201
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Ironside M, Perlo S. Transcranial Direct Current Stimulation for the Treatment of Depression: a Review of the Candidate Mechanisms of Action. Curr Behav Neurosci Rep 2018. [DOI: 10.1007/s40473-018-0138-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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202
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Abstract
Brain stimulation techniques can modulate cognitive functions in many neuropsychiatric diseases. Pilot studies have shown promising effects of brain stimulations on Alzheimer's disease (AD). Brain stimulations can be categorized into non-invasive brain stimulation (NIBS) and invasive brain stimulation (IBS). IBS includes deep brain stimulation (DBS), and invasive vagus nerve stimulation (VNS), whereas NIBS includes transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), electroconvulsive treatment (ECT), magnetic seizure therapy (MST), cranial electrostimulation (CES), and non-invasive VNS. We reviewed the cutting-edge research on these brain stimulation techniques and discussed their therapeutic effects on AD. Both IBS and NIBS may have potential to be developed as novel treatments for AD; however, mixed findings may result from different study designs, patients selection, population, or samples sizes. Therefore, the efficacy of NIBS and IBS in AD remains uncertain, and needs to be further investigated. Moreover, more standardized study designs with larger sample sizes and longitudinal follow-up are warranted for establishing a structural guide for future studies and clinical application.
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Affiliation(s)
- Chun-Hung Chang
- Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.,Department of Psychiatry & Brain Disease Research Center, China Medical University Hospital, Taichung, Taiwan
| | - Hsien-Yuan Lane
- Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.,Department of Psychiatry & Brain Disease Research Center, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan.,Department of Psychology, College of Medical and Health Sciences, Asia University, Taichung, Taiwan
| | - Chieh-Hsin Lin
- Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.,Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan.,Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
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203
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Esmaeilpour Z, Marangolo P, Hampstead BM, Bestmann S, Galletta E, Knotkova H, Bikson M. Incomplete evidence that increasing current intensity of tDCS boosts outcomes. Brain Stimul 2017; 11:310-321. [PMID: 29258808 DOI: 10.1016/j.brs.2017.12.002] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 12/06/2017] [Accepted: 12/08/2017] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Transcranial direct current stimulation (tDCS) is investigated to modulate neuronal function by applying a fixed low-intensity direct current to scalp. OBJECTIVES We critically discuss evidence for a monotonic response in effect size with increasing current intensity, with a specific focus on a question if increasing applied current enhance the efficacy of tDCS. METHODS We analyzed tDCS intensity does-response from different perspectives including biophysical modeling, animal modeling, human neurophysiology, neuroimaging and behavioral/clinical measures. Further, we discuss approaches to design dose-response trials. RESULTS Physical models predict electric field in the brain increases with applied tDCS intensity. Data from animal studies are lacking since a range of relevant low-intensities is rarely tested. Results from imaging studies are ambiguous while human neurophysiology, including using transcranial magnetic stimulation (TMS) as a probe, suggests a complex state-dependent non-monotonic dose response. The diffusivity of brain current flow produced by conventional tDCS montages complicates this analysis, with relatively few studies on focal High Definition (HD)-tDCS. In behavioral and clinical trials, only a limited range of intensities (1-2 mA), and typically just one intensity, are conventionally tested; moreover, outcomes are subject brain-state dependent. Measurements and models of current flow show that for the same applied current, substantial differences in brain current occur across individuals. Trials are thus subject to inter-individual differences that complicate consideration of population-level dose response. CONCLUSION The presence or absence of simple dose response does not impact how efficacious a given tDCS dose is for a given indication. Understanding dose-response in human applications of tDCS is needed for protocol optimization including individualized dose to reduce outcome variability, which requires intelligent design of dose-response studies.
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Affiliation(s)
- Zeinab Esmaeilpour
- Department of Biomedical Engineering, The City College of New York of CUNY, New York, NY 10031, USA; Biomedical Engineering Department, Amirkabir University of Technology, Tehran, Iran.
| | - Paola Marangolo
- Dipartimento di Studi Umanistici, University Federico II, Naples and IRCCS Fondazione Santa Lucia, Rome Italy
| | - Benjamin M Hampstead
- VA Ann Arbor Healthcare System, Ann Arbor, MI 48105, USA; Department of Psychiatry, University of Michigan, Ann Arbor, MI 48105, USA
| | - Sven Bestmann
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, UK
| | - Elisabeth Galletta
- Rusk Rehabilitation Medicine, New York University Langone Medical Center, USA
| | - Helena Knotkova
- MJHS Institute for Innovation in Palliative Care, New York, NY, USA; Department of Family and Social Medicine, Albert Einstein College of Medicine, The Bronx, NY, USA
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York of CUNY, New York, NY 10031, USA
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204
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205
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Abstract
Transcranial electrical brain stimulation can modulate cortical excitability and plasticity in humans and rodents. The most common form of stimulation in humans is transcranial direct current stimulation (tDCS). Less frequently, transcranial alternating current stimulation (tACS) or transcranial random noise stimulation (tRNS), a specific form of tACS using an electrical current applied randomly within a pre-defined frequency range, is used. The increase of noninvasive electrical brain stimulation research in humans, both for experimental and clinical purposes, has yielded an increased need for basic, mechanistic, safety studies in animals. This article describes a model for transcranial electrical brain stimulation (tES) through the intact skull targeting the motor system in alert rodents. The protocol provides step-by-step instructions for the surgical set-up of a permanent epicranial electrode socket combined with an implanted counter electrode on the chest. By placing a stimulation electrode into the epicranial socket, different electrical stimulation types, comparable to tDCS, tACS, and tRNS in humans, can be delivered. Moreover, the practical steps for tES in alert rodents are introduced. The applied current density, stimulation duration, and stimulation type may be chosen depending on the experimental needs. The caveats, advantages, and disadvantages of this set-up are discussed, as well as safety and tolerability aspects.
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Affiliation(s)
- Brita Fritsch
- Department of Neurology, Albert-Ludwigs-University Freiburg;
| | | | - Janine Reis
- Department of Neurology, Albert-Ludwigs-University Freiburg
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206
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Polarity-independent effects of tDCS on paired associative stimulation-induced plasticity. Brain Stimul 2017; 10:1061-1069. [DOI: 10.1016/j.brs.2017.07.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 07/24/2017] [Accepted: 07/25/2017] [Indexed: 12/19/2022] Open
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207
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Lafon B, Henin S, Huang Y, Friedman D, Melloni L, Thesen T, Doyle W, Buzsáki G, Devinsky O, Parra LC, A Liu A. Low frequency transcranial electrical stimulation does not entrain sleep rhythms measured by human intracranial recordings. Nat Commun 2017; 8:1199. [PMID: 29084960 PMCID: PMC5662600 DOI: 10.1038/s41467-017-01045-x] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 08/15/2017] [Indexed: 01/20/2023] Open
Abstract
Transcranial electrical stimulation has widespread clinical and research applications, yet its effect on ongoing neural activity in humans is not well established. Previous reports argue that transcranial alternating current stimulation (tACS) can entrain and enhance neural rhythms related to memory, but the evidence from non-invasive recordings has remained inconclusive. Here, we measure endogenous spindle and theta activity intracranially in humans during low-frequency tACS and find no stable entrainment of spindle power during non-REM sleep, nor of theta power during resting wakefulness. As positive controls, we find robust entrainment of spindle activity to endogenous slow-wave activity in 66% of electrodes as well as entrainment to rhythmic noise-burst acoustic stimulation in 14% of electrodes. We conclude that low-frequency tACS at common stimulation intensities neither acutely modulates spindle activity during sleep nor theta activity during waking rest, likely because of the attenuated electrical fields reaching the cortical surface.
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Affiliation(s)
- Belen Lafon
- Department of Biomedical Engineering, City College of New York, 160 Convent Ave, New York, NY, 10031, USA
| | - Simon Henin
- New York University Comprehensive Epilepsy Center, 223 East 34th Street, New York, NY, 10016, USA
- Department of Neurology, New York University School of Medicine, 240 East 38th St, 20th Floor, New York, NY, 10016, USA
| | - Yu Huang
- Department of Biomedical Engineering, City College of New York, 160 Convent Ave, New York, NY, 10031, USA
| | - Daniel Friedman
- New York University Comprehensive Epilepsy Center, 223 East 34th Street, New York, NY, 10016, USA
- Department of Neurology, New York University School of Medicine, 240 East 38th St, 20th Floor, New York, NY, 10016, USA
| | - Lucia Melloni
- New York University Comprehensive Epilepsy Center, 223 East 34th Street, New York, NY, 10016, USA
- Department of Neurology, New York University School of Medicine, 240 East 38th St, 20th Floor, New York, NY, 10016, USA
- Department of Neuroscience, Max Planck Institute for Empirical Aesthetics, Gruneburgweg 14, 60322, Frankfurt am Main, Germany
| | - Thomas Thesen
- Department of Neurology, New York University School of Medicine, 240 East 38th St, 20th Floor, New York, NY, 10016, USA
- Department of Physiology and Neuroscience, St. George's University, St. George's, Grenada
| | - Werner Doyle
- New York University Comprehensive Epilepsy Center, 223 East 34th Street, New York, NY, 10016, USA
- Department of Neurosurgery NYU School of Medicine, 530 1st Avenue, Suite 7W, New York, NY, 10016, USA
| | - György Buzsáki
- Department of Neurology, New York University School of Medicine, 240 East 38th St, 20th Floor, New York, NY, 10016, USA
- New York University Neuroscience Institute, 450 East 29th St, New York, NY, 10016, USA
| | - Orrin Devinsky
- New York University Comprehensive Epilepsy Center, 223 East 34th Street, New York, NY, 10016, USA
- Department of Neurology, New York University School of Medicine, 240 East 38th St, 20th Floor, New York, NY, 10016, USA
| | - Lucas C Parra
- Department of Biomedical Engineering, City College of New York, 160 Convent Ave, New York, NY, 10031, USA
| | - Anli A Liu
- New York University Comprehensive Epilepsy Center, 223 East 34th Street, New York, NY, 10016, USA.
- Department of Neurology, New York University School of Medicine, 240 East 38th St, 20th Floor, New York, NY, 10016, USA.
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208
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Bolzoni F, Esposti R, Bruttini C, Zenoni G, Jankowska E, Cavallari P. Direct current stimulation modulates the excitability of the sensory and motor fibres in the human posterior tibial nerve, with a long-lasting effect on the H-reflex. Eur J Neurosci 2017; 46:2499-2506. [PMID: 28892581 DOI: 10.1111/ejn.13696] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 08/30/2017] [Accepted: 08/30/2017] [Indexed: 02/06/2023]
Abstract
Several studies demonstrated that transcutaneous direct current stimulation (DCS) may modulate central nervous system excitability. However, much less is known about how DC affects peripheral nerve fibres. We investigated the action of DCS on motor and sensory fibres of the human posterior tibial nerve, with supplementary analysis in acute experiments on rats. In forty human subjects, electric pulses at the popliteal fossa were used to elicit either M-waves or H-reflexes in the Soleus, before (15 min), during (10 min) and after (30 min) DCS. Cathodal or anodal current (2 mA) was applied to the same nerve. Cathodal DCS significantly increased the H-reflex amplitude; the post-polarization effect lasted up to ~ 25 min after the termination of DCS. Anodal DCS instead significantly decreased the reflex amplitude for up to ~ 5 min after DCS end. DCS effects on M-wave showed the same polarity dependence but with considerably shorter after-effects, which never exceeded 5 min. DCS changed the excitability of both motor and sensory fibres. These effects and especially the long-lasting modulation of the H-reflex suggest a possible rehabilitative application of DCS that could be applied either to compensate an altered peripheral excitability or to modulate the afferent transmission to spinal and supraspinal structures. In animal experiments, DCS was applied, under anaesthesia, to either the exposed peroneus nerve or its Dorsal Root, and its effects closely resembled those found in human subjects. They validate therefore the use of the animal models for future investigations on the DCS mechanisms.
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Affiliation(s)
- Francesco Bolzoni
- Human Physiology Section of the De.P.T., Università degli Studi di Milano, Via Mangiagalli 32, I-20133, Milan, Italy.,Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Roberto Esposti
- Human Physiology Section of the De.P.T., Università degli Studi di Milano, Via Mangiagalli 32, I-20133, Milan, Italy
| | - Carlo Bruttini
- Human Physiology Section of the De.P.T., Università degli Studi di Milano, Via Mangiagalli 32, I-20133, Milan, Italy
| | - Giuseppe Zenoni
- Human Physiology Section of the De.P.T., Università degli Studi di Milano, Via Mangiagalli 32, I-20133, Milan, Italy
| | - Elzbieta Jankowska
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Paolo Cavallari
- Human Physiology Section of the De.P.T., Università degli Studi di Milano, Via Mangiagalli 32, I-20133, Milan, Italy
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209
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Chrysikou EG, Berryhill ME, Bikson M, Coslett HB. Editorial: Revisiting the Effectiveness of Transcranial Direct Current Brain Stimulation for Cognition: Evidence, Challenges, and Open Questions. Front Hum Neurosci 2017; 11:448. [PMID: 28943844 PMCID: PMC5596096 DOI: 10.3389/fnhum.2017.00448] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 08/23/2017] [Indexed: 11/22/2022] Open
Affiliation(s)
| | | | - Marom Bikson
- Department of Biomedical Engineering, City University of New YorkNew York, NY, United States
| | - H Branch Coslett
- Department of Neurology, University of PennsylvaniaPhiladelphia, PA, United States
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210
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Jackson MP, Truong D, Brownlow ML, Wagner JA, McKinley RA, Bikson M, Jankord R. Safety parameter considerations of anodal transcranial Direct Current Stimulation in rats. Brain Behav Immun 2017; 64:152-161. [PMID: 28427911 PMCID: PMC5969807 DOI: 10.1016/j.bbi.2017.04.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 04/04/2017] [Accepted: 04/11/2017] [Indexed: 01/04/2023] Open
Abstract
A commonly referenced transcranial Direct Current Stimulation (tDCS) safety threshold derives from tDCS lesion studies in the rat and relies on electrode current density (and related electrode charge density) to support clinical guidelines. Concerns about the role of polarity (e.g. anodal tDCS), sub-lesion threshold injury (e.g. neuroinflammatory processes), and role of electrode montage across rodent and human studies support further investigation into animal models of tDCS safety. Thirty-two anesthetized rats received anodal tDCS between 0 and 5mA for 60min through one of three epicranial electrode montages. Tissue damage was evaluated using hemotoxylin and eosin (H&E) staining, Iba-1 immunohistochemistry, and computational brain current density modeling. Brain lesion occurred after anodal tDCS at and above 0.5mA using a 25.0mm2 electrode (electrode current density: 20.0A/m2). Lesion initially occurred using smaller 10.6mm2 or 5.3mm2 electrodes at 0.25mA (23.5A/m2) and 0.5mA (94.2A/m2), respectively. Histological damage was correlated with computational brain current density predictions. Changes in microglial phenotype occurred in higher stimulation groups. Lesions were observed using anodal tDCS at an electrode current density of 20.0A/m2, which is below the previously reported safety threshold of 142.9A/m2 using cathodal tDCS. The lesion area is not simply predicted by electrode current density (and so not by charge density as duration was fixed); rather computational modeling suggests average brain current density as a better predictor for anodal tDCS. Nonetheless, under the assumption that rodent epicranial stimulation is a hypersensitive model, an electrode current density of 20.0A/m2 represents a conservative threshold for clinical tDCS, which typically uses an electrode current density of 2A/m2 when electrodes are placed on the skin (resulting in a lower brain current density).
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Affiliation(s)
- Mark P. Jackson
- 711 Human Performance Wing, Air Force Research Laboratory, Wright Patterson AFB, OH 45433,Department of Biomedical Engineering, The City College of The City University of New York, CDI Building, 85 St. Nicholas Terrace, New York, NY 10031
| | - Dennis Truong
- Department of Biomedical Engineering, The City College of The City University of New York, CDI Building, 85 St. Nicholas Terrace, New York, NY 10031
| | - Milene L. Brownlow
- 711 Human Performance Wing, Air Force Research Laboratory, Wright Patterson AFB, OH 45433,Research Associateship Program, National Research Council, National Academies of Science, Washington DC 20001
| | - Jessica A. Wagner
- 711 Human Performance Wing, Air Force Research Laboratory, Wright Patterson AFB, OH 45433
| | - R. Andy McKinley
- 711 Human Performance Wing, Air Force Research Laboratory, Wright Patterson AFB, OH 45433
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of The City University of New York, CDI Building, 85 St. Nicholas Terrace, New York, NY 10031
| | - Ryan Jankord
- 711th Human Performance Wing, Air Force Research Laboratory, Wright Patterson AFB, OH 45433, United States.
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211
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Philip NS, Nelson BG, Frohlich F, Lim KO, Widge AS, Carpenter LL. Low-Intensity Transcranial Current Stimulation in Psychiatry. Am J Psychiatry 2017; 174:628-639. [PMID: 28231716 PMCID: PMC5495602 DOI: 10.1176/appi.ajp.2017.16090996] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Neurostimulation is rapidly emerging as an important treatment modality for psychiatric disorders. One of the fastest-growing and least-regulated approaches to noninvasive therapeutic stimulation involves the application of weak electrical currents. Widespread enthusiasm for low-intensity transcranial electrical current stimulation (tCS) is reflected by the recent surge in direct-to-consumer device marketing, do-it-yourself enthusiasm, and an escalating number of clinical trials. In the wake of this rapid growth, clinicians may lack sufficient information about tCS to inform their clinical practices. Interpretation of tCS clinical trial data is aided by familiarity with basic neurophysiological principles, potential mechanisms of action of tCS, and the complicated regulatory history governing tCS devices. A growing literature includes randomized controlled trials of tCS for major depression, schizophrenia, cognitive disorders, and substance use disorders. The relative ease of use and abundant access to tCS may represent a broad-reaching and important advance for future mental health care. Evidence supports application of one type of tCS, transcranial direct current stimulation (tDCS), for major depression. However, tDCS devices do not have regulatory approval for treating medical disorders, evidence is largely inconclusive for other therapeutic areas, and their use is associated with some physical and psychiatric risks. One unexpected finding to arise from this review is that the use of cranial electrotherapy stimulation devices-the only category of tCS devices cleared for use in psychiatric disorders-is supported by low-quality evidence.
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Affiliation(s)
- Noah S. Philip
- From the Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, and the Center of Excellence for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, R.I.; the Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, Mass., and the Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Mass.; the Department of Psychiatry, the Department of Biomedical Engineering, the
| | - Brent G. Nelson
- From the Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, and the Center of Excellence for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, R.I.; the Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, Mass., and the Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Mass.; the Department of Psychiatry, the Department of Biomedical Engineering, the
| | - Flavio Frohlich
- From the Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, and the Center of Excellence for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, R.I.; the Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, Mass., and the Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Mass.; the Department of Psychiatry, the Department of Biomedical Engineering, the
| | - Kelvin O. Lim
- From the Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, and the Center of Excellence for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, R.I.; the Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, Mass., and the Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Mass.; the Department of Psychiatry, the Department of Biomedical Engineering, the
| | - Alik S. Widge
- From the Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, and the Center of Excellence for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, R.I.; the Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, Mass., and the Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Mass.; the Department of Psychiatry, the Department of Biomedical Engineering, the
| | - Linda L. Carpenter
- From the Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, and the Center of Excellence for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, R.I.; the Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, Mass., and the Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Mass.; the Department of Psychiatry, the Department of Biomedical Engineering, the
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212
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Tremblay S, Hannah R, Rawji V, Rothwell JC. Modulation of iTBS after-effects via concurrent directional TDCS: A proof of principle study. Brain Stimul 2017; 10:744-747. [PMID: 28404455 PMCID: PMC5487022 DOI: 10.1016/j.brs.2017.03.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 03/16/2017] [Accepted: 03/20/2017] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Polarising currents can modulate membrane potentials in animals, affecting the after-effect of theta burst stimulation (TBS) on synaptic strength. OBJECTIVE We examined whether a similar phenomenon could also be observed in human motor cortex (M1) using transcranial direct current stimulation (TDCS) during monophasic intermittent TBS (iTBS). METHODS TDCS was applied during posterior-anterior iTBS using three different conditions: posterior-anterior TDCS (anode 3.5 cm posterior to M1, cathode 3.5 cm anterior to M1), anterior-posterior TDCS (cathode 3.5 cm posterior to M1, anode 3.5 cm anterior to M1), and sham TDCS. RESULTS When the direction of TDCS (posterior-anterior) matched the direction of the electrical field induced by iTBS, we found a 19% non-significant increase in excitability changes in comparison with iTBS combined with sham TDCS. When the TDCS was reversed (anterior-posterior), the excitatory effect of iTBS was abolished. CONCLUSION Our findings suggest that excitatory after-effects of iTBS can be modulated by directionally-specific TDCS.
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Affiliation(s)
- Sara Tremblay
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, UK.
| | - Ricci Hannah
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, UK
| | - Vishal Rawji
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, UK
| | - John C Rothwell
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, UK
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213
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Huang Y, Liu AA, Lafon B, Friedman D, Dayan M, Wang X, Bikson M, Doyle WK, Devinsky O, Parra LC. Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation. eLife 2017; 6:18834. [PMID: 28169833 PMCID: PMC5370189 DOI: 10.7554/elife.18834] [Citation(s) in RCA: 321] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 02/06/2017] [Indexed: 11/13/2022] Open
Abstract
Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimated electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.8 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r = 0.86) and depth (r = 0.88) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials. DOI:http://dx.doi.org/10.7554/eLife.18834.001
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Affiliation(s)
- Yu Huang
- Department of Biomedical Engineering, City College of the City University of New York, New York, United States
| | - Anli A Liu
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, United States
| | - Belen Lafon
- Department of Biomedical Engineering, City College of the City University of New York, New York, United States
| | - Daniel Friedman
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, United States
| | - Michael Dayan
- Department of Neurology, Mayo Clinic, Rochester, United States
| | - Xiuyuan Wang
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, United States
| | - Marom Bikson
- Department of Biomedical Engineering, City College of the City University of New York, New York, United States
| | - Werner K Doyle
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, United States
| | - Orrin Devinsky
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, United States
| | - Lucas C Parra
- Department of Biomedical Engineering, City College of the City University of New York, New York, United States
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214
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Mervis JE, Capizzi RJ, Boroda E, MacDonald AW. Transcranial Direct Current Stimulation over the Dorsolateral Prefrontal Cortex in Schizophrenia: A Quantitative Review of Cognitive Outcomes. Front Hum Neurosci 2017; 11:44. [PMID: 28210217 PMCID: PMC5288642 DOI: 10.3389/fnhum.2017.00044] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 01/20/2017] [Indexed: 11/13/2022] Open
Abstract
Cognitive deficits are a core and disabling feature of psychotic disorders, specifically schizophrenia. Current treatments for impaired cognition in schizophrenia remain insufficient. Recent research suggests transcranial direct current stimulation (tDCS) targeting the dorsolateral prefrontal cortex can potentiate cognitive improvements in healthy individuals and those with psychiatric conditions, such as schizophrenia. However, this burgeoning literature has not been quantitatively evaluated. Through a literature search and quantitative review, we identified 194 papers on tDCS, psychosis, and cognition. Selection criteria included pre/post design and sham control to achieve specific sham-adjusted effect sizes. The 6 retained studies all address schizophrenia populations and include single and repeated stimulation, as well as within and between subject designs. Small positive effects were found for anodal stimulation on behavioral measures of attention and working memory, with tentative findings for cognitive ability and memory. Cathodal stimulation yielded a small positive effect on behaviorally measured cognitive ability. Neurophysiological measures of attention showed a small to medium down-modulation effect for anodal stimulation. Implications of these findings and guidelines for future research are discussed. As revealed by this report, due to the paucity of data available, much remains unknown regarding the clinical efficacy of tDCS in schizophrenia.
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Affiliation(s)
- Joshua E Mervis
- Department of Psychology, University of Minnesota Minneapolis, MN, USA
| | - Riley J Capizzi
- Department of Psychology, University of Minnesota Minneapolis, MN, USA
| | - Elias Boroda
- Department of Neuroscience, University of Minnesota Minneapolis, MN, USA
| | - Angus W MacDonald
- Department of Psychology, University of MinnesotaMinneapolis, MN, USA; Department of Psychiatry, University of Minnesota Medical SchoolMinneapolis, MN, USA
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