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Sommakia S, Lee HC, Gaire J, Otto KJ. Materials approaches for modulating neural tissue responses to implanted microelectrodes through mechanical and biochemical means. CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE 2014; 18:319-328. [PMID: 25530703 PMCID: PMC4267064 DOI: 10.1016/j.cossms.2014.07.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Implantable intracortical microelectrodes face an uphill struggle for widespread clinical use. Their potential for treating a wide range of traumatic and degenerative neural disease is hampered by their unreliability in chronic settings. A major factor in this decline in chronic performance is a reactive response of brain tissue, which aims to isolate the implanted device from the rest of the healthy tissue. In this review we present a discussion of materials approaches aimed at modulating the reactive tissue response through mechanical and biochemical means. Benefits and challenges associated with these approaches are analyzed, and the importance of multimodal solutions tested in emerging animal models are presented.
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Affiliation(s)
- Salah Sommakia
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907-1791
| | - Heui C. Lee
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907-1791
| | - Janak Gaire
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1791
| | - Kevin J. Otto
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907-1791
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1791
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102
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A strategy to passively reduce neuroinflammation surrounding devices implanted chronically in brain tissue by manipulating device surface permeability. Biomaterials 2014; 36:33-43. [PMID: 25310936 DOI: 10.1016/j.biomaterials.2014.08.039] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 08/24/2014] [Indexed: 01/08/2023]
Abstract
Available evidence indicates that pro-inflammatory cytokines produced by immune cells are likely responsible for the negative sequela associated with the foreign body response (FBR) to chronic indwelling implants in brain tissue. In this study a computational modeling approach was used to design a diffusion sink placed at the device surface that would retain pro-inflammatory cytokines for sufficient time to passively antagonize their impact on the FBR. Using quantitative immunohistochemistry, we examined the FBR to such engineered devices after a 16-week implantation period in the cortex of adult male Sprague-Dawley rats. Our results indicate that thick permeable surface coatings, which served as diffusion sinks, significantly reduced the FBR compared to implants either with no coating or with a thinner coating. The results suggest that increasing surface permeability of solid implanted devices to create a diffusion sink can be used to reduce the FBR and improve biocompatibility of chronic indwelling devices in brain tissue.
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103
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Leung RT, Nayagam DAX, Williams RA, Allen PJ, Salinas-La Rosa CM, Luu CD, Shivdasani MN, Ayton LN, Basa M, Yeoh J, Saunders AL, Shepherd RK, Williams CE. Safety and efficacy of explanting or replacing suprachoroidal electrode arrays in a feline model. Clin Exp Ophthalmol 2014; 43:247-58. [PMID: 25196241 DOI: 10.1111/ceo.12428] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 08/24/2014] [Indexed: 11/26/2022]
Abstract
BACKGROUND A key requirement for retinal prostheses is the ability for safe removal or replacement. We examined whether suprachoroidal electrode arrays can be removed or replaced after implantation. METHODS Suprachoroidal electrode arrays were unilaterally implanted into 13 adult felines. After 1 month, arrays were surgically explanted (n = 6), replaced (n = 5) or undisturbed (n = 2). The retina was assessed periodically using fundus photography and optical coherence tomography. Three months after the initial implantation, the function of replaced or undisturbed arrays was assessed by measuring the responses of the visual cortex to retinal electrical stimulation. The histopathology of tissues surrounding the implant was examined. RESULTS Array explantation or replacement was successful in all cases. Fundus photography showed localized disruption to the tapetum lucidum near the implant's tip in seven subjects following implantation. Although optical coherence tomography showed localized retinal changes, there were no widespread statistically significant differences in the thickness of the retinal layers or choroid. The distance between the electrodes and retina increased after device replacement but returned to control values within eight weeks (P < 0.03). Staphylomas developed near the scleral wound in five animals after device explantation. Device replacement did not alter the cortical evoked potential threshold. Histopathology showed localized outer nuclear layer thinning, tapetal disruption and pseudo-rosette formation, but the overall retinal morphology was preserved. CONCLUSIONS It is feasible to remove or replace conformable medical grade silicone electrode arrays implanted suprachoroidally. The scleral wound requires careful closure to minimize the risk of staphylomas.
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Affiliation(s)
- Ronald T Leung
- Bionics Institute, Melbourne, Victoria, Australia; Department of Pathology, The University of Melbourne, Melbourne, Victoria, Australia
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Hu X, Wang Y, Zhao T, Gunduz A. Neural coding for effective rehabilitation. BIOMED RESEARCH INTERNATIONAL 2014; 2014:286505. [PMID: 25258708 PMCID: PMC4167232 DOI: 10.1155/2014/286505] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/23/2014] [Accepted: 08/10/2014] [Indexed: 01/31/2023]
Abstract
Successful neurological rehabilitation depends on accurate diagnosis, effective treatment, and quantitative evaluation. Neural coding, a technology for interpretation of functional and structural information of the nervous system, has contributed to the advancements in neuroimaging, brain-machine interface (BMI), and design of training devices for rehabilitation purposes. In this review, we summarized the latest breakthroughs in neuroimaging from microscale to macroscale levels with potential diagnostic applications for rehabilitation. We also reviewed the achievements in electrocorticography (ECoG) coding with both animal models and human beings for BMI design, electromyography (EMG) interpretation for interaction with external robotic systems, and robot-assisted quantitative evaluation on the progress of rehabilitation programs. Future rehabilitation would be more home-based, automatic, and self-served by patients. Further investigations and breakthroughs are mainly needed in aspects of improving the computational efficiency in neuroimaging and multichannel ECoG by selection of localized neuroinformatics, validation of the effectiveness in BMI guided rehabilitation programs, and simplification of the system operation in training devices.
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Affiliation(s)
- Xiaoling Hu
- Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Yiwen Wang
- Qiushi Academy for Advanced Studies, Zhejiang University, Zhejiang 310027, China
| | - Ting Zhao
- Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, VA 20147, USA
| | - Aysegul Gunduz
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA
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105
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Lee Y, Jun SB. Strategies for minimizing glial response to chronically-implanted microelectrode arrays for neural interface. Biomed Eng Lett 2014. [DOI: 10.1007/s13534-014-0134-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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106
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Jeffery AF, Churchward MA, Mushahwar VK, Todd KG, Elias AL. Hyaluronic Acid-Based 3D Culture Model for In Vitro Testing of Electrode Biocompatibility. Biomacromolecules 2014; 15:2157-65. [DOI: 10.1021/bm500318d] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Andrea F. Jeffery
- Chemical
and Materials Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada
- Alberta Innovates-Health
Solutions Interdisciplinary Team in Smart Neural Prostheses (Project
SMART), University of Alberta, AB, Canada
| | - Matthew A. Churchward
- Department
of Psychiatry, University of Alberta, Edmonton, AB T6G 2G3, Canada
- Alberta Innovates-Health
Solutions Interdisciplinary Team in Smart Neural Prostheses (Project
SMART), University of Alberta, AB, Canada
| | - Vivian K. Mushahwar
- Division
of Physical Medicine and Rehabilitation, University of Alberta, Edmonton, AB T6G 2E1, Canada
- Centre
for Neuroscience, University of Alberta, Edmonton, AB T6G 2E1, Canada
- Alberta Innovates-Health
Solutions Interdisciplinary Team in Smart Neural Prostheses (Project
SMART), University of Alberta, AB, Canada
| | - Kathryn G. Todd
- Department
of Psychiatry, University of Alberta, Edmonton, AB T6G 2G3, Canada
- Centre
for Neuroscience, University of Alberta, Edmonton, AB T6G 2E1, Canada
- Alberta Innovates-Health
Solutions Interdisciplinary Team in Smart Neural Prostheses (Project
SMART), University of Alberta, AB, Canada
| | - Anastasia L. Elias
- Chemical
and Materials Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada
- Alberta Innovates-Health
Solutions Interdisciplinary Team in Smart Neural Prostheses (Project
SMART), University of Alberta, AB, Canada
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Ejserholm F, Köhler P, Granmo M, Schouenborg J, Bengtsson M, Wallman L. μ-Foil Polymer Electrode Array for Intracortical Neural Recordings. IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE-JTEHM 2014; 2:1500207. [PMID: 27170864 PMCID: PMC4848100 DOI: 10.1109/jtehm.2014.2326859] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 04/09/2014] [Accepted: 05/05/2013] [Indexed: 11/13/2022]
Abstract
We
have developed a multichannel electrode array—termed \documentclass[12pt]{minimal}
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\begin{document}
}{}\(\mu \) \end{document}-foil—that comprises ultrathin
and flexible electrodes protruding from a thin foil at fixed distances. In
addition to allowing some of the active sites to reach less compromised tissue,
the barb-like protrusions that also serves the purpose of anchoring the electrode
array into the tissue. This paper is an early evaluation of technical aspects
and performance of this electrode array in acute in vitro/in
vivo experiments. The interface impedance was reduced by up to two
decades by electroplating the active sites with platinum black. The platinum
black also allowed for a reduced phase lag for higher frequency components.
The distance between the protrusions of the electrode array was tailored to
match the architecture of the rat cerebral cortex. In vivo acute
measurements confirmed a high signal-to-noise ratio for the neural recordings,
and no significant crosstalk between recording channels.
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108
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Sawyer AJ, Tian W, Saucier-Sawyer JK, Rizk PJ, Saltzman WM, Bellamkonda RV, Kyriakides TR. The effect of inflammatory cell-derived MCP-1 loss on neuronal survival during chronic neuroinflammation. Biomaterials 2014; 35:6698-706. [PMID: 24881026 DOI: 10.1016/j.biomaterials.2014.05.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 05/01/2014] [Indexed: 01/22/2023]
Abstract
Intracranial implants elicit neurodegeneration via the foreign body response (FBR) that includes BBB leakage, macrophage/microglia accumulation, and reactive astrogliosis, in addition to neuronal degradation that limit their useful lifespan. Previously, monocyte chemoattractant protein 1 (MCP-1, also CCL2), which plays an important role in monocyte recruitment and propagation of inflammation, was shown to be critical for various aspects of the FBR in a tissue-specific manner. However, participation of MCP-1 in the brain FBR has not been evaluated. Here we examined the FBR to intracortical silicon implants in MCP-1 KO mice at 1, 2, and 8 weeks after implantation. MCP-1 KO mice had a diminished FBR compared to WT mice, characterized by reductions in BBB leakage, macrophage/microglia accumulation, and astrogliosis, and an increased neuronal density. Moreover, pharmacological inhibition of MCP-1 in implant-bearing WT mice maintained the increased neuronal density. To elucidate the relative contribution of microglia and macrophages, bone marrow chimeras were generated between MCP-1 KO and WT mice. Increased neuronal density was observed only in MCP-1 knockout mice transplanted with MCP-1 knockout marrow, which indicates that resident cells in the brain are major contributors. We hypothesized that these improvements are the result of a phenotypic switch of the macrophages/microglia polarization state, which we confirmed using PCR for common activation markers. Our observations suggest that MCP-1 influences neuronal loss, which is integral to the progression of neurological disorders like Alzheimer's and Parkinson disease, via BBB leakage and macrophage polarization.
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Affiliation(s)
- Andrew J Sawyer
- Department of Pathology, Yale School of Medicine, 310 Cedar Street LH 108, New Haven, CT 06520-8023, USA
| | - Weiming Tian
- Bio-X Center, School of Life Science and Technology, Harbin Institute of Technology, Harbin 150080, PR China
| | | | - Paul J Rizk
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - W Mark Saltzman
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Ravi V Bellamkonda
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Themis R Kyriakides
- Department of Pathology, Yale School of Medicine, 310 Cedar Street LH 108, New Haven, CT 06520-8023, USA; Department of Biomedical Engineering, Yale University, New Haven, CT, USA.
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Sohal HS, Jackson A, Jackson R, Clowry GJ, Vassilevski K, O'Neill A, Baker SN. The sinusoidal probe: a new approach to improve electrode longevity. FRONTIERS IN NEUROENGINEERING 2014; 7:10. [PMID: 24808859 PMCID: PMC4010751 DOI: 10.3389/fneng.2014.00010] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Accepted: 04/07/2014] [Indexed: 11/13/2022]
Abstract
Micromotion between the brain and implanted electrodes is a major contributor to the failure of invasive brain-machine interfaces. Movements of the electrode tip cause recording instabilities while spike amplitudes decline over the weeks/months post-implantation due to glial cell activation caused by sustained mechanical trauma. We have designed a sinusoidal probe in order to reduce movement of the recording tip relative to the surrounding neural tissue. The probe was microfabricated from flexible materials and incorporated a sinusoidal shaft to minimize tethering forces and a 3D spheroid tip to anchor the recording site within the brain. Compared to standard microwire electrodes, the signal-to-noise ratio and local field potential power of sinusoidal probe recordings from rabbits was more stable across recording periods up to 678 days. Histological quantification of microglia and astrocytes showed reduced neuronal tissue damage especially for the tip region between 6 and 24 months post-implantation. We suggest that the micromotion-reducing measures incorporated into our design, at least partially, decreased the magnitude of gliosis, resulting in enhanced longevity of recording.
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Affiliation(s)
- Harbaljit S Sohal
- Newcastle Movement Lab, Institute of Neuroscience, Newcastle University Newcastle Upon Tyne, UK ; School of Electrical and Electronic Engineering, Newcastle University Newcastle Upon Tyne, UK
| | - Andrew Jackson
- Newcastle Movement Lab, Institute of Neuroscience, Newcastle University Newcastle Upon Tyne, UK
| | - Richard Jackson
- School of Electrical and Electronic Engineering, Newcastle University Newcastle Upon Tyne, UK
| | - Gavin J Clowry
- Newcastle Movement Lab, Institute of Neuroscience, Newcastle University Newcastle Upon Tyne, UK
| | - Konstantin Vassilevski
- School of Electrical and Electronic Engineering, Newcastle University Newcastle Upon Tyne, UK
| | - Anthony O'Neill
- School of Electrical and Electronic Engineering, Newcastle University Newcastle Upon Tyne, UK
| | - Stuart N Baker
- Newcastle Movement Lab, Institute of Neuroscience, Newcastle University Newcastle Upon Tyne, UK
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110
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De Faveri S, Maggiolini E, Miele E, De Angelis F, Cesca F, Benfenati F, Fadiga L. Bio-inspired hybrid microelectrodes: a hybrid solution to improve long-term performance of chronic intracortical implants. FRONTIERS IN NEUROENGINEERING 2014; 7:7. [PMID: 24782757 PMCID: PMC3989589 DOI: 10.3389/fneng.2014.00007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/24/2014] [Indexed: 12/16/2022]
Abstract
The use of implants that allow chronic electrical stimulation and recording in the brain of human patients is currently limited by a series of events that cause the deterioration over time of both the electrode surface and the surrounding tissue. The main reason of failure is the tissue inflammatory reaction that eventually causes neuronal loss and glial encapsulation, resulting in a progressive increase of the electrode-electrolyte impedance. Here, we describe a new method to create bio-inspired electrodes to mimic the mechanical properties and biological composition of the host tissue. This combination has a great potential to increase the implant lifetime by reducing tissue reaction and improving electrical coupling. Our method implies coating the electrode with reprogrammed neural or glial cells encapsulated within a hydrogel layer. We chose fibrin as a hydrogel and primary hippocampal neurons or astrocytes from rat brain as cellular layer. We demonstrate that fibrin coating is highly biocompatible, forms uniform coatings of controllable thickness, does not alter the electrochemical properties of the microelectrode and allows good quality recordings. Moreover, it reduces the amount of host reactive astrocytes – over time – compared to a bare wire and is fully reabsorbed by the surrounding tissue within 7 days after implantation, avoiding the common problem of hydrogels swelling. Both astrocytes and neurons could be successfully grown onto the electrode surface within the fibrin hydrogel without altering the electrochemical properties of the microelectrode. This bio-hybrid device has therefore a good potential to improve the electrical integration at the neuron-electrode interface and support the long-term success of neural prostheses.
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Affiliation(s)
- Sara De Faveri
- Department of Robotics, Brain and Cognitive Science, Istituto Italiano di Tecnologia Genova, Italy ; Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genova, Italy
| | - Emma Maggiolini
- Department of Robotics, Brain and Cognitive Science, Istituto Italiano di Tecnologia Genova, Italy
| | - Ermanno Miele
- Department of Nanostructures, Istituto Italiano di Tecnologia Genova, Italy
| | | | - Fabrizia Cesca
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genova, Italy
| | - Fabio Benfenati
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genova, Italy ; Department of Experimental Medicine, University of Genova Genova, Italy
| | - Luciano Fadiga
- Department of Robotics, Brain and Cognitive Science, Istituto Italiano di Tecnologia Genova, Italy ; Section of Human Physiology, University of Ferrara Ferrara, Italy
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111
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Birngruber T, Ghosh A, Hochmeister S, Asslaber M, Kroath T, Pieber TR, Sinner F. Long-term implanted cOFM probe causes minimal tissue reaction in the brain. PLoS One 2014; 9:e90221. [PMID: 24621608 PMCID: PMC3951198 DOI: 10.1371/journal.pone.0090221] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 01/27/2014] [Indexed: 02/07/2023] Open
Abstract
This study investigated the histological tissue reaction to long-term implanted cerebral open flow microperfusion (cOFM) probes in the frontal lobe of the rat brain. Most probe-based cerebral fluid sampling techniques are limited in application time due to the formation of a glial scar that hinders substance exchange between brain tissue and the probe. A glial scar not only functions as a diffusion barrier but also alters metabolism and signaling in extracellular brain fluid. cOFM is a recently developed probe-based technique to continuously sample extracellular brain fluid with an intact blood-brain barrier. After probe implantation, a 2 week healing period is needed for blood-brain barrier reestablishment. Therefore, cOFM probes need to stay in place and functional for at least 15 days after implantation to ensure functionality. Probe design and probe materials are optimized to evoke minimal tissue reaction even after a long implantation period. Qualitative and quantitative histological tissue analysis revealed no continuous glial scar formation around the cOFM probe 30 days after implantation and only a minor tissue reaction regardless of perfusion of the probe.
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Affiliation(s)
- Thomas Birngruber
- HEALTH – Institute of Biomedicine and Health Sciences, JOANNEUM RESEARCH, Graz, Austria
| | - Arijit Ghosh
- Division of Endocrinology and Metabolism, Medical University of Graz, Graz, Austria
| | - Sonja Hochmeister
- Division of General Neurology, Medical University of Graz, Graz, Austria
| | - Martin Asslaber
- Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Thomas Kroath
- HEALTH – Institute of Biomedicine and Health Sciences, JOANNEUM RESEARCH, Graz, Austria
| | - Thomas R. Pieber
- HEALTH – Institute of Biomedicine and Health Sciences, JOANNEUM RESEARCH, Graz, Austria
- Division of Endocrinology and Metabolism, Medical University of Graz, Graz, Austria
| | - Frank Sinner
- HEALTH – Institute of Biomedicine and Health Sciences, JOANNEUM RESEARCH, Graz, Austria
- Division of Endocrinology and Metabolism, Medical University of Graz, Graz, Austria
- * E-mail:
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112
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Prasad A, Xue QS, Dieme R, Sankar V, Mayrand RC, Nishida T, Streit WJ, Sanchez JC. Abiotic-biotic characterization of Pt/Ir microelectrode arrays in chronic implants. FRONTIERS IN NEUROENGINEERING 2014; 7:2. [PMID: 24550823 PMCID: PMC3912984 DOI: 10.3389/fneng.2014.00002] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 01/14/2014] [Indexed: 11/13/2022]
Abstract
Pt/Ir electrodes have been extensively used in neurophysiology research in recent years as they provide a more inert recording surface as compared to tungsten or stainless steel. While floating microelectrode arrays (FMA) consisting of Pt/Ir electrodes are an option for neuroprosthetic applications, long-term in vivo functional performance characterization of these FMAs is lacking. In this study, we have performed comprehensive abiotic-biotic characterization of Pt/Ir arrays in 12 rats with implant periods ranging from 1 week up to 6 months. Each of the FMAs consisted of 16-channel, 1.5 mm long, and 75 μm diameter microwires with tapered tips that were implanted into the somatosensory cortex. Abiotic characterization included (1) pre-implant and post-explant scanning electron microscopy (SEM) to study recording site changes, insulation delamination and cracking, and (2) chronic in vivo electrode impedance spectroscopy. Biotic characterization included study of microglial responses using a panel of antibodies, such as Iba1, ED1, and anti-ferritin, the latter being indicative of blood-brain barrier (BBB) disruption. Significant structural variation was observed pre-implantation among the arrays in the form of irregular insulation, cracks in insulation/recording surface, and insulation delamination. We observed delamination and cracking of insulation in almost all electrodes post-implantation. These changes altered the electrochemical surface area of the electrodes and resulted in declining impedance over the long-term due to formation of electrical leakage pathways. In general, the decline in impedance corresponded with poor electrode functional performance, which was quantified via electrode yield. Our abiotic results suggest that manufacturing variability and insulation material as an important factor contributing to electrode failure. Biotic results show that electrode performance was not correlated with microglial activation (neuroinflammation) as we were able to observe poor performance in the absence of neuroinflammation, as well as good performance in the presence of neuroinflammation. One biotic change that correlated well with poor electrode performance was intraparenchymal bleeding, which was evident macroscopically in some rats and presented microscopically by intense ferritin immunoreactivity in microglia/macrophages. Thus, we currently consider intraparenchymal bleeding, suboptimal electrode fabrication, and insulation delamination as the major factors contributing toward electrode failure.
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Affiliation(s)
- Abhishek Prasad
- Department of Biomedical Engineering, University of Miami Coral Gables, FL, USA
| | - Qing-Shan Xue
- Department of Neuroscience, University of Florida Gainesville, FL, USA
| | - Robert Dieme
- Department of Electrical and Computer Engineering, University of Florida Gainesville, FL, USA
| | - Viswanath Sankar
- Department of Electrical and Computer Engineering, University of Florida Gainesville, FL, USA
| | - Roxanne C Mayrand
- Department of Neuroscience, University of Miami Coral Gables, FL, USA
| | - Toshikazu Nishida
- Department of Electrical and Computer Engineering, University of Florida Gainesville, FL, USA
| | - Wolfgang J Streit
- Department of Neuroscience, University of Florida Gainesville, FL, USA
| | - Justin C Sanchez
- Department of Biomedical Engineering, University of Miami Coral Gables, FL, USA ; Department of Neuroscience, University of Miami Coral Gables, FL, USA ; Miami Project to Cure Paralysis, University of Miami Miami, FL, USA
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113
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Karumbaiah L, Saxena T, Carlson D, Patil K, Patkar R, Gaupp EA, Betancur M, Stanley GB, Carin L, Bellamkonda RV. Relationship between intracortical electrode design and chronic recording function. Biomaterials 2013; 34:8061-74. [DOI: 10.1016/j.biomaterials.2013.07.016] [Citation(s) in RCA: 186] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 07/03/2013] [Indexed: 12/16/2022]
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114
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Lind G, Linsmeier CE, Schouenborg J. The density difference between tissue and neural probes is a key factor for glial scarring. Sci Rep 2013; 3:2942. [PMID: 24127004 PMCID: PMC3796741 DOI: 10.1038/srep02942] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 09/27/2013] [Indexed: 12/21/2022] Open
Abstract
A key to successful chronic neural interfacing is to achieve minimal glial scarring surrounding the implants, as the astrocytes and microglia may functionally insulate the interface. A possible explanation for the development of these reactions is mechanical forces arising between the implants and the brain. Here, we show that the difference between the density of neural probes and that of the tissue, and the resulting inertial forces, are key factors for the development of the glial scar. Two probes of similar size, shape, surface structure and elastic modulus but differing greatly in density were implanted into the rat brain. After six weeks, significantly lower astrocytic and microglial reactions were found surrounding the low-density probes, approaching no reaction at all. This provides a major key to design fully biocompatible neural interfaces and a new platform for in vivo assays of tissue reactions to probes with differing materials, surface structures, and shapes.
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Affiliation(s)
- Gustav Lind
- Neuronano Research Center, Department of Experimental Medical Sciences, Medical Faculty, Lund University
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115
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Gutowski SM, Templeman KL, South AB, Gaulding JC, Shoemaker JT, LaPlaca MC, Bellamkonda RV, Lyon LA, García AJ. Host response to microgel coatings on neural electrodes implanted in the brain. J Biomed Mater Res A 2013; 102:1486-99. [PMID: 23666919 DOI: 10.1002/jbm.a.34799] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 04/15/2013] [Accepted: 05/03/2013] [Indexed: 11/10/2022]
Abstract
The performance of neural electrodes implanted in the brain is often limited by host response in the surrounding brain tissue, including astrocytic scar formation, neuronal cell death, and inflammation around the implant. We applied conformal microgel coatings to silicon neural electrodes and examined host responses to microgel-coated and uncoated electrodes following implantation in the rat brain. In vitro analyses demonstrated significantly reduced astrocyte and microglia adhesion to microgel-coated electrodes compared to uncoated controls. Microgel-coated and uncoated electrodes were implanted in the rat brain cortex and the extent of activated microglia and astrocytes as well as neuron density around the implant were evaluated at 1, 4, and 24 weeks postimplantation. Microgel coatings reduced astrocytic recruitment around the implant at later time points. However, microglial response indicated persistence of inflammation in the area around the electrode. Neuronal density around the implanted electrodes was also lower for both implant groups compared to the uninjured control. These results demonstrate that microgel coatings do not significantly improve host responses to implanted neural electrodes and underscore the need for further improvements in implantable materials.
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Affiliation(s)
- Stacie M Gutowski
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, 30332-0363; Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia, 30332-0363
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Ware T, Simon D, Liu C, Musa T, Vasudevan S, Sloan A, Keefer EW, Rennaker RL, Voit W. Thiol-ene/acrylate substrates for softening intracortical electrodes. J Biomed Mater Res B Appl Biomater 2013; 102:1-11. [DOI: 10.1002/jbmb.32946] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 02/20/2013] [Accepted: 03/06/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Taylor Ware
- The University of Texas at Dallas; Department of Materials Science and Engineering; Richardson Texas
| | - Dustin Simon
- The University of Texas at Dallas; Department of Materials Science and Engineering; Richardson Texas
| | - Clive Liu
- The University of Texas at Dallas; Department of Mechanical Engineering; Richardson Texas
| | | | - Srikanth Vasudevan
- The University of Texas at Arlington; Department of Bioengineering; Arlington Texas
| | - Andrew Sloan
- The University of Texas at Dallas, School of Behavioral and Brain Sciences; Richardson Texas
| | | | - Robert L. Rennaker
- The University of Texas at Dallas, School of Behavioral and Brain Sciences; Richardson Texas
| | - Walter Voit
- The University of Texas at Dallas; Department of Materials Science and Engineering; Richardson Texas
- The University of Texas at Dallas; Department of Mechanical Engineering; Richardson Texas
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117
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Woolley AJ, Desai HA, Otto KJ. Chronic intracortical microelectrode arrays induce non-uniform, depth-related tissue responses. J Neural Eng 2013; 10:026007. [PMID: 23428842 DOI: 10.1088/1741-2560/10/2/026007] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Brain-implanted microelectrode arrays show promise as future clinical devices. However, biological responses to various designs, compositions and locations of these implants have not been fully characterized, and may impact the long-term functionality of these devices. In order to improve our understanding of the tissue conditions at the interface of chronic brain-implanted microdevices, we proposed utilizing advanced histology and microscopy techniques to image implanted devices and surrounding tissue intact within brain slices. We then proposed utilizing these methods to examine whether depth within the cerebral cortex affected tissue conditions around implants. APPROACH Histological data was collected from rodent brain slices containing intact, intracortical microdevices four weeks after implantation surgery. Thick tissue sections containing the chronic implants were processed with fluorescent antibody labels, and imaged in an optical clearing solution using laser confocal microscopy. MAIN RESULTS Tissue surrounding microdevices exhibited two major depth-related phenomena: a non-uniform microglial coating along the device length and a dense mass of cells surrounding the implant in cerebral cortical layers I and II. Detailed views of the monocyte-derived immune cells improve our understanding of the close and complex association that immune cells have with chronic brain implants, and illuminated a possible relationship between cortical depth and the intensity of a chronic monocyte response around penetrating microdevices. The dense mass of cells contained vimentin, a protein not typically expressed highly in CNS cells, evidence that non-CNS cells likely descended down the face of the penetrating devices from the pial surface. SIGNIFICANCE Image data of highly non-uniform and depth-dependent biological responses along a device provides novel insight into the complexity of the tissue response to penetrating brain-implanted microdevices. The presented work also demonstrates the value of in situ histological collection of brain implants for studying the complex tissue changes that occur, and the utility of pairing thick-tissue histology with appropriate optical clearing solutions.
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Affiliation(s)
- Andrew J Woolley
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907-2032, USA.
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118
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Markwardt NT, Stokol J, Rennaker RL. Sub-meninges implantation reduces immune response to neural implants. J Neurosci Methods 2013; 214:119-25. [PMID: 23370311 DOI: 10.1016/j.jneumeth.2013.01.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 01/21/2013] [Accepted: 01/22/2013] [Indexed: 10/27/2022]
Abstract
Glial scar formation around neural interfaces inhibits their ability to acquire usable signals from the surrounding neurons. To improve neural recording performance, the inflammatory response and glial scarring must be minimized. Previous work has indicated that meningeally derived cells participate in the immune response, and it is possible that the meninges may grow down around the shank of a neural implant, contributing to the formation of the glial scar. This study examines whether the glial scar can be reduced by placing a neural probe completely below the meninges. Rats were implanted with sets of loose microwire implants placed either completely below the meninges or implanted conventionally with the upper end penetrating the meninges, but not attached to the skull. Histological analysis was performed 4 weeks following surgical implantation to evaluate the glial scar. Our results found that sub-meninges implants showed an average reduction in reactive astrocyte activity of 63% compared to trans-meninges implants. Microglial activity was also reduced for sub-meninges implants. These results suggest that techniques that isolate implants from the meninges offer the potential to reduce the encapsulation response which should improve chronic recording quality and stability.
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Affiliation(s)
- Neil T Markwardt
- The University of Oklahoma, College of Engineering, Bioengineering Center, 202 W. Boyd St., Carson Eng. Ctr. Rm 107, Norman, OK 73019, United States.
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119
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120
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Ware T, Simon D, Hearon K, Liu C, Shah S, Reeder J, Khodaparast N, Kilgard MP, Maitland DJ, Rennaker RL, Voit WE. Three-Dimensional Flexible Electronics Enabled by Shape Memory Polymer Substrates for Responsive Neural Interfaces. MACROMOLECULAR MATERIALS AND ENGINEERING 2012; 297:1193-1202. [PMID: 25530708 PMCID: PMC4268152 DOI: 10.1002/mame.201200241] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Planar electronics processing methods have enabled neural interfaces to become more precise and deliver more information. However, this processing paradigm is inherently 2D and rigid. The resulting mechanical and geometrical mismatch at the biotic-abiotic interface can elicit an immune response that prevents effective stimulation. In this work, a thiol-ene/acrylate shape memory polymer is utilized to create 3D softening substrates for stimulation electrodes. This substrate system is shown to soften in vivo from more than 600 to 6 MPa. A nerve cuff electrode that coils around the vagus nerve in a rat and that drives neural activity is demonstrated.
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Affiliation(s)
- Taylor Ware
- Assistant Professor, Department of Materials Science and Engineering, The University of Texas at Dallas, Mailstop RL10, 800 West Campbell Rd., Richardson, TX 75080, USA
| | - Dustin Simon
- Assistant Professor, Department of Materials Science and Engineering, The University of Texas at Dallas, Mailstop RL10, 800 West Campbell Rd., Richardson, TX 75080, USA
| | - Keith Hearon
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Clive Liu
- Department of Mechanical Engineering, The University of Texas at Dallas, Mailstop RL10, 800 West Campbell Rd., Richardson, TX 75080, USA
| | - Sagar Shah
- Department of Molecular and Cell Biology, The University of Texas at Dallas, Mailstop RL10, 800 West Campbell Rd., Richardson, TX 75080, USA
| | - Jonathan Reeder
- Department of Mechanical Engineering, The University of Texas at Dallas, Mailstop RL10, 800 West Campbell Rd., Richardson, TX 75080, USA
| | - Navid Khodaparast
- Department of Behavioral and Brain Sciences, The University of Texas at Dallas, Mailstop RL10, 800 West Campbell Rd., Richardson, TX 75080, USA
| | - Michael P Kilgard
- Department of Behavioral and Brain Sciences, The University of Texas at Dallas, Mailstop RL10, 800 West Campbell Rd., Richardson, TX 75080, USA
| | - Duncan J Maitland
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Robert L Rennaker
- School of Behavioral and Brain Sciences, Erik Jonsson School of Engineering, The University of Texas at Dallas, Mailstop RL10, 800 West Campbell Rd., Richardson, TX 75080, USA
| | - Walter E Voit
- Assistant Professor, Department of Materials Science and Engineering, The University of Texas at Dallas, Mailstop RL10, 800 West Campbell Rd., Richardson, TX 75080, USA
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121
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Lind G, Gällentoft L, Danielsen N, Schouenborg J, Pettersson LME. Multiple implants do not aggravate the tissue reaction in rat brain. PLoS One 2012; 7:e47509. [PMID: 23091629 PMCID: PMC3472973 DOI: 10.1371/journal.pone.0047509] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 09/14/2012] [Indexed: 11/18/2022] Open
Abstract
Chronically implanted microelectrodes are an invaluable tool for neuroscientific research, allowing long term recordings in awake and behaving animals. It is known that all such electrodes will evoke a tissue reaction affected by its’ size, shape, surface structure, fixation mode and implantation method. However, the possible correlation between tissue reactions and the number of implanted electrodes is not clear. We implanted multiple wire bundles into the brain of rats and studied the correlation between the astrocytic and microglial reaction and the positioning of the electrode in relation to surrounding electrodes. We found that an electrode implanted in the middle of a row of implants is surrounded by a significantly smaller astrocytic scar than single ones. This possible interaction was only seen between implants within the same hemisphere, no interaction with the contralateral hemisphere was found. More importantly, we found no aggravation of tissue reactions as a result of a larger number of implants. These results highlight the possibility of implanting multiple electrodes without aggravating the glial scar surrounding each implant.
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Affiliation(s)
- Gustav Lind
- Department of Experimental Medical Sciences, Neuronano Research Center, Medical Faculty, Lund University, Lund, Sweden.
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122
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Prasad A, Xue QS, Sankar V, Nishida T, Shaw G, Streit WJ, Sanchez JC. Comprehensive characterization and failure modes of tungsten microwire arrays in chronic neural implants. J Neural Eng 2012; 9:056015. [DOI: 10.1088/1741-2560/9/5/056015] [Citation(s) in RCA: 218] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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123
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Scott KM, Du J, Lester HA, Masmanidis SC. Variability of acute extracellular action potential measurements with multisite silicon probes. J Neurosci Methods 2012; 211:22-30. [PMID: 22971352 DOI: 10.1016/j.jneumeth.2012.08.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 07/31/2012] [Accepted: 08/04/2012] [Indexed: 01/24/2023]
Abstract
Device miniaturization technologies have led to significant advances in sensors for extracellular measurements of electrical activity in the brain. Multisite, silicon-based probes containing implantable electrode arrays afford greater coverage of neuronal activity than single electrodes and therefore potentially offer a more complete view of how neuronal ensembles encode information. However, scaling up the number of sites is not sufficient to ensure capture of multiple neurons, as action potential signals from extracellular electrodes may vary due to numerous factors. In order to understand the large-scale recording capabilities and potential limitations of multisite probes, it is important to quantify this variability, and to determine whether certain key device parameters influence the recordings. Here we investigate the effect of four parameters, namely, electrode surface, width of the structural support shafts, shaft number, and position of the recording site relative to the shaft tip. This study employs acutely implanted silicon probes containing up to 64 recording sites, whose performance is evaluated by the metrics of noise, spike amplitude, and spike detection probability. On average, we find no significant effect of device geometry on spike amplitude and detection probability but we find significant differences among individual experiments, with the likelihood of detecting spikes varying by a factor of approximately three across trials.
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Affiliation(s)
- Kimberly M Scott
- Division of Biology, California Institute of Technology, Pasadena, USA
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124
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Liu X, Demosthenous A, Vanhoestenberghe A, Jiang D, Donaldson N. Active books: the design of an implantable stimulator that minimizes cable count using integrated circuits very close to electrodes. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2012; 6:216-227. [PMID: 23853144 DOI: 10.1109/tbcas.2011.2174360] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This paper presents an integrated stimulator that can be embedded in implantable electrode books for interfacing with nerve roots at the cauda equina. The Active Book overcomes the limitation of conventional nerve root stimulators which can only support a small number of stimulating electrodes due to cable count restriction through the dura. Instead, a distributed stimulation system with many tripole electrodes can be configured using several Active Books which are addressed sequentially. The stimulator was fabricated in a 0.6-μm high-voltage CMOS process and occupies a silicon area of 4.2 × 6.5 mm(2). The circuit was designed to deliver up to 8 mA stimulus current to tripole electrodes from an 18 V power supply. Input pad count is limited to five (two power and three control lines) hence requiring a specific procedure for downloading stimulation commands to the chip and extracting information from it. Supported commands include adjusting the amplitude of stimulus current, varying the current ratio at the two anodes in each channel, and measuring relative humidity inside the chip package. In addition to stimulation mode, the chip supports quiescent mode, dissipating less than 100 nA current from the power supply. The performance of the stimulator chip was verified with bench tests including measurements using tripoles in saline.
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Affiliation(s)
- Xiao Liu
- University College London, London WC1E 6BT, UK.
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125
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Prasad A, Sanchez JC. Quantifying long-term microelectrode array functionality using chronic in vivo impedance testing. J Neural Eng 2012; 9:026028. [PMID: 22442134 DOI: 10.1088/1741-2560/9/2/026028] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Long-term acquisition of high-quality neural recordings is a cornerstone of neuroprosthetic system design. Mitigating the experimental variability of chronically implanted arrays has been a formidable task because the sensor recording sites can be influenced by biotic and abiotic responses. Several studies have implicated changes in electrical interface impedance as a preliminary marker to infer electrode viability. Microelectrode impedance plays an important role in the monitoring of low amplitude and high-resolution extracellular neural signals. In this work, we seek to quantify long-term microelectrode array functionality and derive an impedance-based predictor for electrode functionality that correlates the recording site electrical properties with the functional neuronal recordings in vivo. High temporal resolution metrics of this type would allow one to assess, predict, and improve electrode performance in the future. In a large cohort of animals, we performed daily impedance measurements and neural signal recordings over long periods (up to 21 weeks) of time in rats using tungsten microwire arrays implanted into the somatosensory cortex. This study revealed that there was a time-varying trend in the modulation of impedance that was related to electrode performance. Single units were best detected from electrodes at time points when the electrode entered into the 40-150 KΩ impedance range. This impedance trend was modeled across the full cohort of animals to predict future electrode performance. The model was tested on data from all animals and was able to provide predictions of electrode performance chronically. Insight from this study can be combined with knowledge of electrode materials and histological analysis to provide a more comprehensive predictive model of electrode failure in the future.
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Affiliation(s)
- Abhishek Prasad
- Department of Biomedical Engineering, University of Miami, Miami, FL, USA.
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126
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Prasad A, Xue QS, Sankar V, Nishida T, Shaw G, Streit W, Sanchez JC. Comprehensive characterization of tungsten microwires in chronic neurocortical implants. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2012:755-758. [PMID: 23366002 DOI: 10.1109/embc.2012.6346041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The long-term performance of chronic microelectrode array implants for neural ensemble recording is affected by temporal degradation in signal quality due to several factors including structural changes in the recording surface, electrical responses, and tissue immune reactivity. This study combines the information available from the temporal aggregation of both biotic and abiotic metrics to analyze and quantify the combined effects on long-term performance. Study of a 42-day implant showed there was a functional relationship between the measured impedance and the array neuronal yield. This was correlated with structural changes in the recording sites, microglial activation/degeneration, and elevation of a blood biochemical marker for axonal injury. We seek to elucidate the mechanisms of chronic microelectrode array failure through the study of the combined effects of these biotic and abiotic factors.
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Affiliation(s)
- Abhishek Prasad
- Department of Biomedical Engineering and the Miami Project to Cure Paralysis, University of Miami, Coral Gables, FL 33146, USA.
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127
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Du J, Blanche TJ, Harrison RR, Lester HA, Masmanidis SC. Multiplexed, high density electrophysiology with nanofabricated neural probes. PLoS One 2011; 6:e26204. [PMID: 22022568 PMCID: PMC3192171 DOI: 10.1371/journal.pone.0026204] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2011] [Accepted: 09/22/2011] [Indexed: 12/01/2022] Open
Abstract
Extracellular electrode arrays can reveal the neuronal network correlates of behavior with single-cell, single-spike, and sub-millisecond resolution. However, implantable electrodes are inherently invasive, and efforts to scale up the number and density of recording sites must compromise on device size in order to connect the electrodes. Here, we report on silicon-based neural probes employing nanofabricated, high-density electrical leads. Furthermore, we address the challenge of reading out multichannel data with an application-specific integrated circuit (ASIC) performing signal amplification, band-pass filtering, and multiplexing functions. We demonstrate high spatial resolution extracellular measurements with a fully integrated, low noise 64-channel system weighing just 330 mg. The on-chip multiplexers make possible recordings with substantially fewer external wires than the number of input channels. By combining nanofabricated probes with ASICs we have implemented a system for performing large-scale, high-density electrophysiology in small, freely behaving animals that is both minimally invasive and highly scalable.
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Affiliation(s)
- Jiangang Du
- Division of Biology, California Institute of Technology, Pasadena, California, United States of America
- Kavli Nanoscience Institute, California Institute of Technology, Pasadena, California, United States of America
- Broad Fellows Program in Brain Circuitry, California Institute of Technology, Pasadena, California, United States of America
| | - Timothy J. Blanche
- Redwood Center for Theoretical Neuroscience, Helen Wills Neuroscience Institute, University of California, Berkeley, California, United States of America
| | - Reid R. Harrison
- Intan Technologies, Los Angeles, California, United States of America
| | - Henry A. Lester
- Division of Biology, California Institute of Technology, Pasadena, California, United States of America
| | - Sotiris C. Masmanidis
- Division of Biology, California Institute of Technology, Pasadena, California, United States of America
- Kavli Nanoscience Institute, California Institute of Technology, Pasadena, California, United States of America
- Broad Fellows Program in Brain Circuitry, California Institute of Technology, Pasadena, California, United States of America
- * E-mail:
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128
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A surgical device for minimally invasive implantation of experimental deep brain stimulation leads in large research animals. J Neurosci Methods 2011; 200:41-6. [DOI: 10.1016/j.jneumeth.2011.06.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2011] [Revised: 06/03/2011] [Accepted: 06/14/2011] [Indexed: 11/19/2022]
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129
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Schouenborg J. Biocompatible multichannel electrodes for long-term neurophysiological studies and clinical therapy--novel concepts and design. PROGRESS IN BRAIN RESEARCH 2011; 194:61-70. [PMID: 21867794 DOI: 10.1016/b978-0-444-53815-4.00017-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Chronic neural interfaces that are both structurally and functionally stable inside the brain over long time periods and that have minimal effects on the physiological conditions of the neural tissue to be studied hold great promise to become invaluable research and clinical tool in the near future. In this chapter, I will briefly review the state of the art of neural interfaces and the concepts behind our recent research and development of ultrathin multichannel electrodes.
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Affiliation(s)
- Jens Schouenborg
- Neuronano Research Center, Experimental Medical Science and The Nanometer Consortium, Lund University, Lund, Sweden.
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130
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Linsmeier CE, Thelin J, Danielsen N. Can histology solve the riddle of the nonfunctioning electrode? PROGRESS IN BRAIN RESEARCH 2011; 194:181-9. [DOI: 10.1016/b978-0-444-53815-4.00008-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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131
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Schalk G, Leuthardt EC. Brain-Computer Interfaces Using Electrocorticographic Signals. IEEE Rev Biomed Eng 2011; 4:140-54. [DOI: 10.1109/rbme.2011.2172408] [Citation(s) in RCA: 262] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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132
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Skousen JL, Merriam SME, Srivannavit O, Perlin G, Wise KD, Tresco PA. Reducing surface area while maintaining implant penetrating profile lowers the brain foreign body response to chronically implanted planar silicon microelectrode arrays. PROGRESS IN BRAIN RESEARCH 2011; 194:167-80. [PMID: 21867802 DOI: 10.1016/b978-0-444-53815-4.00009-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A consistent feature of the foreign body response (FBR), irrespective of the type of implant, is persistent inflammation at the biotic-abiotic interface signaled by biomarkers of macrophage/microglial activation. Since macrophage-secreted factors shape the foreign body reaction, implant designs that reduce macrophage activation should improve biocompatibility and, with regard to recording devices, should improve reliability and longevity. At present, it is unclear whether the goal of seamless integration is possible or whether electrode developers can modulate specific aspects of the FBR by intentionally manipulating the constitutive properties of the implant. To explore this area, we studied the chronic brain FBR to planar solid silicon microelectrode arrays and planar lattice arrays with identical penetrating profiles but with reduced surface area in rats after an 8-week indwelling period. Using quantitative immunohistochemistry, we found that presenting less surface area after equivalent iatrogenic injury is accompanied by significantly less persistent macrophage activation, decreased blood brain barrier leakiness, and reduced neuronal cell loss. Our findings show that it is possible for implant developers to modulate specific aspects of the FBR by intentionally manipulating the constitutive properties of the implant. Our results also support the theory that the FBR to implanted electrode arrays, and likely other implants, can be explained by the presence of macrophages at the biotic-abiotic interface, which act as a sustained delivery source of bioactive agents that diffuse into the adjacent tissue and shape various features of the brain FBR. Further, our findings suggest that one method to improve the recording consistency and lifetime of implanted microelectrode arrays is to design implants that reduce the amount of macrophage activation at the biotic-abiotic interface and/or enhance the clearance or impact of their released factors.
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Affiliation(s)
- John L Skousen
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
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