1
|
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.
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
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'.
Collapse
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
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
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: 12] [Impact Index Per Article: 4.0] [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.
Collapse
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
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
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.
Collapse
|
9
|
Kagan ZB, Mize JT, Kosta P, Lazzi G, Normann RA, Warren DJ. Reduced Heat Generation During Magnetic Stimulation of Rat Sciatic Nerve Using Current Waveform Truncation. IEEE Trans Neural Syst Rehabil Eng 2019; 27:937-946. [DOI: 10.1109/tnsre.2019.2911054] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
10
|
Thyagarajan K, Fried SI. Micro-Coil Design Influences the Spatial Extent of Responses to Intracortical Magnetic Stimulation. IEEE Trans Biomed Eng 2018; 66:1680-1694. [PMID: 30369434 DOI: 10.1109/tbme.2018.2877713] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
OBJECTIVE Electrical stimulation via cortically implanted electrodes has been proposed to treat a wide range of neurological disorders. Effectiveness has been limited, however, in part due to the inability of conventional electrodes to activate specific types of neurons while avoiding other types. Recent demonstrations that magnetic stimulation from a micro-coil can selectively activate pyramidal neurons (PNs) while avoiding passing axons suggest the possibility that such an approach can overcome some this limitation and here we use computer simulations to explore how the micro-coil design influences the selectivity with which neurons are activated. METHODS A computational model was developed to compare the selectivity of magnetic stimulation induced by rectangular-, V-, and W-shaped coil designs. The more promising designs (V- and W-shapes) were fabricated for use in electrophysiological experiments including in vitro patch-clamp recording and calcium imaging (GCaMP6f) of mouse brain slices. RESULTS Both V- and W-shaped coils reliably activated layer 5 (L5) PNs but V-coils were more effective while W-coils were more selective. Activation thresholds with double-loop coils were approximately one-half those of single-loop coils. Calcium imaging revealed that both V- and W-coils better confine activation than electrodes. CONCLUSION Individual design features can influence both the strength as well as the selectivity of micro-coils and can be accurately predicted by computer simulations. SIGNIFICANCE Our results show that how coil design influences the response of cortical neurons to stimulation and are an important step toward the development of next-generation cortical prostheses.
Collapse
|
11
|
Park HJ, Kang H, Jo J, Chung E, Kim S. Planar coil-based contact-mode magnetic stimulation: synaptic responses in hippocampal slices and thermal considerations. Sci Rep 2018; 8:13423. [PMID: 30194395 PMCID: PMC6128857 DOI: 10.1038/s41598-018-31536-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 08/16/2018] [Indexed: 12/30/2022] Open
Abstract
Implantable magnetic stimulation is an emerging type of neuromodulation using coils that are small enough to be implanted in the brain. A major advantage of this method is that stimulation performance could be sustained even though the coil is encapsulated by gliosis due to foreign body reactions. Magnetic fields can induce indirect electric fields and currents in neurons. Compared to transcranial magnetic stimulation, the coil size used in implantable magnetic stimulation can be greatly reduced. However, the size reduction is accompanied by an increase in coil resistance. Hence, the coil could potentially damage neurons from the excess heat generated. Therefore, it is necessary to study the stimulation performance and possible thermal damage by implantable magnetic stimulation. Here, we devised contact-mode magnetic stimulation (CMS), wherein magnetic stimulation was applied to hippocampal slices through a customized planar-type coil underneath the slice in the contact mode. With acute hippocampal slices, we investigated the synaptic responses to examine the field excitatory postsynaptic responses of CMS and the temperature rise during CMS. A long-lasting synaptic depression was exhibited in the CA1 stratum radiatum after CMS, while the temperature remained in a safe range so as not to seriously affect the neural responses.
Collapse
Affiliation(s)
- Hee-Jin Park
- School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Heekyung Kang
- Department of Biomedical Science and Neurology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Jihoon Jo
- Biomedical Research Institute, Chonnam National University Hospital, Gwangju, Republic of Korea
| | - Euiheon Chung
- School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea.
- Department of Biomedical Science and Engineering, Institute of Integrated Technology, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea.
| | - Sohee Kim
- Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Republic of Korea.
| |
Collapse
|
12
|
Minusa S, Osanai H, Tateno T. Micromagnetic Stimulation of the Mouse Auditory Cortex In Vivo Using an Implantable Solenoid System. IEEE Trans Biomed Eng 2018; 65:1301-1310. [DOI: 10.1109/tbme.2017.2748136] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
13
|
Osanai H, Minusa S, Tateno T. Micro-coil-induced Inhomogeneous Electric Field Produces sound-driven-like Neural Responses in Microcircuits of the Mouse Auditory Cortex In Vivo. Neuroscience 2018; 371:346-370. [DOI: 10.1016/j.neuroscience.2017.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 11/29/2017] [Accepted: 12/06/2017] [Indexed: 12/27/2022]
|
14
|
Rizou ME, Prodromakis T. Magnetic stimulation in the microscale: the development of a 6 × 6 array of micro-coils for stimulation of excitable cells
in vitro. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aaa0dd] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
15
|
Central nervous system microstimulation: Towards selective micro-neuromodulation. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2017. [DOI: 10.1016/j.cobme.2017.09.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
16
|
Park HJ, Kang HK, Wang M, Jo J, Chung E, Kim S. A pilot study of planar coil based magnetic stimulation using acute hippocampal slice in mice. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:1118-1121. [PMID: 29060071 DOI: 10.1109/embc.2017.8037025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Micromagnetic stimulation using small-sized implantable coils has recently been studied. The main advantage of this method is that it can provide sustainable stimulation performance even if a fibrotic encapsulation layer is formed around the implanted coil by inflammation response, because indirectly induced currents are used to induce neural responses. In previous research, we optimized the geometrical and control parameters used in implantable magnetic stimulation. Based on those results, we fabricated the planar coil and studied the LTP effect in the hippocampal slice by two different magnetic stimulation protocols using the quadripulse stimulation (QPS) pattern. We found that direct magnetic stimulation (DMS) induced insignificant LTP effect and priming magnetic stimulation (PMS) occluded LTP effect after tetanic stimulation, when QPS patterned magnetic stimulation with 1 A current pulse was applied to the planar coil.
Collapse
|
17
|
Lee SW, Fried SI. Enhanced Control of Cortical Pyramidal Neurons With Micromagnetic Stimulation. IEEE Trans Neural Syst Rehabil Eng 2017; 25:1375-1386. [PMID: 27893396 PMCID: PMC5498237 DOI: 10.1109/tnsre.2016.2631446] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Magnetic stimulation is less sensitive to the inflammatory reactions that plague conventional electrode-based cortical implants and therefore may be useful as a next-generation (implanted) cortical prosthetic. The fields arising from micro-coils are quite small however and thus, their ability to modulate cortical activity must first be established. Here, we show that layer V pyramidal neurons (PNs) can be strongly activated by micro-coil stimulation and further, the asymmetric fields arising from such coils do not simultaneously activate horizontally-oriented axon fibers, thus confining activation to a focal region around the coil. The spatially-narrow fields from micro-coils allowed the sensitivity of different regions within a single PN to be compared: while the proximal axon was most sensitive in naïve cells, repetitive stimulation over the apical dendrite led to a change in state of the neuron that reduced thresholds there to below those of the axon. Thus, our results raise the possibility that regardless of the mode of stimulation, penetration depths that target specific portions of the apical dendrite may actually be more effective than those that target Layer 6. Interestingly, the state change had similar properties to state changes described previously at the systems level, suggesting a possible neuronal mechanism underlying such responses.
Collapse
|
18
|
Lee SW, Fallegger F, Casse BDF, Fried SI. Implantable microcoils for intracortical magnetic stimulation. SCIENCE ADVANCES 2016; 2:e1600889. [PMID: 27957537 PMCID: PMC5148213 DOI: 10.1126/sciadv.1600889] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 11/03/2016] [Indexed: 05/20/2023]
Abstract
Neural prostheses that stimulate the neocortex have the potential to treat a wide range of neurological disorders. However, the efficacy of electrode-based implants remains limited, with persistent challenges that include an inability to create precise patterns of neural activity as well as difficulties in maintaining response consistency over time. These problems arise from fundamental limitations of electrodes as well as their susceptibility to implantation and have proven difficult to overcome. Magnetic stimulation can address many of these limitations, but coils small enough to be implanted into the cortex were not thought strong enough to activate neurons. We describe a new microcoil design and demonstrate its effectiveness for both activating cortical neurons and driving behavioral responses. The stimulation of cortical pyramidal neurons in brain slices in vitro was reliable and could be confined to spatially narrow regions (<60 μm). The spatially asymmetric fields arising from the coil helped to avoid the simultaneous activation of passing axons. In vivo implantation was safe and resulted in consistent and predictable behavioral responses. The high permeability of magnetic fields to biological substances may yield another important advantage because it suggests that encapsulation and other adverse effects of implantation will not diminish coil performance over time, as happens to electrodes. These findings suggest that a coil-based implant might be a useful alternative to existing electrode-based devices. The enhanced selectivity of microcoil-based magnetic stimulation will be especially useful for visual prostheses as well as for many brain-computer interface applications that require precise activation of the cortex.
Collapse
Affiliation(s)
- Seung Woo Lee
- Boston Veterans Affairs Healthcare System, Boston, MA 02130, USA
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Florian Fallegger
- Palo Alto Research Center, a Xerox company, Palo Alto, CA 94304, USA
| | | | - Shelley I. Fried
- Boston Veterans Affairs Healthcare System, Boston, MA 02130, USA
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Corresponding author.
| |
Collapse
|
19
|
Mukesh S, Blake DT, McKinnon BJ, Bhatti PT. Modeling Intracochlear Magnetic Stimulation: A Finite-Element Analysis. IEEE Trans Neural Syst Rehabil Eng 2016; 25:1353-1362. [PMID: 27831887 DOI: 10.1109/tnsre.2016.2624275] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study models induced electric fields, and their gradient, produced by pulsatile current stimulation of submillimeter inductors for cochlear implantation. Using finite-element analysis, the lower chamber of the cochlea, scala tympani, is modeled as a cylindrical structure filled with perilymph bounded by tissue, bone, and cochlear neural elements. Single inductors as well as an array of inductors are modeled. The coil strength (~100 nH) and excitation parameters (peak current of 1-5 A, voltages of 16-20 V) are based on a formative feasibility study conducted by our group. In that study, intracochlear micromagnetic stimulation achieved auditory activation as measured through the auditory brainstem response in a feline model. With respect to the finite element simulations, axial symmetry of the inductor geometry is exploited to improve computation time. It is verified that the inductor coil orientation greatly affects the strength of the induced electric field and thereby the ability to affect the transmembrane potential of nearby neural elements. Furthermore, upon comparing an array of micro-inductors with a typical multi-site electrode array, magnetically excited arrays retain greater focus in terms of the gradient of induced electric fields. Once combined with further in vivo analysis, this modeling study may enable further exploration of the mechanism of magnetically induced, and focused neural stimulation.
Collapse
|
20
|
|