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Whitsitt Q, Saxena A, Patel B, Evans BM, Hunt B, Purcell EK. Spatial transcriptomics at the brain-electrode interface in rat motor cortex and the relationship to recording quality. J Neural Eng 2024; 21:046033. [PMID: 38885679 PMCID: PMC11289622 DOI: 10.1088/1741-2552/ad5936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 04/15/2024] [Accepted: 06/17/2024] [Indexed: 06/20/2024]
Abstract
Study of the foreign body reaction to implanted electrodes in the brain is an important area of research for the future development of neuroprostheses and experimental electrophysiology. After electrode implantation in the brain, microglial activation, reactive astrogliosis, and neuronal cell death create an environment immediately surrounding the electrode that is significantly altered from its homeostatic state.Objective.To uncover physiological changes potentially affecting device function and longevity, spatial transcriptomics (ST) was implemented to identify changes in gene expression driven by electrode implantation and compare this differential gene expression to traditional metrics of glial reactivity, neuronal loss, and electrophysiological recording quality.Approach.For these experiments, rats were chronically implanted with functional Michigan-style microelectrode arrays, from which electrophysiological recordings (multi-unit activity, local field potential) were taken over a six-week time course. Brain tissue cryosections surrounding each electrode were then mounted for ST processing. The tissue was immunolabeled for neurons and astrocytes, which provided both a spatial reference for ST and a quantitative measure of glial fibrillary acidic protein and neuronal nuclei immunolabeling surrounding each implant.Main results. Results from rat motor cortex within 300µm of the implanted electrodes at 24 h, 1 week, and 6 weeks post-implantation showed up to 553 significantly differentially expressed (DE) genes between implanted and non-implanted tissue sections. Regression on the significant DE genes identified the 6-7 genes that had the strongest relationship to histological and electrophysiological metrics, revealing potential candidate biomarkers of recording quality and the tissue response to implanted electrodes.Significance. Our analysis has shed new light onto the potential mechanisms involved in the tissue response to implanted electrodes while generating hypotheses regarding potential biomarkers related to recorded signal quality. A new approach has been developed to understand the tissue response to electrodes implanted in the brain using genes identified through transcriptomics, and to screen those results for potential relationships with functional outcomes.
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Affiliation(s)
- Quentin Whitsitt
- Department of Biomedical Engineering and Institute of Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI 48824, United States of America
| | - Akash Saxena
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824, United States of America
| | - Bella Patel
- Department of Biomedical Engineering and Institute of Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI 48824, United States of America
| | - Blake M Evans
- Department of Biomedical Engineering and Institute of Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI 48824, United States of America
| | - Bradley Hunt
- Department of Biomedical Engineering and Institute of Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI 48824, United States of America
| | - Erin K Purcell
- Department of Biomedical Engineering and Institute of Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI 48824, United States of America
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824, United States of America
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Li F, Gallego J, Tirko NN, Greaser J, Bashe D, Patel R, Shaker E, Van Valkenburg GE, Alsubhi AS, Wellman S, Singh V, Padilla CG, Gheres KW, Broussard JI, Bagwell R, Mulvihill M, Kozai TDY. Low-intensity pulsed ultrasound stimulation (LIPUS) modulates microglial activation following intracortical microelectrode implantation. Nat Commun 2024; 15:5512. [PMID: 38951525 PMCID: PMC11217463 DOI: 10.1038/s41467-024-49709-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 06/13/2024] [Indexed: 07/03/2024] Open
Abstract
Microglia are important players in surveillance and repair of the brain. Implanting an electrode into the cortex activates microglia, produces an inflammatory cascade, triggers the foreign body response, and opens the blood-brain barrier. These changes can impede intracortical brain-computer interfaces performance. Using two-photon imaging of implanted microelectrodes, we test the hypothesis that low-intensity pulsed ultrasound stimulation can reduce microglia-mediated neuroinflammation following the implantation of microelectrodes. In the first week of treatment, we found that low-intensity pulsed ultrasound stimulation increased microglia migration speed by 128%, enhanced microglia expansion area by 109%, and a reduction in microglial activation by 17%, indicating improved tissue healing and surveillance. Microglial coverage of the microelectrode was reduced by 50% and astrocytic scarring by 36% resulting in an increase in recording performance at chronic time. The data indicate that low-intensity pulsed ultrasound stimulation helps reduce the foreign body response around chronic intracortical microelectrodes.
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Affiliation(s)
- Fan Li
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Neural Basis of Cognition, Pittsburgh, PA, USA
- Computational Modeling and Simulation PhD Program, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jazlyn Gallego
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Neural Basis of Cognition, Pittsburgh, PA, USA
| | - Natasha N Tirko
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | | | - Derek Bashe
- Washington University in St. Louis, St. Louis, MO, USA
| | - Rudra Patel
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Eric Shaker
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | | | | | | | - Vanshika Singh
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Camila Garcia Padilla
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Neural Basis of Cognition, Pittsburgh, PA, USA
| | | | | | | | | | - Takashi D Y Kozai
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
- Center for Neural Basis of Cognition, Pittsburgh, PA, USA.
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA.
- McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
- NeuroTech Center, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA.
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Wang Y, Yang X, Zhang X, Wang Y, Pei W. Implantable intracortical microelectrodes: reviewing the present with a focus on the future. MICROSYSTEMS & NANOENGINEERING 2023; 9:7. [PMID: 36620394 PMCID: PMC9814492 DOI: 10.1038/s41378-022-00451-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 08/08/2022] [Accepted: 08/22/2022] [Indexed: 06/17/2023]
Abstract
Implantable intracortical microelectrodes can record a neuron's rapidly changing action potentials (spikes). In vivo neural activity recording methods often have either high temporal or spatial resolution, but not both. There is an increasing need to record more neurons over a longer duration in vivo. However, there remain many challenges to overcome before achieving long-term, stable, high-quality recordings and realizing comprehensive, accurate brain activity analysis. Based on the vision of an idealized implantable microelectrode device, the performance requirements for microelectrodes are divided into four aspects, including recording quality, recording stability, recording throughput, and multifunctionality, which are presented in order of importance. The challenges and current possible solutions for implantable microelectrodes are given from the perspective of each aspect. The current developments in microelectrode technology are analyzed and summarized.
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Affiliation(s)
- Yang Wang
- State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, 100083 Beijing, China
- University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Xinze Yang
- State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, 100083 Beijing, China
- University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Xiwen Zhang
- State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, 100083 Beijing, China
- University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Yijun Wang
- State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, 100083 Beijing, China
- University of Chinese Academy of Sciences, 100049 Beijing, China
- Chinese Institute for Brain Research, 102206 Beijing, China
| | - Weihua Pei
- State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, 100083 Beijing, China
- University of Chinese Academy of Sciences, 100049 Beijing, China
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Conrad EC, Shinohara RT, Gugger JJ, Revell AY, Das S, Stein JM, Marsh ED, Davis KA, Litt B. Implanting intracranial electrodes does not affect spikes or network connectivity in nearby or connected brain regions. Netw Neurosci 2022; 6:834-849. [PMID: 36607198 PMCID: PMC9810371 DOI: 10.1162/netn_a_00248] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 04/01/2022] [Indexed: 01/10/2023] Open
Abstract
To determine the effect of implanting electrodes on electrographic features of nearby and connected brain regions in patients with drug-resistant epilepsy, we analyzed intracranial EEG recordings from 10 patients with drug-resistant epilepsy who underwent implant revision (placement of additional electrodes) during their hospitalization. We performed automated spike detection and measured EEG functional networks. We analyzed the original electrodes that remained in place throughout the full EEG recording, and we measured the change in spike rates and network connectivity in these original electrodes in response to implanting new electrodes. There was no change in overall spike rate pre- to post-implant revision (t(9) = 0.1, p = 0.95). The peri-revision change in the distribution of spike rate and connectivity across electrodes was no greater than chance (Monte Carlo method, spikes: p = 0.40, connectivity: p = 0.42). Electrodes closer to or more functionally connected to the revision site had no greater change in spike rate or connectivity than more distant or less connected electrodes. Changes in electrographic features surrounding electrode implantation are no greater than baseline fluctuations occurring throughout the intracranial recording. These findings argue against an implant effect on spikes or network connectivity in nearby or connected brain regions.
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Affiliation(s)
- Erin C. Conrad
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Russell T. Shinohara
- Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, PA, USA
- Penn Statistics in Imaging and Visualization Center, University of Pennsylvania, Philadelphia, PA, USA
- Center for Biomedical Image Computing and Analytics, University of Pennsylvania, Philadelphia, PA, USA
| | - James J. Gugger
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Andrew Y. Revell
- Medical Scientist Training Program, University of Pennsylvania, Philadelphia, PA, USA
| | - Sandhitsu Das
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Joel M. Stein
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Eric D. Marsh
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
- Division of Child Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Kathryn A. Davis
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Brian Litt
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
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Atherton E, Hu Y, Brown S, Papiez E, Ling V, Colvin V, Borton D. A 3D in vitro model of the device-tissue interface: Functional and structural symptoms of innate neuroinflammation are mitigated by antioxidant ceria nanoparticles. J Neural Eng 2022; 19. [PMID: 35447619 DOI: 10.1088/1741-2552/ac6908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 04/20/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The recording instability of neural implants due to neuroinflammation at the device-tissue interface is a primary roadblock to broad adoption of brain-machine interfaces. While a multiphasic immune response, marked by glial scaring, oxidative stress (OS), and neurodegeneration, is well-characterized, the independent contributions of systemic and local "innate" immune responses are not well-understood. We aimed to understand and mitigate the isolated the innate neuroinflammatory response to devices. APPROACH Three-dimensional primary neural cultures provide a unique environment for studying the drivers of neuroinflammation by decoupling the innate and systemic immune systems, while conserving an endogenous extracellular matrix and structural and functional network complexity. We created a three-dimensional in vitro model of the DTI by seeding primary cortical cells around microwires. Live imaging of both dye and AAV-mediated functional, structural, and lipid peroxidation fluorescence was employed to characterize the neuroinflammatory response. MAIN RESULTS Live imaging of microtissues over time revealed independent innate neuroinflammation, marked by increased OS, decreased neuronal density, and increased functional connectivity. We demonstrated the use of this model for therapeutic screening by directly applying drugs to neural tissue, bypassing low bioavailability through the in vivo blood brain barrier. As there is growing interest in long-acting antioxidant therapies, we tested efficacy of "perpetual" antioxidant ceria nanoparticles, which reduced OS, increased neuronal density, and protected functional connectivity. SIGNIFICANCE Our 3D in vitro model of the device-tissue interface exhibited symptoms of OS-mediated innate neuroinflammation, indicating a significant local immune response to devices. The dysregulation of functional connectivity of microcircuits surround implants suggests the presence of an observer effect, in which the process of recording neural activity may fundamentally change the neural signal. Finally, the demonstration of antioxidant ceria nanoparticle treatment exhibited substantial promise as a neuroprotective and anti-inflammatory treatment strategy.
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Affiliation(s)
- Elaina Atherton
- School of Engineering, Brown University, 182 Hope Street, Providence, RI 02912, USA, Providence, Rhode Island, 02912, UNITED STATES
| | - Yue Hu
- Department of Chemistry, Brown University, 182 Hope Street, Providence, RI 02912, USA, Providence, Rhode Island, 02912, UNITED STATES
| | - Sophie Brown
- School of Engineering, Brown University, 182 Hope Street, Providence, RI 02912, USA, Providence, Rhode Island, 02912, UNITED STATES
| | - Emily Papiez
- School of Engineering, Brown University, 182 Hope Street, Providence, RI 02912, USA, Providence, Rhode Island, 02912, UNITED STATES
| | - Vivian Ling
- Department of Chemistry, Brown University, 182 Hope Street, Providence, RI 02912, USA, Providence, Rhode Island, 02912, UNITED STATES
| | - Vicki Colvin
- Department of Chemistry, Brown University, 182 Hope Street, Providence, RI 02912, USA, Providence, Rhode Island, 02912, UNITED STATES
| | - David Borton
- School of Engineering, Brown University, 182 Hope Street, Providence, RI 02912, USA, Providence, Rhode Island, 02912, UNITED STATES
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Khalifa A, Zaeimbashi M, Zhou TX, Abrishami SM, Sun N, Park S, Šumarac T, Qu J, Zohar I, Yacoby A, Cash S, Sun NX. The development of microfabricated solenoids with magnetic cores for micromagnetic neural stimulation. MICROSYSTEMS & NANOENGINEERING 2021; 7:91. [PMID: 34786205 PMCID: PMC8589949 DOI: 10.1038/s41378-021-00320-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/16/2021] [Accepted: 10/11/2021] [Indexed: 05/14/2023]
Abstract
Electrical stimulation via invasive microelectrodes is commonly used to treat a wide range of neurological and psychiatric conditions. Despite its remarkable success, the stimulation performance is not sustainable since the electrodes become encapsulated by gliosis due to foreign body reactions. Magnetic stimulation overcomes these limitations by eliminating the need for a metal-electrode contact. Here, we demonstrate a novel microfabricated solenoid inductor (80 µm × 40 µm) with a magnetic core that can activate neuronal tissue. The characterization and proof-of-concept of the device raise the possibility that micromagnetic stimulation solenoids that are small enough to be implanted within the brain may prove to be an effective alternative to existing electrode-based stimulation devices for chronic neural interfacing applications.
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Affiliation(s)
- Adam Khalifa
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA
| | - Mohsen Zaeimbashi
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA USA
| | - Tony X. Zhou
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA USA
- Department of Physics, Harvard University, Cambridge, MA USA
| | - Seyed Mahdi Abrishami
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA USA
| | - Neville Sun
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA USA
| | - Seunghyun Park
- Department of Physics, Harvard University, Cambridge, MA USA
| | - Tamara Šumarac
- Department of Physics, Harvard University, Cambridge, MA USA
| | - Jason Qu
- Department of Physics, Harvard University, Cambridge, MA USA
| | - Inbar Zohar
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Amir Yacoby
- Department of Physics, Harvard University, Cambridge, MA USA
| | - Sydney Cash
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA
| | - Nian X. Sun
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA USA
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Intracortical Microelectrode Array Unit Yield under Chronic Conditions: A Comparative Evaluation. MICROMACHINES 2021; 12:mi12080972. [PMID: 34442594 PMCID: PMC8400387 DOI: 10.3390/mi12080972] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 08/10/2021] [Accepted: 08/12/2021] [Indexed: 01/01/2023]
Abstract
While microelectrode arrays (MEAs) offer the promise of elucidating functional neural circuitry and serve as the basis for a cortical neuroprosthesis, the challenge of designing and demonstrating chronically reliable technology remains. Numerous studies report “chronic” data but the actual time spans and performance measures corresponding to the experimental work vary. In this study, we reviewed the experimental durations that constitute chronic studies across a range of MEA types and animal species to gain an understanding of the widespread variability in reported study duration. For rodents, which are the most commonly used animal model in chronic studies, we examined active electrode yield (AEY) for different array types as a means to contextualize the study duration variance, as well as investigate and interpret the performance of custom devices in comparison to conventional MEAs. We observed wide-spread variance within species for the chronic implantation period and an AEY that decayed linearly in rodent models that implanted commercially-available devices. These observations provide a benchmark for comparing the performance of new technologies and highlight the need for consistency in chronic MEA studies. Additionally, to fully derive performance under chronic conditions, the duration of abiotic failure modes, biological processes induced by indwelling probes, and intended application of the device are key determinants.
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Pio-Lopez L, Poulkouras R, Depannemaecker D. Visual cortical prosthesis: an electrical perspective. J Med Eng Technol 2021; 45:394-407. [PMID: 33843427 DOI: 10.1080/03091902.2021.1907468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The electrical stimulation of the visual cortices has the potential to restore vision to blind individuals. Until now, the results of visual cortical prosthetics have been limited as no prosthesis has restored a full working vision but the field has shown a renewed interest these last years, thanks to wireless and technological advances. However, several scientific and technical challenges are still open to achieve the therapeutic benefit expected by these new devices. One of the main challenges is the electrical stimulation of the brain itself. In this review, we analyse the results in electrode-based visual cortical prosthetics from the electrical point of view. We first describe what is known about the electrode-tissue interface and safety of electrical stimulation. Then we focus on the psychophysics of prosthetic vision and the state-of-the-art on the interplay between the electrical stimulation of the visual cortex and the phosphene perception. Lastly, we discuss the challenges and perspectives of visual cortex electrical stimulation and electrode array design to develop the new generation implantable cortical visual prostheses.
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Affiliation(s)
| | - Romanos Poulkouras
- Department of Bioelectronics, Ecole Nationale Supérieure des Mines, CMP-EMSE, Gardanne, France.,Institut de Neurosciences de la Timone, UMR 7289, CNRS, Aix-Marseille Université, Marseille, France
| | - Damien Depannemaecker
- Department of Integrative and Computational Neuroscience, Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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Investigating the Association between Motor Function, Neuroinflammation, and Recording Metrics in the Performance of Intracortical Microelectrode Implanted in Motor Cortex. MICROMACHINES 2020; 11:mi11090838. [PMID: 32899336 PMCID: PMC7570280 DOI: 10.3390/mi11090838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/27/2020] [Accepted: 08/28/2020] [Indexed: 11/26/2022]
Abstract
Long-term reliability of intracortical microelectrodes remains a challenge for increased acceptance and deployment. There are conflicting reports comparing measurements associated with recording quality with postmortem histology, in attempts to better understand failure of intracortical microelectrodes (IMEs). Our group has recently introduced the assessment of motor behavior tasks as another metric to evaluate the effects of IME implantation. We hypothesized that adding the third dimension to our analysis, functional behavior testing, could provide substantial insight on the health of the tissue, success of surgery/implantation, and the long-term performance of the implanted device. Here we present our novel analysis scheme including: (1) the use of numerical formal concept analysis (nFCA) and (2) a regression analysis utilizing modern model/variable selection. The analyses found complimentary relationships between the variables. The histological variables for glial cell activation had associations between each other, as well as the neuronal density around the electrode interface. The neuronal density had associations to the electrophysiological recordings and some of the motor behavior metrics analyzed. The novel analyses presented herein describe a valuable tool that can be utilized to assess and understand relationships between diverse variables being investigated. These models can be applied to a wide range of ongoing investigations utilizing various devices and therapeutics.
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Keogh C. Optimizing the neuron-electrode interface for chronic bioelectronic interfacing. Neurosurg Focus 2020; 49:E7. [PMID: 32610294 DOI: 10.3171/2020.4.focus20178] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 04/08/2020] [Indexed: 11/06/2022]
Abstract
Engineering approaches have vast potential to improve the treatment of disease. Brain-machine interfaces have become a well-established means of treating some otherwise medically refractory neurological diseases, and they have shown promise in many more areas. More widespread use of implanted stimulating and recording electrodes for long-term intervention is, however, limited by the difficulty in maintaining a stable interface between implanted electrodes and the local tissue for reliable recording and stimulation.This loss of performance at the neuron-electrode interface is due to a combination of inflammation and glial scar formation in response to the implanted material, as well as electrical factors contributing to a reduction in function over time. An increasing understanding of the factors at play at the neural interface has led to greater focus on the optimization of this neuron-electrode interface in order to maintain long-term implant viability.A wide variety of approaches to improving device interfacing have emerged, targeting the mechanical, electrical, and biological interactions between implanted electrodes and the neural tissue. These approaches are aimed at reducing the initial trauma and long-term tissue reaction through device coatings, optimization of mechanical characteristics for maximal biocompatibility, and implantation techniques. Improved electrode features, optimized stimulation parameters, and novel electrode materials further aim to stabilize the electrical interface, while the integration of biological interventions to reduce inflammation and improve tissue integration has also shown promise.Optimization of the neuron-electrode interface allows the use of long-term, high-resolution stimulation and recording, opening the door to responsive closed-loop systems with highly selective modulation. These new approaches and technologies offer a broad range of options for neural interfacing, representing the possibility of developing specific implant technologies tailor-made to a given task, allowing truly personalized, optimized implant technology for chronic neural interfacing.
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Mahajan S, Hermann JK, Bedell HW, Sharkins JA, Chen L, Chen K, Meade SM, Smith CS, Rayyan J, Feng H, Kim Y, Schiefer MA, Taylor DM, Capadona JR, Ereifej ES. Toward Standardization of Electrophysiology and Computational Tissue Strain in Rodent Intracortical Microelectrode Models. Front Bioeng Biotechnol 2020; 8:416. [PMID: 32457888 PMCID: PMC7225268 DOI: 10.3389/fbioe.2020.00416] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 04/14/2020] [Indexed: 12/26/2022] Open
Abstract
Progress has been made in the field of neural interfacing using both mouse and rat models, yet standardization of these models' interchangeability has yet to be established. The mouse model allows for transgenic, optogenetic, and advanced imaging modalities which can be used to examine the biological impact and failure mechanisms associated with the neural implant itself. The ability to directly compare electrophysiological data between mouse and rat models is crucial for the development and assessment of neural interfaces. The most obvious difference in the two rodent models is size, which raises concern for the role of device-induced tissue strain. Strain exerted on brain tissue by implanted microelectrode arrays is hypothesized to affect long-term recording performance. Therefore, understanding any potential differences in tissue strain caused by differences in the implant to tissue size ratio is crucial for validating the interchangeability of rat and mouse models. Hence, this study is aimed at investigating the electrophysiological variances and predictive device-induced tissue strain. Rat and mouse electrophysiological recordings were collected from implanted animals for eight weeks. A finite element model was utilized to assess the tissue strain from implanted intracortical microelectrodes, taking into account the differences in the depth within the cortex, implantation depth, and electrode geometry between the two models. The rat model demonstrated a larger percentage of channels recording single unit activity and number of units recorded per channel at acute but not chronic time points, relative to the mouse model Additionally, the finite element models also revealed no predictive differences in tissue strain between the two rodent models. Collectively our results show that these two models are comparable after taking into consideration some recommendations to maintain uniform conditions for future studies where direct comparisons of electrophysiological and tissue strain data between the two animal models will be required.
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Affiliation(s)
- Shreya Mahajan
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, United States
| | - John K. Hermann
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Hillary W. Bedell
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Jonah A. Sharkins
- Veteran Affairs Ann Arbor Healthcare System, Ann Arbor, MI, United States
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Lei Chen
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Keying Chen
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Seth M. Meade
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Cara S. Smith
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Jacob Rayyan
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - He Feng
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Youjoung Kim
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Matthew A. Schiefer
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Dawn M. Taylor
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
- Department of Neuroscience, The Cleveland Clinic, Cleveland, OH, United States
| | - Jeffrey R. Capadona
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Evon S. Ereifej
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
- Veteran Affairs Ann Arbor Healthcare System, Ann Arbor, MI, United States
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
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Márton G, Tóth EZ, Wittner L, Fiáth R, Pinke D, Orbán G, Meszéna D, Pál I, Győri EL, Bereczki Z, Kandrács Á, Hofer KT, Pongrácz A, Ulbert I, Tóth K. The neural tissue around SU-8 implants: A quantitative in vivo biocompatibility study. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 112:110870. [PMID: 32409039 DOI: 10.1016/j.msec.2020.110870] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/26/2020] [Accepted: 03/19/2020] [Indexed: 12/30/2022]
Abstract
The use of SU-8 material in the production of neural sensors has grown recently. Despite its widespread application, a detailed systematic quantitative analysis concerning its biocompatibility in the central nervous system is lacking. In this immunohistochemical study, we quantified the neuronal preservation and the severity of astrogliosis around SU-8 devices implanted in the neocortex of rats, after a 2 months survival. We found that the density of neurons significantly decreased up to a distance of 20 μm from the implant, with an averaged density decrease to 24 ± 28% of the control. At 20 to 40 μm distance from the implant, the majority of the neurons was preserved (74 ± 39% of the control) and starting from 40 μm distance from the implant, the neuron density was control-like. The density of synaptic contacts - examined at the electron microscopic level - decreased in the close vicinity of the implant, but it recovered to the control level as close as 24 μm from the implant track. The intensity of the astroglial staining significantly increased compared to the control region, up to 560 μm and 480 μm distance from the track in the superficial and deep layers of the neocortex, respectively. Electron microscopic examination revealed that the thickness of the glial scar was around 5-10 μm thin, and the ratio of glial processes in the neuropil was not more than 16% up to a distance of 12 μm from the implant. Our data suggest that neuronal survival is affected only in a very small area around the implant. The glial scar surrounding the implant is thin, and the presence of glial elements is low in the neuropil, although the signs of astrogliosis could be observed up to about 500 μm from the track. Subsequently, the biocompatibility of the SU-8 material is high. Due to its low cost fabrication and more flexible nature, SU-8 based devices may offer a promising approach to experimental and clinical applications in the future.
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Affiliation(s)
- Gergely Márton
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary; Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Práter utca 50/A, Budapest 1083, Hungary; Doctoral School on Materials Sciences and Technologies, Óbuda University, Bécsi út 96/b, Budapest 1034, Hungary.
| | - Estilla Zsófia Tóth
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary; János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Üllői út 26, Budapest 1085, Hungary.
| | - Lucia Wittner
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary; Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Práter utca 50/A, Budapest 1083, Hungary; National Institute of Clinical Neuroscience, Amerikai út 57, Budapest, Hungary, 1145.
| | - Richárd Fiáth
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary; Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Práter utca 50/A, Budapest 1083, Hungary.
| | - Domonkos Pinke
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Práter utca 50/A, Budapest 1083, Hungary.
| | - Gábor Orbán
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary; Doctoral School on Materials Sciences and Technologies, Óbuda University, Bécsi út 96/b, Budapest 1034, Hungary.
| | - Domokos Meszéna
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary; Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Práter utca 50/A, Budapest 1083, Hungary.
| | - Ildikó Pál
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary.
| | - Edit Lelle Győri
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary; Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Práter utca 50/A, Budapest 1083, Hungary; National Institute of Clinical Neuroscience, Amerikai út 57, Budapest, Hungary, 1145
| | - Zsófia Bereczki
- Department of Control Engineering and Information Technology, Budapest University of Technology and Economics, Magyar tudósok körútja 2, Budapest 1117, Hungary
| | - Ágnes Kandrács
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary; Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Práter utca 50/A, Budapest 1083, Hungary.
| | - Katharina T Hofer
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary; Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Práter utca 50/A, Budapest 1083, Hungary.
| | - Anita Pongrácz
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Práter utca 50/A, Budapest 1083, Hungary; Institute of Technical Physics and Materials Science, Centre for Energy Research, Konkoly Thege Miklós út 29-33, Budapest 1121, Hungary.
| | - István Ulbert
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary; Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Práter utca 50/A, Budapest 1083, Hungary; National Institute of Clinical Neuroscience, Amerikai út 57, Budapest, Hungary, 1145.
| | - Kinga Tóth
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary.
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13
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Thompson CH, Riggins TE, Patel PR, Chestek CA, Li W, Purcell E. Toward guiding principles for the design of biologically-integrated electrodes for the central nervous system. J Neural Eng 2020; 17:021001. [PMID: 31986501 PMCID: PMC7523527 DOI: 10.1088/1741-2552/ab7030] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Innovation in electrode design has produced a myriad of new and creative strategies for interfacing the nervous system with softer, less invasive, more broadly distributed sites with high spatial resolution. However, despite rapid growth in the use of implanted electrode arrays in research and clinical applications, there are no broadly accepted guiding principles for the design of biocompatible chronic recording interfaces in the central nervous system (CNS). Studies suggest that the architecture and flexibility of devices play important roles in determining effective tissue integration: device feature dimensions (varying from 'sub'- to 'supra'-cellular scales, <10 µm to >100 µm), Young's modulus, and bending modulus have all been identified as key features of design. However, critical knowledge gaps remain in the field with respect to the underlying motivation for these designs: (1) a systematic study of the relationship between device design features (materials, architecture, flexibility), biointegration, and signal quality needs to be performed, including controls for interaction effects between design features, (2) benchmarks for success need to be determined (biological integration, recording performance, longevity, stability), and (3) user results, particularly those that champion a specific design or electrode modification, need to be replicated across laboratories. Finally, the ancillary effects of factors such as tethering, site impedance and insertion method need to be considered. Here, we briefly review observations to-date of device design effects on tissue integration and performance, and then highlight the need for comprehensive and systematic testing of these effects moving forward.
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Affiliation(s)
- Cort H Thompson
- Department of Biomedical Engineering, Michigan State University, East Lansing, MI, United States of America
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14
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Vomero M, Mondragon NC, Stieglitz T. Electrochemical Characterization and Surface Analysis of Activated Glassy Carbon Neural Electrodes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2019:3923-3926. [PMID: 31946730 DOI: 10.1109/embc.2019.8856997] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Glassy carbon (GC) neural electrodes have recently gained visibility thanks to their great resistance to corrosion combined to their ability to record and stimulate neuronal activity. To enhance their electrochemical performance, GC electrodes are often subjected to activation, either through electrical or chemical means. In this study, we have compared the activation of GC electrodes performed using electrical biphasic pulses to chemically-induced activation. Because the GC electrodes used for this research are made by pyrolysing SU-8 photoresist - and thus they undergo massive shrinkage during carbonization - 2 electrode diameters were investigated (300 and 50 μm) with the aim of understanding if their surface composition and their ability to get activated change with their geometry. Chemical activation was induced by immersing the electrodes in 2 solutions: A1 and A2, 30 and 150 mM H2O2/PBS (hydrogen peroxide in phosphate buffered saline) respectively. The comparison between activation methods was done by measuring GC electrodes impedance, charge storage capacity (CSC) and by performing surface analysis, before and after the treatments. Results show that impedance drops in all the cases, especially at low frequencies (<; 1 kHz) and that there is always an increase in CSC. Raman spectra and relative intensities of disorder are very similar for both electrode diameters and before and after every treatment. X-Ray photoelectron spectroscopy (XPS) interestingly shows graphite content only on the 300 μm electrodes and a high percentage of graphite only on the pristine one. Apart from oxygen and nitrogen, no other species were present on the electrodes surface. In conclusion, both electrically and chemically-induced activation help improving the electrochemical performance of GC electrodes without harming them.
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15
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Pflüger P, Pinnell RC, Martini N, Hofmann UG. Chronically Implanted Microelectrodes Cause c-fos Expression Along Their Trajectory. Front Neurosci 2020; 13:1367. [PMID: 31998057 PMCID: PMC6965008 DOI: 10.3389/fnins.2019.01367] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 12/03/2019] [Indexed: 01/05/2023] Open
Abstract
When designing electrodes and probes for brain–machine interfaces, one of the challenges faced involves minimizing the brain-tissue response, which would otherwise create an environment that is detrimental for the accurate functioning of such probes. Following the implantation process, the brain reacts with a sterile inflammation response and resulting astrocytic glial scar formation, potentially resulting in neuronal cell loss around the implantation site. Such alterations in the naïve brain tissue can hinder both the quality of neuronal recordings, and the efficacy of deep-brain stimulation. In this study, we chronically implanted a glass-supported polyimide microelectrode in the dorsolateral striatum of Sprague–Dawley rats. The effect of high-frequency stimulation (HFS) was investigated using c-fos immunoreactivity techniques. GFAP and ED1 immunohistochemistry were used to analyze the brain-tissue response. No changes in c-fos expression were found for either the acute or chronic stimulus groups; although a c-fos expression was found along the length of the implantation trajectory, following chronic implantation of our stiffened polyimide microelectrode. Furthermore, we also observed the formation of a glial scar around the microelectrode, with an accompanying low number of inflammation cells. Histological and statistical analysis of NeuN-positive cells did not demonstrate a pronounced “kill zone” with accompanying neuronal cell death around the implantation site, neither on the polymer side, nor on the glass side of the PI-glass probe.
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Affiliation(s)
- Patrick Pflüger
- Section for Neuroelectronic Systems, Clinic for Neurosurgery, Medical Center - University of Freiburg, University of Freiburg, Freiburg im Breisgau, Germany.,Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Richard C Pinnell
- Section for Neuroelectronic Systems, Clinic for Neurosurgery, Medical Center - University of Freiburg, University of Freiburg, Freiburg im Breisgau, Germany.,Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Nadja Martini
- Section for Neuroelectronic Systems, Clinic for Neurosurgery, Medical Center - University of Freiburg, University of Freiburg, Freiburg im Breisgau, Germany.,Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Ulrich G Hofmann
- Section for Neuroelectronic Systems, Clinic for Neurosurgery, Medical Center - University of Freiburg, University of Freiburg, Freiburg im Breisgau, Germany.,Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
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16
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Solarana K, Ye M, Gao YR, Rafi H, Hammer DX. Longitudinal multimodal assessment of neurodegeneration and vascular remodeling correlated with signal degradation in chronic cortical silicon microelectrodes. NEUROPHOTONICS 2020; 7:015004. [PMID: 32042853 PMCID: PMC6991888 DOI: 10.1117/1.nph.7.1.015004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 01/14/2020] [Indexed: 05/19/2023]
Abstract
Significance: Cortically implanted microelectrode arrays provide a direct interface with neuronal populations and are used to restore movement capabilities and provide sensory feedback to patients with paralysis or amputation. Penetrating electrodes experience high rates of signal degradation within the first year that limit effectiveness and lead to eventual device failure. Aim: To assess vascular and neuronal changes over time in mice with implanted electrodes and examine the contribution of the brain tissue response to electrode performance. Approach: We used a multimodal approach combining in vivo electrophysiology and subcellular-level optical imaging. Results: At acute timescales, we observed structural damage from the mechanical trauma of electrode insertion, evidenced by severed dendrites in the electrode path and local hypofluorescence. Superficial vessel growth and remodeling occurred within the first few weeks in both electrode-implanted and window-only animals, but the deeper capillary growth evident in window-only animals was suppressed in electrode-implanted animals. After longer implantation periods, there was evidence of degeneration of transected dendrites superficial to the electrode path and localized neuronal cell body loss, along with deep vascular velocity changes near the electrode. Total spike rate (SR) across all animals reached a peak between 3 and 9 months postimplantation, then decreased. The local field potential signal remained relatively constant for up to 6 months, particularly in the high-gamma band, indicating long-term electrode viability and neuronal functioning at further distances from the electrode, but it showed a reduction in some animals at later time points. Most importantly, we found that progressive high-gamma and SR reductions both correlate positively with localized cell loss and decreasing capillary density within 100 μ m of the electrode. Conclusions: This multifaceted approach provided a more comprehensive picture of the ongoing biological response at the brain-electrode interface than can be achieved with postmortem histology alone and established a real-time relationship between electrophysiology and tissue damage.
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Affiliation(s)
- Krystyna Solarana
- Food and Drug Administration, Center for Radiological Devices, Office of Science and Engineering Laboratories, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Meijun Ye
- Food and Drug Administration, Center for Radiological Devices, Office of Science and Engineering Laboratories, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Yu-Rong Gao
- Food and Drug Administration, Center for Radiological Devices, Office of Science and Engineering Laboratories, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Harmain Rafi
- Food and Drug Administration, Center for Radiological Devices, Office of Science and Engineering Laboratories, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Daniel X. Hammer
- Food and Drug Administration, Center for Radiological Devices, Office of Science and Engineering Laboratories, Division of Biomedical Physics, Silver Spring, Maryland, United States
- Address all correspondence to Daniel X. Hammer, E-mail:
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17
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Olczak KP, McDermott MD, Otto KJ. Electrochemical Evaluation of Layer-by-Layer Drug Delivery Coating for Neural Interfaces. ACS APPLIED BIO MATERIALS 2019; 2:5597-5607. [DOI: 10.1021/acsabm.9b00688] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Cutrone A, Micera S. Implantable Neural Interfaces and Wearable Tactile Systems for Bidirectional Neuroprosthetics Systems. Adv Healthc Mater 2019; 8:e1801345. [PMID: 31763784 DOI: 10.1002/adhm.201801345] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 03/22/2019] [Indexed: 12/12/2022]
Abstract
Neuroprosthetics and neuromodulation represent a promising field for several related applications in the central and peripheral nervous system, such as the treatment of neurological disorders, the control of external robotic devices, and the restoration of lost tactile functions. These actions are allowed by the neural interface, a miniaturized implantable device that most commonly exploits electrical energy to fulfill these operations. A neural interface must be biocompatible, stable over time, low invasive, and highly selective; the challenge is to develop a safe, compact, and reliable tool for clinical applications. In case of anatomical impairments, neuroprosthetics is bound to the need of exploring the surrounding environment by fast-responsive and highly sensitive artificial tactile sensors that mimic the natural sense of touch. Tactile sensors and neural interfaces are closely interconnected since the readouts from the first are required to convey information to the neural implantable apparatus. The role of these devices is pivotal hence technical improvements are essential to ensure a secure system to be eventually adopted in daily life. This review highlights the fundamental criteria for the design and microfabrication of neural interfaces and artificial tactile sensors, their use in clinical applications, and future enhancements for the release of a second generation of devices.
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Affiliation(s)
- Annarita Cutrone
- The Biorobotics Institute, Viale Rinaldo Piaggio 34, 56025, Pontedera, Italy
| | - Silvestro Micera
- The Biorobotics Institute, Viale Rinaldo Piaggio 34, 56025, Pontedera, Italy
- Bertarelli Foundation Chair in Translational Neuroengineering, Centre for Neuroprosthetics and Institute of Bioengineering, School of Engineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, CH-1202, Switzerland
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19
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Golabchi A, Wu B, Cao B, Bettinger CJ, Cui XT. Zwitterionic polymer/polydopamine coating reduce acute inflammatory tissue responses to neural implants. Biomaterials 2019; 225:119519. [PMID: 31600673 PMCID: PMC6896321 DOI: 10.1016/j.biomaterials.2019.119519] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 09/17/2019] [Accepted: 09/23/2019] [Indexed: 12/13/2022]
Abstract
The inflammatory brain tissue response to implanted neural electrode devices has hindered the longevity of these implants. Zwitterionic polymers have a potent anti-fouling effect that decreases the foreign body response to subcutaneous implants. In this study, we developed a nanoscale anti-fouling coating composed of zwitterionic poly (sulfobetaine methacrylate) (PSB) and polydopamine (PDA) for neural probes. The addition of PDA improved the stability of the coating compared to PSB alone, without compromising the anti-fouling properties of the film. PDA-PSB coating reduced protein adsorption by 89% compared to bare Si samples, while fibroblast adhesion was reduced by 86%. PDA-PSB coated silicon based neural probes were implanted into mouse brain, and the inflammatory tissue responses to the implants were assessed by immunohistochemistry one week after implantation. The PSB-PDA coated implants showed a significantly decreased expression of glial fibrillary acidic protein (GFAP), a marker for reactive astrocytes, within 70 μm from the electrode-tissue interface (p < 0.05). Additionally, the coating reduced the microglia activation as shown in decreased Iba-1 and lectin staining, and improved blood-brain barrier integrity indicated by reduced immunoglobulin (IgG) leakage into the tissue around the probes. These findings demonstrate that anti-fouling zwitterionic coating is effective in suppressing the acute inflammatory brain tissue response to implants, and should be further investigated for its potential to improve chronic performance of neural implants.
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Affiliation(s)
- Asiyeh Golabchi
- Department of Bioengineering, University of Pittsburgh, USA; Center for Neural Basis of Cognition, USA
| | - Bingchen Wu
- Department of Bioengineering, University of Pittsburgh, USA; Center for Neural Basis of Cognition, USA
| | - Bin Cao
- Department of Bioengineering, University of Pittsburgh, USA; Center for Neural Basis of Cognition, USA
| | - Christopher J Bettinger
- Department of Biomedical Engineering, Department of Material Science and Engineering, Carnegie Mellon University, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, USA
| | - Xinyan Tracy Cui
- Department of Bioengineering, University of Pittsburgh, USA; Center for Neural Basis of Cognition, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, USA.
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20
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Hermann JK, Capadona JR. Understanding the Role of Innate Immunity in the Response to Intracortical Microelectrodes. Crit Rev Biomed Eng 2019; 46:341-367. [PMID: 30806249 DOI: 10.1615/critrevbiomedeng.2018027166] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intracortical microelectrodes exhibit enormous potential for researching the nervous system, steering assistive devices and functional electrode stimulation systems for severely paralyzed individuals, and augmenting the brain with computing power. Unfortunately, intracortical microelectrodes often fail to consistently record signals over clinically useful periods. Biological mechanisms, such as the foreign body response to intracortical microelectrodes and self-perpetuating neuroinflammatory cascades, contribute to the inconsistencies and decline in recording performance. Unfortunately, few studies have directly correlated microelectrode performance with the neuroinflammatory response to the implanted devices. However, of those select studies that have, the role of the innate immune system remains among the most likely links capable of corroborating the results of different studies, across laboratories. Therefore, the overall goal of this review is to highlight the role of innate immunity signaling in the foreign body response to intracortical microelectrodes and hypothesize as to appropriate strategies that may become the most relevant in enabling brain-dwelling electrodes of any geometry, or location, for a range of clinical applications.
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Affiliation(s)
- John K Hermann
- Department of Biomedical Engineering, Case Western Reserve University, 2071 Martin Luther King Jr. Drive, Wickenden Bldg, Cleveland, OH 44106; Advanced Platform Technology Center, Rehabilitation Research and Development, Louis Stokes Cleveland VA Medical Center, 10701 East Blvd. Mail Stop 151 AW/APT, Cleveland, OH 44106-1702
| | - Jeffrey R Capadona
- Department of Biomedical Engineering, Case Western Reserve University, 2071 Martin Luther King Jr. Drive, Wickenden Bldg, Cleveland, OH 44106; Advanced Platform Technology Center, Rehabilitation Research and Development, Louis Stokes Cleveland VA Medical Center, 10701 East Blvd. Mail Stop 151 AW/APT, Cleveland, OH 44106-1702
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21
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Nambiar A, Nolta NF, Han M. 3D Reconstruction of the Intracortical Volume Around a Hybrid Microelectrode Array. Front Neurosci 2019; 13:393. [PMID: 31068786 PMCID: PMC6491727 DOI: 10.3389/fnins.2019.00393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 04/05/2019] [Indexed: 11/17/2022] Open
Abstract
Extensive research using penetrating electrodes implanted in the central and peripheral nervous systems has been performed for many decades with significant advances made in recent years. While penetrating devices provide proximity to individual neurons in vivo, they suffer from declining performance over the course of months and often fail within a year. 2D histology studies using serial tissue sections have been extremely insightful in identifying and quantifying factors such as astroglial scar formation and neuronal death around the implant sites that may be contributing to failures. However, 2D histology has limitations in providing a holistic picture of the problems occurring at the electrode-tissue interface and struggles to analyze tissue below the electrode tips where the electrode tracks are no longer visible. In this study, we present 3D reconstruction of serial sections to overcome the limitations of 2D histological analysis. We used a cohort of software: XuvStitch, AutoAligner, and Imaris coupled with custom MATLAB programming to correct warping effects. Once the 3D image volume was reconstructed, we were able to use Imaris to quantify neuronal densities around the electrode tips of a hybrid microelectrode array incorporating Blackrock, Microprobes, and NeuroNexus electrodes in the same implant. This paper presents proof-of-concept and detailed methodological description of a technique which can be used to quantify neuronal densities in future studies of implanted electrodes.
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Affiliation(s)
- Aparna Nambiar
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, United States
| | - Nicholas F Nolta
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, United States
| | - Martin Han
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, United States
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22
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Cassar IR, Yu C, Sambangi J, Lee CD, Whalen JJ, Petrossians A, Grill WM. Electrodeposited platinum-iridium coating improves in vivo recording performance of chronically implanted microelectrode arrays. Biomaterials 2019; 205:120-132. [PMID: 30925400 DOI: 10.1016/j.biomaterials.2019.03.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 03/13/2019] [Accepted: 03/13/2019] [Indexed: 02/08/2023]
Abstract
Reliable single unit neuron recordings from chronically implanted microelectrode arrays (MEAs) are essential tools in the field of neural engineering. However, following implantation, MEAs undergo a foreign body response that functionally isolates them from the brain and reduces the useful longevity of the array. We tested a novel electrodeposited platinum-iridium coating (EPIC) on penetrating recording MEAs to determine if it improved recording performance. We chronically implanted the arrays in rats and used electrophysiological and histological measurements to compare quantitatively the single unit recording performance of coated vs. uncoated electrodes over a 12-week period. The coated electrodes had substantially lower impedance at 1 kHz and reduced noise, increased signal-to-noise ratio, and increased number of discernible units per electrode as compared to uncoated electrodes. Post-mortem immunohistochemistry showed no significant differences in the immune response between coated and uncoated electrodes. Overall, the EPIC arrays provided superior recording performance than uncoated arrays, likely due to lower electrode impedance and reduced noise.
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Affiliation(s)
- Isaac R Cassar
- Department of Biomedical Engineering, School of Engineering, Duke University, NC, USA
| | - Chunxiu Yu
- Department of Biomedical Engineering, School of Engineering, Duke University, NC, USA; Department of Biological Science, Michigan Technological University, MI, USA
| | - Jaydeep Sambangi
- Department of Biomedical Engineering, School of Engineering, Duke University, NC, USA
| | | | | | | | - Warren M Grill
- Department of Biomedical Engineering, School of Engineering, Duke University, NC, USA; Department of Neurobiology, School of Medicine, NC, USA; Department of Neurosurgery, School of Medicine, NC, USA; Department of Electrical and Computer Engineering, School of Engineering, Duke University, NC, USA.
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23
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Lee Y, Kong C, Chang JW, Jun SB. Carbon-Fiber Based Microelectrode Array Embedded with a Biodegradable Silk Support for In Vivo Neural Recording. J Korean Med Sci 2019; 34:e24. [PMID: 30686948 PMCID: PMC6345632 DOI: 10.3346/jkms.2019.34.e24] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 12/13/2018] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Recently, carbon fibers have been utilized to develop a depth-type microelectrode array for chronic neural recording. Since the diameter of carbon fibers is smaller than the conventional electrodes made of metal wires or microfabricated silicon, the carbon fiber electrodes showed an improved capability for chronic neural recording with less tissue damages. However, the carbon fiber based microelectrodes have a limitation of short insertion depth due to a low stiffness. METHODS We proposed a carbon fiber based microelectrode array embedded with a mechanical support structure to facilitate the penetration into the deeper brain. The support is made of biodegradable silk fibroin to reduce the reactive tissue responses. The 4-channel carbon fiber based microelectrode arrays were fabricated and accessed in terms of electrochemical impedance, recording capability for 1-month implantation in rat hippocampi. The electrodes with tungsten supports were fabricated and tested as a control group. Immunohistochemical analysis was performed to identify the reactive glial responses. RESULTS The carbon fiber based electrode arrays with silk supports showed about 2-fold impedance increase 2 weeks after implantation while the number of active electrodes decreased simultaneously. However, after 1 month, the electrode impedance decreased back to its initial value and the percentage of active electrodes also increased above 70%. Immunohistochemical staining clearly showed that the electrodes with silk supports induced less reactive glial responses than that with tungsten supports. CONCLUSION The proposed carbon fiber based microelectrode array is expected to be used for long-term in vivo neural recording from deep brain regions with the minimized reactive tissue response.
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Affiliation(s)
- Yena Lee
- Department of Electronic and Electrical Engineering, ELTEC College of Engineering, Ewha Womans University, Seoul, Korea
| | - Chanho Kong
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea
| | - Jin Woo Chang
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea
| | - Sang Beom Jun
- Department of Electronic and Electrical Engineering, ELTEC College of Engineering, Ewha Womans University, Seoul, Korea
- Department of Brain and Cognitive Science, College of Scranton, Ewha Womans University, Seoul, Korea
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Woods V, Trumpis M, Bent B, Palopoli-Trojani K, Chiang CH, Wang C, Yu C, Insanally MN, Froemke RC, Viventi J. Long-term recording reliability of liquid crystal polymer µECoG arrays. J Neural Eng 2018; 15:066024. [PMID: 30246690 PMCID: PMC6342453 DOI: 10.1088/1741-2552/aae39d] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The clinical use of microsignals recorded over broad cortical regions is largely limited by the chronic reliability of the implanted interfaces. APPROACH We evaluated the chronic reliability of novel 61-channel micro-electrocorticographic (µECoG) arrays in rats chronically implanted for over one year and using accelerated aging. Devices were encapsulated with polyimide (PI) or liquid crystal polymer (LCP), and fabricated using commercial manufacturing processes. In vitro failure modes and predicted lifetimes were determined from accelerated soak testing. Successful designs were implanted epidurally over the rodent auditory cortex. Trends in baseline signal level, evoked responses and decoding performance were reported for over one year of implantation. MAIN RESULTS Devices fabricated with LCP consistently had longer in vitro lifetimes than PI encapsulation. Our accelerated aging results predicted device integrity beyond 3.4 years. Five implanted arrays showed stable performance over the entire implantation period (247-435 d). Our regression analysis showed that impedance predicted signal quality and information content only in the first 31 d of recordings and had little predictive value in the chronic phase (>31 d). In the chronic phase, site impedances slightly decreased yet decoding performance became statistically uncorrelated with impedance. We also employed an improved statistical model of spatial variation to measure sensitivity to locally varying fields, which is typically concealed in standard signal power calculations. SIGNIFICANCE These findings show that µECoG arrays can reliably perform in chronic applications in vivo for over one year, which facilitates the development of a high-density, clinically viable interface.
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Affiliation(s)
- Virginia Woods
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
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25
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In vitro electrochemical assessment of electrodes for neurostimulation in roach biobots. PLoS One 2018; 13:e0203880. [PMID: 30303994 PMCID: PMC6179205 DOI: 10.1371/journal.pone.0203880] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 08/24/2018] [Indexed: 11/19/2022] Open
Abstract
Biobotics investigates the use of live insects as biological robots whose locomotion can be controlled by neurostimulation through implanted electrodes. Inactivity in the biobots (biological robots) can sometimes be noticed following extended neurostimulation, partly owing to incompatibility of implanted electrodes with the biobotic application or gradual degradation of the tissue-electrode interface. Implanted electrodes need to sufficiently exhibit consistent, reliable, and stable performance during stimulation experiments, have low tissue-electrode impedance, facilitate good charge injection capacity, and be compact in size or shape. Towards the goal of finding such electrodes suitable for biobotic applications, we compare electrochemical performances of five different types of electrodes in vitro with a saline based electrolytic medium. These include stainless steel wire electrodes, microfabricated flexible gold electrodes coated with PEDOT:PSS conductive polymer, eutectic gallium indium (EGaIn) in a tube, and “hybrid” stainless steel electrodes coated with EGaIn. We also performed accelerated aging of the electrodes to help estimate their longitudinal performance. Based on our experimentation, microfabricated electrodes with PEDOT:PSS and stainless steel electrodes coated with EGaIn performed remarkably well. This is the first time conductive polymer and liquid metal electrodes were studied comparatively for neurostimulation applications. These in vitro comparison results will be used in the future to provide a benchmark for subsequent in vivo tests with implanted electrodes in cockroach biobots.
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Conductively coupled flexible silicon electronic systems for chronic neural electrophysiology. Proc Natl Acad Sci U S A 2018; 115:E9542-E9549. [PMID: 30228119 DOI: 10.1073/pnas.1813187115] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Materials and structures that enable long-term, intimate coupling of flexible electronic devices to biological systems are critically important to the development of advanced biomedical implants for biological research and for clinical medicine. By comparison with simple interfaces based on arrays of passive electrodes, the active electronics in such systems provide powerful and sometimes essential levels of functionality; they also demand long-lived, perfect biofluid barriers to prevent corrosive degradation of the active materials and electrical damage to the adjacent tissues. Recent reports describe strategies that enable relevant capabilities in flexible electronic systems, but only for capacitively coupled interfaces. Here, we introduce schemes that exploit patterns of highly doped silicon nanomembranes chemically bonded to thin, thermally grown layers of SiO2 as leakage-free, chronically stable, conductively coupled interfaces. The results can naturally support high-performance, flexible silicon electronic systems capable of amplified sensing and active matrix multiplexing in biopotential recording and in stimulation via Faradaic charge injection. Systematic in vitro studies highlight key considerations in the materials science and the electrical designs for high-fidelity, chronic operation. The results provide a versatile route to biointegrated forms of flexible electronics that can incorporate the most advanced silicon device technologies with broad applications in electrical interfaces to the brain and to other organ systems.
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27
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Electrophysiological Correlates of Blast-Wave Induced Cerebellar Injury. Sci Rep 2018; 8:13633. [PMID: 30206255 PMCID: PMC6134123 DOI: 10.1038/s41598-018-31728-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 08/24/2018] [Indexed: 12/17/2022] Open
Abstract
Understanding the mechanisms underlying traumatic neural injury and the sequelae of events in the acute phase is important for deciding on the best window of therapeutic intervention. We hypothesized that evoked potentials (EP) recorded from the cerebellar cortex can detect mild levels of neural trauma and provide a qualitative assessment tool for progression of cerebellar injury in time. The cerebellar local field potentials evoked by a mechanical tap on the hand and collected with chronically implanted micro-ECoG arrays on the rat cerebellar cortex demonstrated substantial changes both in amplitude and timing as a result of blast-wave induced injury. The results revealed that the largest EP changes occurred within the first day of injury, and partial recoveries were observed from day-1 to day-3, followed by a period of gradual improvements (day-7 to day-14). The mossy fiber (MF) and climbing fiber (CF) mediated components of the EPs were affected differentially. The behavioral tests (ladder rung walking) and immunohistological analysis (calbindin and caspase-3) did not reveal any detectable changes at these blast pressures that are typically considered as mild (100-130 kPa). The results demonstrate the sensitivity of the electrophysiological method and its use as a tool to monitor the progression of cerebellar injuries in longitudinal animal studies.
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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.
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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.
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29
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Kozai TDY. The History and Horizons of Microscale Neural Interfaces. MICROMACHINES 2018; 9:E445. [PMID: 30424378 PMCID: PMC6187275 DOI: 10.3390/mi9090445] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 08/27/2018] [Accepted: 09/03/2018] [Indexed: 12/29/2022]
Abstract
Microscale neural technologies interface with the nervous system to record and stimulate brain tissue with high spatial and temporal resolution. These devices are being developed to understand the mechanisms that govern brain function, plasticity and cognitive learning, treat neurological diseases, or monitor and restore functions over the lifetime of the patient. Despite decades of use in basic research over days to months, and the growing prevalence of neuromodulation therapies, in many cases the lack of knowledge regarding the fundamental mechanisms driving activation has dramatically limited our ability to interpret data or fine-tune design parameters to improve long-term performance. While advances in materials, microfabrication techniques, packaging, and understanding of the nervous system has enabled tremendous innovation in the field of neural engineering, many challenges and opportunities remain at the frontiers of the neural interface in terms of both neurobiology and engineering. In this short-communication, we explore critical needs in the neural engineering field to overcome these challenges. Disentangling the complexities involved in the chronic neural interface problem requires simultaneous proficiency in multiple scientific and engineering disciplines. The critical component of advancing neural interface knowledge is to prepare the next wave of investigators who have simultaneous multi-disciplinary proficiencies with a diverse set of perspectives necessary to solve the chronic neural interface challenge.
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Affiliation(s)
- Takashi D Y Kozai
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA.
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15213, USA.
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15261, USA.
- McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15212, USA.
- NeuroTech Center, University of Pittsburgh Brain Institute, Pittsburgh, PA 15260, USA.
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30
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Hong G, Viveros RD, Zwang TJ, Yang X, Lieber CM. Tissue-like Neural Probes for Understanding and Modulating the Brain. Biochemistry 2018; 57:3995-4004. [PMID: 29529359 PMCID: PMC6039269 DOI: 10.1021/acs.biochem.8b00122] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Electrophysiology tools have contributed substantially to understanding brain function, yet the capabilities of conventional electrophysiology probes have remained limited in key ways because of large structural and mechanical mismatches with respect to neural tissue. In this Perspective, we discuss how the general goal of probe design in biochemistry, that the probe or label have a minimal impact on the properties and function of the system being studied, can be realized by minimizing structural, mechanical, and topological differences between neural probes and brain tissue, thus leading to a new paradigm of tissue-like mesh electronics. The unique properties and capabilities of the tissue-like mesh electronics as well as future opportunities are summarized. First, we discuss the design of an ultraflexible and open mesh structure of electronics that is tissue-like and can be delivered in the brain via minimally invasive syringe injection like molecular and macromolecular pharmaceuticals. Second, we describe the unprecedented tissue healing without chronic immune response that leads to seamless three-dimensional integration with a natural distribution of neurons and other key cells through these tissue-like probes. These unique characteristics lead to unmatched stable long-term, multiplexed mapping and modulation of neural circuits at the single-neuron level on a year time scale. Last, we offer insights on several exciting future directions for the tissue-like electronics paradigm that capitalize on their unique properties to explore biochemical interactions and signaling in a "natural" brain environment.
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Affiliation(s)
- Guosong Hong
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Robert D. Viveros
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Theodore J. Zwang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Xiao Yang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Charles M. Lieber
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
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31
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Downey JE, Schwed N, Chase SM, Schwartz AB, Collinger JL. Intracortical recording stability in human brain–computer interface users. J Neural Eng 2018; 15:046016. [PMID: 29553484 DOI: 10.1088/1741-2552/aab7a0] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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32
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Dubey A, Jangir H, Pandey M, Dubey MM, Verma S, Roy M, Singh SK, Philip D, Sarkar S, Das M. An eco-friendly, low-power charge storage device from bio-tolerable nano cerium oxide electrodes for bioelectrical and biomedical applications. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aaa282] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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33
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Prospects for a Robust Cortical Recording Interface. Neuromodulation 2018. [DOI: 10.1016/b978-0-12-805353-9.00028-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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34
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Vomero M, Castagnola E, Ordonez JS, Carli S, Zucchini E, Maggiolini E, Gueli C, Goshi N, Ciarpella F, Cea C, Fadiga L, Ricci D, Kassegne S, Stieglitz T. Incorporation of Silicon Carbide and Diamond‐Like Carbon as Adhesion Promoters Improves In Vitro and In Vivo Stability of Thin‐Film Glassy Carbon Electrocorticography Arrays. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/adbi.201700081] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Maria Vomero
- Institute of Microsystem Technology (IMTEK) Laboratory for Biomedical Microtechnology Georges‐Koehler‐Allee 102 D‐79110 Freiburg Germany
- Cluster of Excellence BrainLinks‐BrainTools Georges‐Koehler‐Allee 80 79110 Freiburg Germany
| | - Elisa Castagnola
- MEMS Research Laboratory Department of Mechanical Engineering College of Engineering San Diego State University 5500 Campanile Drive San Diego CA 92182‐1323 USA
- Center for Sensorimotor Neural Engineering (CSNE) Box 37, 1414 NE 42nd St., Suite 204 Seattle WA 98105–6271 USA
| | - Juan S. Ordonez
- Institute of Microsystem Technology (IMTEK) Laboratory for Biomedical Microtechnology Georges‐Koehler‐Allee 102 D‐79110 Freiburg Germany
| | - Stefano Carli
- Center for Translational Neurophysiology of Speech and Communication Istituto Italiano di Tecnologia Via Fossato di Mortara 17/19 44121 Ferrara Italy
| | - Elena Zucchini
- Center for Translational Neurophysiology of Speech and Communication Istituto Italiano di Tecnologia Via Fossato di Mortara 17/19 44121 Ferrara Italy
| | - Emma Maggiolini
- Center for Translational Neurophysiology of Speech and Communication Istituto Italiano di Tecnologia Via Fossato di Mortara 17/19 44121 Ferrara Italy
| | - Calogero Gueli
- Institute of Microsystem Technology (IMTEK) Laboratory for Biomedical Microtechnology Georges‐Koehler‐Allee 102 D‐79110 Freiburg Germany
| | - Noah Goshi
- MEMS Research Laboratory Department of Mechanical Engineering College of Engineering San Diego State University 5500 Campanile Drive San Diego CA 92182‐1323 USA
- Center for Sensorimotor Neural Engineering (CSNE) Box 37, 1414 NE 42nd St., Suite 204 Seattle WA 98105–6271 USA
| | - Francesca Ciarpella
- Center for Translational Neurophysiology of Speech and Communication Istituto Italiano di Tecnologia Via Fossato di Mortara 17/19 44121 Ferrara Italy
| | - Claudia Cea
- MEMS Research Laboratory Department of Mechanical Engineering College of Engineering San Diego State University 5500 Campanile Drive San Diego CA 92182‐1323 USA
- Center for Sensorimotor Neural Engineering (CSNE) Box 37, 1414 NE 42nd St., Suite 204 Seattle WA 98105–6271 USA
| | - Luciano Fadiga
- Center for Translational Neurophysiology of Speech and Communication Istituto Italiano di Tecnologia Via Fossato di Mortara 17/19 44121 Ferrara Italy
- Section of Human Physiology University of Ferrara Via Fossato di Mortara 17/19 44121 Ferrara Italy
| | - Davide Ricci
- Center for Translational Neurophysiology of Speech and Communication Istituto Italiano di Tecnologia Via Fossato di Mortara 17/19 44121 Ferrara Italy
| | - Sam Kassegne
- MEMS Research Laboratory Department of Mechanical Engineering College of Engineering San Diego State University 5500 Campanile Drive San Diego CA 92182‐1323 USA
- Center for Sensorimotor Neural Engineering (CSNE) Box 37, 1414 NE 42nd St., Suite 204 Seattle WA 98105–6271 USA
| | - Thomas Stieglitz
- Institute of Microsystem Technology (IMTEK) Laboratory for Biomedical Microtechnology Georges‐Koehler‐Allee 102 D‐79110 Freiburg Germany
- Cluster of Excellence BrainLinks‐BrainTools Georges‐Koehler‐Allee 80 79110 Freiburg Germany
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35
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Salatino JW, Ludwig KA, Kozai TDY, Purcell EK. Glial responses to implanted electrodes in the brain. Nat Biomed Eng 2017; 1:862-877. [PMID: 30505625 PMCID: PMC6261524 DOI: 10.1038/s41551-017-0154-1] [Citation(s) in RCA: 305] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 10/04/2017] [Indexed: 01/20/2023]
Abstract
The use of implants that can electrically stimulate or record electrophysiological or neurochemical activity in nervous tissue is rapidly expanding. Despite remarkable results in clinical studies and increasing market approvals, the mechanisms underlying the therapeutic effects of neuroprosthetic and neuromodulation devices, as well as their side effects and reasons for their failure, remain poorly understood. A major assumption has been that the signal-generating neurons are the only important target cells of neural-interface technologies. However, recent evidence indicates that the supporting glial cells remodel the structure and function of neuronal networks and are an effector of stimulation-based therapy. Here, we reframe the traditional view of glia as a passive barrier, and discuss their role as an active determinant of the outcomes of device implantation. We also discuss the implications that this has on the development of bioelectronic medical devices.
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Affiliation(s)
- Joseph W. Salatino
- Department of Biomedical Engineering, Michigan State University, East Lansing, MI, USA
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
| | - Kip A. Ludwig
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Takashi D. Y. Kozai
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Neurotech Center, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA
| | - Erin K. Purcell
- Department of Biomedical Engineering, Michigan State University, East Lansing, MI, USA
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
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36
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Ung H, Baldassano SN, Bink H, Krieger AM, Williams S, Vitale F, Wu C, Freestone D, Nurse E, Leyde K, Davis KA, Cook M, Litt B. Intracranial EEG fluctuates over months after implanting electrodes in human brain. J Neural Eng 2017; 14:056011. [PMID: 28862995 PMCID: PMC5860812 DOI: 10.1088/1741-2552/aa7f40] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Implanting subdural and penetrating electrodes in the brain causes acute trauma and inflammation that affect intracranial electroencephalographic (iEEG) recordings. This behavior and its potential impact on clinical decision-making and algorithms for implanted devices have not been assessed in detail. In this study we aim to characterize the temporal and spatial variability of continuous, prolonged human iEEG recordings. APPROACH Intracranial electroencephalography from 15 patients with drug-refractory epilepsy, each implanted with 16 subdural electrodes and continuously monitored for an average of 18 months, was included in this study. Time and spectral domain features were computed each day for each channel for the duration of each patient's recording. Metrics to capture post-implantation feature changes and inflexion points were computed on group and individual levels. A linear mixed model was used to characterize transient group-level changes in feature values post-implantation and independent linear models were used to describe individual variability. MAIN RESULTS A significant decline in features important to seizure detection and prediction algorithms (mean line length, energy, and half-wave), as well as mean power in the Berger and high gamma bands, was observed in many patients over 100 d following implantation. In addition, spatial variability across electrodes declines post-implantation following a similar timeframe. All selected features decreased by 14-50% in the initial 75 d of recording on the group level, and at least one feature demonstrated this pattern in 13 of the 15 patients. Our findings indicate that iEEG signal features demonstrate increased variability following implantation, most notably in the weeks immediately post-implant. SIGNIFICANCE These findings suggest that conclusions drawn from iEEG, both clinically and for research, should account for spatiotemporal signal variability and that properly assessing the iEEG in patients, depending upon the application, may require extended monitoring.
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Affiliation(s)
- Hoameng Ung
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia PA, USA
| | - Steven N. Baldassano
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia PA, USA
| | - Hank Bink
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia PA, USA
| | - Abba M Krieger
- Department of Statistics, University of Pennsylvania, Philadelphia, PA, USA
| | - Shawniqua Williams
- Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia PA, USA
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Flavia Vitale
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia PA, USA
| | - Chengyuan Wu
- Department of Neurosurgery, Thomas Jefferson University Hospitals, Philadelphia, PA, USA
| | - Dean Freestone
- Department of Medicine, St. Vincent's Hospital, University of Melbourne, Victoria, Australia
| | - Ewan Nurse
- Department of Medicine, St. Vincent's Hospital, University of Melbourne, Victoria, Australia
- Department of Biomedical Engineering, University of Melbourne, Victoria, Australia
| | - Kent Leyde
- Cascade Medical Devices, Seattle, Washington
| | - Kathryn A Davis
- Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia PA, USA
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Mark Cook
- Department of Medicine, St. Vincent's Hospital, University of Melbourne, Victoria, Australia
| | - Brian Litt
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia PA, USA
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
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37
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Lee HC, Gaire J, Currlin SW, McDermott MD, Park K, Otto KJ. Foreign Body Response to Intracortical Microelectrodes Is Not Altered with Dip-Coating of Polyethylene Glycol (PEG). Front Neurosci 2017; 11:513. [PMID: 28959183 PMCID: PMC5603673 DOI: 10.3389/fnins.2017.00513] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 08/31/2017] [Indexed: 11/24/2022] Open
Abstract
Poly(ethylene glycol) (PEG) is a frequently used polymer for neural implants due to its biocompatible property. As a follow-up to our recent study that used PEG for stiffening flexible neural probes, we have evaluated the biological implications of using devices dip-coated with PEG for chronic neural implants. Mice (wild-type and CX3CR1-GFP) received bilateral implants within the sensorimotor cortex, one hemisphere with a PEG-coated probe and the other with a non-coated probe for 4 weeks. Quantitative analyses were performed using biomarkers for activated microglia/macrophages, astrocytes, blood-brain barrier leakage, and neuronal nuclei to determine the degree of foreign body response (FBR) resulting from the implanted microelectrodes. Despite its well-known acute anti-biofouling property, we observed that PEG-coated devices caused no significantly different FBR compared to non-coated controls at 4 weeks. A repetition using CX3CR1-GFP mice cohort showed similar results. Our histological findings suggest that there is no significant impact of acute delivery of PEG on the FBR in the long-term, and that temporary increase in the device footprint due to the coating of PEG also does not have a significant impact. Large variability seen within the same treatment group also implies that avoiding large superficial vasculature during implantation is not sufficient to minimize inter-animal variability.
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Affiliation(s)
- Heui C Lee
- Weldon School of Biomedical Engineering, Purdue UniversityWest Lafayette, IN, United States.,J. Crayton Pruitt Family Department of Biomedical Engineering, University of FloridaGainesville, FL, United States
| | - Janak Gaire
- Department of Neuroscience, University of FloridaGainesville, FL, United States
| | - Seth W Currlin
- Department of Neuroscience, University of FloridaGainesville, FL, United States
| | - Matthew D McDermott
- Weldon School of Biomedical Engineering, Purdue UniversityWest Lafayette, IN, United States
| | - Kinam Park
- Weldon School of Biomedical Engineering, Purdue UniversityWest Lafayette, IN, United States.,Department of Industrial and Physical Pharmacy, Purdue UniversityWest Lafayette, IN, United States
| | - Kevin J Otto
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of FloridaGainesville, FL, United States.,Department of Neuroscience, University of FloridaGainesville, FL, United States.,Department of Materials Science and Engineering, University of FloridaGainesville, FL, United States.,Department of Neurology, University of FloridaGainesville, FL, United States.,Nanoscience Institute for Medical and Engineering Technology, University of FloridaGainesville, FL, United States
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38
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Affiliation(s)
- Eduardo Fernández
- Bioengineering Institute; Miguel Hernández University of Elche and CIBER BBN; Elche 03202 Spain
| | - Pablo Botella
- Instituto de Tecnología Química; Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas; Valencia 46022 Spain
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Lotti F, Ranieri F, Vadalà G, Zollo L, Di Pino G. Invasive Intraneural Interfaces: Foreign Body Reaction Issues. Front Neurosci 2017; 11:497. [PMID: 28932181 PMCID: PMC5592213 DOI: 10.3389/fnins.2017.00497] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 08/23/2017] [Indexed: 12/20/2022] Open
Abstract
Intraneural interfaces are stimulation/registration devices designed to couple the peripheral nervous system (PNS) with the environment. Over the last years, their use has increased in a wide range of applications, such as the control of a new generation of neural-interfaced prostheses. At present, the success of this technology is limited by an electrical impedance increase, due to an inflammatory response called foreign body reaction (FBR), which leads to the formation of a fibrotic tissue around the interface, eventually causing an inefficient transduction of the electrical signal. Based on recent developments in biomaterials and inflammatory/fibrotic pathologies, we explore and select the biological solutions that might be adopted in the neural interfaces FBR context: modifications of the interface surface, such as organic and synthetic coatings; the use of specific drugs or molecular biology tools to target the microenvironment around the interface; the development of bio-engineered-scaffold to reduce immune response and promote interface-tissue integration. By linking what we believe are the major crucial steps of the FBR process with related solutions, we point out the main issues that future research has to focus on: biocompatibility without losing signal conduction properties, good reproducible in vitro/in vivo models, drugs exhaustion and undesired side effects. The underlined pros and cons of proposed solutions show clearly the importance of a better understanding of all the molecular and cellular pathways involved and the need of a multi-target action based on a bio-engineered combination approach.
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Affiliation(s)
- Fiorenza Lotti
- NeXT: Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Università Campus Bio-MedicoRome, Italy.,Research Unit of Orthopaedic and Trauma Surgery, Università Campus Bio-MedicoRome, Italy
| | - Federico Ranieri
- NeXT: Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Università Campus Bio-MedicoRome, Italy.,Fondazione Alberto Sordi-Research Institute for AgingRome, Italy.,Research Unit of Neurology, Neurophysiology and Neurobiology, Università Campus Bio-MedicoRome, Italy
| | - Gianluca Vadalà
- Research Unit of Orthopaedic and Trauma Surgery, Università Campus Bio-MedicoRome, Italy
| | - Loredana Zollo
- Research Unit of Biomedical Robotics and Biomicrosystems, Università Campus Bio-MedicoRome, Italy
| | - Giovanni Di Pino
- NeXT: Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Università Campus Bio-MedicoRome, Italy.,Research Unit of Neurology, Neurophysiology and Neurobiology, Università Campus Bio-MedicoRome, Italy
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40
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Slutzky MW, Flint RD. Physiological properties of brain-machine interface input signals. J Neurophysiol 2017; 118:1329-1343. [PMID: 28615329 DOI: 10.1152/jn.00070.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 06/08/2017] [Accepted: 06/08/2017] [Indexed: 12/16/2022] Open
Abstract
Brain-machine interfaces (BMIs), also called brain-computer interfaces (BCIs), decode neural signals and use them to control some type of external device. Despite many experimental successes and terrific demonstrations in animals and humans, a high-performance, clinically viable device has not yet been developed for widespread usage. There are many factors that impact clinical viability and BMI performance. Arguably, the first of these is the selection of brain signals used to control BMIs. In this review, we summarize the physiological characteristics and performance-including movement-related information, longevity, and stability-of multiple types of input signals that have been used in invasive BMIs to date. These include intracortical spikes as well as field potentials obtained inside the cortex, at the surface of the cortex (electrocorticography), and at the surface of the dura mater (epidural signals). We also discuss the potential for future enhancements in input signal performance, both by improving hardware and by leveraging the knowledge of the physiological characteristics of these signals to improve decoding and stability.
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Affiliation(s)
- Marc W Slutzky
- Department of Neurology, Northwestern University, Chicago, Illinois; .,Department of Physiology, Northwestern University, Chicago, Illinois; and.,Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois
| | - Robert D Flint
- Department of Neurology, Northwestern University, Chicago, Illinois
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Capacitively Coupled Arrays of Multiplexed Flexible Silicon Transistors for Long-Term Cardiac Electrophysiology. Nat Biomed Eng 2017; 1. [PMID: 28804678 DOI: 10.1038/s41551-017-0038] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Advanced capabilities in electrical recording are essential for the treatment of heart-rhythm diseases. The most advanced technologies use flexible integrated electronics; however, the penetration of biological fluids into the underlying electronics and any ensuing electrochemical reactions pose significant safety risks. Here, we show that an ultrathin, leakage-free, biocompatible dielectric layer can completely seal an underlying layer of flexible electronics while allowing for electrophysiological measurements through capacitive coupling between tissue and the electronics, and thus without the need for direct metal contact. The resulting current-leakage levels and operational lifetimes are, respectively, four orders of magnitude smaller and between two and three orders of magnitude longer than those of any other flexible-electronics technology. Systematic electrophysiological studies with normal, paced and arrhythmic conditions in Langendorff hearts highlight the capabilities of the capacitive-coupling approach. Our technology provides a realistic pathway towards the broad applicability of biocompatible, flexible electronic implants.
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Ceyssens F, Deprez M, Turner N, Kil D, van Kuyck K, Welkenhuysen M, Nuttin B, Badylak S, Puers R. Extracellular matrix proteins as temporary coating for thin-film neural implants. J Neural Eng 2017; 14:014001. [DOI: 10.1088/1741-2552/14/1/014001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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43
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Harris AR, Paolini AG. Correlation of Impedance and Effective Electrode Area of Iridium Oxide Neural Electrodes. Aust J Chem 2017. [DOI: 10.1071/ch17218] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Iridium oxide is routinely used for bionic applications owing to its high charge injection capacity. The electrode impedance at 1 kHz is typically reported to predict neural recording performance. In this article, the impedance of activated iridium oxide films (AIROFs) has been examined. The impedance of unactivated iridium electrodes was half that of platinum electrodes of similar geometry, indicating some iridium oxide was present on the electrode surface. A two time constant equivalent circuit was used to model the impedance of activated iridium. The impedance at low and intermediate frequencies decreased with increasing number of activation pulses and total activation charge. The impedance at 12 Hz correlated with the steady-state diffusion electroactive area. The impedance at 12 Hz also correlated with the charge density of the electrode. The high charge density and low impedance of AIROFs may provide improved neural stimulation and recording properties compared with typically used platinum electrodes.
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Kim BJ, Kim YR, Seo M, Kim EJ, Jeon J, Chung TD. Electrochemical Impedance Spectroscopy at Well-Controlled dc Bias for Nanoporous Platinum Microelectrodes in Rat Embryo Brain. ChemElectroChem 2016. [DOI: 10.1002/celc.201600404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Beom Jin Kim
- Department of Chemistry; Seoul National University; Seoul 00826 Republic of Korea
| | - Yang-Rae Kim
- Department of Chemistry; Kwangwoon University; Seoul 01897 Republic of Korea
| | - Minjee Seo
- Department of Chemistry; Seoul National University; Seoul 00826 Republic of Korea
| | - Eun Joong Kim
- Department of Chemistry; Seoul National University; Seoul 00826 Republic of Korea
| | - Joohee Jeon
- Department of Chemistry; Seoul National University; Seoul 00826 Republic of Korea
| | - Taek Dong Chung
- Department of Chemistry; Seoul National University; Seoul 00826 Republic of Korea
- Advanced Institutes of Convergence Technology; Suwon-Si Gyeonggi-do 16229 Republic of Korea
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45
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Patel PR, Zhang H, Robbins MT, Nofar JB, Marshall SP, Kobylarek MJ, Kozai TDY, Kotov NA, Chestek CA. Chronic in vivo stability assessment of carbon fiber microelectrode arrays. J Neural Eng 2016; 13:066002. [PMID: 27705958 PMCID: PMC5118062 DOI: 10.1088/1741-2560/13/6/066002] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Individual carbon fiber microelectrodes can record unit activity in both acute and semi-chronic (∼1 month) implants. Additionally, new methods have been developed to insert a 16 channel array of carbon fiber microelectrodes. Before assessing the in vivo long-term viability of these arrays, accelerated soak tests were carried out to determine the most stable site coating material. Next, a multi-animal, multi-month, chronic implantation study was carried out with carbon fiber microelectrode arrays and silicon electrodes. APPROACH Carbon fibers were first functionalized with one of two different formulations of PEDOT and subjected to accelerated aging in a heated water bath. After determining the best PEDOT formula to use, carbon fiber arrays were chronically implanted in rat motor cortex. Some rodents were also implanted with a single silicon electrode, while others received both. At the end of the study a subset of animals were perfused and the brain tissue sliced. Tissue sections were stained for astrocytes, microglia, and neurons. The local reactive responses were assessed using qualitative and quantitative methods. MAIN RESULTS Electrophysiology recordings showed the carbon fibers detecting unit activity for at least 3 months with average amplitudes of ∼200 μV. Histology analysis showed the carbon fiber arrays with a minimal to non-existent glial scarring response with no adverse effects on neuronal density. Silicon electrodes showed large glial scarring that impacted neuronal counts. SIGNIFICANCE This study has validated the use of carbon fiber microelectrode arrays as a chronic neural recording technology. These electrodes have demonstrated the ability to detect single units with high amplitude over 3 months, and show the potential to record for even longer periods. In addition, the minimal reactive response should hold stable indefinitely, as any response by the immune system may reach a steady state after 12 weeks.
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Affiliation(s)
- Paras R Patel
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
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Neural Probes for Chronic Applications. MICROMACHINES 2016; 7:mi7100179. [PMID: 30404352 PMCID: PMC6190051 DOI: 10.3390/mi7100179] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 09/12/2016] [Accepted: 09/26/2016] [Indexed: 12/11/2022]
Abstract
Developed over approximately half a century, neural probe technology is now a mature technology in terms of its fabrication technology and serves as a practical alternative to the traditional microwires for extracellular recording. Through extensive exploration of fabrication methods, structural shapes, materials, and stimulation functionalities, neural probes are now denser, more functional and reliable. Thus, applications of neural probes are not limited to extracellular recording, brain-machine interface, and deep brain stimulation, but also include a wide range of new applications such as brain mapping, restoration of neuronal functions, and investigation of brain disorders. However, the biggest limitation of the current neural probe technology is chronic reliability; neural probes that record with high fidelity in acute settings often fail to function reliably in chronic settings. While chronic viability is imperative for both clinical uses and animal experiments, achieving one is a major technological challenge due to the chronic foreign body response to the implant. Thus, this review aims to outline the factors that potentially affect chronic recording in chronological order of implantation, summarize the methods proposed to minimize each factor, and provide a performance comparison of the neural probes developed for chronic applications.
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Schmidt RF, Wu C, Lang MJ, Soni P, Williams KA, Boorman DW, Evans JJ, Sperling MR, Sharan AD. Complications of subdural and depth electrodes in 269 patients undergoing 317 procedures for invasive monitoring in epilepsy. Epilepsia 2016; 57:1697-1708. [DOI: 10.1111/epi.13503] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Richard F. Schmidt
- Department of Neurological Surgery; Thomas Jefferson University; Philadelphia Pennsylvania U.S.A
| | - Chengyuan Wu
- Department of Neurological Surgery; Thomas Jefferson University; Philadelphia Pennsylvania U.S.A
| | - Michael J. Lang
- Department of Neurological Surgery; Thomas Jefferson University; Philadelphia Pennsylvania U.S.A
| | - Pranay Soni
- Department of Neurological Surgery; Thomas Jefferson University; Philadelphia Pennsylvania U.S.A
| | - Kim A. Williams
- Department of Neurological Surgery; Thomas Jefferson University; Philadelphia Pennsylvania U.S.A
| | - David W. Boorman
- Department of Neurological Surgery; Thomas Jefferson University; Philadelphia Pennsylvania U.S.A
| | - James J. Evans
- Department of Neurological Surgery; Thomas Jefferson University; Philadelphia Pennsylvania U.S.A
| | - Michael R. Sperling
- Department of Neurology; Thomas Jefferson University; Philadelphia Pennsylvania U.S.A
| | - Ashwini D. Sharan
- Department of Neurological Surgery; Thomas Jefferson University; Philadelphia Pennsylvania U.S.A
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Knaack GL, McHail DG, Borda G, Koo B, Peixoto N, Cogan SF, Dumas TC, Pancrazio JJ. In vivo Characterization of Amorphous Silicon Carbide As a Biomaterial for Chronic Neural Interfaces. Front Neurosci 2016; 10:301. [PMID: 27445672 PMCID: PMC4923247 DOI: 10.3389/fnins.2016.00301] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Accepted: 06/15/2016] [Indexed: 11/13/2022] Open
Abstract
Implantable microelectrode arrays (MEAs) offer clinical promise for prosthetic devices by enabling restoration of communication and control of artificial limbs. While proof-of-concept recordings from MEAs have been promising, work in animal models demonstrates that the obtained signals degrade over time. Both material robustness and tissue response are acknowledged to have a role in device lifetime. Amorphous Silicon carbide (a-SiC), a robust material that is corrosion resistant, has emerged as an alternative encapsulation layer for implantable devices. We systematically examined the impact of a-SiC coating on Si probes by immunohistochemical characterization of key markers implicated in tissue-device response. After implantation, we performed device capture immunohistochemical labeling of neurons, astrocytes, and activated microglia/macrophages after 4 and 8 weeks of implantation. Neuron loss and microglia activation were similar between Si and a-SiC coated probes, while tissue implanted with a-SiC displayed a reduction in astrocytes adjacent to the probe. These results suggest that a-SiC has a similar biocompatibility profile as Si, and may be suitable for implantable MEA applications as a hermetic coating to prevent material degradation.
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Affiliation(s)
- Gretchen L Knaack
- Department of Molecular Neuroscience, Krasnow Institute for Advanced Study, George Mason UniversityFairfax, VA, USA; Quantitative Scientific SolutionsArlington, VA, USA
| | - Daniel G McHail
- Department of Molecular Neuroscience, Krasnow Institute for Advanced Study, George Mason University Fairfax, VA, USA
| | - German Borda
- Department of Bioengineering, George Mason University Fairfax, VA, USA
| | - Beomseo Koo
- Department of Bioengineering, George Mason University Fairfax, VA, USA
| | - Nathalia Peixoto
- Electrical and Computer Engineering Department, George Mason University Fairfax, VA, USA
| | - Stuart F Cogan
- Department of Bioengineering, University of Texas at Dallas Richardson, TX, USA
| | - Theodore C Dumas
- Department of Molecular Neuroscience, Krasnow Institute for Advanced Study, George Mason University Fairfax, VA, USA
| | - Joseph J Pancrazio
- Quantitative Scientific SolutionsArlington, VA, USA; Department of Bioengineering, University of Texas at DallasRichardson, TX, USA
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Prodanov D, Delbeke J. A model of space-fractional-order diffusion in the glial scar. J Theor Biol 2016; 403:97-109. [PMID: 27179458 DOI: 10.1016/j.jtbi.2016.04.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 03/23/2016] [Accepted: 04/26/2016] [Indexed: 01/28/2023]
Abstract
Implantation of neuroprosthetic electrodes induces a stereotypical state of neuroinflammation, which is thought to be detrimental for the neurons surrounding the electrode. Mechanisms of this type of neuroinflammation are still poorly understood. Recent experimental and theoretical results point to a possible role of the diffusing species in this process. The paper considers a model of anomalous diffusion occurring in the glial scar around a chronic implant in two simple geometries - a separable rectilinear electrode and a cylindrical electrode, which are solvable exactly. We describe a hypothetical extended source of diffusing species and study its concentration profile in steady-state conditions. Diffusion transport is assumed to obey a fractional-order Fick law, derivable from physically realistic assumptions using a fractional calculus approach. Presented fractional-order distribution morphs into integer-order diffusion in the case of integral fractional exponents. The model demonstrates that accumulation of diffusing species can occur and the scar properties (i.e. tortuosity, fractional order, scar thickness) and boundary conditions can influence such accumulation. The observed shape of the concentration profile corresponds qualitatively with GFAP profiles reported in the literature. The main difference with respect to the previous studies is the explicit incorporation of the apparatus of fractional calculus without assumption of an ad hoc tortuosity parameter. The approach can be adapted to other studies of diffusion in biological tissues, for example of biomolecules or small drug molecules.
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Affiliation(s)
- Dimiter Prodanov
- Environment, Health and Safety, Neuroscience Research Flanders, IMEC, Kapeldreef 75, 3001 Leuven, Belgium.
| | - Jean Delbeke
- LCEN3, Department of Neurology, Institute of Neuroscience, Ghent University, Ghent, Belgium.
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50
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Moorjani S. Miniaturized Technologies for Enhancement of Motor Plasticity. Front Bioeng Biotechnol 2016; 4:30. [PMID: 27148525 PMCID: PMC4834582 DOI: 10.3389/fbioe.2016.00030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 03/21/2016] [Indexed: 11/13/2022] Open
Abstract
The idea that the damaged brain can functionally reorganize itself – so when one part fails, there lies the possibility for another to substitute – is an exciting discovery of the twentieth century. We now know that motor circuits once presumed to be hardwired are not, and motor-skill learning, exercise, and even mental rehearsal of motor tasks can turn genes on or off to shape brain architecture, function, and, consequently, behavior. This is a very significant alteration from our previously static view of the brain and has profound implications for the rescue of function after a motor injury. Presentation of the right cues, applied in relevant spatiotemporal geometries, is required to awaken the dormant plastic forces essential for repair. The focus of this review is to highlight some of the recent progress in neural interfaces designed to harness motor plasticity, and the role of miniaturization in development of strategies that engage diverse elements of the neuronal machinery to synergistically facilitate recovery of function after motor damage.
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Affiliation(s)
- Samira Moorjani
- Department of Physiology and Biophysics, and the Washington National Primate Research Center, University of Washington , Seattle, WA , USA
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