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Du J, Morales A. Electrical Stimulation Induced Current Distribution in Peripheral Nerves Varies Significantly with the Extent of Nerve Damage: A Computational Study Utilizing Convolutional Neural Network and Realistic Nerve Models. Int J Neural Syst 2023; 33:2350022. [PMID: 36916993 PMCID: PMC10561898 DOI: 10.1142/s0129065723500223] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Electrical stimulation of the peripheral nervous system is a promising therapeutic option for several conditions; however, its effects on tissue and the safety of the stimulation remain poorly understood. In order to devise stimulation protocols that enhance therapeutic efficacy without the risk of causing tissue damage, we constructed computational models of peripheral nerve and stimulation cuffs based on extremely high-resolution cross-sectional images of the nerves using the most recent advances in computing power and machine learning techniques. We developed nerve models using nonstimulated (healthy) and over-stimulated (damaged) rat sciatic nerves to explore how nerve damage affects the induced current density distribution. Using our in-house computational, quasi-static, platform, and the Admittance Method (AM), we estimated the induced current distribution within the nerves and compared it for healthy and damaged nerves. We also estimated the extent of localized cell damage in both healthy and damaged nerve samples. When the nerve is damaged, as demonstrated principally by the decreased nerve fiber packing, the current penetrates deeper into the over-stimulated nerve than in the healthy sample. As safety limits for electrical stimulation of peripheral nerves still refer to the Shannon criterion to distinguish between safe and unsafe stimulation, the capability this work demonstrated is an important step toward the development of safety criteria that are specific to peripheral nerve and make use of the latest advances in computational bioelectromagnetics and machine learning, such as Python-based AM and CNN-based nerve image segmentation.
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Vespa S, Stumpp L, Liberati G, Delbeke J, Nonclercq A, Mouraux A, El Tahry R. Characterization of vagus nerve stimulation-induced pupillary responses in epileptic patients. Brain Stimul 2022; 15:1498-1507. [PMID: 36402376 DOI: 10.1016/j.brs.2022.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 10/15/2022] [Accepted: 11/13/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Modulation of the locus coeruleus (LC)-noradrenergic system is a key mechanism of vagus nerve stimulation (VNS). Activation of the LC produces pupil dilation, and the VNS-induced change in pupil diameter was demonstrated in animals as a possible dose-dependent biomarker for treatment titration. OBJECTIVE This study aimed to characterize VNS-induced pupillary responses in epileptic patients. METHODS Pupil diameter was recorded in ten epileptic patients upon four stimulation conditions: three graded levels of VNS intensity and a somatosensory control stimulation (cutaneous electrical stimulation over the left clavicle). For each block, the patients rated the intensity of stimulation on a numerical scale. We extracted the latency of the peak pupil dilation and the magnitude of the early (0-2.5 s) and late components (2.5-5 s) of the pupil dilation response (PDR). RESULTS VNS elicited a peak dilation with longer latency compared to the control condition (p = 0.043). The magnitude of the early PDR was significantly correlated with the intensity of perception (p = 0.046), whereas the late PDR was not (p = 0.19). There was a significant main effect of the VNS level of intensity on the magnitude of the late PDR (p = 0.01) but not on the early PDR (p = 0.2). The relationship between late PDR magnitude and VNS intensity was best fit by a Gaussian model (inverted-U). CONCLUSIONS The late component of the PDR might reflect specific dose-dependent effects of VNS, as compared to control somatosensory stimulation. The inverted-U relationship of late PDR with VNS intensity might indicate the engagement of antagonist central mechanisms at high stimulation intensities.
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Affiliation(s)
- Simone Vespa
- Institute of NeuroScience, Catholic University of Louvain, Brussels, Belgium.
| | - Lars Stumpp
- Institute of NeuroScience, Catholic University of Louvain, Brussels, Belgium
| | - Giulia Liberati
- Institute of NeuroScience, Catholic University of Louvain, Brussels, Belgium
| | - Jean Delbeke
- Institute of NeuroScience, Catholic University of Louvain, Brussels, Belgium
| | | | - André Mouraux
- Institute of NeuroScience, Catholic University of Louvain, Brussels, Belgium
| | - Riëm El Tahry
- Institute of NeuroScience, Catholic University of Louvain, Brussels, Belgium; Department of Neurology, Saint Luc University Hospital, Brussels, Belgium
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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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Laryngeal Muscle-Evoked Potential Recording as an Indicator of Vagal Nerve Fiber Activation. Neuromodulation 2022; 25:461-470. [DOI: 10.1016/j.neurom.2022.01.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/30/2021] [Accepted: 01/04/2022] [Indexed: 11/20/2022]
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Chang YC, Cracchiolo M, Ahmed U, Mughrabi I, Gabalski A, Daytz A, Rieth L, Becker L, Datta-Chaudhuri T, Al-Abed Y, Zanos TP, Zanos S. Quantitative estimation of nerve fiber engagement by vagus nerve stimulation using physiological markers. Brain Stimul 2020; 13:1617-1630. [PMID: 32956868 DOI: 10.1016/j.brs.2020.09.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 07/31/2020] [Accepted: 09/04/2020] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Cervical vagus nerve stimulation (VNS) is an emerging bioelectronic treatment for brain, metabolic, cardiovascular and immune disorders. Its desired and off-target effects are mediated by different nerve fiber populations and knowledge of their engagement could guide calibration and monitoring of VNS therapies. OBJECTIVE Stimulus-evoked compound action potentials (eCAPs) directly provide fiber engagement information but are currently not feasible in humans. A method to estimate fiber engagement through common, noninvasive physiological readouts could be used in place of eCAP measurements. METHODS In anesthetized rats, we recorded eCAPs while registering acute physiological response markers to VNS: cervical electromyography (EMG), changes in heart rate (ΔHR) and breathing interval (ΔBI). Quantitative models were established to capture the relationship between A-, B- and C-fiber type activation and those markers, and to quantitatively estimate fiber activation from physiological markers and stimulation parameters. RESULTS In bivariate analyses, we found that EMG correlates with A-fiber, ΔHR with B-fiber and ΔBI with C-fiber activation, in agreement with known physiological functions of the vagus. We compiled multivariate models for quantitative estimation of fiber engagement from these markers and stimulation parameters. Finally, we compiled frequency gain models that allow estimation of fiber engagement at a wide range of VNS frequencies. Our models, after calibration in humans, could provide noninvasive estimation of fiber engagement in current and future therapeutic applications of VNS.
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Affiliation(s)
- Yao-Chuan Chang
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA
| | - Marina Cracchiolo
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA; The BioRobotics Institute and Department of Excellence in Robotics and AI, Scuola Superiore Sant'Anna, Pisa, 56127, Italy
| | - Umair Ahmed
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA
| | - Ibrahim Mughrabi
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA
| | - Arielle Gabalski
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA
| | - Anna Daytz
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA
| | - Loren Rieth
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA
| | - Lance Becker
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA
| | - Timir Datta-Chaudhuri
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA
| | - Yousef Al-Abed
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA
| | - Theodoros P Zanos
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA
| | - Stavros Zanos
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, USA.
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Vespa S, Stumpp L, Bouckaert C, Delbeke J, Smets H, Cury J, Ferrao Santos S, Rooijakkers H, Nonclercq A, Raedt R, Vonck K, El Tahry R. Vagus Nerve Stimulation-Induced Laryngeal Motor Evoked Potentials: A Possible Biomarker of Effective Nerve Activation. Front Neurosci 2019; 13:880. [PMID: 31507360 PMCID: PMC6718640 DOI: 10.3389/fnins.2019.00880] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 08/05/2019] [Indexed: 11/13/2022] Open
Abstract
Vagus nerve stimulation (VNS) therapy is associated with laryngeal muscle activation and induces voice modifications, well-known side effects of the therapy resulting from co-activation of the recurrent laryngeal nerve. In this study, we describe the non-invasive transcutaneous recording of laryngeal motor evoked potentials (LMEPs), which could serve as a biomarker of effective nerve activation and individual titration in patients with drug-resistant epilepsy. We recruited drug-resistant epileptic patients treated for at least 6 months with a VNS. Trains of 600-1200 VNS pulses were delivered with increasing current outputs. We placed six skin electrodes on the ventral surface of the neck, in order to record LMEPs whenever the laryngeal muscular threshold was reached. We studied the internal consistency and the variability of LMEP recordings, and compared different methods for amplitude calculation. Recruitment curves were built based on the stimulus-response relationship. We also determined the electrical axis of the LMEPs dipole in order to define the optimal electrode placement for LMEPs recording in a clinical setting. LMEPs were successfully recorded in 11/11 patients. The LMEPs threshold ranged from 0.25 to 1 mA (median 0.50 mA), and onset latency was between 5.37 and 8.77 ms. The signal-to-noise ratio was outstanding in 10/11 patients. In these cases, excellent reliability (Intraclass correlation coefficient, ICC > 0.90 across three different amplitude measurements) was achieved with 10 sample averages. Moreover, our recordings showed very good internal consistency (Cronbach's alpha > 0.95 for 10 epochs). Area-under-the-curve and peak-to-peak measurement proved to be complementary methods for amplitude calculation. Finally, we determined that an optimal derivation requires only two recording electrodes, aligned on a horizontal axis around the laryngeal prominence. In conclusion, we describe here an optimal methodology for the recording of VNS-induced motor evoked responses from the larynx. Although further clinical validation is still necessary, LMEPs might be useful as a non-invasive marker of effective nerve activation, and as an aid for the clinician to perform a more rational titration of VNS parameters.
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Affiliation(s)
- Simone Vespa
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Lars Stumpp
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | | | - Jean Delbeke
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Hugo Smets
- Bio, Electro And Mechanical Systems, Université Libre de Bruxelles, Brussels, Belgium
| | - Joaquin Cury
- Bio, Electro And Mechanical Systems, Université Libre de Bruxelles, Brussels, Belgium
| | - Susana Ferrao Santos
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium.,Centre for Refractory Epilepsy, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Herbert Rooijakkers
- Department of Neurosurgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Antoine Nonclercq
- Bio, Electro And Mechanical Systems, Université Libre de Bruxelles, Brussels, Belgium
| | - Robrecht Raedt
- 4Brain, Institute for Neurosciences, Ghent University, Ghent, Belgium
| | - Kristl Vonck
- 4Brain, Institute for Neurosciences, Ghent University, Ghent, Belgium.,Reference Center for Refractory Epilepsy, Department of Neurology, Ghent University, Ghent, Belgium
| | - Riëm El Tahry
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium.,Centre for Refractory Epilepsy, Cliniques Universitaires Saint-Luc, Brussels, Belgium
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Engineer ND, Kimberley TJ, Prudente CN, Dawson J, Tarver WB, Hays SA. Targeted Vagus Nerve Stimulation for Rehabilitation After Stroke. Front Neurosci 2019; 13:280. [PMID: 30983963 PMCID: PMC6449801 DOI: 10.3389/fnins.2019.00280] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/08/2019] [Indexed: 01/14/2023] Open
Abstract
Stroke is a leading cause of disability worldwide, and in approximately 60% of individuals, upper limb deficits persist 6 months after stroke. These deficits adversely affect the functional use of the upper limb and restrict participation in day to day activities. An important goal of stroke rehabilitation is to improve the quality of life by enhancing functional independence and participation in activities. Since upper limb deficits are one of the best predictors of quality of life after stroke, effective interventions targeting these deficits may represent a means to improve quality of life. An increased understanding of the neurobiological processes underlying stroke recovery has led to the development of targeted approaches to improve motor deficits. One such targeted strategy uses brief bursts of Vagus Nerve Stimulation (VNS) paired with rehabilitation to enhance plasticity and support recovery of upper limb function after chronic stroke. Stimulation of the vagus nerve triggers release of plasticity promoting neuromodulators, such as acetylcholine and norepinephrine, throughout the cortex. Timed engagement of neuromodulators concurrent with motor training drives task-specific plasticity in the motor cortex to improve function and provides the basis for paired VNS therapy. A number of studies in preclinical models of ischemic stroke demonstrated that VNS paired with rehabilitative training significantly improved the recovery of forelimb motor function compared to rehabilitative training without VNS. The improvements were associated with synaptic reorganization of cortical motor networks and recruitment of residual motor neurons controlling the impaired forelimb, demonstrating the putative neurobiological mechanisms underlying recovery of motor function. These preclinical studies provided the basis for conducting two multi-site, randomized controlled pilot trials in individuals with moderate to severe upper limb weakness after chronic ischemic stroke. In both studies, VNS paired with rehabilitation improved motor deficits compared to rehabilitation alone. The trials provided support for a 120-patient pivotal study designed to evaluate the efficacy of paired VNS therapy in individuals with chronic ischemic stroke. This manuscript will discuss the neurobiological rationale for VNS therapy, provide an in-depth discussion of both animal and human studies of VNS therapy for stroke, and outline the challenges and opportunities for the future use of VNS therapy.
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Affiliation(s)
| | - Teresa J. Kimberley
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, MGH Institute of Health Professions, Boston, MA, United States
| | | | - Jesse Dawson
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, Queen Elizabeth University Hospital, University of Glasgow, Glasgow, United Kingdom
| | | | - Seth A. Hays
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
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Qing KY, Wasilczuk KM, Ward MP, Phillips EH, Vlachos PP, Goergen CJ, Irazoqui PP. B fibers are the best predictors of cardiac activity during Vagus nerve stimulation: Qing, vagal B fiber activation and cardiac effects. Bioelectron Med 2018; 4:5. [PMID: 32232081 PMCID: PMC7098216 DOI: 10.1186/s42234-018-0005-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 03/14/2018] [Indexed: 12/23/2022] Open
Abstract
Background Vagus nerve stimulation (VNS) is a promising therapy for many neurologic and psychiatric conditions. However, determining stimulus parameters for individual patients is a major challenge. The traditional method of titrating stimulus intensity based on patient perception produces highly variable responses. This study explores using the vagal response to measure stimulation dose and predict physiological effect. Clinicians are investigating the use of VNS for heart failure management, and this work aims to correlate cardiac measures with vagal fiber activity. Results By recording vagal activity during VNS in rats and using regression analysis, we found that cardiac activity across all animals was best correlated to the activation of a specific vagal fiber group. With conduction velocities ranging from 5 to 10 m/s, these fibers are classified as B fibers (using the Erlanger-Gasser system) and correspond to vagal parasympathetic efferents. Conclusions B fiber activation can serve as a standardized, objective measure of stimulus dose across all subjects. Tracking fiber activation provides a more systematic way to study the effects of VNS and in the future, may lead to a more consistent method of therapy delivery.
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Affiliation(s)
- Kurt Y Qing
- 1Biomedical Engineering, Purdue University, West Lafayette, IN USA.,2Indiana University School of Medicine, Indianapolis, IN USA
| | | | - Matthew P Ward
- 1Biomedical Engineering, Purdue University, West Lafayette, IN USA
| | - Evan H Phillips
- 1Biomedical Engineering, Purdue University, West Lafayette, IN USA
| | - Pavlos P Vlachos
- 3Mechanical Engineering, Purdue University, West Lafayette, IN USA
| | - Craig J Goergen
- 1Biomedical Engineering, Purdue University, West Lafayette, IN USA
| | - Pedro P Irazoqui
- 1Biomedical Engineering, Purdue University, West Lafayette, IN USA
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Mourdoukoutas AP, Truong DQ, Adair DK, Simon BJ, Bikson M. High-Resolution Multi-Scale Computational Model for Non-Invasive Cervical Vagus Nerve Stimulation. Neuromodulation 2018; 21:261-268. [PMID: 29076212 PMCID: PMC5895480 DOI: 10.1111/ner.12706] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 07/26/2017] [Accepted: 08/25/2017] [Indexed: 12/28/2022]
Abstract
OBJECTIVES To develop the first high-resolution, multi-scale model of cervical non-invasive vagus nerve stimulation (nVNS) and to predict vagus fiber type activation, given clinically relevant rheobase thresholds. METHODS An MRI-derived Finite Element Method (FEM) model was developed to accurately simulate key macroscopic (e.g., skin, soft tissue, muscle) and mesoscopic (cervical enlargement, vertebral arch and foramen, cerebral spinal fluid [CSF], nerve sheath) tissue components to predict extracellular potential, electric field (E-Field), and activating function along the vagus nerve. Microscopic scale biophysical models of axons were developed to compare axons of varying size (Aα-, Aβ- and Aδ-, B-, and C-fibers). Rheobase threshold estimates were based on a step function waveform. RESULTS Macro-scale accuracy was found to determine E-Field magnitudes around the vagus nerve, while meso-scale precision determined E-field changes (activating function). Mesoscopic anatomical details that capture vagus nerve passage through a changing tissue environment (e.g., bone to soft tissue) profoundly enhanced predicted axon sensitivity while encapsulation in homogenous tissue (e.g., nerve sheath) dulled axon sensitivity to nVNS. CONCLUSIONS These findings indicate that realistic and precise modeling at both macroscopic and mesoscopic scales are needed for quantitative predictions of vagus nerve activation. Based on this approach, we predict conventional cervical nVNS protocols can activate A- and B- but not C-fibers. Our state-of-the-art implementation across scales is equally valuable for models of spinal cord stimulation, cortex/deep brain stimulation, and other peripheral/cranial nerve models.
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Affiliation(s)
- Antonios P. Mourdoukoutas
- Department of Biomedical Engineering, The City College of New York, City University of New York, New York, NY
| | - Dennis Q. Truong
- Department of Biomedical Engineering, The City College of New York, City University of New York, New York, NY
| | - Devin K. Adair
- Department of Psychology, The Graduate Center, City University of New York, New York, New York
| | | | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York, City University of New York, New York, NY
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Mirza KB, Alenda A, Eftekhar A, Grossman N, Nikolic K, Bloom SR, Toumazou C. Influence of Cholecystokinin-8 on Compound Nerve Action Potentials from Ventral Gastric Vagus in Rats. Int J Neural Syst 2018; 28:1850006. [PMID: 29631504 DOI: 10.1142/s0129065718500065] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Vagus Nerve Stimulation (VNS) has shown great promise as a potential therapy for a number of conditions, such as epilepsy, depression and for Neurometabolic Therapies, especially for treating obesity. The objective of this study was to characterize the left ventral subdiaphragmatic gastric trunk of vagus nerve (SubDiaGVN) and to analyze the influence of intravenous injection of gut hormone cholecystokinin octapeptide (CCK-8) on compound nerve action potential (CNAP) observed on the same branch, with the aim of understanding the impact of hormones on VNS and incorporating the methods and results into closed loop implant design. METHODS The cervical region of the left vagus nerve (CerVN) of male Wistar rats was stimulated with electric current and the elicited CNAPs were recorded on the SubDiaGVN under four different conditions: Control (no injection), Saline, CCK1 (100[Formula: see text]pmol/kg) and CCK2 (1000[Formula: see text]pmol/kg) injections. RESULTS We identified the presence of A[Formula: see text], B, C1, C2, C3 and C4 fibers with their respective velocity ranges. Intravenous administration of CCK in vivo results in selective, statistically significant reduction of CNAP components originating from A and B fibers, but with no discernible effect on the C fibers in [Formula: see text] animals. The affected CNAP components exhibit statistically significant ([Formula: see text] and [Formula: see text]) higher normalized stimulation thresholds. CONCLUSION This approach of characterizing the vagus nerve can be used in closed loop systems to determine when to initiate VNS and also to tune the stimulation dose, which is patient-specific and changes over time.
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Affiliation(s)
- Khalid B Mirza
- * Institute of Biomedical Engineering, Department of Electrical and Electronic Engineering, Imperial College London, SW7 2AZ, UK
| | - Andrea Alenda
- * Institute of Biomedical Engineering, Department of Electrical and Electronic Engineering, Imperial College London, SW7 2AZ, UK
| | - Amir Eftekhar
- * Institute of Biomedical Engineering, Department of Electrical and Electronic Engineering, Imperial College London, SW7 2AZ, UK
| | - Nir Grossman
- * Institute of Biomedical Engineering, Department of Electrical and Electronic Engineering, Imperial College London, SW7 2AZ, UK
| | - Konstantin Nikolic
- * Institute of Biomedical Engineering, Department of Electrical and Electronic Engineering, Imperial College London, SW7 2AZ, UK
| | - Stephen R Bloom
- † Division of Diabetes, Endocrinology and Metabolism, Section of Endocrinology and Investigative Medicine, Imperial College London, W12 0NN, UK
| | - Christofer Toumazou
- * Institute of Biomedical Engineering, Department of Electrical and Electronic Engineering, Imperial College London, SW7 2AZ, UK
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12
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Loerwald KW, Borland MS, Rennaker RL, Hays SA, Kilgard MP. The interaction of pulse width and current intensity on the extent of cortical plasticity evoked by vagus nerve stimulation. Brain Stimul 2017; 11:271-277. [PMID: 29174302 DOI: 10.1016/j.brs.2017.11.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 11/10/2017] [Accepted: 11/11/2017] [Indexed: 10/18/2022] Open
Abstract
BACKGROUND Repeatedly pairing a tone with a brief burst of vagus nerve stimulation (VNS) results in a reorganization of primary auditory cortex (A1). The plasticity-enhancing and memory-enhancing effects of VNS follow an inverted-U response to stimulation intensity, in which moderate intensity currents yield greater effects than low or high intensity currents. It is not known how other stimulation parameters effect the plasticity-enhancing effects of VNS. OBJECTIVE We sought to investigate the effect of pulse-width and intensity on VNS efficacy. Here, we used the extent of plasticity induced by VNS-tone pairing to assess VNS efficacy. METHODS Rats were exposed to a 9 kHz tone paired to VNS with varying current intensities and pulse widths. Cortical plasticity was measured as changes in the percent of area of primary auditory cortex responding to a range of sounds in VNS-treated rats relative to naïve rats. RESULTS We find that a combination of low current intensity (200 μA) and short pulse duration (100 μs) is insufficient to drive cortical plasticity. Increasing the pulse duration to 500 μs results in a reorganization of receptive fields in A1 auditory cortex. The extent of plasticity engaged under these conditions is less than that driven by conditions previously reported to drive robust plasticity (800 μA with 100 μs wide pulses). CONCLUSION These results suggest that the plasticity-enhancing and memory-enhancing effects of VNS follow an inverted-U response of stimulation current that is influenced by pulse width. Furthermore, shorter pulse widths may offer a clinical advantage when determining optimal stimulation current. These findings may facilitate determination of optimal VNS parameters for clinical application.
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Affiliation(s)
| | - Michael S Borland
- Texas Biomedical Device Center, Richardson, TX 75080, United States; The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR 41, Richardson, TX 75080-3021, United States
| | - Robert L Rennaker
- Texas Biomedical Device Center, Richardson, TX 75080, United States; The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR 41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, BSB 11, Richardson, TX 75080, United States
| | - Seth A Hays
- Texas Biomedical Device Center, Richardson, TX 75080, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, BSB 11, Richardson, TX 75080, United States
| | - Michael P Kilgard
- Texas Biomedical Device Center, Richardson, TX 75080, United States; The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR 41, Richardson, TX 75080-3021, United States
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Vagus nerve stimulation produces a hippocampal formation theta rhythm in anesthetized rats. Brain Res 2017; 1675:41-50. [DOI: 10.1016/j.brainres.2017.08.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 08/22/2017] [Accepted: 08/26/2017] [Indexed: 12/30/2022]
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14
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Oliveira TVHFD, Francisco AN, Demartini Junior Z, Stebel SL. The role of vagus nerve stimulation in refractory epilepsy. ARQUIVOS DE NEURO-PSIQUIATRIA 2017; 75:657-666. [DOI: 10.1590/0004-282x20170113] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 06/07/2017] [Indexed: 11/22/2022]
Abstract
ABSTRACT Vagus nerve stimulation is an adjunctive therapy used to treat patients with refractory epilepsy who are not candidates for resective surgery or had poor results after surgical procedures. Its mechanism of action is not yet fully comprehended but it possibly involves modulation of the locus coeruleus, thalamus and limbic circuit through noradrenergic and serotonergic projections. There is sufficient evidence to support its use in patients with focal epilepsy and other seizure types. However, it should be recognized that improvement is not immediate and increases over time. The majority of adverse events is stimulation-related, temporary and decreases after adjustment of settings. Future perspectives to improve efficacy and reduce side effects, such as different approaches to increase battery life, transcutaneous stimulation and identification of prognostic factors, should be further investigated.
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15
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Larsen LE, Lysebettens WV, Germonpré C, Carrette S, Daelemans S, Sprengers M, Thyrion L, Wadman WJ, Carrette E, Delbeke J, Boon P, Vonck K, Raedt R. Clinical Vagus Nerve Stimulation Paradigms Induce Pronounced Brain and Body Hypothermia in Rats. Int J Neural Syst 2016; 27:1750016. [PMID: 28178853 DOI: 10.1142/s0129065717500162] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Vagus nerve stimulation (VNS) is a widely used neuromodulation technique that is currently used or being investigated as therapy for a wide array of human diseases such as epilepsy, depression, Alzheimer's disease, tinnitus, inflammatory diseases, pain, heart failure and many others. Here, we report a pronounced decrease in brain and core temperature during VNS in freely moving rats. Two hours of rapid cycle VNS (7s on/18s off) decreased brain temperature by around [Formula: see text]C, while standard cycle VNS (30[Formula: see text]s on/300[Formula: see text]s off) was associated with a decrease of around [Formula: see text]C. Rectal temperature similarly decreased by more than [Formula: see text]C during rapid cycle VNS. The hypothermic effect triggered by VNS was further associated with a vasodilation response in the tail, which reflects an active heat release mechanism. Despite previous evidence indicating an important role of the locus coeruleus-noradrenergic system in therapeutic effects of VNS, lesioning this system with the noradrenergic neurotoxin DSP-4 did not attenuate the hypothermic effect. Since body and brain temperature affect most physiological processes, this finding is of substantial importance for interpretation of several previously published VNS studies and for the future direction of research in the field.
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Affiliation(s)
- Lars Emil Larsen
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
| | - Wouter Van Lysebettens
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
| | - Charlotte Germonpré
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
| | - Sofie Carrette
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
| | - Sofie Daelemans
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
| | - Mathieu Sprengers
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
| | - Lisa Thyrion
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
| | - Wytse Jan Wadman
- 2 Swammerdam Institute of Life Sciences, University of Amsterdam, Science Park 904, Amsterdam, 1090GE, The Netherlands
| | - Evelien Carrette
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
| | - Jean Delbeke
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
| | - Paul Boon
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
| | - Kristl Vonck
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
| | - Robrecht Raedt
- 1 Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Internal Medicine, Ghent University, De Pintelaan 185, Ghent, 9000, Belgium
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16
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Wostyn S, Staljanssens W, De Taeye L, Strobbe G, Gadeyne S, Van Roost D, Raedt R, Vonck K, van Mierlo P. EEG Derived Brain Activity Reflects Treatment Response from Vagus Nerve Stimulation in Patients with Epilepsy. Int J Neural Syst 2016; 27:1650048. [PMID: 27712133 DOI: 10.1142/s0129065716500489] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mechanism of action of vagus nerve stimulation (VNS) is yet to be elucidated. To that end, the effects of VNS on the brain of epileptic patients were studied. Both when VNS was switched "On" and "Off", the brain activity of responders (R, seizure frequency reduction of over 50%) was compared to the brain activity of nonresponders (NR, seizure frequency reduction of less than 50%). Using EEG recordings, a significant increase in P300 amplitude for R and a significant decrease in P300 amplitude for NR were found. We found biomarkers for checking the efficacy of VNS with accuracy up to 94%. The results show that P300 features recorded in nonmidline electrodes are better P300 biomarkers for VNS efficacy than P300 features recorded in midline electrodes. Using source localization and connectivity analyses, the activity of the limbic system, insula and orbitofrontal cortex was found to be dependent on VNS switched "On" versus "Off" or patient group (R versus NR). The results suggest an important role for these areas in the mechanism of action of VNS, although a larger patient study should be done to confirm the findings.
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Affiliation(s)
- Simon Wostyn
- * MEDISIP, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.,† iMinds Medical IT Department, Ghent University, Ghent, Belgium
| | - Willeke Staljanssens
- * MEDISIP, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.,† iMinds Medical IT Department, Ghent University, Ghent, Belgium
| | - Leen De Taeye
- ‡ LCEN3, Department of Neurology, Ghent University, Ghent, Belgium
| | - Gregor Strobbe
- * MEDISIP, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium
| | - Stefanie Gadeyne
- ‡ LCEN3, Department of Neurology, Ghent University, Ghent, Belgium
| | - Dirk Van Roost
- § Department of Neurosurgery, Ghent University Hospital, Ghent, Belgium
| | - Robrecht Raedt
- ‡ LCEN3, Department of Neurology, Ghent University, Ghent, Belgium
| | - Kristl Vonck
- ‡ LCEN3, Department of Neurology, Ghent University, Ghent, Belgium
| | - Pieter van Mierlo
- * MEDISIP, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.,† iMinds Medical IT Department, Ghent University, Ghent, Belgium.,¶ Functional Brain Mapping lab, University of Geneva, Geneva, Switzerland
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17
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Larsen LE, Wadman WJ, Marinazzo D, van Mierlo P, Delbeke J, Daelemans S, Sprengers M, Thyrion L, Van Lysebettens W, Carrette E, Boon P, Vonck K, Raedt R. Vagus Nerve Stimulation Applied with a Rapid Cycle Has More Profound Influence on Hippocampal Electrophysiology Than a Standard Cycle. Neurotherapeutics 2016; 13:592-602. [PMID: 27102987 PMCID: PMC4965402 DOI: 10.1007/s13311-016-0432-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Although vagus nerve stimulation (VNS) is widely used, therapeutic mechanisms and optimal stimulation parameters remain elusive. In the present study, we investigated the effect of VNS on hippocampal field activity and compared the efficiency of different VNS paradigms. Hippocampal electroencephalography (EEG) and perforant path dentate field-evoked potentials were acquired before and during VNS in freely moving rats, using 2 VNS duty cycles: a rapid cycle (7 s on, 18 s off) and standard cycle (30 s on, 300 s off) and various output currents. VNS modulated the evoked potentials, reduced total power of the hippocampal EEG, and slowed the theta rhythm. In the hippocampal EEG, theta (4-8 Hz) and high gamma (75-150 Hz) activity displayed strong phase amplitude coupling that was reduced by VNS. Rapid-cycle VNS had a greater effect than standard-cycle VNS on all outcome measures. Using rapid cycle VNS, a maximal effect on EEG parameters was found at 300 μA, beyond which effects saturated. The findings suggest that rapid-cycle VNS produces a more robust outcome than standard cycle VNS and support already existing preclinical evidence that relatively low output currents are sufficient to produce changes in brain physiology and thus likely also therapeutic efficacy.
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Affiliation(s)
- Lars E Larsen
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium.
| | - Wytse J Wadman
- Swammerdam Institute of Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Daniele Marinazzo
- Department of Data Analysis, Faculty for Psychological and Pedagogical Sciences, Ghent University, Ghent, Belgium
| | - Pieter van Mierlo
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium
- Medical Imaging and Signal Processing, Department of Electronics and Information Systems, iMinds Medical IT Department, Ghent University, Ghent, Belgium
| | - Jean Delbeke
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium
| | - Sofie Daelemans
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium
| | - Mathieu Sprengers
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium
| | - Lisa Thyrion
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium
| | - Wouter Van Lysebettens
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium
| | - Evelien Carrette
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium
| | - Paul Boon
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium
| | - Kristl Vonck
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium
| | - Robrecht Raedt
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium
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Abstract
Pathological neural activity could be treated by directing specific plasticity to renormalize circuits and restore function. Rehabilitative therapies aim to promote adaptive circuit changes after neurological disease or injury, but insufficient or maladaptive plasticity often prevents a full recovery. The development of adjunctive strategies that broadly support plasticity to facilitate the benefits of rehabilitative interventions has the potential to improve treatment of a wide range of neurological disorders. Recently, stimulation of the vagus nerve in conjunction with rehabilitation has emerged as one such potential targeted plasticity therapy. Vagus nerve stimulation (VNS) drives activation of neuromodulatory nuclei that are associated with plasticity, including the cholinergic basal forebrain and the noradrenergic locus coeruleus. Repeatedly pairing brief bursts of VNS sensory or motor events drives robust, event-specific plasticity in neural circuits. Animal models of chronic tinnitus, ischemic stroke, intracerebral hemorrhage, traumatic brain injury, and post-traumatic stress disorder benefit from delivery of VNS paired with successful trials during rehabilitative training. Moreover, mounting evidence from pilot clinical trials provides an initial indication that VNS-based targeted plasticity therapies may be effective in patients with neurological diseases and injuries. Here, I provide a discussion of the current uses and potential future applications of VNS-based targeted plasticity therapies in animal models and patients, and outline challenges for clinical implementation.
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Affiliation(s)
- Seth A Hays
- Texas Biomedical Device Center, Richardson, TX, USA.
- Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, USA.
- School of Behavioral Brain Sciences, The University of Texas at Dallas, Richardson, TX, USA.
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19
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Larsen LE, Wadman WJ, van Mierlo P, Delbeke J, Grimonprez A, Van Nieuwenhuyse B, Portelli J, Boon P, Vonck K, Raedt R. Modulation of Hippocampal Activity by Vagus Nerve Stimulation in Freely Moving Rats. Brain Stimul 2016; 9:124-32. [DOI: 10.1016/j.brs.2015.09.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 08/25/2015] [Accepted: 09/20/2015] [Indexed: 11/16/2022] Open
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20
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Qing KY, Ward MP, Irazoqui PP. Burst-Modulated Waveforms Optimize Electrical Stimuli for Charge Efficiency and Fiber Selectivity. IEEE Trans Neural Syst Rehabil Eng 2015; 23:936-45. [DOI: 10.1109/tnsre.2015.2421732] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Grimonprez A, Raedt R, De Taeye L, Larsen LE, Delbeke J, Boon P, Vonck K. A Preclinical Study of Laryngeal Motor-Evoked Potentials as a Marker Vagus Nerve Activation. Int J Neural Syst 2015; 25:1550034. [PMID: 26510476 DOI: 10.1142/s0129065715500343] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Vagus nerve stimulation (VNS) is a treatment for refractory epilepsy and depression. Previous studies using invasive recording electrodes showed that VNS induces laryngeal motor-evoked potentials (LMEPs) through the co-activation of the recurrent laryngeal nerve and subsequent contractions of the laryngeal muscles. The present study investigates the feasibility of recording LMEPs in chronically VNS-implanted rats, using a minimally-invasive technique, to assess effective current delivery to the nerve and to determine optimal VNS output currents for vagal fiber activation. Three weeks after VNS electrode implantation, signals were recorded using an electromyography (EMG) electrode in the proximity of the laryngeal muscles and a reference electrode on the skull. The VNS output current was gradually ramped up from 0.1 to 1.0 mA in 0.1 mA steps. In 13/27 rats, typical LMEPs were recorded at low VNS output currents (median 0.3 mA, IQR 0.2-0.3 mA). In 11/27 rats, significantly higher output currents were required to evoke electrophysiological responses (median 0.7 mA, IQR 0.5-0.7 mA, p < 0.001). The latencies of these responses deviated significantly from LMEPs (p < 0.05). In 3/27 rats, no electrophysiological responses to simulation were recorded. Minimally invasive LMEP recordings are feasible to assess effective current delivery to the vagus nerve. Furthermore, our results suggest that low output currents are sufficient to activate vagal fibers.
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Affiliation(s)
- Annelies Grimonprez
- 1 Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Robrecht Raedt
- 1 Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Leen De Taeye
- 1 Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Lars Emil Larsen
- 1 Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Jean Delbeke
- 1 Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Paul Boon
- 1 Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Kristl Vonck
- 1 Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
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22
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Bandarabadi M, Rasekhi J, Teixeira CA, Netoff TI, Parhi KK, Dourado A. Early Seizure Detection Using Neuronal Potential Similarity: A Generalized Low-Complexity and Robust Measure. Int J Neural Syst 2015; 25:1550019. [DOI: 10.1142/s0129065715500197] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A novel approach using neuronal potential similarity (NPS) of two intracranial electroencephalogram (iEEG) electrodes placed over the foci is proposed for automated early seizure detection in patients with refractory partial epilepsy. The NPS measure is obtained from the spectral analysis of space-differential iEEG signals. Ratio between the NPS values obtained from two specific frequency bands is then investigated as a robust generalized measure, and reveals invaluable information about seizure initiation trends. A threshold-based classifier is subsequently applied on the proposed measure to generate alarms. The performance of the method was evaluated using cross-validation on a large clinical dataset, involving 183 seizure onsets in 1785 h of long-term continuous iEEG recordings of 11 patients. On average, the results show a high sensitivity of 86.9% (159 out of 183), a very low false detection rate of 1.4 per day, and a mean detection latency of 13.1 s from electrographic seizure onsets, while in average preceding clinical onsets by 6.3 s. These high performance results, specifically the short detection latency, coupled with the very low computational cost of the proposed method make it adequate for using in implantable closed-loop seizure suppression systems.
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Affiliation(s)
| | - Jalil Rasekhi
- Department of Electrical and Computer Engineering, Noshirvani University of Technology, Iran
| | - Cesar A. Teixeira
- Department of Informatics Engineering, University of Coimbra, Portugal
| | - Theoden I. Netoff
- Netoff Epilepsy Lab, Department of Biomedical Engineering, University of Minnesota, USA
| | - Keshab K. Parhi
- Department of Electrical and Computer Engineering, University of Minnesota, USA
| | - Antonio Dourado
- Department of Informatics Engineering, University of Coimbra, Portugal
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