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Malekoshoaraie MH, Wu B, Krahe DD, Ahmed Z, Pupa S, Jain V, Cui XT, Chamanzar M. Fully flexible implantable neural probes for electrophysiology recording and controlled neurochemical modulation. MICROSYSTEMS & NANOENGINEERING 2024; 10:91. [PMID: 38947533 PMCID: PMC11211464 DOI: 10.1038/s41378-024-00685-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 02/01/2024] [Accepted: 02/28/2024] [Indexed: 07/02/2024]
Abstract
Targeted delivery of neurochemicals and biomolecules for neuromodulation of brain activity is a powerful technique that, in addition to electrical recording and stimulation, enables a more thorough investigation of neural circuit dynamics. We have designed a novel, flexible, implantable neural probe capable of controlled, localized chemical stimulation and electrophysiology recording. The neural probe was implemented using planar micromachining processes on Parylene C, a mechanically flexible, biocompatible substrate. The probe shank features two large microelectrodes (chemical sites) for drug loading and sixteen small microelectrodes for electrophysiology recording to monitor neuronal response to drug release. To reduce the impedance while keeping the size of the microelectrodes small, poly(3,4-ethylenedioxythiophene) (PEDOT) was electrochemically coated on recording microelectrodes. In addition, PEDOT doped with mesoporous sulfonated silica nanoparticles (SNPs) was used on chemical sites to achieve controlled, electrically-actuated drug loading and releasing. Different neurotransmitters, including glutamate (Glu) and gamma-aminobutyric acid (GABA), were incorporated into the SNPs and electrically triggered to release repeatedly. An in vitro experiment was conducted to quantify the stimulated release profile by applying a sinusoidal voltage (0.5 V, 2 Hz). The flexible neural probe was implanted in the barrel cortex of the wild-type Sprague Dawley rats. As expected, due to their excitatory and inhibitory effects, Glu and GABA release caused a significant increase and decrease in neural activity, respectively, which was recorded by the recording microelectrodes. This novel flexible neural probe technology, combining on-demand chemical release and high-resolution electrophysiology recording, is an important addition to the neuroscience toolset used to dissect neural circuitry and investigate neural network connectivity.
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Affiliation(s)
| | - Bingchen Wu
- Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260 USA
- Center for Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittburgh, 15213 USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, 15219 USA
| | - Daniela D. Krahe
- Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260 USA
| | - Zabir Ahmed
- Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 USA
| | - Stephen Pupa
- Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 USA
| | - Vishal Jain
- Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 USA
| | - Xinyan Tracy Cui
- Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260 USA
- Center for Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittburgh, 15213 USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, 15219 USA
| | - Maysamreza Chamanzar
- Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 USA
- Carnegie Mellon Neuroscience Institute, Carnegie Mellon University, Pittsburgh, 15213 USA
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2
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Kim Y, Mueller NN, Schwartzman WE, Sarno D, Wynder R, Hoeferlin GF, Gisser K, Capadona JR, Hess-Dunning A. Fabrication Methods and Chronic In Vivo Validation of Mechanically Adaptive Microfluidic Intracortical Devices. MICROMACHINES 2023; 14:1015. [PMID: 37241639 PMCID: PMC10223487 DOI: 10.3390/mi14051015] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/24/2023] [Accepted: 05/04/2023] [Indexed: 05/28/2023]
Abstract
Intracortical neural probes are both a powerful tool in basic neuroscience studies of brain function and a critical component of brain computer interfaces (BCIs) designed to restore function to paralyzed patients. Intracortical neural probes can be used both to detect neural activity at single unit resolution and to stimulate small populations of neurons with high resolution. Unfortunately, intracortical neural probes tend to fail at chronic timepoints in large part due to the neuroinflammatory response that follows implantation and persistent dwelling in the cortex. Many promising approaches are under development to circumvent the inflammatory response, including the development of less inflammatory materials/device designs and the delivery of antioxidant or anti-inflammatory therapies. Here, we report on our recent efforts to integrate the neuroprotective effects of both a dynamically softening polymer substrate designed to minimize tissue strain and localized drug delivery at the intracortical neural probe/tissue interface through the incorporation of microfluidic channels within the probe. The fabrication process and device design were both optimized with respect to the resulting device mechanical properties, stability, and microfluidic functionality. The optimized devices were successfully able to deliver an antioxidant solution throughout a six-week in vivo rat study. Histological data indicated that a multi-outlet design was most effective at reducing markers of inflammation. The ability to reduce inflammation through a combined approach of drug delivery and soft materials as a platform technology allows future studies to explore additional therapeutics to further enhance intracortical neural probes performance and longevity for clinical applications.
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Affiliation(s)
- Youjoung Kim
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; (Y.K.)
- Advanced Platform Technology Center, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA
| | - Natalie N. Mueller
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; (Y.K.)
- Advanced Platform Technology Center, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA
| | - William E. Schwartzman
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; (Y.K.)
- Advanced Platform Technology Center, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA
| | - Danielle Sarno
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; (Y.K.)
- Advanced Platform Technology Center, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA
| | - Reagan Wynder
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; (Y.K.)
- Advanced Platform Technology Center, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA
| | - George F. Hoeferlin
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; (Y.K.)
- Advanced Platform Technology Center, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA
| | - Kaela Gisser
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; (Y.K.)
- Advanced Platform Technology Center, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA
| | - Jeffrey R. Capadona
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; (Y.K.)
- Advanced Platform Technology Center, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA
| | - Allison Hess-Dunning
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; (Y.K.)
- Advanced Platform Technology Center, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA
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3
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Dhawan V, Cui XT. Carbohydrate based biomaterials for neural interface applications. J Mater Chem B 2022; 10:4714-4740. [PMID: 35702979 DOI: 10.1039/d2tb00584k] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Neuroprosthetic devices that record and modulate neural activities have demonstrated immense potential for bypassing or restoring lost neurological functions due to neural injuries and disorders. However, implantable electrical devices interfacing with brain tissue are susceptible to a series of inflammatory tissue responses along with mechanical or electrical failures which can affect the device performance over time. Several biomaterial strategies have been implemented to improve device-tissue integration for high quality and stable performance. Ranging from developing smaller, softer, and more flexible electrode designs to introducing bioactive coatings and drug-eluting layers on the electrode surface, such strategies have shown different degrees of success but with limitations. With their hydrophilic properties and specific bioactivities, carbohydrates offer a potential solution for addressing some of the limitations of the existing biomolecular approaches. In this review, we summarize the role of polysaccharides in the central nervous system, with a primary focus on glycoproteins and proteoglycans, to shed light on their untapped potential as biomaterials for neural implants. Utilization of glycosaminoglycans for neural interface and tissue regeneration applications is comprehensively reviewed to provide the current state of carbohydrate-based biomaterials for neural implants. Finally, we will discuss the challenges and opportunities of applying carbohydrate-based biomaterials for neural tissue interfaces.
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Affiliation(s)
- Vaishnavi Dhawan
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA. .,Center for Neural Basis of Cognition, Pittsburgh, PA, USA
| | - Xinyan Tracy Cui
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA. .,Center for Neural Basis of Cognition, Pittsburgh, PA, USA.,McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA
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4
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Hockley A, Wu C, Shore SE. Olivocochlear projections contribute to superior intensity coding in cochlear nucleus small cells. J Physiol 2022; 600:61-73. [PMID: 34761815 PMCID: PMC9067393 DOI: 10.1113/jp282262] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 11/05/2021] [Indexed: 11/08/2022] Open
Abstract
Understanding communication signals, especially in noisy environments, is crucial to social interactions. Yet, as we age, acoustic signals can be disrupted by cochlear damage and the subsequent auditory nerve fibre degeneration. The most vulnerable medium- and high-threshold-auditory nerve fibres innervate various cell types in the cochlear nucleus, among which the small cells are unique in receiving this input exclusively. Furthermore, small cells project to medial olivocochlear (MOC) neurons, which in turn send branched collaterals back into the small cell cap. Here, we use single-unit recordings to characterise small cell firing characteristics and demonstrate superior intensity coding in this cell class. We show converse effects when activating/blocking the MOC system, demonstrating that small-cell unique coding properties are facilitated by direct cholinergic input from the MOC system. Small cells also maintain tone-level coding in the presence of background noise. Finally, small cells precisely code low-frequency modulation more accurately than other ventral cochlear nucleus cell types, demonstrating accurate envelope coding that may be important for vocalisation processing. These results highlight the small cell olivocochlear circuit as a key player in signal processing in noisy environments, which may be selectively degraded in ageing or after noise insult. KEY POINTS: Cochlear nucleus small cells receive input from low/medium spontaneous rate auditory nerve fibres and medial olivocochlear neurons. Electrical stimulation of medial olivocochlear neurons in the ventral nucleus of the trapezoid body and blocking cholinergic input to small cells using atropine demonstrates an excitatory cholinergic input to small cells, which increases responses to suprathreshold sound. Unique inputs to small cells produce superior sound intensity coding. This coding of intensity is preserved in the presence of background noise, an effect exclusive to this cell type in the cochlear nucleus. These results suggest that small cells serve an essential function in the ascending auditory system, which may be relevant to disorders such as hidden hearing loss.
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Affiliation(s)
- Adam Hockley
- Department of Otolaryngology, Kresge Hearing Research Institute, Ann Arbor, MI, USA
| | - Calvin Wu
- Department of Otolaryngology, Kresge Hearing Research Institute, Ann Arbor, MI, USA
| | - Susan E Shore
- Department of Otolaryngology, Kresge Hearing Research Institute, Ann Arbor, MI, USA
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
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5
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Horowitz LF, Rodriguez AD, Ray T, Folch A. Microfluidics for interrogating live intact tissues. MICROSYSTEMS & NANOENGINEERING 2020; 6:69. [PMID: 32879734 PMCID: PMC7443437 DOI: 10.1038/s41378-020-0164-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 03/10/2020] [Accepted: 03/12/2020] [Indexed: 05/08/2023]
Abstract
The intricate microarchitecture of tissues - the "tissue microenvironment" - is a strong determinant of tissue function. Microfluidics offers an invaluable tool to precisely stimulate, manipulate, and analyze the tissue microenvironment in live tissues and engineer mass transport around and into small tissue volumes. Such control is critical in clinical studies, especially where tissue samples are scarce, in analytical sensors, where testing smaller amounts of analytes results in faster, more portable sensors, and in biological experiments, where accurate control of the cellular microenvironment is needed. Microfluidics also provides inexpensive multiplexing strategies to address the pressing need to test large quantities of drugs and reagents on a single biopsy specimen, increasing testing accuracy, relevance, and speed while reducing overall diagnostic cost. Here, we review the use of microfluidics to study the physiology and pathophysiology of intact live tissues at sub-millimeter scales. We categorize uses as either in vitro studies - where a piece of an organism must be excised and introduced into the microfluidic device - or in vivo studies - where whole organisms are small enough to be introduced into microchannels or where a microfluidic device is interfaced with a live tissue surface (e.g. the skin or inside an internal organ or tumor) that forms part of an animal larger than the device. These microfluidic systems promise to deliver functional measurements obtained directly on intact tissue - such as the response of tissue to drugs or the analysis of tissue secretions - that cannot be obtained otherwise.
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Affiliation(s)
- Lisa F. Horowitz
- Department of Bioengineering, University of Washington, Seattle, WA 98195 USA
| | - Adán D. Rodriguez
- Department of Bioengineering, University of Washington, Seattle, WA 98195 USA
| | - Tyler Ray
- Department of Mechanical Engineering, University of Hawaiʻi at Mānoa, Honolulu, HI 96822 USA
| | - Albert Folch
- Department of Bioengineering, University of Washington, Seattle, WA 98195 USA
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6
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Dagdeviren C, Ramadi KB, Joe P, Spencer K, Schwerdt HN, Shimazu H, Delcasso S, Amemori KI, Nunez-Lopez C, Graybiel AM, Cima MJ, Langer R. Miniaturized neural system for chronic, local intracerebral drug delivery. Sci Transl Med 2019; 10:10/425/eaan2742. [PMID: 29367347 DOI: 10.1126/scitranslmed.aan2742] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 06/14/2017] [Accepted: 01/02/2018] [Indexed: 12/25/2022]
Abstract
Recent advances in medications for neurodegenerative disorders are expanding opportunities for improving the debilitating symptoms suffered by patients. Existing pharmacologic treatments, however, often rely on systemic drug administration, which result in broad drug distribution and consequent increased risk for toxicity. Given that many key neural circuitries have sub-cubic millimeter volumes and cell-specific characteristics, small-volume drug administration into affected brain areas with minimal diffusion and leakage is essential. We report the development of an implantable, remotely controllable, miniaturized neural drug delivery system permitting dynamic adjustment of therapy with pinpoint spatial accuracy. We demonstrate that this device can chemically modulate local neuronal activity in small (rodent) and large (nonhuman primate) animal models, while simultaneously allowing the recording of neural activity to enable feedback control.
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Affiliation(s)
- Canan Dagdeviren
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Media Lab, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Khalil B Ramadi
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Pauline Joe
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Kevin Spencer
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Helen N Schwerdt
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Hideki Shimazu
- McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sebastien Delcasso
- McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ken-Ichi Amemori
- McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Carlos Nunez-Lopez
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,IQS School of Engineering, Ramon Llull University, 08017 Barcelona, Spain
| | - Ann M Graybiel
- McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Michael J Cima
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. .,Department of Materials Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert Langer
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. .,Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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7
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Wen X, Wang B, Huang S, Liu TL, Lee MS, Chung PS, Chow YT, Huang IW, Monbouquette HG, Maidment NT, Chiou PY. Flexible, multifunctional neural probe with liquid metal enabled, ultra-large tunable stiffness for deep-brain chemical sensing and agent delivery. Biosens Bioelectron 2019; 131:37-45. [PMID: 30818131 PMCID: PMC6602555 DOI: 10.1016/j.bios.2019.01.060] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 01/21/2019] [Accepted: 01/24/2019] [Indexed: 10/27/2022]
Abstract
Flexible neural probes have been pursued previously to minimize the mechanical mismatch between soft neural tissues and implants and thereby improve long-term performance. However, difficulties with insertion of such probes deep into the brain severely restricts their utility. We describe a solution to this problem using gallium (Ga) in probe construction, taking advantage of the solid-to-liquid phase change of the metal at body temperature and probe shape deformation to provide temperature-dependent control of stiffness over 5 orders of magnitude. Probes in the stiff state were successfully inserted 2 cm-deep into agarose gel "brain phantoms" and into rat brains under cooled conditions where, upon Ga melting, they became ultra soft, flexible, and stretchable in all directions. The current 30 μm-thick probes incorporated multilayer, deformable microfluidic channels for chemical agent delivery, electrical interconnects through Ga wires, and high-performance electrochemical glutamate sensing. These PDMS-based microprobes of ultra-large tunable stiffness (ULTS) should serve as an attractive platform for multifunctional chronic neural implants.
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Affiliation(s)
- Ximiao Wen
- Department of Mechanical and Aerospace Engineering, University of California at Los Angeles, Los Angeles, CA, USA
| | - Bo Wang
- Department of Psychiatry & Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California at Los Angeles, CA, USA
| | - Shan Huang
- Department of Biological Chemistry, University of California at Los Angeles, CA, USA
| | - Tingyi Leo Liu
- Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, MA, USA
| | - Meng-Shiue Lee
- Department of Mechanical Engineering, National Chiao Tung University, Hsinchu, Taiwan
| | - Pei-Shan Chung
- Department of Bioengineering, University of California at Los Angeles, CA, USA
| | - Yu Ting Chow
- Department of Mechanical and Aerospace Engineering, University of California at Los Angeles, Los Angeles, CA, USA
| | - I-Wen Huang
- Department of Chemical and Biomolecular Engineering, University of California at Los Angeles, CA, USA
| | - Harold G Monbouquette
- Department of Chemical and Biomolecular Engineering, University of California at Los Angeles, CA, USA
| | - Nigel T Maidment
- Department of Psychiatry & Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California at Los Angeles, CA, USA.
| | - Pei-Yu Chiou
- Department of Mechanical and Aerospace Engineering, University of California at Los Angeles, Los Angeles, CA, USA; Department of Bioengineering, University of California at Los Angeles, CA, USA.
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8
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Chronically Implanted Intracranial Electrodes: Tissue Reaction and Electrical Changes. MICROMACHINES 2018; 9:mi9090430. [PMID: 30424363 PMCID: PMC6187588 DOI: 10.3390/mi9090430] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 08/13/2018] [Accepted: 08/22/2018] [Indexed: 12/28/2022]
Abstract
The brain-electrode interface is arguably one of the most important areas of study in neuroscience today. A stronger foundation in this topic will allow us to probe the architecture of the brain in unprecedented functional detail and augment our ability to intervene in disease states. Over many years, significant progress has been made in this field, but some obstacles have remained elusive—notably preventing glial encapsulation and electrode degradation. In this review, we discuss the tissue response to electrode implantation on acute and chronic timescales, the electrical changes that occur in electrode systems over time, and strategies that are being investigated in order to minimize the tissue response to implantation and maximize functional electrode longevity. We also highlight the current and future clinical applications and relevance of electrode technology.
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9
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Scholten K, Meng E. A review of implantable biosensors for closed-loop glucose control and other drug delivery applications. Int J Pharm 2018; 544:319-334. [DOI: 10.1016/j.ijpharm.2018.02.022] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 01/30/2018] [Accepted: 02/15/2018] [Indexed: 12/19/2022]
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10
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Sim JY, Haney MP, Park SI, McCall JG, Jeong JW. Microfluidic neural probes: in vivo tools for advancing neuroscience. LAB ON A CHIP 2017; 17:1406-1435. [PMID: 28349140 DOI: 10.1039/c7lc00103g] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Microfluidic neural probes hold immense potential as in vivo tools for dissecting neural circuit function in complex nervous systems. Miniaturization, integration, and automation of drug delivery tools open up new opportunities for minimally invasive implants. These developments provide unprecedented spatiotemporal resolution in fluid delivery as well as multifunctional interrogation of neural activity using combined electrical and optical modalities. Capitalizing on these unique features, microfluidic technology will greatly advance in vivo pharmacology, electrophysiology, optogenetics, and optopharmacology. In this review, we discuss recent advances in microfluidic neural probe systems. In particular, we will highlight the materials and manufacturing processes of microfluidic probes, device configurations, peripheral devices for fluid handling and packaging, and wireless technologies that can be integrated for the control of these microfluidic probe systems. This article summarizes various microfluidic implants and discusses grand challenges and future directions for further developments.
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Affiliation(s)
- Joo Yong Sim
- Electronics and Telecommunications Research Institute, Bio-Medical IT Convergence Research Department, Daejeon, 34129, Republic of Korea
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11
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Stefanescu RA, Shore SE. Muscarinic acetylcholine receptors control baseline activity and Hebbian stimulus timing-dependent plasticity in fusiform cells of the dorsal cochlear nucleus. J Neurophysiol 2016; 117:1229-1238. [PMID: 28003407 DOI: 10.1152/jn.00270.2016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 12/15/2016] [Accepted: 12/16/2016] [Indexed: 11/22/2022] Open
Abstract
Cholinergic modulation contributes to adaptive sensory processing by controlling spontaneous and stimulus-evoked neural activity and long-term synaptic plasticity. In the dorsal cochlear nucleus (DCN), in vitro activation of muscarinic acetylcholine receptors (mAChRs) alters the spontaneous activity of DCN neurons and interacts with N-methyl-d-aspartate (NMDA) and endocannabinoid receptors to modulate the plasticity of parallel fiber synapses onto fusiform cells by converting Hebbian long-term potentiation to anti-Hebbian long-term depression. Because noise exposure and tinnitus are known to increase spontaneous activity in fusiform cells as well as alter stimulus timing-dependent plasticity (StTDP), it is important to understand the contribution of mAChRs to in vivo spontaneous activity and plasticity in fusiform cells. In the present study, we blocked mAChRs actions by infusing atropine, a mAChR antagonist, into the DCN fusiform cell layer in normal hearing guinea pigs. Atropine delivery leads to decreased spontaneous firing rates and increased synchronization of fusiform cell spiking activity. Consistent with StTDP alterations observed in tinnitus animals, atropine infusion induced a dominant pattern of inversion of StTDP mean population learning rule from a Hebbian to an anti-Hebbian profile. Units preserving their initial Hebbian learning rules shifted toward more excitatory changes in StTDP, whereas units with initial suppressive learning rules transitioned toward a Hebbian profile. Together, these results implicate muscarinic cholinergic modulation as a factor in controlling in vivo fusiform cell baseline activity and plasticity, suggesting a central role in the maladaptive plasticity associated with tinnitus pathology.NEW & NOTEWORTHY This study is the first to use a novel method of atropine infusion directly into the fusiform cell layer of the dorsal cochlear nucleus coupled with simultaneous recordings of neural activity to clarify the contribution of muscarinic acetylcholine receptors (mAChRs) to in vivo fusiform cell baseline activity and auditory-somatosensory plasticity. We have determined that blocking the mAChRs increases the synchronization of spiking activity across the fusiform cell population and induces a dominant pattern of inversion in their stimulus timing-dependent plasticity. These modifications are consistent with similar changes established in previous tinnitus studies, suggesting that mAChRs might have a critical contribution in mediating the maladaptive alterations associated with tinnitus pathology. Blocking mAChRs also resulted in decreased fusiform cell spontaneous firing rates, which is in contrast with their tinnitus hyperactivity, suggesting that changes in the interactions between the cholinergic and GABAergic systems might also be an underlying factor in tinnitus pathology.
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Affiliation(s)
- Roxana A Stefanescu
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan
| | - Susan E Shore
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan; .,Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan; and.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan
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12
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Johnson DG, Borkholder DA. Towards an Implantable, Low Flow Micropump That Uses No Power in the Blocked-Flow State. MICROMACHINES 2016; 7:E99. [PMID: 30404274 PMCID: PMC6189832 DOI: 10.3390/mi7060099] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 04/26/2016] [Accepted: 05/20/2016] [Indexed: 11/25/2022]
Abstract
Low flow rate micropumps play an increasingly important role in drug therapy research. Infusions to small biological structures and lab-on-a-chip applications require ultra-low flow rates and will benefit from the ability to expend no power in the blocked-flow state. Here we present a planar micropump based on gallium phase-change actuation that leverages expansion during solidification to occlude the flow channel in the off-power state. The presented four chamber peristaltic micropump was fabricated with a combination of Micro Electro Mechanical System (MEMS) techniques and additive manufacturing direct write technologies. The device is 7 mm × 13 mm × 1 mm (<100 mm³) with the flow channel and exterior coated with biocompatible Parylene-C, critical for implantable applications. Controllable pump rates from 18 to 104 nL/min were demonstrated, with 11.1 ± 0.35 nL pumped per actuation at an efficiency of 11 mJ/nL. The normally-closed state of the gallium actuator prevents flow and diffusion between the pump and the biological system or lab-on-a-chip, without consuming power. This is especially important for implanted applications with periodic drug delivery regimens.
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Affiliation(s)
- Dean G Johnson
- Rochester Institute of Technology, Microsystems Engineering, Rochester, NY 14623, USA.
| | - David A Borkholder
- Rochester Institute of Technology, Microsystems Engineering, Rochester, NY 14623, USA.
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13
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Lee JH, Kim H, Kim JH, Lee SH. Soft implantable microelectrodes for future medicine: prosthetics, neural signal recording and neuromodulation. LAB ON A CHIP 2016; 16:959-76. [PMID: 26891410 DOI: 10.1039/c5lc00842e] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Implantable devices have provided various potential diagnostic options and therapeutic methods in diverse medical fields. A variety of hard-material-based implantable electrodes have been developed. However, several limitations for their chronic implantation remain, including mechanical mismatches at the interface between the electrode and the soft tissue, and biocompatibility. Soft-material-based implantable devices are suitable candidates for complementing the limitations of hard electrodes. Advances in microtechnology and materials science have largely solved many challenges, such as optimization of shape, minimization of infection, enhancement of biocompatibility and integration with components for diverse functions. Significant strides have also been made in mechanical matching of electrodes to soft tissue. In this review, we provide an overview of recent advances in soft-material-based implantable electrodes for medical applications, categorized according to their implantation site and material composition. We then review specific applications in three categories: neuroprosthetics, neural signal recording, and neuromodulation. Finally, we describe various strategies for the future development and application of implantable, soft-material-based devices.
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Affiliation(s)
- Joong Hoon Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701, Republic of Korea
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14
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Stefanescu RA, Shore SE. NMDA Receptors Mediate Stimulus-Timing-Dependent Plasticity and Neural Synchrony in the Dorsal Cochlear Nucleus. Front Neural Circuits 2015; 9:75. [PMID: 26622224 PMCID: PMC4653590 DOI: 10.3389/fncir.2015.00075] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 10/30/2015] [Indexed: 12/19/2022] Open
Abstract
Auditory information relayed by auditory nerve fibers and somatosensory information relayed by granule cell parallel fibers converge on the fusiform cells (FCs) of the dorsal cochlear nucleus, the first brain station of the auditory pathway. In vitro, parallel fiber synapses on FCs exhibit spike-timing-dependent plasticity with Hebbian learning rules, partially mediated by the NMDA receptor (NMDAr). Well-timed bimodal auditory-somatosensory stimulation, in vivo equivalent of spike-timing-dependent plasticity, can induce stimulus-timing-dependent plasticity (StTDP) of the FCs spontaneous and tone-evoked firing rates. In healthy guinea pigs, the resulting distribution of StTDP learning rules across a FC neural population is dominated by a Hebbian profile while anti-Hebbian, suppressive and enhancing LRs are less frequent. In this study, we investigate in vivo, the NMDAr contribution to FC baseline activity and long term plasticity. We find that blocking the NMDAr decreases the synchronization of FC- spontaneous activity and mediates differential modulation of FC rate-level functions such that low, and high threshold units are more likely to increase, and decrease, respectively, their maximum amplitudes. Three significant alterations in mean learning-rule profiles were identified: transitions from an initial Hebbian profile towards (1) an anti-Hebbian; (2) a suppressive profile; and (3) transitions from an anti-Hebbian to a Hebbian profile. FC units preserving their learning rules showed instead, NMDAr-dependent plasticity to unimodal acoustic stimulation, with persistent depression of tone-evoked responses changing to persistent enhancement following the NMDAr antagonist. These results reveal a crucial role of the NMDAr in mediating FC baseline activity and long-term plasticity which have important implications for signal processing and auditory pathologies related to maladaptive plasticity of dorsal cochlear nucleus circuitry.
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Affiliation(s)
- Roxana A Stefanescu
- Department of Otolaryngology, Kresge Hearing Research Institute, University of Michigan Ann Arbor, MI, USA
| | - Susan E Shore
- Department of Otolaryngology, Kresge Hearing Research Institute, University of Michigan Ann Arbor, MI, USA ; Department of Molecular and Integrative Physiology, University of Michigan Medical School Ann Arbor, MI, USA ; Department of Biomedical Engineering, University of Michigan Ann Arbor, MI, USA
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15
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Senkov O, Mironov A, Dityatev A. A novel versatile hybrid infusion-multielectrode recording (HIME) system for acute drug delivery and multisite acquisition of neuronal activity in freely moving mice. Front Neurosci 2015; 9:425. [PMID: 26594144 PMCID: PMC4633504 DOI: 10.3389/fnins.2015.00425] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 10/20/2015] [Indexed: 12/18/2022] Open
Abstract
To characterize information transfer in defined brain circuits involving multiple brain regions and to evaluate underlying molecular mechanisms and their dysregulation in major brain diseases, a simple and reliable system is ultimately required for electrophysiological recording of local field potentials (LFPs, or local EEG) in combination with local delivery of drugs, enzymes and gene expression-controlling viruses near the place of recording. Here we provide a new design of a versatile reusable hybrid infusion-recording (HIME) system which can be utilized in freely moving mice performing cognitive tasks. The HIME system allows monitoring neuronal activity in multiple layers in several brain structures. Here, we provide examples of bilateral injection and recordings of full spectrum of learning and memory related oscillations, i.e., theta (4-12 Hz), gamma (40-100) and ripple activity (130-150 Hz), in five hippocampal layers as well as in the CA1 and CA2 regions. Furthermore, the system is designed to be used for parallel recordings in the amygdala, cortex and other brain areas, before and after infusion of reagents of interest, either in or off a cognitive test. We anticipate that the HIME system can be particularly convenient to advance functional neuroglycobiological studies and molecular deciphering of mechanisms governing long-term memory consolidation.
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Affiliation(s)
- Oleg Senkov
- Molecular Neuroplasticity Group, Deutsches Zentrum für Neurodegenerative Erkrankungen Magdeburg, Germany
| | - Andrey Mironov
- Neurotechnologies Department, Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod Nizhny Novgorod, Russia ; Nizhny Novgorod State Medical Academy Nizhny Novgorod, Russia
| | - Alexander Dityatev
- Molecular Neuroplasticity Group, Deutsches Zentrum für Neurodegenerative Erkrankungen Magdeburg, Germany ; Medizinische Fakultät, Otto-von-Güricke-Universität Magdeburg Magdeburg, Germany
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16
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Shin H, Lee HJ, Chae U, Kim H, Kim J, Choi N, Woo J, Cho Y, Lee CJ, Yoon ES, Cho IJ. Neural probes with multi-drug delivery capability. LAB ON A CHIP 2015; 15:3730-7. [PMID: 26235309 DOI: 10.1039/c5lc00582e] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Multi-functional neural probes are promising platforms to conduct efficient and effective in-depth studies of brain by recording neural signals as well as modulating the signals with various stimuli. Here we present a neural probe with an embedded microfluidic channel (chemtrode) with multi-drug delivery capability suitable for small animal experiments. We integrated a staggered herringbone mixer (SHM) in a 3-inlet microfluidic chip directly into our chemtrode. This chip, which also serves as a compact interface for the chemtrode, allows for efficient delivery of small volumes of multiple or concentration-modulated drugs via chaotic mixing. We demonstrated the successful infusion of combinatorial inputs of three chemicals with a low flow rate (170 nl min(-1)). By sequentially delivering red, green, and blue inks from each inlet and conducting visual inspections at the tip of the chemtrode, we measured a short residence time of 14 s which corresponds to a small swept volume of 66 nl. Finally, we demonstrated the potential of our proposed chemtrode as an enabling tool through extensive in vivo mice experiments. Through simultaneous infusions of a chemical (pilocarpine or tetrodotoxin (TTX) at inlet 1), a buffer solution (saline at inlet 2), and 4',6-diamidino-2-phenylindole (DAPI at inlet 3) locally into a mouse brain, we not only modulated the neural activities by varying the concentration of the chemical but also locally stained the cells at our target region (CA1 in hippocampus). More specifically, infusion of pilocarpine with a higher concentration resulted in an increase in neural activities while infusion of TTX with a higher concentration resulted in a distinctive reduction. For each chemical, we acquired multiple sets of data using only one mouse through a single implantation of the chemtrode. Our proposed chemtrode offers 1) multiplexed delivery of three drugs through a compact packaging with a small swept volume and 2) simultaneous recording to monitor near real-time effects on neural signals, which allows for more versatile in vivo experiments with a minimum number of animals to be sacrificed.
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Affiliation(s)
- Hyogeun Shin
- Center for BioMicrosystems, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea.
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17
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Kozai TDY, Jaquins-Gerstl AS, Vazquez AL, Michael AC, Cui XT. Brain tissue responses to neural implants impact signal sensitivity and intervention strategies. ACS Chem Neurosci 2015; 6:48-67. [PMID: 25546652 PMCID: PMC4304489 DOI: 10.1021/cn500256e] [Citation(s) in RCA: 353] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
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Implantable biosensors are valuable
scientific tools for basic
neuroscience research and clinical applications. Neurotechnologies
provide direct readouts of neurological signal and neurochemical processes.
These tools are generally most valuable when performance capacities
extend over months and years to facilitate the study of memory, plasticity,
and behavior or to monitor patients’ conditions. These needs
have generated a variety of device designs from microelectrodes for
fast scan cyclic voltammetry (FSCV) and electrophysiology to microdialysis
probes for sampling and detecting various neurochemicals. Regardless
of the technology used, the breaching of the blood–brain barrier
(BBB) to insert devices triggers a cascade of biochemical pathways
resulting in complex molecular and cellular responses to implanted
devices. Molecular and cellular changes in the microenvironment surrounding
an implant include the introduction of mechanical strain, activation
of glial cells, loss of perfusion, secondary metabolic injury, and
neuronal degeneration. Changes to the tissue microenvironment surrounding
the device can dramatically impact electrochemical and electrophysiological
signal sensitivity and stability over time. This review summarizes
the magnitude, variability, and time course of the dynamic molecular
and cellular level neural tissue responses induced by state-of-the-art
implantable devices. Studies show that insertion injuries and foreign
body response can impact signal quality across all implanted central
nervous system (CNS) sensors to varying degrees over both acute (seconds
to minutes) and chronic periods (weeks to months). Understanding the
underlying biological processes behind the brain tissue response to
the devices at the cellular and molecular level leads to a variety
of intervention strategies for improving signal sensitivity and longevity.
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Affiliation(s)
- Takashi D. Y. Kozai
- Department
of Bioengineering, ‡Center for the Neural Basis of Cognition, §McGowan Institute
for Regenerative Medicine, ∥Department of Chemistry, and ⊥Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Andrea S. Jaquins-Gerstl
- Department
of Bioengineering, ‡Center for the Neural Basis of Cognition, §McGowan Institute
for Regenerative Medicine, ∥Department of Chemistry, and ⊥Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Alberto L. Vazquez
- Department
of Bioengineering, ‡Center for the Neural Basis of Cognition, §McGowan Institute
for Regenerative Medicine, ∥Department of Chemistry, and ⊥Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Adrian C. Michael
- Department
of Bioengineering, ‡Center for the Neural Basis of Cognition, §McGowan Institute
for Regenerative Medicine, ∥Department of Chemistry, and ⊥Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - X. Tracy Cui
- Department
of Bioengineering, ‡Center for the Neural Basis of Cognition, §McGowan Institute
for Regenerative Medicine, ∥Department of Chemistry, and ⊥Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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Gunasekera B, Saxena T, Bellamkonda R, Karumbaiah L. Intracortical recording interfaces: current challenges to chronic recording function. ACS Chem Neurosci 2015; 6:68-83. [PMID: 25587704 DOI: 10.1021/cn5002864] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Brain Computer Interfaces (BCIs) offer significant hope to tetraplegic and paraplegic individuals. This technology relies on extracting and translating motor intent to facilitate control of a computer cursor or to enable fine control of an external assistive device such as a prosthetic limb. Intracortical recording interfaces (IRIs) are critical components of BCIs and consist of arrays of penetrating electrodes that are implanted into the motor cortex of the brain. These multielectrode arrays (MEAs) are responsible for recording and conducting neural signals from local ensembles of neurons in the motor cortex with the high speed and spatiotemporal resolution that is required for exercising control of external assistive prostheses. Recent design and technological innovations in the field have led to significant improvements in BCI function. However, long-term (chronic) BCI function is severely compromised by short-term (acute) IRI recording failure. In this review, we will discuss the design and function of current IRIs. We will also review a host of recent advances that contribute significantly to our overall understanding of the cellular and molecular events that lead to acute recording failure of these invasive implants. We will also present recent improvements to IRI design and provide insights into the futuristic design of more chronically functional IRIs.
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Affiliation(s)
- Bhagya Gunasekera
- Regenerative
Bioscience Center, ADS Complex, The University of Georgia, Athens, Georgia 30602-2771, United States
| | - Tarun Saxena
- Wallace
H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0535, United States
| | - Ravi Bellamkonda
- Wallace
H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0535, United States
| | - Lohitash Karumbaiah
- Regenerative
Bioscience Center, ADS Complex, The University of Georgia, Athens, Georgia 30602-2771, United States
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19
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Sommakia S, Lee HC, Gaire J, Otto KJ. Materials approaches for modulating neural tissue responses to implanted microelectrodes through mechanical and biochemical means. CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE 2014; 18:319-328. [PMID: 25530703 PMCID: PMC4267064 DOI: 10.1016/j.cossms.2014.07.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Implantable intracortical microelectrodes face an uphill struggle for widespread clinical use. Their potential for treating a wide range of traumatic and degenerative neural disease is hampered by their unreliability in chronic settings. A major factor in this decline in chronic performance is a reactive response of brain tissue, which aims to isolate the implanted device from the rest of the healthy tissue. In this review we present a discussion of materials approaches aimed at modulating the reactive tissue response through mechanical and biochemical means. Benefits and challenges associated with these approaches are analyzed, and the importance of multimodal solutions tested in emerging animal models are presented.
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Affiliation(s)
- Salah Sommakia
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907-1791
| | - Heui C. Lee
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907-1791
| | - Janak Gaire
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1791
| | - Kevin J. Otto
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907-1791
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1791
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20
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Lee Y, Jun SB. Strategies for minimizing glial response to chronically-implanted microelectrode arrays for neural interface. Biomed Eng Lett 2014. [DOI: 10.1007/s13534-014-0134-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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21
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Cima MJ, Lee H, Daniel K, Tanenbaum LM, Mantzavinou A, Spencer KC, Ong Q, Sy JC, Santini J, Schoellhammer CM, Blankschtein D, Langer RS. Single compartment drug delivery. J Control Release 2014; 190:157-71. [PMID: 24798478 DOI: 10.1016/j.jconrel.2014.04.049] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/18/2014] [Accepted: 04/25/2014] [Indexed: 02/06/2023]
Abstract
Drug design is built on the concept that key molecular targets of disease are isolated in the diseased tissue. Systemic drug administration would be sufficient for targeting in such a case. It is, however, common for enzymes or receptors that are integral to disease to be structurally similar or identical to those that play important biological roles in normal tissues of the body. Additionally, systemic administration may not lead to local drug concentrations high enough to yield disease modification because of rapid systemic metabolism or lack of sufficient partitioning into the diseased tissue compartment. This review focuses on drug delivery methods that physically target drugs to individual compartments of the body. Compartments such as the bladder, peritoneum, brain, eye and skin are often sites of disease and can sometimes be viewed as "privileged," since they intrinsically hinder partitioning of systemically administered agents. These compartments have become the focus of a wide array of procedures and devices for direct administration of drugs. We discuss the rationale behind single compartment drug delivery for each of these compartments, and give an overview of examples at different development stages, from the lab bench to phase III clinical trials to clinical practice. We approach single compartment drug delivery from both a translational and a technological perspective.
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Affiliation(s)
- Michael J Cima
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Materials Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Heejin Lee
- TARIS Biomedical, Inc., Lexington, MA 02421, USA
| | - Karen Daniel
- TARIS Biomedical, Inc., Lexington, MA 02421, USA
| | - Laura M Tanenbaum
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Aikaterini Mantzavinou
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Kevin C Spencer
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Materials Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Qunya Ong
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jay C Sy
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - John Santini
- On Demand Therapeutics, Inc., Menlo Park, CA 94025, USA
| | - Carl M Schoellhammer
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Daniel Blankschtein
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert S Langer
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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22
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Design, fabrication and characterization of drug delivery systems based on lab-on-a-chip technology. Adv Drug Deliv Rev 2013; 65:1403-19. [PMID: 23726943 DOI: 10.1016/j.addr.2013.05.008] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 05/16/2013] [Accepted: 05/22/2013] [Indexed: 11/23/2022]
Abstract
Lab-on-a-chip technology is an emerging field evolving from the recent advances of micro- and nanotechnologies. The technology allows the integration of various components into a single microdevice. Microfluidics, the science and engineering of fluid flow in microscale, is the enabling underlying concept for lab-on-a-chip technology. The present paper reviews the design, fabrication and characterization of drug delivery systems based on this amazing technology. The systems are categorized and discussed according to the scales at which the drug is administered. Starting with the fundamentals on scaling laws of mass transfer and basic fabrication techniques, the paper reviews and discusses drug delivery devices for cellular, tissue and organism levels. At the cellular level, a concentration gradient generator integrated with a cell culture platform is the main drug delivery scheme of interest. At the tissue level, the synthesis of smart particles as drug carriers using lab-on-a-chip technology is the main focus of recent developments. At the organism level, microneedles and implantable devices with fluid-handling components are the main drug delivery systems. For drug delivery to a small organism that can fit into a microchip, devices similar to those of cellular level can be used.
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23
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Rudà R, Magliola U, Bertero L, Trevisan E, Bosa C, Mantovani C, Ricardi U, Castiglione A, Monagheddu C, Soffietti R. Seizure control following radiotherapy in patients with diffuse gliomas: a retrospective study. Neuro Oncol 2013; 15:1739-49. [PMID: 23897633 DOI: 10.1093/neuonc/not109] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Little information is available regarding the effect of conventional radiotherapy on glioma-related seizures. METHODS In this retrospective study, we analyzed the seizure response and outcome following conventional radiotherapy in a cohort of 43 patients with glioma (33 grade II, 10 grade III) and medically intractable epilepsy. RESULTS At 3 months after radiotherapy, seizure reduction was significant (≥ 50% reduction of frequency compared with baseline) in 31/43 patients (72%) of the whole series and in 25/33 patients (76%) with grade II gliomas, whereas at 12 months seizure reduction was significant in 26/34 (76%) and in 19/25 (76%) patients, respectively. Seizure reduction was observed more often among patients displaying an objective tumor response on MRI, but patients with no change on MRI also had a significant seizure reduction. Seizure freedom (Engel class I) was achieved at 12 months in 32% of all patients and in 38% of patients with grade II tumors. Timing of radiotherapy and duration of seizures prior to radiotherapy were significantly associated with seizure reduction. CONCLUSIONS This study showed that a high proportion of patients with medically intractable epilepsy from diffuse gliomas derive a significant and durable benefit from radiotherapy in terms of epilepsy control and that this positive effect is not strictly associated with tumor shrinkage as shown on MRI. Radiotherapy at tumor progression seems as effective as early radiotherapy after surgery. Prospective studies must confirm and better characterize the response to radiotherapy.
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Affiliation(s)
- Roberta Rudà
- Corresponding Author: Roberta Rudà, MD, Department of Neuro-Oncology, Via Cherasco 15, 10126 Torino, Italy.
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24
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Rudà R, Bello L, Duffau H, Soffietti R. Seizures in low-grade gliomas: natural history, pathogenesis, and outcome after treatments. Neuro Oncol 2013; 14 Suppl 4:iv55-64. [PMID: 23095831 DOI: 10.1093/neuonc/nos199] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Seizures represent a common symptom in low-grade gliomas; when uncontrolled, they significantly contribute to patient morbidity and negatively impact quality of life. Tumor location and histology influence the risk for epilepsy. The pathogenesis of tumor-related epilepsy is multifactorial and may differ among tumor histologies (glioneuronal tumors vs diffuse grade II gliomas). Gross total resection is the strongest predictor of seizure freedom in addition to clinical factors, such as preoperative seizure duration, type, and control with antiepileptic drugs (AEDs). Epilepsy surgery may improve seizure control. Radiotherapy and chemotherapy with alkylating agents (procarbazine + CCNU+ vincristine, temozolomide) are effective in reducing the frequency of seizures in patients with pharmacoresistant epilepsy. Newer AEDs (levetiracetam, topiramate, lacosamide) seem to be better tolerated than the old AEDs (phenobarbital, phenytoin, carbamazepine), but there is lack of evidence regarding their superiority in terms of efficacy.
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Affiliation(s)
- Roberta Rudà
- Department of Neuro-Oncology, University of Turin and San Giovanni Battista Hospital, Turin, Italy.
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25
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Kent AR, Grill WM. Neural origin of evoked potentials during thalamic deep brain stimulation. J Neurophysiol 2013; 110:826-43. [PMID: 23719207 DOI: 10.1152/jn.00074.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Closed-loop deep brain stimulation (DBS) systems could provide automatic adjustment of stimulation parameters and improve outcomes in the treatment of Parkinson's disease and essential tremor. The evoked compound action potential (ECAP), generated by activated neurons near the DBS electrode, may provide a suitable feedback control signal for closed-loop DBS. The objectives of this work were to characterize the ECAP across stimulation parameters and determine the neural elements contributing to the signal. We recorded ECAPs during thalamic DBS in anesthetized cats and conducted computer simulations to calculate the ECAP of a population of thalamic neurons. The experimental and computational ECAPs were similar in shape and had characteristics that were correlated across stimulation parameters (R(2) = 0.80-0.95, P < 0.002). The ECAP signal energy increased with larger DBS amplitudes (P < 0.0001) and pulse widths (P < 0.002), and the signal energy of secondary ECAP phases was larger at 10-Hz than at 100-Hz DBS (P < 0.002). The computational model indicated that these changes resulted from a greater extent of neural activation and an increased synchronization of postsynaptic thalamocortical activity, respectively. Administration of tetrodotoxin, lidocaine, or isoflurane abolished or reduced the magnitude of the experimental and computational ECAPs, glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and D(-)-2-amino-5-phosphonopentanoic acid (APV) reduced secondary ECAP phases by decreasing postsynaptic excitation, and the GABAA receptor agonist muscimol increased the latency of the secondary phases by augmenting postsynaptic hyperpolarization. This study demonstrates that the ECAP provides information about the type and extent of neural activation generated during DBS, and the ECAP may serve as a feedback control signal for closed-loop DBS.
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Affiliation(s)
- Alexander R Kent
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708-0281, USA
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26
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Altuna A, Bellistri E, Cid E, Aivar P, Gal B, Berganzo J, Gabriel G, Guimerà A, Villa R, Fernández LJ, Menendez de la Prida L. SU-8 based microprobes for simultaneous neural depth recording and drug delivery in the brain. LAB ON A CHIP 2013; 13:1422-1430. [PMID: 23407672 DOI: 10.1039/c3lc41364k] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
While novel influential concepts in neuroscience bring the focus to local activities generated within a few tens of cubic micrometers in the brain, we are still devoid of appropriate tools to record and manipulate pharmacologically neuronal activity at this fine scale. Here we designed, fabricated and encapsulated microprobes for simultaneous depth recording and drug delivery using exclusively the polymer SU-8 as structural material. A tetrode- and linear-like electrode patterning was combined for the first time with single and double fluidic microchannels for independent drug delivery. The device was tested experimentally using the in vivo anesthetized rat preparation. Both probe types successfully recorded detailed spatiotemporal features of local field potentials and single-cell activity at a resolution never attained before with integrated fluidic probes. Drug delivery was achieved with high spatial and temporal precision in a range from tens of nanoliters to a few microliters, as confirmed histologically. These technological advancements will foster a wide range of neural applications aimed at simultaneous monitoring of brain activity and delivery at a very precise micrometer scale.
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Affiliation(s)
- Ane Altuna
- MEMS/MST Department, Ikerlan S. Coop., Mondragón, Spain.
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27
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Kozai TDY, Vazquez AL, Weaver CL, Kim SG, Cui XT. In vivo two-photon microscopy reveals immediate microglial reaction to implantation of microelectrode through extension of processes. J Neural Eng 2012; 9:066001. [PMID: 23075490 DOI: 10.1088/1741-2560/9/6/066001] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Penetrating cortical neural probe technologies allow investigators to record electrical signals in the brain. Implantation of probes results in acute tissue damage, and microglia density increases around implanted devices over weeks. However, the mechanisms underlying this encapsulation are not well understood in the acute temporal domain. The objective here was to evaluate dynamic microglial response to implanted probes using two-photon microscopy. APPROACH Using two-photon in vivo microscopy, cortical microglia ∼200 µm below the surface of the visual cortex were imaged every minute in mice with green fluorescent protein-expressing microglia. MAIN RESULTS Following probe insertion, nearby microglia immediately extended processes toward the probe at (1.6 ± 1.3) µm min(-1) during the first 30-45 min, but showed negligible cell body movement for the first 6 h. Six hours following probe insertion, microglia at distances <130.0 µm (p = 0.5) from the probe surface exhibit morphological characteristics of transitional stage (T-stage) activation, similar to the microglial response observed with laser-induced blood-brain barrier damage. T-stage morphology and microglia directionality indexes were developed to characterize microglial response to implanted probes. Evidence suggesting vascular reorganization after probe insertion and distant vessel damage was also observed hours after probe insertion. SIGNIFICANCE A precise temporal understanding of the cellular response to microelectrode implantation will facilitate the search for molecular cues initiating and attenuating the reactive tissue response.
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Microscale electrode implantation during nerve repair: effects on nerve morphology, electromyography, and recovery of muscle contractile function. Plast Reconstr Surg 2011; 128:270e-278e. [PMID: 21921739 DOI: 10.1097/prs.0b013e3182268ac8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The authors' goal is to develop a peripheral nerve electrode with long-term stability and fidelity for use in nerve/machine interfaces. Microelectromechanical systems use silicon probes that contain multichannel actuators, sensors, and electronics. The authors tested the null hypothesis that implantation of microelectromechanical systems probes does not have a detrimental effect on peripheral nerve function or regeneration. METHODS A rat hind-limb, peroneal nerve model was used in all experimental groups: intact nerve (control group, n=10); nerve division and repair (repair group, n=9); and nerve division, insertion of microelectromechanical systems probe, and repair (repair plus probe group, n=9). Nerve morphology, nerve to compound muscle action potential studies, walking tracks, and extensor digitorum longus muscle function tests were evaluated following an 80-day recovery. RESULTS Repair and repair plus probe showed no differences in axon count, axon size, percentage nonneural area, compound muscle action potential amplitude, latency, muscle mass, muscle force, or walking track scores. Although there was some local fibrosis around each microelectromechanical systems probe, this did not lead to measurable detrimental effects in any anatomical or functional outcome measurements. CONCLUSION The absence of a significant difference between the repair and the repair plus probe groups regarding histology, compound muscle action potential, walking tracks, and muscle force suggests that microelectromechanical systems electrodes are compatible with regenerating axons and show promise for establishing chemical and electrical interfaces with peripheral nerves.
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Ludwig KA, Langhals NB, Joseph MD, Richardson-Burns SM, Hendricks JL, Kipke DR. Poly(3,4-ethylenedioxythiophene) (PEDOT) polymer coatings facilitate smaller neural recording electrodes. J Neural Eng 2011; 8:014001. [PMID: 21245527 PMCID: PMC3415981 DOI: 10.1088/1741-2560/8/1/014001] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We investigated using poly(3,4-ethylenedioxythiophene) (PEDOT) to lower the impedance of small, gold recording electrodes with initial impedances outside of the effective recording range. Smaller electrode sites enable more densely packed arrays, increasing the number of input and output channels to and from the brain. Moreover, smaller electrode sizes promote smaller probe designs; decreasing the dimensions of the implanted probe has been demonstrated to decrease the inherent immune response, a known contributor to the failure of long-term implants. As expected, chronically implanted control electrodes were unable to record well-isolated unit activity, primarily as a result of a dramatically increased noise floor. Conversely, electrodes coated with PEDOT consistently recorded high-quality neural activity, and exhibited a much lower noise floor than controls. These results demonstrate that PEDOT coatings enable electrode designs 15 µm in diameter.
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Affiliation(s)
- Kip A Ludwig
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
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Azizi F, Lu H, Chiel HJ, Mastrangelo CH. Chemical neurostimulation using pulse code modulation (PCM) microfluidic chips. J Neurosci Methods 2010; 192:193-8. [PMID: 20670654 DOI: 10.1016/j.jneumeth.2010.07.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 07/09/2010] [Accepted: 07/11/2010] [Indexed: 11/28/2022]
Abstract
We report the implementation of a chemical neurostimulation technique using microfluidic devices. The microfluidic chip in this research is used for the in vitro study of the nervous system of Aplysia californica under localized chemical stimulation. The polydimethylsiloxane (PDMS) device is a one-bit pulse code modulator that digitally controls the concentration of the non-hydrolysable cholinergic agonist carbachol injected directly above a ganglion. The chip was successful in repeatedly and controllably inducing bursts of ingestive-like patterns. The ability of the chip to induce rhythmic activity through the sheath of the ganglion suggests that it could serve as the basis for an implantable, in vivo device to control neural activity and motor behavior using chemical stimulation.
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Affiliation(s)
- Farouk Azizi
- Department of Electrical and Computer Engineering, Purdue University Calumet, Hammond, IN 46323, USA.
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Kozai TDY, Marzullo TC, Hooi F, Langhals NB, Majewska AK, Brown EB, Kipke DR. Reduction of neurovascular damage resulting from microelectrode insertion into the cerebral cortex using in vivo two-photon mapping. J Neural Eng 2010; 7:046011. [PMID: 20644246 DOI: 10.1088/1741-2560/7/4/046011] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Penetrating neural probe technologies allow investigators to record electrical signals in the brain. The implantation of probes causes acute tissue damage, partially due to vasculature disruption during probe implantation. This trauma can cause abnormal electrophysiological responses and temporary increases in neurotransmitter levels, and perpetuate chronic immune responses. A significant challenge for investigators is to examine neurovascular features below the surface of the brain in vivo. The objective of this study was to investigate localized bleeding resulting from inserting microscale neural probes into the cortex using two-photon microscopy (TPM) and to explore an approach to minimize blood vessel disruption through insertion methods and probe design. 3D TPM images of cortical neurovasculature were obtained from mice and used to select preferred insertion positions for probe insertion to reduce neurovasculature damage. There was an 82.8 +/- 14.3% reduction in neurovascular damage for probes inserted in regions devoid of major (>5 microm) sub-surface vessels. Also, the deviation of surface vessels from the vector normal to the surface as a function of depth and vessel diameter was measured and characterized. 68% of the major vessels were found to deviate less than 49 microm from their surface origin up to a depth of 500 microm. Inserting probes more than 49 microm from major surface vessels can reduce the chances of severing major sub-surface neurovasculature without using TPM.
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Affiliation(s)
- T D Y Kozai
- Neural Engineering Lab, Department of Biomedical Engineering, College of Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
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Stieglitz T. Integration of Microfluidic Capabilities into Micromachined Neural Implants. ACTA ACUST UNITED AC 2010. [DOI: 10.1260/1759-3093.1.2.139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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