an unmyelinated axon, we found two different types (A and B) of axon activation by the figure-eight micro-coil, mediated by coil currents of reversed direction. Type A activation is triggered by membrane hyperpolarization followed by depolarization; Type B activation is triggered by direct membrane depolarization. Consequently, the two types of stimulation are governed by distinct ion channel mechanisms. In comparison to the circular micro-coil, the figure-eight micro-coil requires significantly less current for axonal activation. Under figure-eight micro-coil stimulation, the site of axonal activation does not change with the reversal of the coil current, displacement of the coil, or changes in the intensity of the stimulation. Ultimately, the figure-eight micro-coil provides a more efficient and consistent site of activation than the circular micro-coil in μMS.
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17
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Ye H, Hendee J, Ruan J, Zhirova A, Ye J, Dima M. Neuron matters: neuromodulation with electromagnetic stimulation must consider neurons as dynamic identities. J Neuroeng Rehabil 2022; 19:116. [PMID: 36329492 PMCID: PMC9632094 DOI: 10.1186/s12984-022-01094-4] [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: 05/14/2022] [Accepted: 10/15/2022] [Indexed: 11/06/2022] Open
Abstract
Neuromodulation with electromagnetic stimulation is widely used for the control of abnormal neural activity, and has been proven to be a valuable alternative to pharmacological tools for the treatment of many neurological diseases. Tremendous efforts have been focused on the design of the stimulation apparatus (i.e., electrodes and magnetic coils) that delivers the electric current to the neural tissue, and the optimization of the stimulation parameters. Less attention has been given to the complicated, dynamic properties of the neurons, and their context-dependent impact on the stimulation effects. This review focuses on the neuronal factors that influence the outcomes of electromagnetic stimulation in neuromodulation. Evidence from multiple levels (tissue, cellular, and single ion channel) are reviewed. Properties of the neural elements and their dynamic changes play a significant role in the outcome of electromagnetic stimulation. This angle of understanding yields a comprehensive perspective of neural activity during electrical neuromodulation, and provides insights in the design and development of novel stimulation technology.
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Affiliation(s)
- Hui Ye
- grid.164971.c0000 0001 1089 6558Department of Biology, Quinlan Life Sciences Education and Research Center, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL 60660 USA
| | - Jenna Hendee
- grid.164971.c0000 0001 1089 6558Department of Biology, Quinlan Life Sciences Education and Research Center, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL 60660 USA
| | - Joyce Ruan
- grid.164971.c0000 0001 1089 6558Department of Biology, Quinlan Life Sciences Education and Research Center, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL 60660 USA
| | - Alena Zhirova
- grid.164971.c0000 0001 1089 6558Department of Biology, Quinlan Life Sciences Education and Research Center, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL 60660 USA
| | - Jayden Ye
- grid.164971.c0000 0001 1089 6558Department of Biology, Quinlan Life Sciences Education and Research Center, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL 60660 USA
| | - Maria Dima
- grid.164971.c0000 0001 1089 6558Department of Biology, Quinlan Life Sciences Education and Research Center, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL 60660 USA
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18
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Zhang E, Abdel-Mottaleb M, Liang P, Navarrete B, Yildirim YA, Campos MA, Smith IT, Wang P, Yildirim B, Yang L, Chen S, Smith I, Lur G, Nguyen T, Jin X, Noga BR, Ganzer P, Khizroev S. Magnetic-field-synchronized wireless modulation of neural activity by magnetoelectric nanoparticles. Brain Stimul 2022; 15:1451-1462. [PMID: 36374738 DOI: 10.1016/j.brs.2022.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 10/15/2022] [Accepted: 10/19/2022] [Indexed: 12/30/2022] Open
Abstract
The in vitro study demonstrates wirelessly controlled modulation of neural activity using magnetoelectric nanoparticles (MENPs), synchronized to magnetic field application with a sub-25-msec temporal response. Herein, MENPs are sub-30-nm CoFe2O4@BaTiO3 core-shell nanostructures. MENPs were added to E18 rat hippocampal cell cultures (0.5 μg of MENPs per 100,000 neurons) tagged with fluorescent Ca2+ sensitive indicator cal520. MENPs were shown to wirelessly induce calcium transients which were synchronized with application of 1200-Oe bipolar 25-msec magnetic pulses at a rate of 20 pulses/sec. The observed calcium transients were similar, in shape and magnitude, to those generated through the control electric field stimulation with a 50-μA current, and they were inhibited by the sodium channel blocker tetrodotoxin. The observed MENP-based magnetic excitation of neural activity is in agreement with the non-linear M - H hysteresis loop of the MENPs, wherein the MENPs' coercivity value sets the threshold for the externally applied magnetic field.
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Affiliation(s)
- E Zhang
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA
| | - M Abdel-Mottaleb
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA
| | - P Liang
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA; Cellular Nanomed, Inc, Irvine, CA, USA.
| | - B Navarrete
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA
| | - Y Akin Yildirim
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA
| | - M Alberteris Campos
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA
| | - I T Smith
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA
| | - P Wang
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA
| | - B Yildirim
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA
| | - L Yang
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA
| | - S Chen
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA; Cellular Nanomed, Inc, Irvine, CA, USA
| | - I Smith
- Department of Neurobiology and Behavior, University of California, Irvine, CA, USA
| | - G Lur
- Department of Neurobiology and Behavior, University of California, Irvine, CA, USA
| | - T Nguyen
- Stark Neuroscience Institute, Indiana University - Purdue University at Indianapolis, Indianapolis, IN, USA
| | - X Jin
- Stark Neuroscience Institute, Indiana University - Purdue University at Indianapolis, Indianapolis, IN, USA
| | - B R Noga
- The Miami Project to Cure Paralysis, University of Miami, FL, USA
| | - P Ganzer
- The Miami Project to Cure Paralysis, University of Miami, FL, USA
| | - S Khizroev
- Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL, USA; Biochemistry and Molecular Biology, University of Miami, Miami, FL, USA.
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19
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Kim T, Kadji H, Whalen AJ, Ashourvan A, Freeman E, Fried SI, Tadigadapa S, Schiff SJ. Thermal effects on neurons during stimulation of the brain. J Neural Eng 2022; 19:056029. [PMID: 36126646 PMCID: PMC9855718 DOI: 10.1088/1741-2552/ac9339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 09/13/2022] [Accepted: 09/20/2022] [Indexed: 01/25/2023]
Abstract
All electric and magnetic stimulation of the brain deposits thermal energy in the brain. This occurs through either Joule heating of the conductors carrying current through electrodes and magnetic coils, or through dissipation of energy in the conductive brain.Objective.Although electrical interaction with brain tissue is inseparable from thermal effects when electrodes are used, magnetic induction enables us to separate Joule heating from induction effects by contrasting AC and DC driving of magnetic coils using the same energy deposition within the conductors. Since mammalian cortical neurons have no known sensitivity to static magnetic fields, and if there is no evidence of effect on spike timing to oscillating magnetic fields, we can presume that the induced electrical currents within the brain are below the molecular shot noise where any interaction with tissue is purely thermal.Approach.In this study, we examined a range of frequencies produced from micromagnetic coils operating below the molecular shot noise threshold for electrical interaction with single neurons.Main results.We found that small temperature increases and decreases of 1∘C caused consistent transient suppression and excitation of neurons during temperature change. Numerical modeling of the biophysics demonstrated that the Na-K pump, and to a lesser extent the Nernst potential, could account for these transient effects. Such effects are dependent upon compartmental ion fluxes and the rate of temperature change.Significance.A new bifurcation is described in the model dynamics that accounts for the transient suppression and excitation; in addition, we note the remarkable similarity of this bifurcation's rate dependency with other thermal rate-dependent tipping points in planetary warming dynamics. These experimental and theoretical findings demonstrate that stimulation of the brain must take into account small thermal effects that are ubiquitously present in electrical and magnetic stimulation. More sophisticated models of electrical current interaction with neurons combined with thermal effects will lead to more accurate modulation of neuronal activity.
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Affiliation(s)
- TaeKen Kim
- Department of Physics, The Pennsylvania State University, University Park, PA, United States of America
| | - Herve Kadji
- Center for Neural Engineering, Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, United States of America
- Department of Radiation Oncology, Hackensack Meridian Health Mountainside Medical Center, Montclair, NJ, United States of America
| | - Andrew J Whalen
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA, United States of America
- Department of Neurosurgery, Harvard Medical School, Massachusetts General Hospital, Boston, MA, United States of America
| | - Arian Ashourvan
- Center for Neural Engineering, Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, United States of America
| | - Eugene Freeman
- Department of Electrical Engineering, The Pennsylvania State University, University Park, PA, United States of America
- Honeywell International Aerospace Advanced Technology, Plymouth, MN, United States of America
| | - Shelley I Fried
- Department of Neurosurgery, Harvard Medical School, Massachusetts General Hospital, Boston, MA, United States of America
- Boston VA Healthcare System, Boston 02130, United States of America
| | - Srinivas Tadigadapa
- Department of Electrical Engineering, The Pennsylvania State University, University Park, PA, United States of America
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, United States of America
| | - Steven J Schiff
- Department of Physics, The Pennsylvania State University, University Park, PA, United States of America
- Center for Neural Engineering, Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, United States of America
- Department of Neurosurgery, Penn State College of Medicine, Hershey, PA 17033, United States of America
- Department of Neurosurgery, Yale University, 333 Cedar Street, TMP 410, New Haven, CT 06510, United States of America
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20
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Jeong H, Cho A, Ay I, Bonmassar G. Short-pulsed micro-magnetic stimulation of the vagus nerve. Front Physiol 2022; 13:938101. [PMID: 36277182 PMCID: PMC9585240 DOI: 10.3389/fphys.2022.938101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 09/01/2022] [Indexed: 11/30/2022] Open
Abstract
Vagus nerve stimulation (VNS) is commonly used to treat drug-resistant epilepsy and depression. The therapeutic effect of VNS depends on stimulating the afferent vagal fibers. However, the vagus is a mixed nerve containing afferent and efferent fibers, and the stimulation of cardiac efferent fibers during VNS may produce a rare but severe risk of bradyarrhythmia. This side effect is challenging to mitigate since VNS, via electrical stimulation technology used in clinical practice, requires unique electrode design and pulse optimization for selective stimulation of only the afferent fibers. Here we describe a method of VNS using micro-magnetic stimulation (µMS), which may be an alternative technique to induce a focal stimulation, enabling a selective fiber stimulation. Micro-coils were implanted into the cervical vagus nerve in adult male Wistar rats. For comparison, the physiological responses were recorded continuously before, during, and after stimulation with arterial blood pressure (ABP), respiration rate (RR), and heart rate (HR). The electrical VNS caused a decrease in ABP, RR, and HR, whereas µM-VNS only caused a transient reduction in RR. The absence of an HR modulation indicated that µM-VNS might provide an alternative technology to VNS with fewer heart-related side effects, such as bradyarrhythmia. Numerical electromagnetic simulations helped estimate the optimal coil orientation with respect to the nerve to provide information on the electric field’s spatial distribution and strength. Furthermore, a transmission emission microscope provided very high-resolution images of the cervical vagus nerve in rats, which identified two different populations of nerve fibers categorized as large and small myelinated fibers.
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Affiliation(s)
- Hongbae Jeong
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Annabel Cho
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
- Department of Bioengineering, Harvard University, Cambridge, MA, United States
| | - Ilknur Ay
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Giorgio Bonmassar
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
- *Correspondence: Giorgio Bonmassar,
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21
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Boyer M, Baudin P, Stengel C, Valero-Cabré A, Lohof AM, Charpier S, Sherrard RM, Mahon S. In vivo low-intensity magnetic pulses durably alter neocortical neuron excitability and spontaneous activity. J Physiol 2022; 600:4019-4037. [PMID: 35899578 DOI: 10.1113/jp283244] [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: 04/23/2022] [Accepted: 07/21/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Repetitive transcranial magnetic stimulation (rTMS) is a promising technique to alleviate neurological and psychiatric disorders caused by alterations in cortical activity. Our knowledge of the cellular mechanisms underlying rTMS-based therapies remains limited. We combined in vivo focal application of low-intensity rTMS (LI-rTMS) to the rat somatosensory cortex with intracellular recordings of subjacent pyramidal neurons to characterize the effects of weak magnetic fields at single cell level. Ten minutes of LI-rTMS delivered at 10 Hz reliably evoked action potentials in cortical neurons during the stimulation period, and induced durable attenuation of their intrinsic excitability, synaptic activity, and spontaneous firing. These results help us better understand the mechanisms of weak magnetic stimulation and should allow optimizing the effectiveness of stimulation protocols for clinical use. ABSTRACT Magnetic brain stimulation is a promising treatment for neurological and psychiatric disorders. However, a better understanding of its effects at the individual neuron level is essential to improve its clinical application. We combined focal low-intensity repetitive transcranial magnetic stimulation (LI-rTMS) to the rat somatosensory cortex with intracellular recordings of subjacent pyramidal neurons in vivo. Continuous 10 Hz LI-rTMS reliably evoked firing at ∼4-5 Hz during the stimulation period and induced durable attenuation of synaptic activity and spontaneous firing in cortical neurons, through membrane hyperpolarization and a reduced intrinsic excitability. However, inducing firing in individual neurons by repeated intracellular current injection did not reproduce LI-rTMS effects on neuronal properties. These data provide novel understanding of mechanisms underlying magnetic brain stimulation showing that, in addition to inducing biochemical plasticity, even weak magnetic fields can activate neurons and enduringly modulate their excitability. Abstract figure legend We examined by means of in vivo intracellular recordings in the rodent the effects of low-intensity (10 mT) repetitive transcranial magnetic stimulation (LI-rTMS) on the functional properties of primary somatosensory cortex pyramidal neurons. After a baseline period, during which cortical spontaneous activity and excitability were measured (Pre), LI-rTMS was applied at 10 Hz for 10 minutes. Despite their low intensity, magnetic pulses reliably evoked action potentials in cortical neurons. Ten minutes of LI-rTMS induced a progressive and long-lasting hyperpolarization of the neuronal membrane and a marked decrease in cell firing rate (Post). This was associated with an altered intrinsic neuronal excitability, characterized by reduced membrane input resistance and increased minimal current required to induce neuronal firing. A portion of this figure was created with biorender.com. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Manon Boyer
- IBPS-B2A, UMR 8256 Biological Adaptation and Ageing, Sorbonne Université & CNRS, Paris, 75005, France.,Paris Brain Institute-ICM, INSERM, CNRS, APHP, Pitié-Salpêtrière Hospital, team 'Network Dynamics and cellular excitability', Sorbonne Université, Paris, France, 75013
| | - Paul Baudin
- Paris Brain Institute-ICM, INSERM, CNRS, APHP, Pitié-Salpêtrière Hospital, team 'Network Dynamics and cellular excitability', Sorbonne Université, Paris, France, 75013
| | - Chloé Stengel
- Paris Brain Institute-ICM, INSERM, CNRS, Pitié-Salpêtrière Hospital, team Cerebral Dynamics, Plasticity and Rehabilitation Group, FRONTLAB team, Sorbonne Université, Paris, 75013, France
| | - Antoni Valero-Cabré
- Paris Brain Institute-ICM, INSERM, CNRS, Pitié-Salpêtrière Hospital, team Cerebral Dynamics, Plasticity and Rehabilitation Group, FRONTLAB team, Sorbonne Université, Paris, 75013, France
| | - Ann M Lohof
- IBPS-B2A, UMR 8256 Biological Adaptation and Ageing, Sorbonne Université & CNRS, Paris, 75005, France
| | - Stéphane Charpier
- Paris Brain Institute-ICM, INSERM, CNRS, APHP, Pitié-Salpêtrière Hospital, team 'Network Dynamics and cellular excitability', Sorbonne Université, Paris, France, 75013
| | - Rachel M Sherrard
- IBPS-B2A, UMR 8256 Biological Adaptation and Ageing, Sorbonne Université & CNRS, Paris, 75005, France
| | - Séverine Mahon
- Paris Brain Institute-ICM, INSERM, CNRS, APHP, Pitié-Salpêtrière Hospital, team 'Network Dynamics and cellular excitability', Sorbonne Université, Paris, France, 75013
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22
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Lee SW, Fried SI. Micro-magnetic stimulation of primary visual cortex induces focal and sustained activation of secondary visual cortex. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2022; 380:20210019. [PMID: 35658677 DOI: 10.1098/rsta.2021.0019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 10/01/2021] [Indexed: 06/15/2023]
Abstract
Cortical visual prostheses that aim to restore sight to the blind require the ability to create neural activity in the visual cortex. Electric stimulation delivered via microelectrodes implanted in the primary visual cortex (V1) has been the most common approach, although conventional electrodes may not effectively confine activation to focal regions and thus the acuity they create may be limited. Magnetic stimulation from microcoils confines activation to single cortical columns of V1 and thus may prove to be more effective than conventional microelectrodes, but the ability of microcoils to drive synaptic connections has not been explored. Here, we show that magnetic stimulation of V1 using microcoils induces spatially confined activation in the secondary visual cortex (V2) in mouse brain slices. Single-loop microcoils were fabricated using platinum-iridium flat microwires, and their effectiveness was evaluated using calcium imaging and compared with that of monopolar and bipolar electrodes. Our results show that compared to the electrodes, the microcoils better confined activation to a small region in V1. In addition, they produced more precise and sustained activation in V2. The finding that microcoil-based stimulation propagates to higher visual centres raises the possibility that complex visual perception, e.g. that requiring sustained synaptic inputs, may be achievable. This article is part of the theme issue 'Advanced neurotechnologies: translating innovation for health and well-being'.
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Affiliation(s)
- Seung Woo Lee
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Shelley I Fried
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Boston VA Healthcare System, Boston, MA, USA
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Cellular mechanisms underlying state-dependent neural inhibition with magnetic stimulation. Sci Rep 2022; 12:12131. [PMID: 35840656 PMCID: PMC9287388 DOI: 10.1038/s41598-022-16494-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 07/11/2022] [Indexed: 12/29/2022] Open
Abstract
Novel stimulation protocols for neuromodulation with magnetic fields are explored in clinical and laboratory settings. Recent evidence suggests that the activation state of the nervous system plays a significant role in the outcome of magnetic stimulation, but the underlying cellular and molecular mechanisms of state-dependency have not been completely investigated. We recently reported that high frequency magnetic stimulation could inhibit neural activity when the neuron was in a low active state. In this paper, we investigate state-dependent neural modulation by applying a magnetic field to single neurons, using the novel micro-coil technology. High frequency magnetic stimulation suppressed single neuron activity in a state-dependent manner. It inhibited neurons in slow-firing states, but spared neurons from fast-firing states, when the same magnetic stimuli were applied. Using a multi-compartment NEURON model, we found that dynamics of voltage-dependent sodium and potassium channels were significantly altered by the magnetic stimulation in the slow-firing neurons, but not in the fast-firing neurons. Variability in neural activity should be monitored and explored to optimize the outcome of magnetic stimulation in basic laboratory research and clinical practice. If selective stimulation can be programmed to match the appropriate neural state, prosthetic implants and brain-machine interfaces can be designed based on these concepts to achieve optimal results.
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Ye H. Finding the Location of Axonal Activation by a Miniature Magnetic Coil. Front Comput Neurosci 2022; 16:932615. [PMID: 35847967 PMCID: PMC9276924 DOI: 10.3389/fncom.2022.932615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 06/03/2022] [Indexed: 11/17/2022] Open
Abstract
Magnetic stimulation for neural activation is widely used in clinical and lab research. In comparison to electric stimulation using an implanted electrode, stimulation with a large magnetic coil is associated with poor spatial specificity and incapability to stimulate deep brain structures. Recent developments in micromagnetic stimulation (μMS) technology mitigates some of these shortcomings. The sub-millimeter coils can be covered with soft, biocompatible material, and chronically implanted. They can provide highly specific neural stimulation in the deep neural structure. Although the μMS technology is expected to provide a precise location of neural stimulation, the exact site of neural activation is difficult to determine. Furthermore, factors that could cause the shifting of the activation site during μMS have not been fully investigated. To estimate the location of axon activation in μMS, we first derived an analytical expression of the activating function, which predicts the location of membrane depolarization in an unmyelinated axon. Then, we developed a multi-compartment, Hodgkin-Huxley (H-H) type of NEURON model of an unmyelinated axon to test the impact of several important coil parameters on the location of axonal activation. The location of axonal activation was dependent on both the parameters of the stimulus and the biophysics properties of the targeted axon during μMS. The activating function analysis predicted that the location of membrane depolarization and activation could shift due to the reversal of the coil current and the change in the coil-axon distance. The NEURON modeling confirmed these predictions. Interestingly, the NEURON simulation further revealed that the intensity of stimulation played a significant role in the activation location. Moderate or strong coil currents activated the axon at different locations, mediated by two distinct ion channel mechanisms. This study reports several experimental factors that could cause a potential shift in the location of neural activation during μMS, which is essential for further development of this novel technology.
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Ning S, Jorfi M, Patel SR, Kim DY, Tanzi RE. Neurotechnological Approaches to the Diagnosis and Treatment of Alzheimer’s Disease. Front Neurosci 2022; 16:854992. [PMID: 35401082 PMCID: PMC8989850 DOI: 10.3389/fnins.2022.854992] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 02/25/2022] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common cause of dementia in the elderly, clinically defined by progressive cognitive decline and pathologically, by brain atrophy, neuroinflammation, and accumulation of extracellular amyloid plaques and intracellular neurofibrillary tangles. Neurotechnological approaches, including optogenetics and deep brain stimulation, have exploded as new tools for not only the study of the brain but also for application in the treatment of neurological diseases. Here, we review the current state of AD therapeutics and recent advancements in both invasive and non-invasive neurotechnologies that can be used to ameliorate AD pathology, including neurostimulation via optogenetics, photobiomodulation, electrical stimulation, ultrasound stimulation, and magnetic neurostimulation, as well as nanotechnologies employing nanovectors, magnetic nanoparticles, and quantum dots. We also discuss the current challenges in developing these neurotechnological tools and the prospects for implementing them in the treatment of AD and other neurodegenerative diseases.
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Affiliation(s)
- Shen Ning
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
- Graduate Program for Neuroscience, Boston University School of Medicine, Boston, MA, United States
| | - Mehdi Jorfi
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
- Center for Engineering in Medicine and Surgery, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
- *Correspondence: Mehdi Jorfi,
| | - Shaun R. Patel
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Doo Yeon Kim
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Rudolph E. Tanzi
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
- Rudolph E. Tanzi,
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Lee KS, Clennell B, Steward TGJ, Gialeli A, Cordero-Llana O, Whitcomb DJ. Focused Ultrasound Stimulation as a Neuromodulatory Tool for Parkinson's Disease: A Scoping Review. Brain Sci 2022; 12:brainsci12020289. [PMID: 35204052 PMCID: PMC8869888 DOI: 10.3390/brainsci12020289] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/15/2022] [Accepted: 02/18/2022] [Indexed: 02/01/2023] Open
Abstract
Non-invasive focused ultrasound stimulation (FUS) is a non-ionising neuromodulatory technique that employs acoustic energy to acutely and reversibly modulate brain activity of deep-brain structures. It is currently being investigated as a potential novel treatment for Parkinson’s disease (PD). This scoping review was carried out to map available evidence pertaining to the provision of FUS as a PD neuromodulatory tool. In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Extension for Scoping Reviews, a search was applied to Ovid MEDLINE, Embase, Web of Science and Cochrane Central Register of Controlled Trials on 13 January 2022, with no limits applied. In total, 11 studies were included: 8 were from China and 1 each from Belgium, South Korea and Taiwan. All 11 studies were preclinical (6 in vivo, 2 in vitro, 2 mix of in vivo and in vitro and 1 in silico). The preclinical evidence indicates that FUS is safe and has beneficial neuromodulatory effects on motor behaviour in PD. FUS appears to have a therapeutic role in influencing the disease processes of PD, and therefore holds great promise as an attractive and powerful neuromodulatory tool for PD. Though these initial studies are encouraging, further study to understand the underlying cellular and molecular mechanisms is required before FUS can be routinely used in PD.
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Affiliation(s)
- Keng Siang Lee
- Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol BS8 1TH, UK; (K.S.L.); (B.C.); (T.G.J.S.); (A.G.); (O.C.-L.)
- Regenerative Medicine Laboratory, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
- Institute of Clinical Neurosciences, Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Benjamin Clennell
- Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol BS8 1TH, UK; (K.S.L.); (B.C.); (T.G.J.S.); (A.G.); (O.C.-L.)
- Institute of Clinical Neurosciences, Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Tom G. J. Steward
- Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol BS8 1TH, UK; (K.S.L.); (B.C.); (T.G.J.S.); (A.G.); (O.C.-L.)
- Institute of Clinical Neurosciences, Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Andriana Gialeli
- Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol BS8 1TH, UK; (K.S.L.); (B.C.); (T.G.J.S.); (A.G.); (O.C.-L.)
- Regenerative Medicine Laboratory, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Oscar Cordero-Llana
- Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol BS8 1TH, UK; (K.S.L.); (B.C.); (T.G.J.S.); (A.G.); (O.C.-L.)
- Regenerative Medicine Laboratory, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Daniel J. Whitcomb
- Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol BS8 1TH, UK; (K.S.L.); (B.C.); (T.G.J.S.); (A.G.); (O.C.-L.)
- Institute of Clinical Neurosciences, Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol BS8 1TH, UK
- Correspondence:
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Saha R, Wu K, Bloom RP, Liang S, Tonini D, Wang JP. A review on magnetic and spintronic neurostimulation: challenges and prospects. NANOTECHNOLOGY 2022; 33:182004. [PMID: 35013010 DOI: 10.1088/1361-6528/ac49be] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
In the treatment of neurodegenerative, sensory and cardiovascular diseases, electrical probes and arrays have shown quite a promising success rate. However, despite the outstanding clinical outcomes, their operation is significantly hindered by non-selective control of electric fields. A promising alternative is micromagnetic stimulation (μMS) due to the high permeability of magnetic field through biological tissues. The induced electric field from the time-varying magnetic field generated by magnetic neurostimulators is used to remotely stimulate neighboring neurons. Due to the spatial asymmetry of the induced electric field, high spatial selectivity of neurostimulation has been realized. Herein, some popular choices of magnetic neurostimulators such as microcoils (μcoils) and spintronic nanodevices are reviewed. The neurostimulator features such as power consumption and resolution (aiming at cellular level) are discussed. In addition, the chronic stability and biocompatibility of these implantable neurostimulator are commented in favor of further translation to clinical settings. Furthermore, magnetic nanoparticles (MNPs), as another invaluable neurostimulation material, has emerged in recent years. Thus, in this review we have also included MNPs as a remote neurostimulation solution that overcomes physical limitations of invasive implants. Overall, this review provides peers with the recent development of ultra-low power, cellular-level, spatially selective magnetic neurostimulators of dimensions within micro- to nano-range for treating chronic neurological disorders. At the end of this review, some potential applications of next generation neuro-devices have also been discussed.
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Affiliation(s)
- Renata Saha
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, United States of America
| | - Kai Wu
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, United States of America
| | - Robert P Bloom
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, United States of America
| | - Shuang Liang
- Department of Chemical Engineering and Material Science, University of Minnesota, Minneapolis, MN 55455, United States of America
| | - Denis Tonini
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, United States of America
| | - Jian-Ping Wang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, United States of America
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28
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Saha R, Faramarzi S, Bloom R, Benally OJ, Wu K, di Girolamo A, Tonini D, Keirstead SA, Low WC, Netoff T, Wang JP. Strength-frequency curve for micromagnetic neurostimulation through excitatory postsynaptic potentials (EPSPs) on rat hippocampal neurons and numerical modeling of magnetic microcoil (μcoil). J Neural Eng 2022; 19. [PMID: 35030549 DOI: 10.1088/1741-2552/ac4baf] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 01/14/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The objective of this study was to measure the effect of micromagnetic stimulation (μMS) on hippocampal neurons, by using single microcoil (μcoil) prototype, Magnetic Pen (MagPen). MagPen will be used to stimulate the CA3 magnetically and excitatory post synaptic potential (EPSP) measurements will be made from the CA1. The threshold for μMS as a function of stimulation frequency of the current driving the µcoil will be demonstrated. Finally, the optimal stimulation frequency of the current driving the μcoil to minimize power will be estimated. APPROACH A biocompatible prototype, MagPen was built, and customized such that it is easy to adjust the orientation of the μcoil over the hippocampal tissue in an in vitro setting. Finite element modeling (FEM) of the μcoil was performed to estimate the spatial profiles of the magnetic flux density (in T) and the induced electric fields (in V/m). The induced electric field profiles generated at different values of current applied to the µcoil whether can elicit a neuron response was validated by numerical modeling. The modeling settings were replicated in experiments on rat hippocampal neurons. MAIN RESULTS The preferred orientation of MagPen over the Schaffer Collateral fibers was demonstrated such that they elicit a neuron response. The recorded EPSPs from CA1 due to μMS at CA3 were validated by applying tetrodotoxin (TTX). Finally, it was interpreted through numerical analysis that increasing frequency of the current driving the μcoil, led to a decrease in the current amplitude threshold for μMS. SIGNIFICANCE This work reports that μMS can be used to evoke population EPSPs in the CA1 of hippocampus. It demonstrates the strength-frequency curve for µMS and its unique features related to orientation dependence of the µcoils, spatial selectivity and distance dependence. Finally, the challenges related to µMS experiments were studied including ways to overcome them.
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Affiliation(s)
- Renata Saha
- Electrical and Computer Engineering, University of Minnesota Twin Cities, 200 Union Street SE, Kenneth Keller Hall, Rm 6-147D, Minneapolis, Minnesota, 55455, UNITED STATES
| | - Sadegh Faramarzi
- Department of Biomedical Engineering, University of Minnesota Twin Cities, Nils Hasselmo Hall,, 312 Church St SE,, Minneapolis, Minnesota, 55455, UNITED STATES
| | - Robert Bloom
- Department of Electrical and Computer Engineering, University of Minnesota, 200 Union Street SE, 4-174 Keller Hall, Minneapolis, Minneapolis, Minnesota, 55455, UNITED STATES
| | - Onri J Benally
- Department of Electrical and Computer Engineering, University of Minnesota Twin Cities, 200 Union Street SE,, Kenneth Keller Hall, Minneapolis, Minnesota, 55455, UNITED STATES
| | - Kai Wu
- Electrical and Computer Engineering, University of Minnesota Twin Cities, 200 Union Street SE, Minneapolis, Minnesota, 55455, UNITED STATES
| | - Arturo di Girolamo
- Department of Electrical and Computer Engineering, University of Minnesota Twin Cities, 200 Union Street SE, Kenneth Keller Hall, Minneapolis, Minnesota, 55455, UNITED STATES
| | - Denis Tonini
- Department of Electrical and Computer Engineering, University of Minnesota Twin Cities, 200 Union Street SE,, Kenneth Keller Hall, Minneapolis, Minnesota, 55455, UNITED STATES
| | - Susan A Keirstead
- Department of Integrative Biology & Physiology, University of Minnesota Twin Cities, Stem Cell Institute, LRB/MTRF 2873B (Campus Delivery Code), 2001 6th St SE, Minneapolis, Minnesota, 55455, UNITED STATES
| | - Walter C Low
- Department of Neurosurgery, University of Minnesota Twin Cities, LRB/MTRF 2873J (Campus Delivery Code), 2001 6th St SE, Minneapolis, Minnesota, 55455, UNITED STATES
| | - Theoden Netoff
- Department of Biomedical Engineering, University of Minnesota Twin Cities, 312 Church Street SE, 7-105 Nils Hasselmo Hall, Minneapolis, Minnesota, 55455, UNITED STATES
| | - Jian-Ping Wang
- Department of Electrical and Computer Engineering, University of Minnesota Twin Cities, 200 Union Street SE, Kenneth Keller Hall, Minneapolis, Minnesota, 55455, UNITED STATES
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Wetting ridge assisted programmed magnetic actuation of droplets on ferrofluid-infused surface. Nat Commun 2021; 12:7136. [PMID: 34880250 PMCID: PMC8654979 DOI: 10.1038/s41467-021-27503-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 11/17/2021] [Indexed: 11/26/2022] Open
Abstract
Flexible actuation of droplets is crucial for biomedical and industrial applications. Hence, various approaches using optical, electrical, and magnetic forces have been exploited to actuate droplets. For broad applicability, an ideal approach should be programmable and be able to actuate droplets of arbitrary size and composition. Here we present an "additive-free" magnetic actuation method to programmably manipulate droplets of water, organic, and biological fluids of arbitrary composition, as well as solid samples, on a ferrofluid-infused porous surface. We specifically exploit the spontaneously formed ferrofluid wetting ridges to actuate droplets using spatially varying magnetic fields. We demonstrate programmed processing and analysis of biological samples in individual drops as well as the collective actuation of large ensembles of micrometer-sized droplets. Such model respiratory droplets can be accumulated for improved quantitative and sensitive bioanalysis - an otherwise prohibitively difficult task that may be useful in tracking coronavirus.
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30
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Yang X, McGlynn E, Das R, Paşca SP, Cui B, Heidari H. Nanotechnology Enables Novel Modalities for Neuromodulation. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2103208. [PMID: 34668249 PMCID: PMC8712412 DOI: 10.1002/adma.202103208] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/27/2021] [Indexed: 05/18/2023]
Abstract
Neuromodulation is of great importance both as a fundamental neuroscience research tool for analyzing and understanding the brain function, and as a therapeutic avenue for treating brain disorders. Here, an overview of conceptual and technical progress in developing neuromodulation strategies is provided, and it is suggested that recent advances in nanotechnology are enabling novel neuromodulation modalities with less invasiveness, improved biointerfaces, deeper penetration, and higher spatiotemporal precision. The use of nanotechnology and the employment of versatile nanomaterials and nanoscale devices with tailored physical properties have led to considerable research progress. To conclude, an outlook discussing current challenges and future directions for next-generation neuromodulation modalities is presented.
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Affiliation(s)
- Xiao Yang
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, 94305, USA
- Stanford Brain Organogenesis, Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, 94305, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, 94305, USA
- Department of Chemistry, Stanford University, Stanford, CA, 94305, USA
| | - Eve McGlynn
- Microelectronics Lab (meLAB), James Watt School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Rupam Das
- Microelectronics Lab (meLAB), James Watt School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Sergiu P Paşca
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, 94305, USA
- Stanford Brain Organogenesis, Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, 94305, USA
| | - Bianxiao Cui
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, 94305, USA
- Department of Chemistry, Stanford University, Stanford, CA, 94305, USA
| | - Hadi Heidari
- Microelectronics Lab (meLAB), James Watt School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
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31
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Jeong H, Deng J, Bonmassar G. Planar figure-8 coils for ultra-focal and directional micromagnetic brain stimulation. JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY. B, NANOTECHNOLOGY & MICROELECTRONICS : MATERIALS, PROCESSING, MEASUREMENT, & PHENOMENA : JVST B 2021; 39:063202. [PMID: 34692236 PMCID: PMC8516478 DOI: 10.1116/6.0001281] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 09/13/2021] [Indexed: 06/13/2023]
Abstract
Recently, white-matter fiber tract pathways carrying neural signals through the brain were shown to follow curved, orthogonal grids. This study focuses on how these white-matter fibers may be selectively excited using micromagnetic stimulation (μMS), a new type of neuronal stimulation, which generates microscopic eddy currents capable of directionally activating neurons. One of the most remarkable properties of this novel type of stimulation is that the μMS fields provide unique directional activation of neuronal elements not seen with traditional electrical stimulation. An initial prototype built with SU-8 based photolithography technology shows that the structure can be fabricated. The coil design was optimized through electrical resistance calculations and electric field simulations to elicit the brain's maximal focal and directional neural responses.
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Affiliation(s)
- Hongbae Jeong
- A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129
| | - Jiangdong Deng
- Center for Nanoscale Systems, Harvard University, Cambridge, Massachusetts 02138
| | - Giorgio Bonmassar
- A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129
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32
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Khalifa A, Zaeimbashi M, Zhou TX, Abrishami SM, Sun N, Park S, Šumarac T, Qu J, Zohar I, Yacoby A, Cash S, Sun NX. The development of microfabricated solenoids with magnetic cores for micromagnetic neural stimulation. MICROSYSTEMS & NANOENGINEERING 2021; 7:91. [PMID: 34786205 PMCID: PMC8589949 DOI: 10.1038/s41378-021-00320-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/16/2021] [Accepted: 10/11/2021] [Indexed: 05/14/2023]
Abstract
Electrical stimulation via invasive microelectrodes is commonly used to treat a wide range of neurological and psychiatric conditions. Despite its remarkable success, the stimulation performance is not sustainable since the electrodes become encapsulated by gliosis due to foreign body reactions. Magnetic stimulation overcomes these limitations by eliminating the need for a metal-electrode contact. Here, we demonstrate a novel microfabricated solenoid inductor (80 µm × 40 µm) with a magnetic core that can activate neuronal tissue. The characterization and proof-of-concept of the device raise the possibility that micromagnetic stimulation solenoids that are small enough to be implanted within the brain may prove to be an effective alternative to existing electrode-based stimulation devices for chronic neural interfacing applications.
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Affiliation(s)
- Adam Khalifa
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA
| | - Mohsen Zaeimbashi
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA USA
| | - Tony X. Zhou
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA USA
- Department of Physics, Harvard University, Cambridge, MA USA
| | - Seyed Mahdi Abrishami
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA USA
| | - Neville Sun
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA USA
| | - Seunghyun Park
- Department of Physics, Harvard University, Cambridge, MA USA
| | - Tamara Šumarac
- Department of Physics, Harvard University, Cambridge, MA USA
| | - Jason Qu
- Department of Physics, Harvard University, Cambridge, MA USA
| | - Inbar Zohar
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Amir Yacoby
- Department of Physics, Harvard University, Cambridge, MA USA
| | - Sydney Cash
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA
| | - Nian X. Sun
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA USA
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33
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Le HT, Haque RI, Ouyang Z, Lee SW, Fried SI, Zhao D, Qiu M, Han A. MEMS inductor fabrication and emerging applications in power electronics and neurotechnologies. MICROSYSTEMS & NANOENGINEERING 2021; 7:59. [PMID: 34567771 PMCID: PMC8433479 DOI: 10.1038/s41378-021-00275-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 05/04/2021] [Accepted: 05/10/2021] [Indexed: 05/08/2023]
Abstract
MEMS inductors are used in a wide range of applications in micro- and nanotechnology, including RF MEMS, sensors, power electronics, and Bio-MEMS. Fabrication technologies set the boundary conditions for inductor design and their electrical and mechanical performance. This review provides a comprehensive overview of state-of-the-art MEMS technologies for inductor fabrication, presents recent advances in 3D additive fabrication technologies, and discusses the challenges and opportunities of MEMS inductors for two emerging applications, namely, integrated power electronics and neurotechnologies. Among the four top-down MEMS fabrication approaches, 3D surface micromachining and through-substrate-via (TSV) fabrication technology have been intensively studied to fabricate 3D inductors such as solenoid and toroid in-substrate TSV inductors. While 3D inductors are preferred for their high-quality factor, high power density, and low parasitic capacitance, in-substrate TSV inductors offer an additional unique advantage for 3D system integration and efficient thermal dissipation. These features make in-substrate TSV inductors promising to achieve the ultimate goal of monolithically integrated power converters. From another perspective, 3D bottom-up additive techniques such as ice lithography have great potential for fabricating inductors with geometries and specifications that are very challenging to achieve with established MEMS technologies. Finally, we discuss inspiring and emerging research opportunities for MEMS inductors.
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Affiliation(s)
- Hoa Thanh Le
- The Rowland Institute at Harvard, Harvard University, Cambridge, MA USA
| | - Rubaiyet I. Haque
- Department of Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Ziwei Ouyang
- Department of Electrical Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Seung Woo Lee
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA
| | - Shelley I. Fried
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA
- Boston VA Healthcare System, Boston, MA USA
| | - Ding Zhao
- Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province, School of Engineering, Westlake University, Hangzhou, China
- Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou, China
| | - Min Qiu
- Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province, School of Engineering, Westlake University, Hangzhou, China
- Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou, China
| | - Anpan Han
- Department of Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark
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Abstract
Electric currents can produce quick, reversible control of neural activity. Externally applied electric currents have been used in inhibiting certain ganglion cells in clinical practices. Via electromagnetic induction, a miniature-sized magnetic coil could provide focal stimulation to the ganglion neurons. Here we report that high-frequency stimulation with the miniature coil could reversibly block ganglion cell activity in marine mollusk Aplysia californica, regardless the firing frequency of the neurons, or concentration of potassium ions around the ganglion neurons. Presence of the ganglion sheath has minimal impact on the inhibitory effects of the coil. The inhibitory effect was local to the soma, and was sufficient in blocking the neuron's functional output. Biophysical modeling confirmed that the miniature coil induced a sufficient electric field in the vicinity of the targeted soma. Using a multi-compartment model of Aplysia ganglion neuron, we found that the high-frequency magnetic stimuli altered the ion channel dynamics that were essential for the sustained firing of action potentials in the soma. Results from this study produces several critical insights to further developing the miniature coil technology for neural control by targeting ganglion cells. The miniature coil provides an interesting neural modulation strategy in clinical applications and laboratory research.
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Affiliation(s)
- Hui Ye
- Department of Biology, Quinlan Life Sciences Education and Research Center, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA.
| | - Lauryn Barrett
- Department of Biology, Quinlan Life Sciences Education and Research Center, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA
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Zheng Y, Xia P, Dong L, Tian L, Tian C. Development and review of a sub-millimeter-sized cell-scale micro-magnetic stimulation device. Biomed Phys Eng Express 2021; 7. [PMID: 34020437 DOI: 10.1088/2057-1976/ac0409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 05/21/2021] [Indexed: 11/12/2022]
Abstract
The development of modern micro-processing technology has led to the design and production of sub-millimeter-sized coils. A novel type of micro-magnetic stimulation (μMS) regulatory technology has widely been researched in recent years. This technology has several advantages, including small size, no contact between tissues and the metal coil, and high spatial resolution. Considering some problems with theμMS control technology in practical applications, different kinds ofμMS devices have been developed, including anin vitrosingle-pointμMS device, anin vivoimplantable single-pointμMs device, a discrete-arrayμMS device, and anin vivoimplantable-arrayμMs device. Given the problems that currently exist in the design and implementation of this device, such as the key problems of structural design, implantation method, experimental safety, and reliability of the device, we review the development process in detail. We also discuss the precise targeting advantage of this device, which is likely to be of great significance for wide-ranging applications of magnetic stimulation technology.
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Affiliation(s)
- Yu Zheng
- School of Life Sciences, Tiangong university, Tianjin 300387, People's Republic of China
| | - Pei Xia
- School of Life Sciences, Tiangong university, Tianjin 300387, People's Republic of China
| | - Lei Dong
- State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Lei Tian
- School of Life Sciences, Tiangong university, Tianjin 300387, People's Republic of China
| | - Chunxiao Tian
- School of Life Sciences, Tiangong university, Tianjin 300387, People's Republic of China
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McGlynn E, Nabaei V, Ren E, Galeote‐Checa G, Das R, Curia G, Heidari H. The Future of Neuroscience: Flexible and Wireless Implantable Neural Electronics. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2002693. [PMID: 34026431 PMCID: PMC8132070 DOI: 10.1002/advs.202002693] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 01/15/2021] [Indexed: 05/04/2023]
Abstract
Neurological diseases are a prevalent cause of global mortality and are of growing concern when considering an ageing global population. Traditional treatments are accompanied by serious side effects including repeated treatment sessions, invasive surgeries, or infections. For example, in the case of deep brain stimulation, large, stiff, and battery powered neural probes recruit thousands of neurons with each pulse, and can invoke a vigorous immune response. This paper presents challenges in engineering and neuroscience in developing miniaturized and biointegrated alternatives, in the form of microelectrode probes. Progress in design and topology of neural implants has shifted the goal post toward highly specific recording and stimulation, targeting small groups of neurons and reducing the foreign body response with biomimetic design principles. Implantable device design recommendations, fabrication techniques, and clinical evaluation of the impact flexible, integrated probes will have on the treatment of neurological disorders are provided in this report. The choice of biocompatible material dictates fabrication techniques as novel methods reduce the complexity of manufacture. Wireless power, the final hurdle to truly implantable neural interfaces, is discussed. These aspects are the driving force behind continued research: significant breakthroughs in any one of these areas will revolutionize the treatment of neurological disorders.
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Affiliation(s)
- Eve McGlynn
- Microelectronics LabJames Watt School of EngineeringUniversity of GlasgowGlasgowG12 8QQUnited Kingdom
| | - Vahid Nabaei
- Microelectronics LabJames Watt School of EngineeringUniversity of GlasgowGlasgowG12 8QQUnited Kingdom
| | - Elisa Ren
- Laboratory of Experimental Electroencephalography and NeurophysiologyDepartment of BiomedicalMetabolic and Neural SciencesUniversity of Modena and Reggio EmiliaModena41125Italy
| | - Gabriel Galeote‐Checa
- Microelectronics LabJames Watt School of EngineeringUniversity of GlasgowGlasgowG12 8QQUnited Kingdom
| | - Rupam Das
- Microelectronics LabJames Watt School of EngineeringUniversity of GlasgowGlasgowG12 8QQUnited Kingdom
| | - Giulia Curia
- Laboratory of Experimental Electroencephalography and NeurophysiologyDepartment of BiomedicalMetabolic and Neural SciencesUniversity of Modena and Reggio EmiliaModena41125Italy
| | - Hadi Heidari
- Microelectronics LabJames Watt School of EngineeringUniversity of GlasgowGlasgowG12 8QQUnited Kingdom
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Moleirinho S, Whalen AJ, Fried SI, Pezaris JS. The impact of synchronous versus asynchronous electrical stimulation in artificial vision. J Neural Eng 2021; 18. [PMID: 33900206 DOI: 10.1088/1741-2552/abecf1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 03/09/2021] [Indexed: 11/12/2022]
Abstract
Visual prosthesis devices designed to restore sight to the blind have been under development in the laboratory for several decades. Clinical translation continues to be challenging, due in part to gaps in our understanding of critical parameters such as how phosphenes, the electrically-generated pixels of artificial vision, can be combined to form images. In this review we explore the effects that synchronous and asynchronous electrical stimulation across multiple electrodes have in evoking phosphenes. Understanding how electrical patterns influence phosphene generation to control object binding and perception of visual form is fundamental to creation of a clinically successful prosthesis.
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Affiliation(s)
- Susana Moleirinho
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, United States of America.,Department of Neurosurgery, Harvard Medical School, Boston, MA, United States of America
| | - Andrew J Whalen
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, United States of America.,Department of Neurosurgery, Harvard Medical School, Boston, MA, United States of America
| | - Shelley I Fried
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, United States of America.,Department of Neurosurgery, Harvard Medical School, Boston, MA, United States of America.,Boston VA Healthcare System, Boston, MA, United States of America
| | - John S Pezaris
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, United States of America.,Department of Neurosurgery, Harvard Medical School, Boston, MA, United States of America
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Gebrehiwot AN, Kato T, Nakazawa K. Inducing lateralized phosphenes over the occipital lobe using transcranial magnetic stimulation to navigate a virtual environment. PLoS One 2021; 16:e0249996. [PMID: 33852643 PMCID: PMC8046218 DOI: 10.1371/journal.pone.0249996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 03/29/2021] [Indexed: 11/19/2022] Open
Abstract
Electrical stimulation involving visual areas of the brain produces artificial light percepts called phosphenes. These visual percepts have been extensively investigated in previous studies involving intracortical microsimulation (ICMS) and serve as the basis for developing a visual prosthesis for the blind. Although advances have been achieved, many challenges still remain with implementing a functional ICMS for visual rehabilitation purposes. Transcranial magnetic stimulation (TMS) over the primary occipital lobe offers an alternative method to produce phosphenes non-invasively. A main challenge facing blind individuals involves navigation. Within the scientific community, methods to evaluate the ability of a visual prosthesis to facilitate in navigation has been neglected. In this study, we investigate the effectiveness of evoking lateralized phosphenes to navigate a computer simulated virtual environment. More importantly, we demonstrate how virtual environments along with the development of a visual prosthesis share a mutual relationship benefiting both patients and researchers. Using two TMS devices, a pair of 40mm figure-of-eight coils were placed over each occipital hemisphere resulting in lateralized phosphene perception. Participants were tasked with making a series of left and right turns using peripheral devices depending on the visual hemifield in which a phosphene is present. If a participant was able to accurately perceive all ten phosphenes, the simulated target is able to advance and fully exit the virtual environment. Our findings demonstrate that participants can interpret lateralized phosphenes while highlighting the integration of computer based virtual environments to evaluate the capability of a visual prosthesis during navigation.
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Affiliation(s)
| | - Tatsuya Kato
- Department of Life Sciences, The University of Tokyo, Tokyo, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Kimitaka Nakazawa
- Department of Life Sciences, The University of Tokyo, Tokyo, Japan
- * E-mail:
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39
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Kosta P, Mize J, Warren DJ, Lazzi G. Simulation-Based Optimization of Figure-of-Eight Coil Designs and Orientations for Magnetic Stimulation of Peripheral Nerve. IEEE Trans Neural Syst Rehabil Eng 2020; 28:2901-2913. [PMID: 33201821 DOI: 10.1109/tnsre.2020.3038406] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Although magnetic neural stimulation has many advantages over electrical neural stimulation, its main disadvantages are higher energy requirement and poor stimulation selectivity. The orientation and location of the coil with respect to the stimulation site play a critical role in determining the stimulation threshold and stimulation selectivity. Utilizing numerical simulations in this work, we optimized the design parameters, orientation, and positioning of magnetic coils with respect to the peripheral nerve for improved stimulation efficacy. Specifically, we investigated different orientations and positions of the figure-of-eight coils for neural stimulation of the rat sciatic nerve. We also examined the effect of coil design parameters (number of layers and turns) and different coil electrical configurations (opposite vs. same direction of coil currents and series vs. parallel coil connections) on the stimulation threshold. We leveraged the multi-resolution impedance method and a heterogeneous multi-fascicular anatomical model of rat sciatic nerve to explore the possibility of selective stimulation as well. Neural excitation of a nerve fiber was implemented by an equivalent cable model and Frankenhaeuser-Huxley equations using NEURON software. Results suggest that inter-fascicular selectivity could be achieved by properly orienting and positioning the coil with respect to the nerve. Further, by orienting the figure-of-eight coil at an angle of 90° and 6 mm offset, we could switch between primarily activating one fascicle (and barely activating the other) and reversing those roles by merely switching the current direction in the two coils of the figure-of-eight coil.
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40
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Lee SW. Selective Activation of Cortical Columns Using Multichannel Magnetic Stimulation With a Bent Flat Microwire Array. IEEE Trans Biomed Eng 2020; 68:2164-2175. [PMID: 33095707 DOI: 10.1109/tbme.2020.3033491] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE Cortical neural prostheses that aim to restore useful vision, hearing, and tactile sensations require the ability to selectively target different cortical regions simultaneously. Electrical stimulation via intracortical electrodes has been used to create spatial patterns of cortical activation. However, their efficacy remains limited due to the inability of conventional electrodes to confine activation to specific cortical regions around each electrode. Magnetic stimulation from single bent wires can selectively activate pyramidal neurons while avoiding passing axons, thereby confining activation to small cortical regions. This paper presents a novel bent flat microwire array and demonstrates its effectiveness for selective activation of cortical columns in mouse brain slices. METHODS A computational model was developed to compare the spatial resolution of magnetic stimulation from bent wire arrays with 280 and 530 μm tip spacings. The same array designs were fabricated for use in electrophysiological experiments, i.e., calcium imaging (GCaMP6s) of mouse brain slices. RESULTS All fabricated array designs reliably produced spatially discrete cortical activations at low stimulus amplitudes, but the 280-μm-spacing produced strong interference (constructive or destructive) at high stimulus amplitudes, thereby resulting in single strong activations or two asymmetric activations. 4-channel bent wire arrays with spacing of 340 μm avoided the interference and produced clearer spatial patterns of activation than electrodes. CONCLUSION Bent wire array designs can influence the strength or the spatial resolution of multichannel magnetic stimulation. SIGNIFICANCE These results suggest that bent microwire arrays can enhance the selectivity of multichannel stimulation of brain and therefore may help to develop reliable and effective cortical neural prostheses.
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Skach J, Conway C, Barrett L, Ye H. Axonal blockage with microscopic magnetic stimulation. Sci Rep 2020; 10:18030. [PMID: 33093520 PMCID: PMC7582966 DOI: 10.1038/s41598-020-74891-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/05/2020] [Indexed: 12/27/2022] Open
Abstract
Numerous neurological dysfunctions are characterized by undesirable nerve activity. By providing reversible nerve blockage, electric stimulation with an implanted electrode holds promise in the treatment of these conditions. However, there are several limitations to its application, including poor bio-compatibility and decreased efficacy during chronic implantation. A magnetic coil of miniature size can mitigate some of these problems, by coating it with biocompatible material for chronic implantation. However, it is unknown if miniature coils could be effective in axonal blockage and, if so, what the underlying mechanisms are. Here we demonstrate that a submillimeter magnetic coil can reversibly block action potentials in the unmyelinated axons from the marine mollusk Aplysia californica. Using a multi-compartment model of the Aplysia axon, we demonstrate that the miniature coil causes a significant local depolarization in the axon, alters activation dynamics of the sodium channels, and prevents the traveling of the invading action potentials. With improved biocompatibility and capability of emitting high-frequency stimuli, micro coils provide an interesting alternative for electric blockage of axonal conductance in clinical settings.
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Affiliation(s)
- Jordan Skach
- Department of Biology, Loyola University Chicago, Chicago, IL, USA
| | - Catherine Conway
- Department of Biology, Loyola University Chicago, Chicago, IL, USA
| | - Lauryn Barrett
- Department of Biology, Loyola University Chicago, Chicago, IL, USA
| | - Hui Ye
- Department of Biology, Loyola University Chicago, Chicago, IL, USA. .,Department of Biology, Quinlan Life Sciences Education and Research Center, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA.
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42
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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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Bae M, Yi HG, Jang J, Cho DW. Microphysiological Systems for Neurodegenerative Diseases in Central Nervous System. MICROMACHINES 2020; 11:E855. [PMID: 32947879 PMCID: PMC7570039 DOI: 10.3390/mi11090855] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 09/13/2020] [Accepted: 09/14/2020] [Indexed: 12/19/2022]
Abstract
Neurodegenerative diseases are among the most severe problems in aging societies. Various conventional experimental models, including 2D and animal models, have been used to investigate the pathogenesis of (and therapeutic mechanisms for) neurodegenerative diseases. However, the physiological gap between humans and the current models remains a hurdle to determining the complexity of an irreversible dysfunction in a neurodegenerative disease. Therefore, preclinical research requires advanced experimental models, i.e., those more physiologically relevant to the native nervous system, to bridge the gap between preclinical stages and patients. The neural microphysiological system (neural MPS) has emerged as an approach to summarizing the anatomical, biochemical, and pathological physiology of the nervous system for investigation of neurodegenerative diseases. This review introduces the components (such as cells and materials) and fabrication methods for designing a neural MPS. Moreover, the review discusses future perspectives for improving the physiological relevance to native neural systems.
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Affiliation(s)
- Mihyeon Bae
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), 77 Chungam-ro, Nam-gu, Pohang 37673, Korea;
| | - Hee-Gyeong Yi
- Department of Rural and Biosystems Engineering, College of Agricultural Sciences, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 61186, Korea
| | - Jinah Jang
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), 77 Chungam-ro, Nam-gu, Pohang 37673, Korea;
- Department of Creative IT Engineering, Pohang University of Science and Technology (POSTECH), 77 Chungam-ro, Nam-gu, Pohang 37673, Korea
- Institute of Convergence Science, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea
| | - Dong-Woo Cho
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), 77 Chungam-ro, Nam-gu, Pohang 37673, Korea;
- Institute of Convergence Science, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea
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Makarov SN, Wartman WA, Daneshzand M, Fujimoto K, Raij T, Nummenmaa A. A software toolkit for TMS electric-field modeling with boundary element fast multipole method: an efficient MATLAB implementation. J Neural Eng 2020; 17:046023. [PMID: 32235065 DOI: 10.1088/1741-2552/ab85b3] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Objective To present and disseminate our transcranial magnetic stimulation (TMS) modeling software toolkit, including several new algorithmic developments, and to apply this software to realistic TMS modeling scenarios given a high-resolution model of the human head including cortical geometry and an accurate coil model. Approach The recently developed charge-based boundary element fast multipole method (BEM-FMM) is employed as an alternative to the 1st order finite element method (FEM) most commonly used today. The BEM-FMM approach provides high accuracy and unconstrained numerical field resolution close to and across cortical interfaces. Here, the previously proposed BEM-FMM algorithm has been improved in several novel ways. Main results The improvements resulted in a threefold increase in computational speed while maintaining the same solution accuracy. The computational code based on the MATLAB® platform is made available to all interested researchers, along with a coil model repository and examples to create custom coils, head model repository, and supporting documentation. The presented software toolkit may be useful for post-hoc analyses of navigated TMS data using high-resolution subject-specific head models as well as accurate and fast modeling for the purposes of TMS coil/hardware development. Significance TMS is currently the only non-invasive neurostimulation modality that enables painless and safe supra-threshold stimulation by employing electromagnetic induction to efficiently penetrate the skull. Accurate, fast, and high resolution modeling of the electric fields may significantly improve individualized targeting and dosing of TMS and therefore enhance the efficiency of existing clinical protocols as well as help establish new application domains.
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Affiliation(s)
- Sergey N Makarov
- Electrical & Computer Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609 United States of America. Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115 United States of America. Author to whom any correspondence should be addressed
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Shim S, Eom K, Jeong J, Kim SJ. Retinal Prosthetic Approaches to Enhance Visual Perception for Blind Patients. MICROMACHINES 2020; 11:E535. [PMID: 32456341 PMCID: PMC7281011 DOI: 10.3390/mi11050535] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/22/2020] [Accepted: 05/22/2020] [Indexed: 12/14/2022]
Abstract
Retinal prostheses are implantable devices that aim to restore the vision of blind patients suffering from retinal degeneration, mainly by artificially stimulating the remaining retinal neurons. Some retinal prostheses have successfully reached the stage of clinical trials; however, these devices can only restore vision partially and remain insufficient to enable patients to conduct everyday life independently. The visual acuity of the artificial vision is limited by various factors from both engineering and physiological perspectives. To overcome those issues and further enhance the visual resolution of retinal prostheses, a variety of retinal prosthetic approaches have been proposed, based on optimization of the geometries of electrode arrays and stimulation pulse parameters. Other retinal stimulation modalities such as optics, ultrasound, and magnetics have also been utilized to address the limitations in conventional electrical stimulation. Although none of these approaches have been clinically proven to fully restore the function of a degenerated retina, the extensive efforts made in this field have demonstrated a series of encouraging findings for the next generation of retinal prostheses, and these could potentially enhance the visual acuity of retinal prostheses. In this article, a comprehensive and up-to-date overview of retinal prosthetic strategies is provided, with a specific focus on a quantitative assessment of visual acuity results from various retinal stimulation technologies. The aim is to highlight future directions toward high-resolution retinal prostheses.
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Affiliation(s)
- Shinyong Shim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea;
- Inter-university Semiconductor Research Center, College of Engineering, Seoul National University, Seoul 08826, Korea
| | - Kyungsik Eom
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan 46241, Korea
| | - Joonsoo Jeong
- School of Biomedical Convergence Engineering, College of Information and Biomedical Engineering, Pusan National University, Yangsan 50612, Korea
| | - Sung June Kim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea;
- Inter-university Semiconductor Research Center, College of Engineering, Seoul National University, Seoul 08826, Korea
- Institute on Aging, College of Medicine, Seoul National University, Seoul 08826, Korea
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Bonmassar G, Serano P. MRI-Induced Heating of Coils for Microscopic Magnetic Stimulation at 1.5 Tesla: An Initial Study. Front Hum Neurosci 2020; 14:53. [PMID: 32231526 PMCID: PMC7082860 DOI: 10.3389/fnhum.2020.00053] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 02/05/2020] [Indexed: 11/13/2022] Open
Abstract
Purpose Deep brain stimulation (DBS) has proved to be effective in the treatment of movement disorders. However, the direct contact between the metal contacts of the DBS electrode and the brain can cause RF heating in magnetic resonance imaging (MRI) scanning, due to an increase of local specific absorption rate (SAR). Recently, micro coils (μMS) have demonstrated excitation of neuronal tissue through the electromagnetic induction both in vitro and in vivo experiments. In contrast to electrical stimulation, in μMS, there is no direct contact between the metal and the biological tissue. Methods We compared the heating of a μMS coil with a control case of a metal wire. The heating was induced by RF fields in a 1.5 T MRI head birdcage coil (often used for imaging patients with implants) at 64 MHz, and normalized results to 3.2 W/kg whole head average SAR. Results The μMS coil or wire implants were placed inside an anatomically accurate head saline-gel filled phantom inserted in the RF coil, and we observed approximately 1°C initial temperature rise at the μMS coil, while the wire exhibited a 10°C temperature rise in the proximity of the exposed end. The numerical simulations showed a 32-times increase of local SAR induced at the tips of the metal wire compared to the μMS. Conclusion In this work, we show with measurements and electromagnetic numerical simulations that the RF-induced increase in local SAR and induced heating during MRI scanning can be greatly reduced by using magnetic stimulation with the proposed μMS technology.
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Affiliation(s)
- Giorgio Bonmassar
- Athinoula A. Martinos Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Peter Serano
- Athinoula A. Martinos Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States.,ANSYS Inc., Canonsburg, PA, United States
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Focal Suppression of Epileptiform Activity in the Hippocampus by a High-frequency Magnetic Field. Neuroscience 2020; 432:1-14. [PMID: 32105740 DOI: 10.1016/j.neuroscience.2020.02.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 02/13/2020] [Accepted: 02/14/2020] [Indexed: 12/21/2022]
Abstract
Electric current has been used for epilepsy treatment by targeting specific neural circuitries. Despite its success, direct contact between the electrode and tissue could cause side effects including pain, inflammation, and adverse biological reactions. Magnetic stimulation overcomes these limitations by offering advantages over biocompatibility and operational feasibility. However, the underlying neurological mechanisms of its action are largely unknown. In this work, a magnetic generating system was assembled that included a miniature coil. The coil was positioned above the CA3 area of mouse hippocampal slices. Epileptiform activity (EFA) was induced with low Mg2+/high K+ perfusion or with 100 µM 4-aminopyridine (4-AP). The miniature coil generated a sizable electric field that suppressed the local EFA in the hippocampus in the low-Mg2+/high-K+ model. The inhibition effect was dependent on the frequency and duration of the magnetic stimulus, with high frequency being more effective in suppressing EFA. EFA suppression by the magnetic field was also observed in the 4-AP model, in a frequency and duration - dependent manner. The study provides a platform for further investigation of cellular and molecular mechanisms underlying epilepsy treatment with time varying magnetic fields.
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Abstract
Developments of new strategies to restore vision and improving on current strategies by harnessing new advancements in material and electrical sciences, and biological and genetic-based technologies are of upmost health priorities around the world. Federal and private entities are spending billions of dollars on visual prosthetics technologies. This review describes the most current and state-of-the-art bioengineering technologies to restore vision. This includes a thorough description of traditional electrode-based visual prosthetics that have improved substantially since early prototypes. Recent advances in molecular and synthetic biology have transformed vision-assisted technologies; For example, optogenetic technologies that introduce light-responsive proteins offer excellent resolution but cortical applications are restricted by fiber implantation and tissue damage. Other stimulation modalities, such as magnetic fields, have been explored to achieve non-invasive neuromodulation. Miniature magnetic coils are currently being developed to activate select groups of neurons. Magnetically-responsive nanoparticles or exogenous proteins can significantly enhance the coupling between external electromagnetic devices and any neurons affiliated with these modifications. The need to minimize cytotoxic effects for nanoparticle-based therapies will likely restrict the number of usable materials. Nevertheless, advances in identifying and utilizing proteins that respond to magnetic fields may lead to non-invasive, cell-specific stimulation and may overcome many of the limitations that currently exist with other methods. Finally, sensory substitution systems also serve as viable visual prostheses by converting visual input to auditory and somatosensory stimuli. This review also discusses major challenges in the field and offers bioengineering strategies to overcome those.
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Affiliation(s)
- Alexander Farnum
- Department of Biomedical Engineering, College of Engineering, Michigan State University, East Lansing, MI, United States
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, United States
| | - Galit Pelled
- Department of Biomedical Engineering, College of Engineering, Michigan State University, East Lansing, MI, United States
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, United States
- Department of Radiology, College of Human Medicine, Michigan State University, East Lansing, MI, United States
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Hosseini S, Laursen K, Rashidi A, Moradi F. Multi-Ring Ultrasonic Transducer on a Single Piezoelectric Disk For Powering Biomedical Implants. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2019:3827-3830. [PMID: 31946708 DOI: 10.1109/embc.2019.8857473] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This paper presents a novel ultrasonic transmitter with the ability of focusing ultrasonic waves for maximum power transmission at different depths for brain neurostimula-tor implants. The most important advantages of the proposed multi-ring ultrasonic transducer (MRUT) is its simplicity and no requirement of any lens or air cavity for focusing the ultrasonic waves. Furthermore, adjusting the focal point compared to the conventional transducers is significantly easier, especially as the location of implants may vary due to, for example, head movement or the need of using these implants at different depths. By the use of multiple rings on a single piezoelectric disk in our transducer, not only more focused ultrasound beams can be achieved, but also the side lobes can be diminished by exciting each rings with different electrical signal. The proposed transmitter is envisioned to be used for optogenetic stimulation of neurons in freely-moving animals.
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Colella M, Laher RM, Press DZ, McIlduff CE, Rutkove SB, Pascual-Leone A, Apollonio F, Liberti M, Bonmassar G. Ultra-focal Magnetic Stimulation Using a µTMS coil: a Computational Study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2019:3987-3990. [PMID: 31946745 DOI: 10.1109/embc.2019.8857349] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A new miniaturized figure-of-eight coil (μCoil) for TMS applications has been developed taking advantage of the Flex circuit technology. First experiments on volunteers demonstrated the ability of the μCoil to elicit sensorial action potentials of the peripheral nervous system. The necessity of reducing the size of standard TMS stimulator arises from the poor spatial resolution of the latter. This study aims to model the μCoil and study the electromagnetic fields induced inside the arm during peripheral nerve stimulation. Results confirmed that the μCoil is capable of inducing a focalized electric field inside the tissues with amplitudes up to 70V/m consistent with the observed peripheral nerve stimulation in healthy volunteers.
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