1
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Czerwonky DM, Aberra AS, Gomez LJ. A boundary element method of bidomain modeling for predicting cellular responses to electromagnetic fields. J Neural Eng 2024; 21:036050. [PMID: 38862011 DOI: 10.1088/1741-2552/ad5704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 06/11/2024] [Indexed: 06/13/2024]
Abstract
Objective.Commonly used cable equation approaches for simulating the effects of electromagnetic fields on excitable cells make several simplifying assumptions that could limit their predictive power. Bidomain or 'whole' finite element methods have been developed to fully couple cells and electric fields for more realistic neuron modeling. Here, we introduce a novel bidomain integral equation designed for determining the full electromagnetic coupling between stimulation devices and the intracellular, membrane, and extracellular regions of neurons.Approach.Our proposed boundary element formulation offers a solution to an integral equation that connects the device, tissue inhomogeneity, and cell membrane-induced E-fields. We solve this integral equation using first-order nodal elements and an unconditionally stable Crank-Nicholson time-stepping scheme. To validate and demonstrate our approach, we simulated cylindrical Hodgkin-Huxley axons and spherical cells in multiple brain stimulation scenarios.Main Results.Comparison studies show that a boundary element approach produces accurate results for both electric and magnetic stimulation. Unlike bidomain finite element methods, the bidomain boundary element method does not require volume meshes containing features at multiple scales. As a result, modeling cells, or tightly packed populations of cells, with microscale features embedded in a macroscale head model, is simplified, and the relative placement of devices and cells can be varied without the need to generate a new mesh.Significance.Device-induced electromagnetic fields are commonly used to modulate brain activity for research and therapeutic applications. Bidomain solvers allow for the full incorporation of realistic cell geometries, device E-fields, and neuron populations. Thus, multi-cell studies of advanced neuronal mechanisms would greatly benefit from the development of fast-bidomain solvers to ensure scalability and the practical execution of neural network simulations with realistic neuron morphologies.
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Affiliation(s)
- David M Czerwonky
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, United States of America
| | - Aman S Aberra
- Dartmouth Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, United States of America
| | - Luis J Gomez
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, United States of America
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Yang C, Cheng Z, Li P, Tian B. Exploring Present and Future Directions in Nano-Enhanced Optoelectronic Neuromodulation. Acc Chem Res 2024; 57:1398-1410. [PMID: 38652467 DOI: 10.1021/acs.accounts.4c00086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Electrical neuromodulation has achieved significant translational advancements, including the development of deep brain stimulators for managing neural disorders and vagus nerve stimulators for seizure treatment. Optoelectronics, in contrast to wired electrical systems, offers the leadless feature that guides multisite and high spatiotemporal neural system targeting, ensuring high specificity and precision in translational therapies known as "photoelectroceuticals". This Account provides a concise overview of developments in novel optoelectronic nanomaterials that are engineered through innovative molecular, chemical, and nanostructure designs to facilitate neural interfacing with high efficiency and minimally invasive implantation.This Account outlines the progress made both within our laboratory and across the broader scientific community, with particular attention to implications in materials innovation strategies, studying bioelectrical activation with spatiotemporal methods, and applications in regenerative medicine. In materials innovation, we highlight a nongenetic, biocompatible, and minimally invasive approach for neuromodulation that spans various length scales, from single neurons to nerve tissues using nanosized particles and monolithic membranes. Furthermore, our discussion exposes the critical unresolved questions in the field, including mechanisms of interaction at the nanobio interface, the precision of cellular or tissue targeting, and integration into existing neural networks with high spatiotemporal modulation. In addition, we present the challenges and pressing needs for long-term stability and biocompatibility, scalability for clinical applications, and the development of noninvasive monitoring and control systems.In addressing the existing challenges in the field of nanobio interfaces, particularly for neural applications, we envisage promising strategic directions that could significantly advance this burgeoning domain. This involves a deeper theoretical understanding of nanobiointerfaces, where simulations and experimental validations on how nanomaterials interact spatiotemporally with biological systems are crucial. The development of more durable materials is vital for prolonged applications in dynamic neural interfaces, and the ability to manipulate neural activity with high specificity and spatial resolution, paves the way for targeting individual neurons or specific neural circuits. Additionally, integrating these interfaces with advanced control systems, possibly leveraging artificial intelligence and machine learning algorithms and programming dynamically responsive materials designs, could significantly ease the implementation of stimulation and recording. These innovations hold the potential to introduce novel treatment modalities for a wide range of neurological and systemic disorders.
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Affiliation(s)
- Chuanwang Yang
- The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
| | - Zhe Cheng
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Pengju Li
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | - Bozhi Tian
- The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
- The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
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Borgheai SB, Opri E, Isbaine F, Cole E, Deligani RJ, Laxpati N, Risk BB, Willie JT, Gross RE, Yong NA, McIntyre CC, Miocinovic S. Neural pathway activation in the subthalamic region depends on stimulation polarity. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.05.01.24306044. [PMID: 38746250 PMCID: PMC11092741 DOI: 10.1101/2024.05.01.24306044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Deep brain stimulation (DBS) is an effective treatment for Parkinson's disease (PD); however, there is limited understanding of which subthalamic pathways are recruited in response to stimulation. Here, by focusing on the polarity of the stimulus waveform (cathodic vs. anodic), our goal was to elucidate biophysical mechanisms that underlie electrical stimulation in the human brain. In clinical studies, cathodic stimulation more easily triggers behavioral responses, but anodic DBS broadens the therapeutic window. This suggests that neural pathways involved respond preferentially depending on stimulus polarity. To experimentally compare the activation of therapeutically relevant pathways during cathodic and anodic subthalamic nucleus (STN) DBS, pathway activation was quantified by measuring evoked potentials resulting from antidromic or orthodromic activation in 15 PD patients undergoing DBS implantation. Cortical evoked potentials (cEP) were recorded using subdural electrocorticography, DBS local evoked potentials (DLEP) were recorded from non-stimulating contacts and EMG activity was recorded from arm and face muscles. We measured: 1) the amplitude of short-latency cEP, previously demonstrated to reflect activation of the cortico-STN hyperdirect pathway, 2) DLEP amplitude thought to reflect activation of STN-globus pallidus (GP) pathway, and 3) amplitudes of very short-latency cEP and motor evoked potentials (mEP) for activation of cortico-spinal/bulbar tract (CSBT). We constructed recruitment and strength-duration curves for each EP/pathway to compare the excitability for different stimulation polarities. We compared experimental data with the most advanced DBS computational models. Our results provide experimental evidence that subcortical cathodic and anodic stimulation activate the same pathways in the STN region and that cathodic stimulation is in general more efficient. However, relative efficiency varies for different pathways so that anodic stimulation is the least efficient in activating CSBT, more efficient in activating the HDP and as efficient as cathodic in activating STN-GP pathway. Our experiments confirm biophysical model predictions regarding neural activations in the central nervous system and provide evidence that stimulus polarity has differential effects on passing axons, terminal synapses, and local neurons. Comparison of experimental results with clinical DBS studies provides further evidence that the hyperdirect pathway may be involved in the therapeutic mechanisms of DBS.
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Czerwonky DM, Aberra AS, Gomez LJ. A Boundary Element Method of Bidomain Modeling for Predicting Cellular Responses to Electromagnetic Fields. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.15.571917. [PMID: 38168351 PMCID: PMC10760105 DOI: 10.1101/2023.12.15.571917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Objective Commonly used cable equation-based approaches for determining the effects of electromagnetic fields on excitable cells make several simplifying assumptions that could limit their predictive power. Bidomain or "whole" finite element methods have been developed to fully couple cells and electric fields for more realistic neuron modeling. Here, we introduce a novel bidomain integral equation designed for determining the full electromagnetic coupling between stimulation devices and the intracellular, membrane, and extracellular regions of neurons. Methods Our proposed boundary element formulation offers a solution to an integral equation that connects the device, tissue inhomogeneity, and cell membrane-induced E-fields. We solve this integral equation using first-order nodal elements and an unconditionally stable Crank-Nicholson time-stepping scheme. To validate and demonstrate our approach, we simulated cylindrical Hodgkin-Huxley axons and spherical cells in multiple brain stimulation scenarios. Main Results Comparison studies show that a boundary element approach produces accurate results for both electric and magnetic stimulation. Unlike bidomain finite element methods, the bidomain boundary element method does not require volume meshes containing features at multiple scales. As a result, modeling cells, or tightly packed populations of cells, with microscale features embedded in a macroscale head model, is made computationally tractable, and the relative placement of devices and cells can be varied without the need to generate a new mesh. Significance Device-induced electromagnetic fields are commonly used to modulate brain activity for research and therapeutic applications. Bidomain solvers allow for the full incorporation of realistic cell geometries, device E-fields, and neuron populations. Thus, multi-cell studies of advanced neuronal mechanisms would greatly benefit from the development of fast-bidomain solvers to ensure scalability and the practical execution of neural network simulations with realistic neuron morphologies.
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Affiliation(s)
- David M Czerwonky
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA-47907
| | - Aman S Aberra
- Dartmouth Department of Biological Sciences Dartmouth College Hanover, NH 03755
| | - Luis J Gomez
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA-47907
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5
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Hu Y, Feng Z, Zheng L, Ye X. Interactions between cathodic- and anodic-pulses during high-frequency stimulations with the monophasic-pulses alternating in polarity at axons-experiment and simulation studies. J Neural Eng 2023; 20:056021. [PMID: 37703869 DOI: 10.1088/1741-2552/acf959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 09/13/2023] [Indexed: 09/15/2023]
Abstract
Background. Electrical neuromodulation therapies commonly utilize high-frequency stimulations (HFS) of biphasic-pulses to treat neurological disorders. The biphasic pulse consists of a leading cathodic-phase to activate neurons and a lagging anodic-phase to balance electrical charges. Because both monophasic cathodic- and anodic-pulses can depolarize neuronal membranes, splitting biphasic-pulses into alternate cathodic- and anodic-pulses could be a feasible strategy to improve stimulation efficiency.Objective. We speculated that neurons in the volume initially activated by both polarity pulses could change to be activated only by anodic-pulses during sustained HFS of alternate monophasic-pulses. To verify the hypothesis, we investigated the interactions of the monophasic pulses during HFS and revealed possible underlying mechanisms.Approach. Different types of pulse stimulations were applied at the alvear fibers (i.e. the axons of CA1 pyramidal neurons) to antidromically activate the neuronal cell bodies in the hippocampal CA1 region of anesthetized ratsin-vivo. Sequences of antidromic HFS (A-HFS) were applied with alternate monophasic-pulses or biphasic-pulses. The pulse frequency in the A-HFS sequences was 50 or 100 Hz. The A-HFS duration was 120 s. The amplitude of antidromically-evoked population spike was measured to evaluate the neuronal firing induced by each pulse. A computational model of axon was used to explore the possible mechanisms of neuronal modulations. The changes of model variables during sustained A-HFS were analyzed.Main results. In rat experiments, with a same pulse intensity, the activation volume of a cathodic-pulse was greater than that of an anodic-pulse. In paired-pulse tests, a preceding cathodic-pulse was able to prevent a following anodic-pulse from activating neurons due to refractory period. This indicated that the activation volume of a cathodic-pulse covered that of an anodic-pulse. However, during sustained A-HFS of alternate monophasic-pulses, the anodic-pulses were able to prevail over the cathodic-pulses in activating neurons in the overlapped activation volume. Model simulation results show the mechanisms of the activation failures of cathodic-pulses. They include the excessive membrane depolarization caused by an accumulation of potassium ions, the obstacle of hyperpolarization in the conduction pathway and the interactions from anodic-pulses.Significance. The study firstly showed the domination of anodic-pulses over cathodic-pulses in their competitions to activate neurons during sustained HFS. The finding provides new clues for designing HFS paradigms to improve the efficiency of neuromodulation therapies.
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Affiliation(s)
- Yifan Hu
- Key Laboratory of Biomedical Engineering for Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Zhouyan Feng
- Key Laboratory of Biomedical Engineering for Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Lvpiao Zheng
- Key Laboratory of Biomedical Engineering for Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Xiangyu Ye
- Key Laboratory of Biomedical Engineering for Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
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Licata JP, Schwab KH, Har-El YE, Gerstenhaber JA, Lelkes PI. Bioreactor Technologies for Enhanced Organoid Culture. Int J Mol Sci 2023; 24:11427. [PMID: 37511186 PMCID: PMC10380004 DOI: 10.3390/ijms241411427] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/07/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
An organoid is a 3D organization of cells that can recapitulate some of the structure and function of native tissue. Recent work has seen organoids gain prominence as a valuable model for studying tissue development, drug discovery, and potential clinical applications. The requirements for the successful culture of organoids in vitro differ significantly from those of traditional monolayer cell cultures. The generation and maturation of high-fidelity organoids entails developing and optimizing environmental conditions to provide the optimal cues for growth and 3D maturation, such as oxygenation, mechanical and fluidic activation, nutrition gradients, etc. To this end, we discuss the four main categories of bioreactors used for organoid culture: stirred bioreactors (SBR), microfluidic bioreactors (MFB), rotating wall vessels (RWV), and electrically stimulating (ES) bioreactors. We aim to lay out the state-of-the-art of both commercial and in-house developed bioreactor systems, their benefits to the culture of organoids derived from various cells and tissues, and the limitations of bioreactor technology, including sterilization, accessibility, and suitability and ease of use for long-term culture. Finally, we discuss future directions for improvements to existing bioreactor technology and how they may be used to enhance organoid culture for specific applications.
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Affiliation(s)
- Joseph P Licata
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA 19122, USA
| | - Kyle H Schwab
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA 19122, USA
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yah-El Har-El
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA 19122, USA
| | - Jonathan A Gerstenhaber
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA 19122, USA
| | - Peter I Lelkes
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA 19122, USA
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7
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Li P, Kim S, Tian B. Nanoenabled Trainable Systems: From Biointerfaces to Biomimetics. ACS NANO 2022; 16:19651-19664. [PMID: 36516872 PMCID: PMC9798864 DOI: 10.1021/acsnano.2c08042] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 12/09/2022] [Indexed: 05/30/2023]
Abstract
In the dynamic biological system, cells and tissues adapt to diverse environmental conditions and form memories, an essential aspect of training for survival and evolution. An understanding of the biological training principles will inform the design of biomimetic materials whose properties evolve with the environment and offer routes to programmable soft materials, neuromorphic computing, living materials, and biohybrid robotics. In this perspective, we examine the mechanisms by which cells are trained by environmental cues. We outline the artificial platforms that enable biological training and examine the relationship between biological training and biomimetic materials design. We place emphasis on nanoscale material platforms which, given their applicability to chemical, mechanical and electrical stimulation, are critical to bridging natural and synthetic systems.
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Affiliation(s)
- Pengju Li
- Pritzker
School of Molecular Engineering, The University
of Chicago, Chicago, Illinois 60637, United States
| | - Saehyun Kim
- Department
of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Bozhi Tian
- Department
of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
- The
James Franck Institute, The University of
Chicago, Chicago, Illinois 60637, United States
- The
Institute for Biophysical Dynamics, University
of Chicago, Chicago, Illinois 60637, United States
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Jeong H, Cho A, Ay I, Bonmassar G. Short-pulsed micro-magnetic stimulation of the vagus nerve. Front Physiol 2022; 13:938101. [PMID: 36277182 PMCID: PMC9585240 DOI: 10.3389/fphys.2022.938101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 09/01/2022] [Indexed: 11/30/2022] Open
Abstract
Vagus nerve stimulation (VNS) is commonly used to treat drug-resistant epilepsy and depression. The therapeutic effect of VNS depends on stimulating the afferent vagal fibers. However, the vagus is a mixed nerve containing afferent and efferent fibers, and the stimulation of cardiac efferent fibers during VNS may produce a rare but severe risk of bradyarrhythmia. This side effect is challenging to mitigate since VNS, via electrical stimulation technology used in clinical practice, requires unique electrode design and pulse optimization for selective stimulation of only the afferent fibers. Here we describe a method of VNS using micro-magnetic stimulation (µMS), which may be an alternative technique to induce a focal stimulation, enabling a selective fiber stimulation. Micro-coils were implanted into the cervical vagus nerve in adult male Wistar rats. For comparison, the physiological responses were recorded continuously before, during, and after stimulation with arterial blood pressure (ABP), respiration rate (RR), and heart rate (HR). The electrical VNS caused a decrease in ABP, RR, and HR, whereas µM-VNS only caused a transient reduction in RR. The absence of an HR modulation indicated that µM-VNS might provide an alternative technology to VNS with fewer heart-related side effects, such as bradyarrhythmia. Numerical electromagnetic simulations helped estimate the optimal coil orientation with respect to the nerve to provide information on the electric field’s spatial distribution and strength. Furthermore, a transmission emission microscope provided very high-resolution images of the cervical vagus nerve in rats, which identified two different populations of nerve fibers categorized as large and small myelinated fibers.
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Affiliation(s)
- Hongbae Jeong
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Annabel Cho
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
- Department of Bioengineering, Harvard University, Cambridge, MA, United States
| | - Ilknur Ay
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Giorgio Bonmassar
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
- *Correspondence: Giorgio Bonmassar,
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Campbell BA, Cho H, Faulhammer RM, Hogue O, Tsai JPC, Hussain MS, Machado AG, Baker KB. Stability and Effect of Parkinsonian State on Deep Brain Stimulation Cortical Evoked Potentials. Neuromodulation 2022; 25:804-816. [PMID: 34309115 PMCID: PMC10246651 DOI: 10.1111/ner.13508] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/09/2021] [Accepted: 07/06/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To characterize and compare the stability of cortical potentials evoked by deep brain stimulation (DBS) of the subthalamic nucleus (STN) across the naïve, parkinsonian, and pharmacologically treated parkinsonian states. To advance cortical potentials as possible biomarkers for DBS programming. MATERIALS AND METHODS Serial electrocorticographic (ECoG) recordings were made more than nine months from a single non-human primate instrumented with bilateral ECoG grids spanning anterior parietal to prefrontal cortex. Cortical evoked potentials (CEPs) were generated through time-lock averaging of the ECoG recordings to DBS pulses delivered unilaterally in the STN region using a chronically implanted, six-contact, scaled DBS lead. Recordings were made across the naïve followed by mild and moderate parkinsonian conditions achieved by staged injections of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxin. In addition to characterizing the spatial distribution and stability of the response within each state, changes in the amplitude and latency of CEP components as well as in the frequency content were examined in relation to parkinsonian severity and dopamine replacement. RESULTS In the naïve state, the STN DBS CEP presented as a multiphase response maximal over M1 cortex, with components attributable to physiological activity distinguishable from stimulus artifact as early as 0.45-0.75 msec poststimulation. When delivered using therapeutically effective parameters in the parkinsonian state, the CEP was highly stable across multiple recording sessions within each behavioral state. Across states, significant differences were present with respect to both the latency and amplitude of individual response components, with greater differences present for longer-latency components (all p < 0.05). Power spectral density analysis revealed a high-beta peak within the evoked response, with significant changes in power between disease states across multiple frequency bands. CONCLUSIONS Our findings underscore the spatiotemporal specificity and relative stability of the DBS-CEP associated with different disease states and with therapeutic benefit. DBS-CEP may be a viable biomarker for therapeutic programming.
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Affiliation(s)
- Brett A Campbell
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA; Department of Neurosciences, Cleveland Clinic, Cleveland, OH, USA
| | - Hanbin Cho
- Department of Neurosciences, Cleveland Clinic, Cleveland, OH, USA
| | | | - Olivia Hogue
- Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH, USA
| | | | | | - Andre G Machado
- Neurological Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Kenneth B Baker
- Department of Neurosciences, Cleveland Clinic, Cleveland, OH, USA.
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Ye H. Finding the Location of Axonal Activation by a Miniature Magnetic Coil. Front Comput Neurosci 2022; 16:932615. [PMID: 35847967 PMCID: PMC9276924 DOI: 10.3389/fncom.2022.932615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 06/03/2022] [Indexed: 11/17/2022] Open
Abstract
Magnetic stimulation for neural activation is widely used in clinical and lab research. In comparison to electric stimulation using an implanted electrode, stimulation with a large magnetic coil is associated with poor spatial specificity and incapability to stimulate deep brain structures. Recent developments in micromagnetic stimulation (μMS) technology mitigates some of these shortcomings. The sub-millimeter coils can be covered with soft, biocompatible material, and chronically implanted. They can provide highly specific neural stimulation in the deep neural structure. Although the μMS technology is expected to provide a precise location of neural stimulation, the exact site of neural activation is difficult to determine. Furthermore, factors that could cause the shifting of the activation site during μMS have not been fully investigated. To estimate the location of axon activation in μMS, we first derived an analytical expression of the activating function, which predicts the location of membrane depolarization in an unmyelinated axon. Then, we developed a multi-compartment, Hodgkin-Huxley (H-H) type of NEURON model of an unmyelinated axon to test the impact of several important coil parameters on the location of axonal activation. The location of axonal activation was dependent on both the parameters of the stimulus and the biophysics properties of the targeted axon during μMS. The activating function analysis predicted that the location of membrane depolarization and activation could shift due to the reversal of the coil current and the change in the coil-axon distance. The NEURON modeling confirmed these predictions. Interestingly, the NEURON simulation further revealed that the intensity of stimulation played a significant role in the activation location. Moderate or strong coil currents activated the axon at different locations, mediated by two distinct ion channel mechanisms. This study reports several experimental factors that could cause a potential shift in the location of neural activation during μMS, which is essential for further development of this novel technology.
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11
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Kwon H, Park HC, Barrera AC, Rutkove SB, Sanchez B. On the measurement of skeletal muscle anisotropic permittivity property with a single cross-shaped needle insertion. Sci Rep 2022; 12:8494. [PMID: 35589764 PMCID: PMC9120124 DOI: 10.1038/s41598-022-12289-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 05/09/2022] [Indexed: 11/10/2022] Open
Abstract
Application of minimally invasive methods to enable the measurement of tissue permittivity in the neuromuscular clinic remain elusive. This paper provides a theoretical and modeling study on the measurement of the permittivity of two-dimensional anisotropic tissues such as skeletal muscle with a multi-electrode cross-shaped needle. For this, we design a novel cross-shaped needle with multiple-electrodes and analyse apparent impedance corresponding to the measured impedance. In addition, we propose three methods of estimate anisotropic muscle permittivity. Compared to existing electrical impedance-based needle methods that we have developed, the new needle design and numerical methods associated enable estimating in vivo muscle permittivity values with only a single needle insertion. Being able to measure muscle permittivity directly with a single needle insertion could open up an entirely new area of research with direct clinical application, including using these values to assist in neuromuscular diagnosis and to assess subtle effects of therapeutic intervention on muscle health.
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Affiliation(s)
- Hyeuknam Kwon
- Division of Software, Yonsei University, Wonju, Republic of Korea.
| | - Hyoung Churl Park
- Department of Mathematics, Yonsei University, Wonju, Republic of Korea
| | - Albert Cheto Barrera
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, 84112, USA
| | - Seward B Rutkove
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | - Benjamin Sanchez
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, 84112, USA.
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12
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Sensory Thresholds and Peripheral Nerve Responses in Chronic Tension-Type Headache and Neuropsychological Correlation. J Clin Med 2022; 11:jcm11071905. [PMID: 35407512 PMCID: PMC8999240 DOI: 10.3390/jcm11071905] [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: 03/12/2022] [Revised: 03/25/2022] [Accepted: 03/27/2022] [Indexed: 02/06/2023] Open
Abstract
Chronic tension-type headache (CTTH) is a common disease with no fully defined pathophysiological processes. We designed a study to value electrophysiological responses in these patients and their correlation with possible psychopathological manifestations in order to deepen understanding of central and peripheral mechanisms of CTTH. In 40 patients with CTTH and 40 healthy controls, we used electrical stimulation to determine sensory threshold (SPT) and pain perception threshold (PPT) and the characteristics of the electrophysiological sensory nerve action potential (SNAP): initial sensory response (ISR) and supramaximal response (SMR). We then calculated the intensity differences between thresholds (IDT), namely SPT-PPT, ISR-SMR and SMR-PPT, and correlated these IDTs with psychological characteristics: trait and state anxiety, depression, and emotional regulation. The SPT, together with the ISR and SMR thresholds, were higher (p < 0.01) in CTTH patients. The SMR-PPT IDT was smaller and correlated with significantly higher indicators of depression, state and trait anxiety, and poorer cognitive reappraisal. CTTH patients have less capacity to recognize non-nociceptive sensory stimuli, greater tendency toward pain facilitation, and a poor central pain control requiring higher stimulation intensity thresholds to reach the start and the peak amplitude of the SNAP. This is consistent with relative hypoexcitability of the Aβ nerve fibers in distant regions from the site of pain, and therefore, it could be considered a generalized dysfunction with a focal expression. Pain facilitation is directly associated with psychological comorbidity.
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Rogers ER, Zander HJ, Lempka SF. Neural Recruitment During Conventional, Burst, and 10-kHz Spinal Cord Stimulation for Pain. THE JOURNAL OF PAIN 2022; 23:434-449. [PMID: 34583022 PMCID: PMC8925309 DOI: 10.1016/j.jpain.2021.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 09/09/2021] [Accepted: 09/11/2021] [Indexed: 10/20/2022]
Abstract
Spinal cord stimulation (SCS) is a popular neurostimulation therapy for severe chronic pain. To improve stimulation efficacy, multiple modes are now used clinically, including conventional, burst, and 10-kHz SCS. Clinical observations have produced speculation that these modes target different neural elements and/or work via distinct mechanisms of action. However, in humans, these hypotheses cannot be conclusively answered via experimental methods. Therefore, we utilized computational modeling to assess the response of primary afferents, interneurons, and projection neurons to conventional, burst, and 10-kHz SCS. We found that local cell thresholds were always higher than afferent thresholds, arguing against direct recruitment of these local cells. Furthermore, although we observed relative threshold differences between conventional, burst, and 10-kHz SCS, the recruitment order was the same. Finally, contrary to previous reports, axon collateralization produced complex changes in activation thresholds of primary afferents. These results motivate future work to contextualize clinical observations across SCS paradigms. PERSPECTIVE: This article presents the first computational modeling study to investigate neural recruitment during conventional, burst, and 10-kilohertz spinal cord stimulation for chronic pain within a single modeling framework. The results provide insight into these treatments' unknown mechanisms of action and offer context to interpreting clinical observations.
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Affiliation(s)
- Evan R. Rogers
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA,Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA
| | - Hans J. Zander
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA,Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA
| | - Scott F. Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA,Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA,Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA
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14
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Mezzasalma SA, Grassi L, Grassi M. Physical and chemical properties of carbon nanotubes in view of mechanistic neuroscience investigations. Some outlook from condensed matter, materials science and physical chemistry. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2021; 131:112480. [PMID: 34857266 DOI: 10.1016/j.msec.2021.112480] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 09/08/2021] [Accepted: 10/07/2021] [Indexed: 01/17/2023]
Abstract
The open border between non-living and living matter, suggested by increasingly emerging fields of nanoscience interfaced to biological systems, requires a detailed knowledge of nanomaterials properties. An account of the wide spectrum of phenomena, belonging to physical chemistry of interfaces, materials science, solid state physics at the nanoscale and bioelectrochemistry, thus is acquainted for a comprehensive application of carbon nanotubes interphased with neuron cells. This review points out a number of conceptual tools to further address the ongoing advances in coupling neuronal networks with (carbon) nanotube meshworks, and to deepen the basic issues that govern a biological cell or tissue interacting with a nanomaterial. Emphasis is given here to the properties and roles of carbon nanotube systems at relevant spatiotemporal scales of individual molecules, junctions and molecular layers, as well as to the point of view of a condensed matter or materials scientist. Carbon nanotube interactions with blood-brain barrier, drug delivery, biocompatibility and functionalization issues are also regarded.
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Affiliation(s)
- Stefano A Mezzasalma
- Ruder Bošković Institute, Materials Physics Division, Bijeniška cesta 54, 10000 Zagreb, Croatia; Lund Institute for advanced Neutron and X-ray Science (LINXS), Lund University, IDEON Building, Delta 5, Scheelevägen 19, 223 70 Lund, Sweden.
| | - Lucia Grassi
- Department of Engineering and Architecture, Trieste University, via Valerio 6, I-34127 Trieste, Italy
| | - Mario Grassi
- Department of Engineering and Architecture, Trieste University, via Valerio 6, I-34127 Trieste, Italy.
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15
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Schweigmann M, Caudal LC, Stopper G, Scheller A, Koch KP, Kirchhoff F. Versatile Surface Electrodes for Combined Electrophysiology and Two-Photon Imaging of the Mouse Central Nervous System. Front Cell Neurosci 2021; 15:720675. [PMID: 34447299 PMCID: PMC8383317 DOI: 10.3389/fncel.2021.720675] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 07/19/2021] [Indexed: 11/23/2022] Open
Abstract
Understanding and modulating CNS function in physiological as well as pathophysiological contexts remains a significant ambition in research and clinical applications. The investigation of the multifaceted CNS cell types including their interactions and contributions to neural function requires a combination of the state-of-the-art in vivo electrophysiology and imaging techniques. We developed a novel type of liquid crystal polymer (LCP) surface micro-electrode manufactured in three customized designs with up to 16 channels for recording and stimulation of brain activity. All designs include spare central spaces for simultaneous 2P-imaging. Nanoporous platinum-plated contact sites ensure a low impedance and high current transfer. The epidural implantation of the LCP micro-electrodes could be combined with standard cranial window surgery. The epidurally positioned electrodes did not only display long-term biocompatibility, but we also observed an additional stabilization of the underlying CNS tissue. We demonstrate the electrode’s versatility in combination with in vivo 2P-imaging by monitoring anesthesia-awake cycles of transgenic mice with GCaMP3 expression in neurons or astrocytes. Cortical stimulation and simultaneous 2P Ca2+ imaging in neurons or astrocytes highlighted the astrocytes’ integrative character in neuronal activity processing. Furthermore, we confirmed that spontaneous astroglial Ca2+ signals are dampened under anesthesia, while evoked signals in neurons and astrocytes showed stronger dependency on stimulation intensity rather than on various levels of anesthesia. Finally, we show that the electrodes provide recordings of the electrocorticogram (ECoG) with a high signal-to noise ratio and spatial signal differences which help to decipher brain activity states during experimental procedures. Summarizing, the novel LCP surface micro-electrode is a versatile, convenient, and reliable tool to investigate brain function in vivo.
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Affiliation(s)
- Michael Schweigmann
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany.,Department of Electrical Engineering, Trier University of Applied Sciences, Trier, Germany
| | - Laura C Caudal
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Gebhard Stopper
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Klaus P Koch
- Department of Electrical Engineering, Trier University of Applied Sciences, Trier, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
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16
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Saska S, Pilatti L, Blay A, Shibli JA. Bioresorbable Polymers: Advanced Materials and 4D Printing for Tissue Engineering. Polymers (Basel) 2021; 13:563. [PMID: 33668617 PMCID: PMC7918883 DOI: 10.3390/polym13040563] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/08/2021] [Accepted: 02/08/2021] [Indexed: 01/10/2023] Open
Abstract
Three-dimensional (3D) printing is a valuable tool in the production of complexes structures with specific shapes for tissue engineering. Differently from native tissues, the printed structures are static and do not transform their shape in response to different environment changes. Stimuli-responsive biocompatible materials have emerged in the biomedical field due to the ability of responding to other stimuli (physical, chemical, and/or biological), resulting in microstructures modifications. Four-dimensional (4D) printing arises as a new technology that implements dynamic improvements in printed structures using smart materials (stimuli-responsive materials) and/or cells. These dynamic scaffolds enable engineered tissues to undergo morphological changes in a pre-planned way. Stimuli-responsive polymeric hydrogels are the most promising material for 4D bio-fabrication because they produce a biocompatible and bioresorbable 3D shape environment similar to the extracellular matrix and allow deposition of cells on the scaffold surface as well as in the inside. Subsequently, this review presents different bioresorbable advanced polymers and discusses its use in 4D printing for tissue engineering applications.
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Affiliation(s)
- Sybele Saska
- M3 Health Industria e Comercio de Produtos Medicos, Odontologicos e Correlatos S.A., Jundiaí, Sao Paulo 13212-213, Brazil; (S.S.); (L.P.); (A.B.)
| | - Livia Pilatti
- M3 Health Industria e Comercio de Produtos Medicos, Odontologicos e Correlatos S.A., Jundiaí, Sao Paulo 13212-213, Brazil; (S.S.); (L.P.); (A.B.)
| | - Alberto Blay
- M3 Health Industria e Comercio de Produtos Medicos, Odontologicos e Correlatos S.A., Jundiaí, Sao Paulo 13212-213, Brazil; (S.S.); (L.P.); (A.B.)
| | - Jamil Awad Shibli
- M3 Health Industria e Comercio de Produtos Medicos, Odontologicos e Correlatos S.A., Jundiaí, Sao Paulo 13212-213, Brazil; (S.S.); (L.P.); (A.B.)
- Department of Periodontology and Oral Implantology, Dental Research Division, University of Guarulhos, Guarulhos, Sao Paulo 07023-070, Brazil
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17
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Cao J, Grover P. STIMULUS: Noninvasive Dynamic Patterns of Neurostimulation Using Spatio-Temporal Interference. IEEE Trans Biomed Eng 2020; 67:726-737. [DOI: 10.1109/tbme.2019.2919912] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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18
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Holden AV, Begg GA, Bounford K, Stegemann B, Tayebjee MH. Phase Entrainment of Induced Ventricular Fibrillation: A Human Feasibility and Proof of Concept Study. J Atr Fibrillation 2019; 12:2217. [PMID: 32435345 DOI: 10.4022/jafib.2217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/19/2019] [Accepted: 09/21/2019] [Indexed: 11/10/2022]
Abstract
Cardioversion and defibrillation by a single high energy shock applied by myocardial or body surface electrodes is painful, causes long term tissue damage, and is associated with worsening long term outcomes, but is almost always required for treatment of ventricular fibrillation . As a initial step towards developing methods that can terminate ventricular arrhythmias painlessly, we aim to determine if pacing stimuli at a rate of 5/s applied via an implantable cardiac defibrillator (ICD) can modify human ventricular fibrillation. In 8 patients undergoing defibrillation testing of a new/exchanged intracardiac defibrillator, five seconds of pacing at five stimuli per second was applied during the 10-20 seconds of induced ventricular fibrillation before the defibrillation shock was automatically applied, and the cardiac electrograms recorded and analyzed. The high frequency pacing did not entrain the ventricular fibrillation, but altered the dominant frequency in all 8 patients, and modulated the phase computed via the Hilbert Transform, in four of the patients. In this pilot study we demonstrate that high frequency pacing applied via ICD electrodes during VF can alter the dominant frequency and modulate the probability density of the phase of the electrogram of the ventricular fibrillation.
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Affiliation(s)
- Arun V Holden
- School of Biomedical Sciences, University of Leeds, Leeds, LS2 9JT; UK
| | - Gordon A Begg
- West Yorkshire Arrhythmia Service, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX, UK
| | - Katrina Bounford
- West Yorkshire Arrhythmia Service, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX, UK
| | - Berthold Stegemann
- Medtronic Plc, Bakken Research Center, Endepolsdomein 5, 6229 GW Maastricht, The Netherlands
| | - Muzahir H Tayebjee
- West Yorkshire Arrhythmia Service, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX, UK
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19
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Rapid four-ring birdcage coil analysis: Design optimization for high efficiency, low interference, and improved body loading tolerance. Magn Reson Imaging 2019; 66:30-35. [PMID: 31765689 DOI: 10.1016/j.mri.2019.11.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 11/21/2019] [Accepted: 11/21/2019] [Indexed: 11/24/2022]
Abstract
The Design accuracy of MRI system with dual-tuned four-ring birdcage coils remains challenging due to inter-coil interference that tends to deteriorate signal-to-noise ratio and thus image quality. In this study, we develop an accurate and efficient FEM modeling strategy by optimizing model geometries, meshing density, and boundary conditions in accord with the correlated measurements on test vehicles. By taking full advantages of simulation accuracy and efficiency, we are able to proceed with sensitivity analysis on critical RF characteristics such as resonance pattern, quality factor, coil coupling, and body loading effects, etc., which may further serve as guidelines for coil design optimization.
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20
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Khadka N, Truong DQ, Williams P, Martin JH, Bikson M. The Quasi-uniform assumption for Spinal Cord Stimulation translational research. J Neurosci Methods 2019; 328:108446. [PMID: 31589892 DOI: 10.1016/j.jneumeth.2019.108446] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 09/23/2019] [Accepted: 09/25/2019] [Indexed: 12/18/2022]
Abstract
BACKGROUND Quasi-uniform assumption is a general theory that postulates local electric field predicts neuronal activation. Computational current flow model of spinal cord stimulation (SCS) of humans and animal models inform how the quasi-uniform assumption can support scaling neuromodulation dose between humans and translational animal. NEW METHOD Here we developed finite element models of cat and rat SCS, and brain slice, alongside SCS models. Boundary conditions related to species specific electrode dimensions applied, and electric fields per unit current (mA) predicted. RESULTS Clinically and across animal, electric fields change abruptly over small distance compared to the neuronal morphology, such that each neuron is exposed to multiple electric fields. Per unit current, electric fields generally decrease with body mass, but not necessarily and proportionally across tissues. Peak electric field in dorsal column rat and cat were ∼17x and ∼1x of clinical values, for scaled electrodes and equal current. Within the spinal cord, the electric field for rat, cat, and human decreased to 50% of peak value caudo-rostrally (C5-C6) at 0.48 mm, 3.2 mm, and 8 mm, and mediolaterally at 0.14 mm, 2.3 mm, and 3.1 mm. Because these space constants are different, electric field across species cannot be matched without selecting a region of interest (ROI). COMPARISON WITH EXISTING METHOD This is the first computational model to support scaling neuromodulation dose between humans and translational animal. CONCLUSIONS Inter-species reproduction of the electric field profile across the entire surface of neuron populations is intractable. Approximating quasi-uniform electric field in a ROI is a rational step to translational scaling.
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Affiliation(s)
- Niranjan Khadka
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA.
| | - Dennis Q Truong
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
| | - Preston Williams
- Department of Molecular, Cellular, and Biomedical Sciences, City University of NY School of Medicine, New York, NY, 10031, USA
| | - John H Martin
- CUNY Graduate Center, New York, NY, 10031, USA; Department of Molecular, Cellular, and Biomedical Sciences, City University of NY School of Medicine, New York, NY, 10031, USA
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA.
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21
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Caravaca AS, Gallina AL, Tarnawski L, Tracey KJ, Pavlov VA, Levine YA, Olofsson PS. An Effective Method for Acute Vagus Nerve Stimulation in Experimental Inflammation. Front Neurosci 2019; 13:877. [PMID: 31551672 PMCID: PMC6736627 DOI: 10.3389/fnins.2019.00877] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 08/05/2019] [Indexed: 11/29/2022] Open
Abstract
Neural reflexes regulate inflammation and electrical activation of the vagus nerve reduces inflammation in models of inflammatory disease. These discoveries have generated an increasing interest in targeted neurostimulation as treatment for chronic inflammatory diseases. Data from the first clinical trials that use vagus nerve stimulation (VNS) in treatment of rheumatoid arthritis and Crohn’s disease suggest that there is a therapeutic potential of electrical VNS in diseases characterized by excessive inflammation. Accordingly, there is an interest to further explore the molecular mechanisms and therapeutic potential of electrical VNS in a range of experimental settings and available genetic mouse models of disease. Here, we describe a method for electrical VNS in experimental inflammation in mice.
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Affiliation(s)
- April S Caravaca
- Laboratory of Immunobiology, Center for Bioelectronic Medicine, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden
| | - Alessandro L Gallina
- Laboratory of Immunobiology, Center for Bioelectronic Medicine, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden
| | - Laura Tarnawski
- Laboratory of Immunobiology, Center for Bioelectronic Medicine, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden
| | - Kevin J Tracey
- Center for Biomedical Science and Bioelectronic Medicine, The Feinstein Institute for Medical Research, Manhasset, NY, United States
| | - Valentin A Pavlov
- Center for Biomedical Science and Bioelectronic Medicine, The Feinstein Institute for Medical Research, Manhasset, NY, United States
| | | | - Peder S Olofsson
- Laboratory of Immunobiology, Center for Bioelectronic Medicine, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden.,Center for Biomedical Science and Bioelectronic Medicine, The Feinstein Institute for Medical Research, Manhasset, NY, United States
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22
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Arabkheradmand G, Krieg TD, Salinas FS, Fox PT, Mogul DJ. Predicting TMS-induced activation in human neocortex using concurrent TMS/PET, finite element analysis and computational modeling. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/aaf202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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23
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Palza H, Zapata PA, Angulo-Pineda C. Electroactive Smart Polymers for Biomedical Applications. MATERIALS (BASEL, SWITZERLAND) 2019; 12:E277. [PMID: 30654487 PMCID: PMC6357059 DOI: 10.3390/ma12020277] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 01/02/2019] [Accepted: 01/09/2019] [Indexed: 01/05/2023]
Abstract
The flexibility in polymer properties has allowed the development of a broad range of materials with electroactivity, such as intrinsically conductive conjugated polymers, percolated conductive composites, and ionic conductive hydrogels. These smart electroactive polymers can be designed to respond rationally under an electric stimulus, triggering outstanding properties suitable for biomedical applications. This review presents a general overview of the potential applications of these electroactive smart polymers in the field of tissue engineering and biomaterials. In particular, details about the ability of these electroactive polymers to: (1) stimulate cells in the context of tissue engineering by providing electrical current; (2) mimic muscles by converting electric energy into mechanical energy through an electromechanical response; (3) deliver drugs by changing their internal configuration under an electrical stimulus; and (4) have antimicrobial behavior due to the conduction of electricity, are discussed.
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Affiliation(s)
- Humberto Palza
- Departamento de Ingeniería Química, Biotecnología y Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, 8370456 Santiago, Chile.
- Millenium Nuclei in Soft Smart Mechanical Metamaterials, Universidad de Chile, 8370456 Santiago, Chile.
| | - Paula Andrea Zapata
- Grupo de Polímeros, Facultad de Química y Biología, Universidad de Santiago de Chile, 8350709 Santiago, Chile.
| | - Carolina Angulo-Pineda
- Departamento de Ingeniería Química, Biotecnología y Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, 8370456 Santiago, Chile.
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Ye H, Ng J. Shielding effects of myelin sheath on axolemma depolarization under transverse electric field stimulation. PeerJ 2018; 6:e6020. [PMID: 30533309 PMCID: PMC6282940 DOI: 10.7717/peerj.6020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 10/29/2018] [Indexed: 01/14/2023] Open
Abstract
Axonal stimulation with electric currents is an effective method for controlling neural activity. An electric field parallel to the axon is widely accepted as the predominant component in the activation of an axon. However, recent studies indicate that the transverse component to the axolemma is also effective in depolarizing the axon. To quantitatively investigate the amount of axolemma polarization induced by a transverse electric field, we computed the transmembrane potential (Vm) for a conductive body that represents an unmyelinated axon (or the bare axon between the myelin sheath in a myelinated axon). We also computed the transmembrane potential of the sheath-covered axonal segment in a myelinated axon. We then systematically analyzed the biophysical factors that affect axonal polarization under transverse electric stimulation for both the bare and sheath-covered axons. Geometrical patterns of polarization of both axon types were dependent on field properties (magnitude and field orientation to the axon). Polarization of both axons was also dependent on their axolemma radii and electrical conductivities. The myelin provided a significant “shielding effect” against the transverse electric fields, preventing excessive axolemma depolarization. Demyelination could allow for prominent axolemma depolarization in the transverse electric field, via a significant increase in myelin conductivity. This shifts the voltage drop of the myelin sheath to the axolemma. Pathological changes at a cellular level should be considered when electric fields are used for the treatment of demyelination diseases. The calculated term for membrane polarization (Vm) could be used to modify the current cable equation that describes axon excitation by an external electric field to account for the activating effects of both parallel and transverse fields surrounding the target axon.
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Affiliation(s)
- Hui Ye
- Department of Biology, Loyola University of Chicago, Chicago, IL, USA
| | - Jeffrey Ng
- Department of Biology, Loyola University of Chicago, Chicago, IL, USA
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25
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Anderson DN, Duffley G, Vorwerk J, Dorval AD, Butson CR. Anodic stimulation misunderstood: preferential activation of fiber orientations with anodic waveforms in deep brain stimulation. J Neural Eng 2018; 16:016026. [PMID: 30275348 DOI: 10.1088/1741-2552/aae590] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE During deep brain stimulation (DBS), it is well understood that extracellular cathodic stimulation can cause activation of passing axons. Activation can be predicted from the second derivative of the electric potential along an axon, which depends on axonal orientation with respect to the stimulation source. We hypothesize that fiber orientation influences activation thresholds and that fiber orientations can be selectively targeted with DBS waveforms. APPROACH We used bioelectric field and multicompartment NEURON models to explore preferential activation based on fiber orientation during monopolar or bipolar stimulation. Preferential fiber orientation was extracted from the principal eigenvectors and eigenvalues of the Hessian matrix of the electric potential. We tested cathodic, anodic, and charge-balanced pulses to target neurons based on fiber orientation in general and clinical scenarios. MAIN RESULTS Axons passing the DBS lead have positive second derivatives around a cathode, whereas orthogonal axons have positive second derivatives around an anode, as indicated by the Hessian. Multicompartment NEURON models confirm that passing fibers are activated by cathodic stimulation, and orthogonal fibers are activated by anodic stimulation. Additionally, orthogonal axons have lower thresholds compared to passing axons. In a clinical scenario, fiber pathways associated with therapeutic benefit can be targeted with anodic stimulation at 50% lower stimulation amplitudes. SIGNIFICANCE Fiber orientations can be selectively targeted with simple changes to the stimulus waveform. Anodic stimulation preferentially activates orthogonal fibers, approaching or leaving the electrode, at lower thresholds for similar therapeutic benefit in DBS with decreased power consumption.
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Affiliation(s)
- Daria Nesterovich Anderson
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States of America. Scientific Computing & Imaging (SCI) Institute, University of Utah, Salt Lake City, UT, United States of America
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26
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Kirsch AD, Hassin-Baer S, Matthies C, Volkmann J, Steigerwald F. Anodic versus cathodic neurostimulation of the subthalamic nucleus: A randomized-controlled study of acute clinical effects. Parkinsonism Relat Disord 2018; 55:61-67. [DOI: 10.1016/j.parkreldis.2018.05.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 05/13/2018] [Accepted: 05/14/2018] [Indexed: 10/16/2022]
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27
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Paradigms for restoration of somatosensory feedback via stimulation of the peripheral nervous system. Clin Neurophysiol 2018; 129:851-862. [DOI: 10.1016/j.clinph.2017.12.027] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 12/05/2017] [Accepted: 12/13/2017] [Indexed: 02/08/2023]
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28
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Gill EL, Marks M, Yost RA, Vedam-Mai V, Garrett TJ. Monitoring Dopamine ex Vivo during Electrical Stimulation Using Liquid-Microjunction Surface Sampling. Anal Chem 2017; 89:13658-13665. [DOI: 10.1021/acs.analchem.7b04463] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Emily L. Gill
- Department of Chemistry, ‡Department of Neurosurgery, and §Department of
Pathology, Immunology
and Laboratory Medicine, University of Florida, Gainesville, Florida 32611, United States
| | - Megan Marks
- Department of Chemistry, ‡Department of Neurosurgery, and §Department of
Pathology, Immunology
and Laboratory Medicine, University of Florida, Gainesville, Florida 32611, United States
| | - Richard A. Yost
- Department of Chemistry, ‡Department of Neurosurgery, and §Department of
Pathology, Immunology
and Laboratory Medicine, University of Florida, Gainesville, Florida 32611, United States
| | - Vinata Vedam-Mai
- Department of Chemistry, ‡Department of Neurosurgery, and §Department of
Pathology, Immunology
and Laboratory Medicine, University of Florida, Gainesville, Florida 32611, United States
| | - Timothy J. Garrett
- Department of Chemistry, ‡Department of Neurosurgery, and §Department of
Pathology, Immunology
and Laboratory Medicine, University of Florida, Gainesville, Florida 32611, United States
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29
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Städele C, DeMaegd ML, Stein W. Extracellular Axon Stimulation. Bio Protoc 2017; 7:e2151. [PMID: 34458467 DOI: 10.21769/bioprotoc.2151] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 01/15/2017] [Accepted: 02/08/2017] [Indexed: 11/02/2022] Open
Abstract
This is a detailed protocol explaining how to perform extracellular axon stimulations as described in Städele and Stein, 2016. The ability to stimulate and record action potentials is essential to electrophysiological examinations of neuronal function. Extracellular stimulation of axons traveling in fiber bundles (nerves) is a classical technique in brain research and a fundamental tool in neurophysiology (Abbas and Miller, 2004; Barry, 2015; Basser and Roth, 2000; Cogan, 2008). It allows for activating action potentials in individual or multiple axons, controlling their firing frequency, provides information about the speed of neuronal communication, and neuron health and function.
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Affiliation(s)
- Carola Städele
- School of Biological Sciences, Illinois State University, Normal, IL, USA
| | | | - Wolfgang Stein
- School of Biological Sciences, Illinois State University, Normal, IL, USA
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Bonaiuto JJ, de Berker A, Bestmann S. Response repetition biases in human perceptual decisions are explained by activity decay in competitive attractor models. eLife 2016; 5:e20047. [PMID: 28005007 PMCID: PMC5243027 DOI: 10.7554/elife.20047] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 12/19/2016] [Indexed: 12/21/2022] Open
Abstract
Animals and humans have a tendency to repeat recent choices, a phenomenon known as choice hysteresis. The mechanism for this choice bias remains unclear. Using an established, biophysically informed model of a competitive attractor network for decision making, we found that decaying tail activity from the previous trial caused choice hysteresis, especially during difficult trials, and accurately predicted human perceptual choices. In the model, choice variability could be directionally altered through amplification or dampening of post-trial activity decay through simulated depolarizing or hyperpolarizing network stimulation. An analogous intervention using transcranial direct current stimulation (tDCS) over left dorsolateral prefrontal cortex (dlPFC) yielded a close match between model predictions and experimental results: net soma depolarizing currents increased choice hysteresis, while hyperpolarizing currents suppressed it. Residual activity in competitive attractor networks within dlPFC may thus give rise to biases in perceptual choices, which can be directionally controlled through non-invasive brain stimulation.
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Affiliation(s)
- James J Bonaiuto
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London, United Kingdom
| | - Archy de Berker
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London, United Kingdom
| | - Sven Bestmann
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London, United Kingdom
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Broniatowski M, Grundfest-Broniatowski S, Tucker HM, Tyler DJ. Artificial Voice Modulation in Dogs by Recurrent Laryngeal Nerve Stimulation: Electrophysiological Confirmation of Anatomic Data. Ann Otol Rhinol Laryngol 2016; 116:145-55. [PMID: 17388239 DOI: 10.1177/000348940711600211] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objectives: We hypothesized that voice may be artificially manipulated to ameliorate dystonias considered to be a failure in dynamic integration between competing neuromuscular systems. Methods: Orderly intrinsic laryngeal muscle recruitment by anodal block via the recurrent laryngeal and vagus nerves has allowed us to define specific values based on differential excitabilities, but has precluded voice fluency because of focused breaks during stimulation and the need to treat several neural conduits. Such problems may be obviated by a circuit capable of stimulating some axons while simultaneously blocking others in the recurrent laryngeal nerve, which carries innervation to all intrinsic laryngeal muscles, including the arguably intrinsic cricothyroideus. In 5 dogs, both recurrent laryngeal nerves received 40-Hz quasi-trapezoidal pulses (0 to 2,000 μA, 0 to 2,000 μs, 0 to 500 μs decay) via tripolar electrodes. Electromyograms were matched with audio intensities and fundamental frequencies recorded under a constant flow of humidified air. Data were digitized and evaluated for potential correlations. Results: Orderly recruitment of the thyroarytenoideus, posterior cricoarytenoideus, and cricothyroideus was correlated with stimulating intensities (p < .001), and posterior cricoarytenoideus opposition to the thyroarytenoideus and cricothyroideus was instrumental in manipulating audio intensities and fundamental frequencies. Conclusions: Manipulation of canine voice parameters appears feasible via the sole recurrent laryngeal nerve within appropriate stimulation envelopes, and offers promise in human laryngeal dystonias.
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Affiliation(s)
- Michael Broniatowski
- Department of Surgery (Otolaryngology-Head and Neck Surgery), Saint Vincent Charity Hospital, University Hospitals Health System, USA
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Schweigmann M, Kirchhoff F, Koch KP. Modeling and Simulations in Time Domain of a Stimulation Set-up for Cortical Applications. Eur J Transl Myol 2016; 26:6017. [PMID: 27478564 PMCID: PMC4942707 DOI: 10.4081/ejtm.2016.6017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Electrical stimulation is used for example to treat neuronal disorders and depression with deep brain stimulation or transcranial electrical stimulation. Depending on the application, different electrodes are used and thus different electrical characteristics exist, which have to be handled by the stimulator. Without a measuring device the user would have to rely on the stimulator being able to deliver the needed stimulation signal. Therefore, the objective of this paper is to present a method to increase the level of confidence with characterization and modelling of the electrical behavior by using the example of one channel of our stimulation device for experimental use. In several simulation studies with an electrode model with values in a typical range for cortical applications the influence of the load onto the stimulator and the possibility to pre-estimate measuring signals in complex networks are shown.
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Affiliation(s)
- Michael Schweigmann
- Department of Electrical Engineering, Trier University of applied Sciences, Trier, Germany; Department of Molecular Physiology, School of Medicine, University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Department of Molecular Physiology, School of Medicine, University of Saarland , Homburg, Germany
| | - Klaus P Koch
- Department of Electrical Engineering, Trier University of applied Sciences , Trier, Germany
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A comparative study of the effects of pulse parameters for intracranial direct electrical stimulation in epilepsy. Clin Neurophysiol 2016; 127:91-101. [DOI: 10.1016/j.clinph.2015.02.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 12/31/2014] [Accepted: 02/13/2015] [Indexed: 11/18/2022]
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Kunori N, Takashima I. A transparent epidural electrode array for use in conjunction with optical imaging. J Neurosci Methods 2015; 251:130-7. [DOI: 10.1016/j.jneumeth.2015.05.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Revised: 05/25/2015] [Accepted: 05/26/2015] [Indexed: 11/26/2022]
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Krämer J, Deppe M, Göbel K, Tabelow K, Wiendl H, Meuth SG. Recovery of thalamic microstructural damage after Shiga toxin 2-associated hemolytic-uremic syndrome. J Neurol Sci 2015; 356:175-83. [PMID: 26189050 DOI: 10.1016/j.jns.2015.06.045] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 05/26/2015] [Accepted: 06/22/2015] [Indexed: 10/23/2022]
Abstract
INTRODUCTION The underlying pathophysiology of neurological complications in patients with hemolytic-uremic syndrome (HUS) remains unclear. It was recently attributed to a direct cytotoxic effect of Shiga toxin 2 (Stx2) in the thalamus. Conventional MRI of patients with Stx2-caused HUS revealed - despite severe neurological symptoms - only mild alterations if any, mostly in the thalamus. Against this background, we questioned: Does diffusion tensor imaging (DTI) capture the thalamic damage better than conventional MRI? Are neurological symptoms and disease course better reflected by thalamic alterations as detected by DTI? Are other brain regions also affected? METHODS Three women with serious neurological deficits due to Stx2-associated HUS were admitted to MRI/DTI at disease onset. Two of them were longitudinally examined. Fractional anisotropy (FA) and mean diffusivity were computed to assess Stx2-caused microstructural damage. RESULTS Compared to 90 healthy women, all three patients had significantly reduced thalamic FA. Thalamic mean diffusivity was only reduced in two patients. DTI of the longitudinally examined women demonstrated slow normalization of thalamic FA, which was paralleled by clinical improvement. CONCLUSION Whereas conventional MRI only shows slight alterations based on subjective evaluation, DTI permits quantitative, objective, and longitudinal assessment of cytotoxic cerebral damage in individual patients.
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Affiliation(s)
- Julia Krämer
- Department of Neurology, Westfälische Wilhelms University, Albert-Schweitzer-Campus 1, Gebäude A1, 48149 Münster, Germany.
| | - Michael Deppe
- Department of Neurology, Westfälische Wilhelms University, Albert-Schweitzer-Campus 1, Gebäude A1, 48149 Münster, Germany.
| | - Kerstin Göbel
- Department of Neurology, Westfälische Wilhelms University, Albert-Schweitzer-Campus 1, Gebäude A1, 48149 Münster, Germany.
| | | | - Heinz Wiendl
- Department of Neurology, Westfälische Wilhelms University, Albert-Schweitzer-Campus 1, Gebäude A1, 48149 Münster, Germany.
| | - Sven G Meuth
- Department of Neurology, Westfälische Wilhelms University, Albert-Schweitzer-Campus 1, Gebäude A1, 48149 Münster, Germany.
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Krieg TD, Salinas FS, Narayana S, Fox PT, Mogul DJ. Computational and experimental analysis of TMS-induced electric field vectors critical to neuronal activation. J Neural Eng 2015; 12:046014. [PMID: 26052136 DOI: 10.1088/1741-2560/12/4/046014] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Transcranial magnetic stimulation (TMS) represents a powerful technique to noninvasively modulate cortical neurophysiology in the brain. However, the relationship between the magnetic fields created by TMS coils and neuronal activation in the cortex is still not well-understood, making predictable cortical activation by TMS difficult to achieve. Our goal in this study was to investigate the relationship between induced electric fields and cortical activation measured by blood flow response. Particularly, we sought to discover the E-field characteristics that lead to cortical activation. APPROACH Subject-specific finite element models (FEMs) of the head and brain were constructed for each of six subjects using magnetic resonance image scans. Positron emission tomography (PET) measured each subject's cortical response to image-guided robotically-positioned TMS to the primary motor cortex. FEM models that employed the given coil position, orientation, and stimulus intensity in experimental applications of TMS were used to calculate the electric field (E-field) vectors within a region of interest for each subject. TMS-induced E-fields were analyzed to better understand what vector components led to regional cerebral blood flow (CBF) responses recorded by PET. MAIN RESULTS This study found that decomposing the E-field into orthogonal vector components based on the cortical surface geometry (and hence, cortical neuron directions) led to significant differences between the regions of cortex that were active and nonactive. Specifically, active regions had significantly higher E-field components in the normal inward direction (i.e., parallel to pyramidal neurons in the dendrite-to-axon orientation) and in the tangential direction (i.e., parallel to interneurons) at high gradient. In contrast, nonactive regions had higher E-field vectors in the outward normal direction suggesting inhibitory responses. SIGNIFICANCE These results provide critical new understanding of the factors by which TMS induces cortical activation necessary for predictive and repeatable use of this noninvasive stimulation modality.
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Affiliation(s)
- Todd D Krieg
- Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL, USA
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Weiss C, Tursunova I, Neuschmelting V, Lockau H, Nettekoven C, Oros-Peusquens AM, Stoffels G, Rehme AK, Faymonville AM, Shah NJ, Langen KJ, Goldbrunner R, Grefkes C. Improved nTMS- and DTI-derived CST tractography through anatomical ROI seeding on anterior pontine level compared to internal capsule. NEUROIMAGE-CLINICAL 2015; 7:424-37. [PMID: 25685709 PMCID: PMC4314616 DOI: 10.1016/j.nicl.2015.01.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 01/07/2015] [Accepted: 01/08/2015] [Indexed: 12/16/2022]
Abstract
Imaging of the course of the corticospinal tract (CST) by diffusion tensor imaging (DTI) is useful for function-preserving tumour surgery. The integration of functional localizer data into tracking algorithms offers to establish a direct structure–function relationship in DTI data. However, alterations of MRI signals in and adjacent to brain tumours often lead to spurious tracking results. We here compared the impact of subcortical seed regions placed at different positions and the influences of the somatotopic location of the cortical seed and clinical co-factors on fibre tracking plausibility in brain tumour patients. The CST of 32 patients with intracranial tumours was investigated by means of deterministic DTI and neuronavigated transcranial magnetic stimulation (nTMS). The cortical seeds were defined by the nTMS hot spots of the primary motor area (M1) of the hand, the foot and the tongue representation. The CST originating from the contralesional M1 hand area was mapped as intra-individual reference. As subcortical region of interests (ROI), we used the posterior limb of the internal capsule (PLIC) and/or the anterior inferior pontine region (aiP). The plausibility of the fibre trajectories was assessed by a-priori defined anatomical criteria. The following potential co-factors were analysed: Karnofsky Performance Scale (KPS), resting motor threshold (RMT), T1-CE tumour volume, T2 oedema volume, presence of oedema within the PLIC, the fractional anisotropy threshold (FAT) to elicit a minimum amount of fibres and the minimal fibre length. The results showed a higher proportion of plausible fibre tracts for the aiP-ROI compared to the PLIC-ROI. Low FAT values and the presence of peritumoural oedema within the PLIC led to less plausible fibre tracking results. Most plausible results were obtained when the FAT ranged above a cut-off of 0.105. In addition, there was a strong effect of somatotopic location of the seed ROI; best plausibility was obtained for the contralateral hand CST (100%), followed by the ipsilesional hand CST (>95%), the ipsilesional foot (>85%) and tongue (>75%) CST. In summary, we found that the aiP-ROI yielded better tracking results compared to the IC-ROI when using deterministic CST tractography in brain tumour patients, especially when the M1 hand area was tracked. In case of FAT values lower than 0.10, the result of the respective CST tractography should be interpreted with caution with respect to spurious tracking results. Moreover, the presence of oedema within the internal capsule should be considered a negative predictor for plausible CST tracking. Somatotopic CST tractography was done in 32 patients with eloquent brain tumours. Seeding ROIs were defined by navigated TMS of the M1 hot spot (hand, foot, tongue). Using the anterior pons as a second ROI yielded more plausible tracts than the PLIC. Low FAT and oedema of the internal capsule were negative predictors.
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Key Words
- ANOVA, analysis of variance
- APB, abductor pollicis brevis muscle
- AUC, area under the curve
- BOLD, blood oxygenation level dependent
- CST
- CST, corticospinal tract
- DTI
- DTI, diffusion tensor imaging
- FA(T), fractional anisotropy (threshold)
- FACT, fibre assignment by continuous tracking
- FMRI, functional magnetic resonance imaging
- FOV, field-of-view
- FWE, family-wise error
- Fractional anisotropy
- KPS, Karnofsky performance scale
- LDA/C, linear discriminant analysis/coefficient
- LT, lateral tongue muscle, anterior third
- M1, primary motor cortex
- MEP, motor evoked potential
- MFL, minimal fibre length
- MPRAGE, magnetization prepared rapid acquisition gradient echo (T1 MR sequence)
- OR, odd's ratio
- PLIC, posterior limb of the internal capsule
- PM, plantar muscle
- RMT, resting motor threshold
- ROI
- ROI, region-of-interest
- SD, standard deviation
- SE, standard error
- Somatotopic
- X-sq, X-squared (Pearson's chi-square test)
- aiP, anterior inferior pons
- nTMS
- nTMS, neuronavigated transcranial magnetic stimulation
- pxsq, p-value according to Pearson's chi-square test.
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Affiliation(s)
- Carolin Weiss
- Department of Neurosurgery, University of Cologne, Cologne 50924, Germany
| | - Irada Tursunova
- Department of Neurosurgery, University of Cologne, Cologne 50924, Germany ; Department of Neurosurgery, University of Cologne, Cologne 50924, Germany
| | | | - Hannah Lockau
- Department of Radiology, University of Cologne, Cologne 50937, Germany
| | - Charlotte Nettekoven
- Institute of Neuroscience and Medicine, Research Centre Jülich, Jülich 52425, Germany
| | | | - Gabriele Stoffels
- Institute of Neuroscience and Medicine, Research Centre Jülich, Jülich 52425, Germany
| | - Anne K Rehme
- Institute of Neuroscience and Medicine, Research Centre Jülich, Jülich 52425, Germany ; Department of Neurology, University of Cologne, Cologne 50924, Germany
| | | | - N Jon Shah
- Institute of Neuroscience and Medicine, Research Centre Jülich, Jülich 52425, Germany ; Department of Neurology, University Clinic Aachen, RWTH Aachen University, Aachen 52074, Germany
| | - Karl Josef Langen
- Institute of Neuroscience and Medicine, Research Centre Jülich, Jülich 52425, Germany
| | - Roland Goldbrunner
- Department of Neurosurgery, University of Cologne, Cologne 50924, Germany
| | - Christian Grefkes
- Institute of Neuroscience and Medicine, Research Centre Jülich, Jülich 52425, Germany ; Department of Neurology, University of Cologne, Cologne 50924, Germany
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Tahayori B, Meffin H, Sergeev EN, Mareels IMY, Burkitt AN, Grayden DB. Modelling extracellular electrical stimulation: part 4. Effect of the cellular composition of neural tissue on its spatio-temporal filtering properties. J Neural Eng 2014; 11:065005. [PMID: 25419652 DOI: 10.1088/1741-2560/11/6/065005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The objective of this paper is to present a concrete application of the cellular composite model for calculating the membrane potential, described in an accompanying paper. APPROACH A composite model that is used to determine the membrane potential for both longitudinal and transverse modes of stimulation is demonstrated. MAIN RESULTS Two extreme limits of the model, near-field and far-field for an electrode close to or distant from a neuron, respectively, are derived in this paper. Results for typical neural tissue are compared using the composite, near-field and far-field models as well as the standard isotropic volume conductor model. The self-consistency of the composite model, its spatial profile response and the extracellular potential time behaviour are presented. The magnitudes of the longitudinal and transverse components for different values of electrode-neurite separations are compared. SIGNIFICANCE The unique features of the composite model and its simplified versions can be used to accurately estimate the spatio-temporal response of neural tissue to extracellular electrical stimulation.
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Affiliation(s)
- Bahman Tahayori
- NeuroEngineering Laboratory, Department of Electrical and Electronic Engineering, The University of Melbourne, VIC 3010, Australia
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Laakso I, Matsumoto H, Hirata A, Terao Y, Hanajima R, Ugawa Y. Multi-scale simulations predict responses to non-invasive nerve root stimulation. J Neural Eng 2014; 11:056013. [DOI: 10.1088/1741-2560/11/5/056013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Brunoni AR, Shiozawa P, Truong D, Javitt DC, Elkis H, Fregni F, Bikson M. Understanding tDCS effects in schizophrenia: a systematic review of clinical data and an integrated computation modeling analysis. Expert Rev Med Devices 2014; 11:383-94. [PMID: 24754366 DOI: 10.1586/17434440.2014.911082] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Although recent clinical studies using transcranial direct current stimulation (tDCS) for schizophrenia showed encouraging results, several tDCS montages were employed and their current flow pattern has not been investigated. We performed a systematic review to identify clinical tDCS studies in schizophrenia. We then applied computer head modeling analysis for prediction of current flow. Out of 41 references, we identified 12 relevant studies. The most employed montage was anode and cathode over the left dorsolateral prefrontal and temporoparietal cortex, respectively. Computational model analysis predicted activation and under-activation under the anode and the cathode, respectively, occurring in areas respectively associated with negative and positive symptoms. We also identified tDCS-induced electrical currents in cortical areas between the electrodes (frontoparietal network) and, to a lesser extent, in deeper structures involved in schizophrenia pathophysiology. Mechanisms of tDCS effects in schizophrenia and the usefulness of computer modeling techniques for planning tDCS trials in schizophrenia are discussed.
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Affiliation(s)
- Andre R Brunoni
- Department and Institute of Psychiatry, University of São Paulo, São Paulo, Brazil
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Bai S, Dokos S, Ho KA, Loo C. A computational modelling study of transcranial direct current stimulation montages used in depression. Neuroimage 2013; 87:332-44. [PMID: 24246487 DOI: 10.1016/j.neuroimage.2013.11.015] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Revised: 10/12/2013] [Accepted: 11/05/2013] [Indexed: 10/26/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) is a neuromodulatory technique which involves passing a mild electric current to the brain through electrodes placed on the scalp. Several clinical studies suggest that tDCS may have clinically meaningful efficacy in the treatment of depression. The objective of this study was to simulate and compare the effects of several tDCS montages either used in clinical trials or proposed, for the treatment of depression, in different high-resolution anatomically-accurate head models. Detailed segmented finite element head models of two subjects were presented, and a total of eleven tDCS electrode montages were simulated. Sensitivity analysis on the effects of changing the size of the anode, rotating both electrodes and displacing the anode was also conducted on selected montages. The F3-F8 and F3-F4 montages have been used in clinical trials reporting significant antidepressant effects and both result in relatively high electric fields in dorsolateral prefrontal cortices. Other montages using a fronto-extracephalic or fronto-occipital approach result in greater stimulation of central structures (e.g. anterior cingulate cortex) which may be advantageous in treating depression, but their efficacy has yet to be tested in randomised controlled trials. Results from sensitivity analysis suggest that electrode position and size may be adjusted slightly to accommodate other priorities, such as skin discomfort and damage.
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Affiliation(s)
- Siwei Bai
- Graduate School of Biomedical Engineering, Faculty of Engineering, University of New South Wales (UNSW), NSW 2052, Australia.
| | - Socrates Dokos
- Graduate School of Biomedical Engineering, Faculty of Engineering, University of New South Wales (UNSW), NSW 2052, Australia.
| | - Kerrie-Anne Ho
- School of Psychiatry, UNSW, NSW 2052, Australia; Black Dog Institute, NSW 2031, Australia.
| | - Colleen Loo
- School of Psychiatry, UNSW, NSW 2052, Australia; Department of Psychiatry, St George Hospital, NSW 2217, Australia; Black Dog Institute, NSW 2031, Australia.
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Krieg TD, Salinas FS, Narayana S, Fox PT, Mogul DJ. PET-based confirmation of orientation sensitivity of TMS-induced cortical activation in humans. Brain Stimul 2013; 6:898-904. [PMID: 23827648 PMCID: PMC5293002 DOI: 10.1016/j.brs.2013.05.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 05/16/2013] [Accepted: 05/25/2013] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Currently, it is difficult to predict precise regions of cortical activation in response to transcranial magnetic stimulation (TMS). Most analytical approaches focus on applied magnetic field strength in the target region as the primary factor, placing activation on the gyral crowns. However, imaging studies support M1 targets being typically located in the sulcal banks. OBJECTIVE/HYPOTHESIS To more thoroughly investigate this inconsistency, we sought to determine whether neocortical surface orientation was a critical determinant of regional activation. METHODS MR images were used to construct cortical and scalp surfaces for 18 subjects. The angle (θ) between the cortical surface normal and its nearest scalp normal for ~50,000 cortical points per subject was used to quantify cortical location (i.e., gyral vs. sulcal). TMS-induced activations of primary motor cortex (M1) were compared to brain activations recorded during a finger-tapping task using concurrent positron emission tomographic (PET) imaging. RESULTS Brain activations were primarily sulcal for both the TMS and task activations (P < 0.001 for both) compared to the overall cortical surface orientation. Also, the location of maximal blood flow in response to either TMS or finger-tapping correlated well using the cortical surface orientation angle or distance to scalp (P < 0.001 for both) as criteria for comparison between different neocortical activation modalities. CONCLUSION This study provides further evidence that a major factor in cortical activation using TMS is the orientation of the cortical surface with respect to the induced electric field. The results show that, despite the gyral crown of the cortex being subjected to a larger magnetic field magnitude, the sulcal bank of M1 had larger cerebral blood flow (CBF) responses during TMS.
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Affiliation(s)
- Todd D. Krieg
- Department of Biomedical Engineering, Illinois Institute of Technology, Wishnick Hall 314, 3255 S. Dearborn St., Chicago, IL 60616, USA
| | - Felipe S. Salinas
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Shalini Narayana
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Peter T. Fox
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- South Texas Veterans Health Care System, San Antonio, TX, USA
| | - David J. Mogul
- Department of Biomedical Engineering, Illinois Institute of Technology, Wishnick Hall 314, 3255 S. Dearborn St., Chicago, IL 60616, USA
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An implantable neural interface with electromagnetic stimulation capabilities. Med Hypotheses 2013; 81:322-7. [DOI: 10.1016/j.mehy.2013.04.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 04/04/2013] [Accepted: 04/08/2013] [Indexed: 11/17/2022]
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The polarity sensitivity of the electrically stimulated human auditory nerve measured at the level of the brainstem. J Assoc Res Otolaryngol 2013; 14:359-77. [PMID: 23479187 DOI: 10.1007/s10162-013-0377-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 01/31/2013] [Indexed: 10/27/2022] Open
Abstract
Recent behavioral studies have suggested that the human auditory nerve of cochlear implant (CI) users is mainly excited by the positive (anodic) polarity. Those findings were only obtained using asymmetric pseudomonophasic (PS) pulses where the effect of one phase was measured in the presence of a counteracting phase of opposite polarity, longer duration, and lower amplitude than the former phase. It was assumed that only the short high-amplitude phase was responsible for the excitation. Similarly, it has been shown that electrically evoked compound action potentials could only be obtained in response to the anodic phases of asymmetric pulses. Here, experiment 1 measured electrically evoked auditory brainstem responses to standard symmetric, PS, reversed pseudomonophasic, and reversed pseudomonophasic with inter-phase gap (6 ms) pulses presented for both polarities. Responses were time locked to the short high-amplitude phase of asymmetric pulses and were smaller, but still measurable, when that phase was cathodic than when it was anodic. This provides the first evidence that cathodic stimulation can excite the auditory system of human CI listeners and confirms that this stimulation is nevertheless less effective than for the anodic polarity. A second experiment studied the polarity sensitivity at different intensities by means of a loudness balancing task between pseudomonophasic anodic (PSA) and pseudomonophasic cathodic (PSC) stimuli. Previous studies had demonstrated greater sensitivity to anodic stimulation only for stimuli producing loud percepts. The results showed that PSC stimuli required higher amplitudes than PSA stimuli to reach the same loudness and that this held for current levels ranging from 10 to 100% of the dynamic range.
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Rahman A, Reato D, Arlotti M, Gasca F, Datta A, Parra LC, Bikson M. Cellular effects of acute direct current stimulation: somatic and synaptic terminal effects. J Physiol 2013; 591:2563-78. [PMID: 23478132 DOI: 10.1113/jphysiol.2012.247171] [Citation(s) in RCA: 364] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique to modulate cortical excitability. Although increased/decreased excitability under the anode/cathode electrode is nominally associated with membrane depolarization/hyperpolarization, which cellular compartments (somas, dendrites, axons and their terminals) mediate changes in cortical excitability remains unaddressed. Here we consider the acute effects of DCS on excitatory synaptic efficacy. Using multi-scale computational models and rat cortical brain slices, we show the following. (1) Typical tDCS montages produce predominantly tangential (relative to the cortical surface) direction currents (4-12 times radial direction currents), even directly under electrodes. (2) Radial current flow (parallel to the somatodendritic axis) modulates synaptic efficacy consistent with somatic polarization, with depolarization facilitating synaptic efficacy. (3) Tangential current flow (perpendicular to the somatodendritic axis) modulates synaptic efficacy acutely (during stimulation) in an afferent pathway-specific manner that is consistent with terminal polarization, with hyperpolarization facilitating synaptic efficacy. (4) Maximal polarization during uniform DCS is expected at distal (the branch length is more than three times the membrane length constant) synaptic terminals, independent of and two-three times more susceptible than pyramidal neuron somas. We conclude that during acute DCS the cellular targets responsible for modulation of synaptic efficacy are concurrently somata and axon terminals, with the direction of cortical current flow determining the relative influence.
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Affiliation(s)
- Asif Rahman
- Department of Biomedical Engineering, The City College of The City University of New York, Convent Avenue at 140th Street, Steinman Hall, 4th Floor, T-454, New York, NY 10031, USA.
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Weiss C, Nettekoven C, Rehme AK, Neuschmelting V, Eisenbeis A, Goldbrunner R, Grefkes C. Mapping the hand, foot and face representations in the primary motor cortex — Retest reliability of neuronavigated TMS versus functional MRI. Neuroimage 2013; 66:531-42. [DOI: 10.1016/j.neuroimage.2012.10.046] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 10/11/2012] [Accepted: 10/19/2012] [Indexed: 12/15/2022] Open
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Bareket-Keren L, Hanein Y. Carbon nanotube-based multi electrode arrays for neuronal interfacing: progress and prospects. Front Neural Circuits 2013; 6:122. [PMID: 23316141 PMCID: PMC3540767 DOI: 10.3389/fncir.2012.00122] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 12/22/2012] [Indexed: 12/17/2022] Open
Abstract
Carbon nanotube (CNT) coatings have been demonstrated over the past several years as a promising material for neuronal interfacing applications. In particular, in the realm of neuronal implants, CNTs have major advantages owing to their unique mechanical and electrical properties. Here we review recent investigations utilizing CNTs in neuro-interfacing applications. Cell adhesion, neuronal engineering and multi electrode recordings with CNTs are described. We also highlight prospective advances in this field, in particular, progress toward flexible, bio-compatible CNT-based technology.
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Affiliation(s)
- Lilach Bareket-Keren
- School of Electrical Engineering, Tel-Aviv UniversityTel-Aviv, Israel
- Tel-Aviv University Center for Nanoscience and Nanotechnology, Tel-Aviv UniversityTel-Aviv, Israel
| | - Yael Hanein
- School of Electrical Engineering, Tel-Aviv UniversityTel-Aviv, Israel
- Tel-Aviv University Center for Nanoscience and Nanotechnology, Tel-Aviv UniversityTel-Aviv, Israel
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Abstract
Deep brain stimulation is a remarkable therapy that has mainstreamed electrical stimulation of the brain for the treatment of neurological dysfunction. To appreciate the mechanisms of deep brain stimulation, we need to understand the excitability of neural tissue. Here, we survey the pertinent principles of electrical excitation in the brain. The amount of current delivered and the tissue conductivity together determine the strength and extent of potentials generated by stimulation. The electrode-tissue interface is an important junction where electrical charge carriers in the stimulation hardware are converted to ionic charge carriers in the tissue. Cathodic stimulation tends to depolarize neural elements more easily than anodic stimulation. The current-distance relationship describes how the amount of current needed to excite an axon increases as a function of its distance from the electrode. This relationship also depends on the axon's diameter because large-diameter axons are excited more easily than small-diameter axons. For a given axon, the strength-duration relationship describes the inverse relationship between threshold current amplitude and pulse duration. Specific stimulation parameters must be considered to avoid stimulation-induced tissue damage. A strong foundation in these principles facilitates understanding of the complex effects of electrical stimulation in the brain.
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Affiliation(s)
- David T Brocker
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, USA
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Peterchev AV, Wagner TA, Miranda PC, Nitsche MA, Paulus W, Lisanby SH, Pascual-Leone A, Bikson M. Fundamentals of transcranial electric and magnetic stimulation dose: definition, selection, and reporting practices. Brain Stimul 2012; 5:435-53. [PMID: 22305345 PMCID: PMC3346863 DOI: 10.1016/j.brs.2011.10.001] [Citation(s) in RCA: 239] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 10/05/2011] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The growing use of transcranial electric and magnetic (EM) brain stimulation in basic research and in clinical applications necessitates a clear understanding of what constitutes the dose of EM stimulation and how it should be reported. METHODS This paper provides fundamental definitions and principles for reporting of dose that encompass any transcranial EM brain stimulation protocol. RESULTS The biologic effects of EM stimulation are mediated through an electromagnetic field injected (via electric stimulation) or induced (via magnetic stimulation) in the body. Therefore, transcranial EM stimulation dose ought to be defined by all parameters of the stimulation device that affect the electromagnetic field generated in the body, including the stimulation electrode or coil configuration parameters: shape, size, position, and electrical properties, as well as the electrode or coil current (or voltage) waveform parameters: pulse shape, amplitude, width, polarity, and repetition frequency; duration of and interval between bursts or trains of pulses; total number of pulses; and interval between stimulation sessions and total number of sessions. Knowledge of the electromagnetic field generated in the body may not be sufficient but is necessary to understand the biologic effects of EM stimulation. CONCLUSIONS We believe that reporting of EM stimulation dose should be guided by the principle of reproducibility: sufficient information about the stimulation parameters should be provided so that the dose can be replicated.
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Affiliation(s)
- Angel V Peterchev
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, North Carolina 27710, USA.
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Extended Broca's area in the functional connectome of language in adults: combined cortical and subcortical single-subject analysis using fMRI and DTI tractography. Brain Topogr 2012; 26:428-41. [PMID: 23001727 DOI: 10.1007/s10548-012-0257-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 09/07/2012] [Indexed: 10/27/2022]
Abstract
Traditional models of the human language circuitry encompass three cortical areas, Broca's, Geschwind's and Wernicke's, and their connectivity through white matter fascicles. The neural connectivity deep to these cortical areas remains poorly understood, as does the macroscopic functional organization of the cortico-subcortical language circuitry. In an effort to expand current knowledge, we combined functional MRI (fMRI) and diffusion tensor imaging to explore subject-specific structural and functional macroscopic connectivity, focusing on Broca's area. Fascicles were studied using diffusion tensor imaging fiber tracking seeded from volumes placed manually within the white matter. White matter fascicles and fMRI-derived clusters (antonym-generation task) of positive and negative blood-oxygen-level-dependent (BOLD) signal were co-registered with 3-D renderings of the brain in 12 healthy subjects. Fascicles connecting BOLD-derived clusters were analyzed within specific cortical areas: Broca's, with the pars triangularis, the pars opercularis, and the pars orbitaris; Geschwind's and Wernicke's; the premotor cortex, the dorsal supplementary motor area, the middle temporal gyrus, the dorsal prefrontal cortex and the frontopolar region. We found a functional connectome divisible into three systems-anterior, superior and inferior-around the insula, more complex than previously thought, particularly with respect to a new extended Broca's area. The extended Broca's area involves two new fascicles: the operculo-premotor fascicle comprised of well-organized U-shaped fibers that connect the pars opercularis with the premotor region; and (2) the triangulo-orbitaris system comprised of intermingled U-shaped fibers that connect the pars triangularis with the pars orbitaris. The findings enhance our understanding of language function.
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