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Hodaj H, Payen JF, Hodaj E, Sorel M, Dumolard A, Vercueil L, Delon-Martin C, Lefaucheur JP. Long-term analgesic effect of trans-spinal direct current stimulation compared to non-invasive motor cortex stimulation in complex regional pain syndrome. Brain Commun 2023; 5:fcad191. [PMID: 37545548 PMCID: PMC10400160 DOI: 10.1093/braincomms/fcad191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 05/26/2023] [Accepted: 06/30/2023] [Indexed: 08/08/2023] Open
Abstract
The aim of the present study was to compare the analgesic effect of motor cortex stimulation using high-frequency repetitive transcranial magnetic stimulation or transcranial direct current stimulation and transcutaneous spinal direct current stimulation in patients with complex regional pain syndrome. Thirty-three patients with complex regional pain syndrome were randomized to one of the three treatment groups (repetitive transcranial magnetic stimulation, n = 11; transcranial direct current stimulation, n = 10; transcutaneous spinal direct current stimulation, n = 12) and received a series of 12 sessions of stimulation for 3 weeks (induction phase) and 11 sessions for 4 months (maintenance therapy). The primary end-point was the mean pain intensity assessed weekly with a visual numerical scale during the month prior to treatment (baseline), the 5-month stimulation period and 1 month after the treatment. The weekly visual numerical scale pain score was significantly reduced at all time points compared to baseline in the transcutaneous spinal direct current stimulation group, at the last two time points in the repetitive transcranial magnetic stimulation group (end of the 5-month stimulation period and 1 month later), but at no time point in the transcranial direct current stimulation group. A significant pain relief was observed at the end of induction phase using transcutaneous spinal direct current stimulation compared to repetitive transcranial magnetic stimulation (P = 0.008) and to transcranial direct current stimulation (P = 0.003). In this trial, transcutaneous spinal direct current stimulation was more efficient to relieve pain in patients with complex regional pain syndrome compared to motor cortex stimulation techniques (repetitive transcranial magnetic stimulation, transcranial direct current stimulation). This efficacy was found during the induction phase and was maintained thereafter. This study warrants further investigation to confirm the potentiality of transcutaneous spinal direct current stimulation as a therapeutic option in complex regional pain syndrome.
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Affiliation(s)
- Hasan Hodaj
- Correspondence to: Hasan Hodaj Pôle Anesthésie Réanimation CHU Grenoble Alpes, BP217, 38043 Grenoble, FranceE-mail:
| | - Jean-Francois Payen
- Centre de la Douleur, Pôle Anesthésie Réanimation, CHU Grenoble Alpes, 38000 Grenoble, France
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, 38000 Grenoble, France
| | - Enkelejda Hodaj
- Centre d'Investigation Clinique, CHU Grenoble Alpes, 38000, Grenoble, France
| | - Marc Sorel
- Centre d'Evaluation et de Traitement de la Douleur, Hôpital Sud-Seine-et-Marne, site Nemours, Nemours, France
- EA 4391, Excitabilité Nerveuse et Thérapeutique, Faculté de Santé, Univ. Paris Est Créteil, Créteil, France
| | - Anne Dumolard
- Centre de la Douleur, Pôle Anesthésie Réanimation, CHU Grenoble Alpes, 38000 Grenoble, France
| | - Laurent Vercueil
- Service de Neurologie, CHU Grenoble Alpes, 38000, Grenoble, France
| | - Chantal Delon-Martin
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, 38000 Grenoble, France
| | - Jean-Pascal Lefaucheur
- EA 4391, Excitabilité Nerveuse et Thérapeutique, Faculté de Santé, Univ. Paris Est Créteil, Créteil, France
- Unité de Neurophysiologie Clinique, Service de Physiologie—Explorations Fonctionnelles, Hôpital Henri Mondor, Assistance Publique—Hôpitaux de Paris, Créteil, France
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Pereira M, Fernandes SR, Miranda PC, de Carvalho M. Lumbar trans-spinal direct current stimulation: A modeling-experimental approach to dorsal root ganglia stimulation. Front Neurosci 2022; 16:1041932. [PMID: 36570853 PMCID: PMC9773993 DOI: 10.3389/fnins.2022.1041932] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 11/23/2022] [Indexed: 12/14/2022] Open
Abstract
Introduction The excitability of spinal motor neurons (MN) can be altered through subthreshold currents, such as transcutaneous spinal direct-current stimulation (tsDCS). Current evidence shows that tsDCS can interfere with ascending somatosensory pathways and lower motor neurons' (LMN) excitability, which points to its therapeutic potential for repairing altered spinal responses. We aim to define the best tsDCS montage for maximizing the electric field (E-field) in the lumbar spinal cord (L-SC) by computer modeling; and to apply this montage to measure the effect on LMN excitability and somatosensory evoked potentials (SSEP). Methods A human volume conductor model was obtained from an available database. The E-field distribution was calculated considering three different electrode settings aiming at maximizing the field at L-SC and right dorsal root ganglia (DRG). The best electrode setting was then selected and applied in a blind crossover pseudo-randomized study including 14 subjects. tsDCS was delivered for 15 min (cathodal vs. sham) over L2 vertebra level (4 mA, 144 mC/cm2), and its effect on F-waves, H-reflex (including homosynaptic depression, HD) and SSEPs was investigated in the lower limbs. Results All simulated montages showed higher current density and E-field magnitudes between the electrodes (>0.15 V/m), with a major longitudinal component and with rostral-caudal direction. The induced E-field involved the sensory ganglia and was maximum in the right T8-left L2 montage, which was the one selected for the experimental protocol. We disclosed a statistically significant increase of the H-reflex amplitude at 0.1 Hz, after cathodal tsDCS (c-tsDCS) on both sides. No other significant change was observed. Discussion Our results can suggest the c-tsDCS applied to the L-SC and DRG can modulate synaptic efficiency increasing lower motor neurons response to Ia fibers excitation. The possible implications of our findings for treating clinical conditions will be addressed in future studies.
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Affiliation(s)
- Mariana Pereira
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Sofia Rita Fernandes
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal,Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Pedro Cavaleiro Miranda
- Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Mamede de Carvalho
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal,Departamento de Neurociências e Saúde Mental, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Lisboa, Portugal,*Correspondence: Mamede de Carvalho,
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Williams PT, Truong DQ, Seifert AC, Xu J, Bikson M, Martin JH. Selective augmentation of corticospinal motor drive with trans-spinal direct current stimulation in the cat. Brain Stimul 2022; 15:624-634. [DOI: 10.1016/j.brs.2022.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 03/26/2022] [Accepted: 03/27/2022] [Indexed: 11/30/2022] Open
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Abstract
The sudden loss of movement after spinal cord injury (SCI) is life-changing and is a major impetus to study spinal cord motor system plasticity and devise novel repair strategies. This review focuses on the motor cortex and the corticospinal tract, which are key to producing voluntary movements. The motor cortex projects directly to the spinal cord, via the corticospinal tract, and indirectly, via relays in the brain stem. With loss of the corticospinal tract after SCI, the indirect paths may bypass the injury and play an important role in voluntary control. In health and after injury, the spinal cord is a key site for activity-dependent neuroplasticity of the corticospinal system. Three kinds of activity-dependent plasticity have been identified: (1) corticospinal tract axon sprouting after electrical stimulation of the motor cortex; (2) synaptic competition between corticospinal tract and proprioceptive afferent fiber terminations; and (3) long-term potentiation (LTP) at the corticospinal tract-spinal interneuron synapse. SCI damages descending motor pathway connections and, in turn, triggers a loss of down-stream activity-dependent processes. This activity loss produces spinal interneuron degeneration and several activity-dependent maladaptive changes that underly hyperreflexia, spasticity, and spasms. Animal studies show that phasic electrical and tonic direct current stimulation can be used to supplement activity after SCI to reduce the activity-dependent degenerative and maladaptive changes. Importantly, when applied chronically neuromodulation recruits spinal neuroplasticity to improve function after SCI by promoting activity-dependent corticospinal axon sprouting and synapse formation. This helps establish new functional connections and strengthens spared connections. Combining neuromodulation to promote repair and motor rehabilitation to train circuits can most effectively promote motor recovery.
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Affiliation(s)
- John H Martin
- Department of Molecular, Cellular, and Biomedical Sciences, Center for Discovery and Innovation, City University of New York School of Medicine, New York, NY, United States; Neuroscience Program, Graduate Center of the City University of New York, New York, NY, United States.
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Zareen N, Shinozaki M, Ryan D, Alexander H, Amer A, Truong DQ, Khadka N, Sarkar A, Naeem S, Bikson M, Martin JH. Motor cortex and spinal cord neuromodulation promote corticospinal tract axonal outgrowth and motor recovery after cervical contusion spinal cord injury. Exp Neurol 2017; 297:179-189. [PMID: 28803750 DOI: 10.1016/j.expneurol.2017.08.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 08/04/2017] [Accepted: 08/09/2017] [Indexed: 01/15/2023]
Abstract
Cervical injuries are the most common form of SCI. In this study, we used a neuromodulatory approach to promote skilled movement recovery and repair of the corticospinal tract (CST) after a moderately severe C4 midline contusion in adult rats. We used bilateral epidural intermittent theta burst (iTBS) electrical stimulation of motor cortex to promote CST axonal sprouting and cathodal trans-spinal direct current stimulation (tsDCS) to enhance spinal cord activation to motor cortex stimulation after injury. We used Finite Element Method (FEM) modeling to direct tsDCS to the cervical enlargement. Combined iTBS-tsDCS was delivered for 30min daily for 10days. We compared the effect of stimulation on performance in the horizontal ladder and the Irvine Beattie and Bresnahan forepaw manipulation tasks and CST axonal sprouting in injury-only and injury+stimulation animals. The contusion eliminated the dorsal CST in all animals. tsDCS significantly enhanced motor cortex evoked responses after C4 injury. Using this combined spinal-M1 neuromodulatory approach, we found significant recovery of skilled locomotion and forepaw manipulation skills compared with injury-only controls. The spared CST axons caudal to the lesion in both animal groups derived mostly from lateral CST axons that populated the contralateral intermediate zone. Stimulation enhanced injury-dependent CST axonal outgrowth below and above the level of the injury. This dual neuromodulatory approach produced partial recovery of skilled motor behaviors that normally require integration of posture, upper limb sensory information, and intent for performance. We propose that the motor systems use these new CST projections to control movements better after injury.
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Affiliation(s)
- N Zareen
- Department of Molecular, Cellular, and Biomedical Sciences, City University of NY School of Medicine, New York, NY 10031, USA
| | - M Shinozaki
- Department of Molecular, Cellular, and Biomedical Sciences, City University of NY School of Medicine, New York, NY 10031, USA
| | - D Ryan
- Department of Molecular, Cellular, and Biomedical Sciences, City University of NY School of Medicine, New York, NY 10031, USA
| | - H Alexander
- Department of Molecular, Cellular, and Biomedical Sciences, City University of NY School of Medicine, New York, NY 10031, USA
| | - A Amer
- Department of Molecular, Cellular, and Biomedical Sciences, City University of NY School of Medicine, New York, NY 10031, USA; CUNY Graduate Center, New York, NY 10031, USA
| | - D Q Truong
- Department of Biomedical Engineering, City College of NY, 10031, USA
| | - N Khadka
- Department of Biomedical Engineering, City College of NY, 10031, USA
| | - A Sarkar
- Department of Molecular, Cellular, and Biomedical Sciences, City University of NY School of Medicine, New York, NY 10031, USA
| | - S Naeem
- Department of Molecular, Cellular, and Biomedical Sciences, City University of NY School of Medicine, New York, NY 10031, USA
| | - M Bikson
- Department of Biomedical Engineering, City College of NY, 10031, USA
| | - J H Martin
- Department of Molecular, Cellular, and Biomedical Sciences, City University of NY School of Medicine, New York, NY 10031, USA; CUNY Graduate Center, New York, NY 10031, USA.
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Schweizer L, Meyer-Frießem CH, Zahn PK, Tegenthoff M, Schmidt-Wilcke T. Transcutaneous Spinal Direct Current Stimulation Alters Resting-State Functional Connectivity. Brain Connect 2017; 7:357-365. [DOI: 10.1089/brain.2017.0505] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Lauren Schweizer
- Department of Neurology, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil GmbH Bochum, Ruhr-University Bochum, Bochum, Germany
| | - Christine H. Meyer-Frießem
- Department of Anesthesiology, Intensive Care Medicine, Palliative Care Medicine and Pain Management, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil GmbH Bochum, Medical Faculty of Ruhr-University Bochum, Bochum, Germany
| | - Peter K. Zahn
- Department of Anesthesiology, Intensive Care Medicine, Palliative Care Medicine and Pain Management, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil GmbH Bochum, Medical Faculty of Ruhr-University Bochum, Bochum, Germany
| | - Martin Tegenthoff
- Department of Neurology, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil GmbH Bochum, Ruhr-University Bochum, Bochum, Germany
| | - Tobias Schmidt-Wilcke
- Department of Neurology, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil GmbH Bochum, Ruhr-University Bochum, Bochum, Germany
- Department of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
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Paired Stimulation to Promote Lasting Augmentation of Corticospinal Circuits. Neural Plast 2016; 2016:7043767. [PMID: 27800189 PMCID: PMC5075312 DOI: 10.1155/2016/7043767] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 08/11/2016] [Indexed: 01/22/2023] Open
Abstract
After injury, electrical stimulation of the nervous system can augment plasticity of spared or latent circuits through focal modulation. Pairing stimulation of two parts of a spared circuit can target modulation more specifically to the intended circuit. We discuss 3 kinds of paired stimulation in the context of the corticospinal system, because of its importance in clinical neurorehabilitation. The first uses principles of Hebbian plasticity: by altering the stimulation timing of presynaptic neurons and their postsynaptic targets, synapse function can be modulated up or down. The second form uses synchronized presynaptic inputs onto a common synaptic target. We dub this a “convergent” mechanism, because stimuli have to converge on a common target with coordinated timing. The third form induces focal modulation by tonic excitation of one region (e.g., the spinal cord) during phasic stimulation of another (e.g., motor cortex). Additionally, endogenous neural activity may be paired with exogenous electrical stimulation. This review addresses what is known about paired stimulation of the corticospinal system of both humans and animal models, emphasizes how it qualitatively differs from single-site stimulation, and discusses the gaps in knowledge that must be addressed to maximize its use and efficacy in neurorehabilitation.
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Woods AJ, Antal A, Bikson M, Boggio PS, Brunoni AR, Celnik P, Cohen LG, Fregni F, Herrmann CS, Kappenman ES, Knotkova H, Liebetanz D, Miniussi C, Miranda PC, Paulus W, Priori A, Reato D, Stagg C, Wenderoth N, Nitsche MA. A technical guide to tDCS, and related non-invasive brain stimulation tools. Clin Neurophysiol 2015; 127:1031-1048. [PMID: 26652115 DOI: 10.1016/j.clinph.2015.11.012] [Citation(s) in RCA: 793] [Impact Index Per Article: 88.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 11/14/2015] [Accepted: 11/17/2015] [Indexed: 01/29/2023]
Abstract
Transcranial electrical stimulation (tES), including transcranial direct and alternating current stimulation (tDCS, tACS) are non-invasive brain stimulation techniques increasingly used for modulation of central nervous system excitability in humans. Here we address methodological issues required for tES application. This review covers technical aspects of tES, as well as applications like exploration of brain physiology, modelling approaches, tES in cognitive neurosciences, and interventional approaches. It aims to help the reader to appropriately design and conduct studies involving these brain stimulation techniques, understand limitations and avoid shortcomings, which might hamper the scientific rigor and potential applications in the clinical domain.
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Affiliation(s)
- A J Woods
- Center for Cognitive Aging and Memory, Institute on Aging, McKnight Brain Institute, Department of Aging and Geriatric Research, Department of Neuroscience, University of Florida, Gainesville, FL, USA.
| | - A Antal
- University Medical Center, Dept. Clinical Neurophysiology, Georg-August-University, Goettingen, Germany
| | - M Bikson
- Department of Biomedical Engineering, The City College of New York, USA
| | - P S Boggio
- Social and Cognitive Neuroscience Laboratory and Developmental Disorders Program, Center for Health and Biological Science, Mackenzie Presbyterian University, São Paulo, SP, Brazil
| | - A R Brunoni
- Service of Interdisciplinary Neuromodulation, Department and Institute of Psychiatry, University of São Paulo, São Paulo, Brazil
| | - P Celnik
- Department of Physical Medicine and Rehabilitation, Johns Hopkins Medical Institution, Baltimore, MD, USA
| | - L G Cohen
- Human Cortical Physiology and Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - F Fregni
- Laboratory of Neuromodulation, Center for Clinical Research Learning, Department of Physical Medicine and Rehabilitation, Harvard University, USA
| | - C S Herrmann
- Experimental Psychology Lab, Center of excellence Hearing4all, Department for Psychology, Faculty for Medicine and Health Sciences, Carl von Ossietzky Universität, Ammerländer Heerstr, Oldenburg, Germany
| | - E S Kappenman
- Center for Mind & Brain and Department of Psychology, University of California, Davis, CA, USA
| | - H Knotkova
- MJHS Institute for Innovation in Palliative Care, New York, NY, USA
| | - D Liebetanz
- University Medical Center, Dept. Clinical Neurophysiology, Georg-August-University, Goettingen, Germany
| | - C Miniussi
- Neuroscience Section, Department of Clinical and Experimental Sciences, University of Brescia & Cognitive Neuroscience Section, IRCCS Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - P C Miranda
- Institute of Biophysics and Biomedical Engineering (IBEB), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
| | - W Paulus
- University Medical Center, Dept. Clinical Neurophysiology, Georg-August-University, Goettingen, Germany
| | - A Priori
- Direttore Clinica Neurologica III, Università degli Studi di Milano, Ospedale San Paolo, Milan, Italy
| | - D Reato
- Department of Biomedical Engineering, The City College of New York, USA
| | - C Stagg
- Centre for Functional MRI of the Brain (FMRIB) Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; Oxford Centre for Human Brain Activity (OHBA), Department of Psychiatry, University of Oxford, Oxford, UK
| | - N Wenderoth
- Neural Control of Movement Lab, Dept. Health Sciences and Technology, ETH Zürich, Switzerland
| | - M A Nitsche
- University Medical Center, Dept. Clinical Neurophysiology, Georg-August-University, Goettingen, Germany; Leibniz Research Center for Working Environment and Human Factors, Dortmund, Germany; Department of Neurology, BG University Hospital Bergmannsheil, Ruhr-University Bochum, Germany
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9
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Song W, Truong DQ, Bikson M, Martin JH. Transspinal direct current stimulation immediately modifies motor cortex sensorimotor maps. J Neurophysiol 2015; 113:2801-11. [PMID: 25673738 DOI: 10.1152/jn.00784.2014] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 02/06/2015] [Indexed: 01/16/2023] Open
Abstract
Motor cortex (MCX) motor representation reorganization occurs after injury, learning, and different long-term stimulation paradigms. The neuromodulatory approach of transspinal direct current stimulation (tsDCS) has been used to promote evoked cortical motor responses. In the present study, we used cathodal tsDCS (c-tsDCS) of the rat cervical cord to determine if spinal cord activation can modify the MCX forelimb motor map. We used a finite-element method model based on coregistered high-resolution rat MRI and microcomputed tomography imaging data to predict spinal current density to target stimulation to the caudal cervical enlargement. We examined the effects of cathodal and anodal tsDCS on the H-reflex and c-tsDCS on responses evoked by intracortical microstimulation (ICMS). To determine if cervical c-tsDCS also modified MCX somatic sensory processing, we examined sensory evoked potentials (SEPs) produced by wrist electrical stimulation and induced changes in ongoing activity. Cervical c-tsDCS enhanced the H-reflex, and anodal depressed the H-reflex. Using cathodal stimulation to examine cortical effects, we found that cervical c-tsDCS immediately modified the forelimb MCX motor map, with decreased thresholds and an expanded area. c-tsDCS also increased SEP amplitude in the MCX. The magnitude of changes produced by c-tsDCS were greater on the motor than sensory response. Cervical c-tsDCS more strongly enhanced forelimb than hindlimb motor representation and had no effect on vibrissal representation. The finite-element model indicated current density localized to caudal cervical segments, informing forelimb motor selectivity. Our results suggest that c-tsDCS augments spinal excitability in a spatially selective manner and may improve voluntary motor function through MCX representational plasticity.
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Affiliation(s)
- Weiguo Song
- Department of Physiology, Pharmacology and Neuroscience, City College of the City University of New York, New York, New York
| | - Dennis Q Truong
- Department of Biomedical Engineering, City College of the City University of New York, New York, New York; and
| | - Marom Bikson
- Department of Biomedical Engineering, City College of the City University of New York, New York, New York; and
| | - John H Martin
- Department of Physiology, Pharmacology and Neuroscience, City College of the City University of New York, New York, New York; Graduate Center of the City University of New York, New York, New York
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Does trans-spinal direct current stimulation alter phrenic motoneurons and respiratory neuromechanical outputs in humans? A double-blind, sham-controlled, randomized, crossover study. J Neurosci 2015; 34:14420-9. [PMID: 25339753 DOI: 10.1523/jneurosci.1288-14.2014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Although compelling evidence has demonstrated considerable neuroplasticity in the respiratory control system, few studies have explored the possibility of altering descending projections to phrenic motoneurons (PMNs) using noninvasive stimulation protocols. The present study was designed to investigate the immediate and long-lasting effects of a single session of transcutaneous spinal direct current stimulation (tsDCS), a promising technique for modulating spinal cord functions, on descending ventilatory commands in healthy humans. Using a double-blind, controlled, randomized, crossover approach, we examined the effects of anodal, cathodal, and sham tsDCS delivered to the C3-C5 level on (1) diaphragm motor-evoked potentials (DiMEPs) elicited by transcranial magnetic stimulation and (2) spontaneous ventilation, as measured by respiratory inductance plethysmography. Both anodal and cathodal tsDCS induced a progressive increase in DiMEP amplitude during stimulation that persisted for at least 15 min after current offset. Interestingly, cathodal, but not anodal, tsDCS induced a persistent increase in tidal volume. In addition, (1) short-interval intracortical inhibition, (2) nonlinear complexity of the tidal volume signal (related to medullary ventilatory command), (3) autonomic function, and (4) compound muscle action potentials evoked by cervical magnetic stimulation were unaffected by tsDCS. This suggests that tsDCS-induced aftereffects did not occur at brainstem or cortical levels and were likely not attributable to direct polarization of cranial nerves or ventral roots. Instead, we argue that tsDCS could induce sustained changes in PMN output. Increased tidal volume after cathodal tsDCS opens up the perspective of harnessing respiratory neuroplasticity as a therapeutic tool for the management of several respiratory disorders.
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Bolzoni F, Jankowska E. Presynaptic and postsynaptic effects of local cathodal DC polarization within the spinal cord in anaesthetized animal preparations. J Physiol 2014; 593:947-66. [PMID: 25416625 DOI: 10.1113/jphysiol.2014.285940] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 11/11/2014] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Trans-spinal DC stimulation affects both postsynaptic neurons and the presynaptic axons providing input to these neurons. In the present study, we show that intraspinally applied cathodal current replicates the effects of trans-spinal direct current stimulation in deeply anaesthetized animals and affects spinal neurons both during the actual current application and during a post-polarization period. Presynaptic effects of local cathodal polarization were expressed in an increase in the excitability of skin afferents (in the dorsal horn) and group Ia afferents (in motor nuclei), both during and at least 30 min after DC application. However, although the postsynaptic facilitation (i.e. more effective) activation of motoneurons by stimuli applied in a motor nucleus was very potent during local DC application, it was only negligible once DC was discontinued. The results suggest that the prolonged effects of cathodal polarization are primarily associated with changes in synaptic transmission. ABSTRACT The present study aimed to compare presynaptic and postsynaptic actions of direct current polarization in the spinal cord, focusing on DC effects on primary afferents and motoneurons. To reduce the directly affected spinal cord region, a weak polarizing direct current (0.1-0.3 μA) was applied locally in deeply anaesthetized cats and rats; within the hindlimb motor nuclei in the caudal lumbar segments, or in the dorsal horn within the terminal projection area of low threshold skin afferents. Changes in the excitability of primary afferents activated by intraspinal stimuli (20-50 μA) were estimated using increases or decreases in compound action potentials recorded from the dorsal roots or peripheral nerves as their measure. Changes in the postsynaptic actions of the afferents were assessed from intracellularly recorded monosynaptic EPSPs in hindlimb motoneurons and monosynaptic extracellular field potentials (evoked by group Ia afferents in motor nuclei, or by low threshold cutaneous afferents in the dorsal horn). The excitability of motoneurons activated by intraspinal stimuli was assessed using intracellular records or motoneuronal discharges recorded from a ventral root or a muscle nerve. Cathodal polarization was found to affect motoneurons and afferents providing input to them to a different extent. The excitability of both was markedly increased during DC application, although post-polarization facilitation was found to involve presynaptic afferents and some of their postsynaptic actions, but only negligibly motoneurons themselves. Taken together, these results indicate that long-lasting post-polarization facilitation of spinal activity induced by locally applied cathodal current primarily reflects the facilitation of synaptic transmission.
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Affiliation(s)
- F Bolzoni
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Human Physiology Section of the DEPT, Università degli Studi di Milano, Milano, Italy
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