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Tsapa D, Ahmadlou M, Heimel JA. Long-term enhancement of visual responses by repeated transcranial electrical stimulation of the mouse visual cortex. Brain Stimul 2019; 12:1421-1428. [PMID: 31331791 DOI: 10.1016/j.brs.2019.07.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 07/15/2019] [Accepted: 07/16/2019] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Transcranial electrical stimulation (tES) is a popular method to modulate brain activity by sending a weak electric current through the head. Despite its popularity, long-term effects are poorly understood. OBJECTIVE We wanted to test if anodal tES immediately changes cerebral responses to visual stimuli, and if repeated sessions of tES produce plasticity in these responses. METHODS We applied repeated anodal tES, like transcranial direct current stimulation (tDCS), but pulsed (8 s on, 10 s off), to the visual cortex of mice while visually presenting gratings. We measured the responses to these visual stimuli in the visual cortex using the genetically encoded calcium indicator GCaMP3. RESULTS We found an increase in the visual response when concurrently applying tES on the bone without skin (epicranially). This increase was only transient when tES was applied through the skin (transcutaneous). There was no immediate after-effect of tES. However, repeated transcutaneous tES for four sessions at two-day intervals increased the visual response in the visual cortex. This increase was not specific to the grating stimulus coupled to tES and also occurred for an orthogonal grating presented in the same sessions but without concurrent tES. No increase was found in mice that received no tES. CONCLUSION Our study provides evidence that tES induces long-term changes in the mouse brain. Results in mice do not directly translate to humans, because of differences in stimulation protocols and the way current translates to electric field strength in vastly different heads.
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Affiliation(s)
- Despoina Tsapa
- Cortical Structure & Function Group, Netherlands Institute for Neuroscience, Institute of the Royal Academy for Arts and Sciences, Amsterdam, the Netherlands
| | - Mehran Ahmadlou
- Cortical Structure & Function Group, Netherlands Institute for Neuroscience, Institute of the Royal Academy for Arts and Sciences, Amsterdam, the Netherlands
| | - J Alexander Heimel
- Cortical Structure & Function Group, Netherlands Institute for Neuroscience, Institute of the Royal Academy for Arts and Sciences, Amsterdam, the Netherlands.
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52
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Lefaucheur JP, Wendling F. Mechanisms of action of tDCS: A brief and practical overview. Neurophysiol Clin 2019; 49:269-275. [PMID: 31350060 DOI: 10.1016/j.neucli.2019.07.013] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 07/10/2019] [Accepted: 07/11/2019] [Indexed: 12/20/2022] Open
Affiliation(s)
- Jean-Pascal Lefaucheur
- Unité de neurophysiologie clinique, EA4391, Henri-Mondor Hospital, Paris-Est Créteil University,, 94000 Créteil, France.
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53
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Van Overwalle F, Manto M, Leggio M, Delgado-García JM. The sequencing process generated by the cerebellum crucially contributes to social interactions. Med Hypotheses 2019; 128:33-42. [PMID: 31203906 DOI: 10.1016/j.mehy.2019.05.014] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 04/29/2019] [Accepted: 05/12/2019] [Indexed: 11/25/2022]
Abstract
The capacity to understand another person's emotions, intentions, beliefs and personality traits, based on observed or communicated behaviors, is termed social cognition. During the last decade, social neuroscience has made great progress in understanding the neural correlates of social cognition. However, because the cerebellum is traditionally viewed as only involved in motor processing, the contribution of this major part of the brain in social processing has been largely ignored and its specific role in social cognition remains unclear. Nevertheless, recent meta-analyses have made its crucial contribution to social cognition evident. This raises the question: What is the exact function of the cerebellum in social cognition? We hypothesize that the cerebellum builds internal action models of our social inter-actions to predict how other people's actions will be executed, what our most likely responses are to these actions, so that we can automatize our interactions and instantly detect disruptions in these action sequences. This mechanism likely allows to better anticipate action sequences during social interactions in an automatic and intuitive way and to fine-tune these anticipations, making it easier to understand behaviors and to detect violations. This hypothesis has major implications in neurological disorders affecting the cerebellum such as autism, with detrimental effects on social functionality, especially on more complex and abstract social cognitive processes. Because the fundamental anatomical organization of the cerebellum is identical in many species (cerebellar microcomplexes), this hypothesis could have major impacts to elucidate social interactions in social animals.
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Affiliation(s)
| | - Mario Manto
- Service de Neurologie, CHU-Charleroi, Belgium & Service des Neurosciences, Université de Mons, Belgium.
| | - Maria Leggio
- Department of Psychology, University of Rome 'Sapienza', Rome, Italy; Ataxia Laboratory, IRCCS Fondazione Santa Lucia, Rome, Italy.
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Guggisberg AG, Koch PJ, Hummel FC, Buetefisch CM. Brain networks and their relevance for stroke rehabilitation. Clin Neurophysiol 2019; 130:1098-1124. [PMID: 31082786 DOI: 10.1016/j.clinph.2019.04.004] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 03/04/2019] [Accepted: 04/08/2019] [Indexed: 12/21/2022]
Abstract
Stroke has long been regarded as focal disease with circumscribed damage leading to neurological deficits. However, advances in methods for assessing the human brain and in statistics have enabled new tools for the examination of the consequences of stroke on brain structure and function. Thereby, it has become evident that stroke has impact on the entire brain and its network properties and can therefore be considered as a network disease. The present review first gives an overview of current methodological opportunities and pitfalls for assessing stroke-induced changes and reorganization in the human brain. We then summarize principles of plasticity after stroke that have emerged from the assessment of networks. Thereby, it is shown that neurological deficits do not only arise from focal tissue damage but also from local and remote changes in white-matter tracts and in neural interactions among wide-spread networks. Similarly, plasticity and clinical improvements are associated with specific compensatory structural and functional patterns of neural network interactions. Innovative treatment approaches have started to target such network patterns to enhance recovery. Network assessments to predict treatment response and to individualize rehabilitation is a promising way to enhance specific treatment effects and overall outcome after stroke.
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Affiliation(s)
- Adrian G Guggisberg
- Division of Neurorehabilitation, Department of Clinical Neurosciences, University Hospital Geneva, Switzerland.
| | - Philipp J Koch
- Defitech Chair of Clinical Neuroengineering, Center for Neuroprosthetics (CNP) and Brain Mind Institute (BMI), Swiss Federal Institute of Technology (EPFL), 1202 Geneva, Switzerland; Defitech Chair of Clinical Neuroengineering, Center for Neuroprosthetics (CNP) and Brain Mind Institute (BMI), Swiss Federal Institute of Technology Valais (EPFL Valais), Clinique Romande de Réadaptation, 1951 Sion, Switzerland
| | - Friedhelm C Hummel
- Defitech Chair of Clinical Neuroengineering, Center for Neuroprosthetics (CNP) and Brain Mind Institute (BMI), Swiss Federal Institute of Technology (EPFL), 1202 Geneva, Switzerland; Defitech Chair of Clinical Neuroengineering, Center for Neuroprosthetics (CNP) and Brain Mind Institute (BMI), Swiss Federal Institute of Technology Valais (EPFL Valais), Clinique Romande de Réadaptation, 1951 Sion, Switzerland; Department of Clinical Neuroscience, University Hospital Geneva, 1202 Geneva, Switzerland
| | - Cathrin M Buetefisch
- Depts of Neurology, Rehabilitation Medicine, Radiology, Emory University, Atlanta, GA, USA
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Colmenárez-Raga AC, Díaz I, Pernia M, Pérez-González D, Delgado-García JM, Carro J, Plaza I, Merchán MA. Reversible Functional Changes Evoked by Anodal Epidural Direct Current Electrical Stimulation of the Rat Auditory Cortex. Front Neurosci 2019; 13:356. [PMID: 31031588 PMCID: PMC6473088 DOI: 10.3389/fnins.2019.00356] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 03/28/2019] [Indexed: 12/26/2022] Open
Abstract
Rat auditory cortex was subjected to 0.1 mA anodal direct current in seven 10-min sessions on alternate days. Based on the well-known auditory cortex control of olivocochlear regulation through corticofugal projections, auditory brainstem responses (ABRs) were recorded as an indirect test of the effectiveness and reversibility of the multisession protocol of epidural stimulation. Increases of 20-30 dB ABR auditory thresholds shown after epidural stimulation reverted back to control levels 10 min after a single session. However, increases in thresholds revert 4 days after multisession stimulation. Less changes in wave amplitudes and threshold shifts were shown in ABR recorded contralaterally to the electrically stimulated side of the brain. To assess tissue effects of epidural electric stimulation on the brain cortex, well characterized functional anatomical markers of glial cells (GFAP/astrocytes and Iba1/microglial cells) and neurons (c-Fos) were analyzed in alternate serial sections by quantitative immunocytochemistry. Restricted astroglial and microglial reactivity was observed within the cytoarchitectural limits of the auditory cortex. However, interstitial GFAP overstaining was also observed in the ventricular surface and around blood vessels, thus supporting a potential global electrolytic stimulation of the brain. These results correlate with extensive changes in the distribution of c-Fos immunoreactive neurons among layers along sensory cortices after multisession stimulation. Quantitative immunocytochemical analysis supported this idea by showing a significant increase in the number of positive neurons in supragranular layers and a decrease in layer 6 with no quantitative changes detected in layer 5. Our data indicate that epidural stimulation of the auditory cortex induces a reversible decrease in hearing sensitivity due to local, restricted epidural stimulation. A global plastic response of the sensory cortices, also reported here, may be related to electrolytic effects of electric currents.
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Affiliation(s)
| | - Iván Díaz
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | - Marianny Pernia
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | - David Pérez-González
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | | | - Juan Carro
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | - Ignacio Plaza
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | - Miguel A. Merchán
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
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Hypothesis of the optimal therapeutic effect of transcranial direct current stimulation (tDCS) for psychiatric disorders: Integration of positive cognitive tasks during the neuroplastic process. Med Hypotheses 2019; 125:1-4. [DOI: 10.1016/j.mehy.2019.02.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 02/01/2019] [Accepted: 02/02/2019] [Indexed: 11/18/2022]
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57
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Transcranial direct current stimulation induces hippocampal metaplasticity mediated by brain-derived neurotrophic factor. Neuropharmacology 2019; 144:358-367. [DOI: 10.1016/j.neuropharm.2018.11.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 10/05/2018] [Accepted: 11/09/2018] [Indexed: 12/12/2022]
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Ruffini G, Wendling F, Sanchez-Todo R, Santarnecchi E. Targeting brain networks with multichannel transcranial current stimulation (tCS). CURRENT OPINION IN BIOMEDICAL ENGINEERING 2018. [DOI: 10.1016/j.cobme.2018.11.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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59
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Physiological effects of low-magnitude electric fields on brain activity: advances from in vitro, in vivo and in silico models. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2018; 8:38-44. [PMID: 31106284 DOI: 10.1016/j.cobme.2018.09.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
While electrical stimulation of brain tissue has been thoroughly investigated over the last decades, ongoing questions remain regarding the neurophysiological effects of low-level electric fields (on the order of 1 V/m) on brain activity. Electric fields at such levels are, for example, induced by transcranial direct/alternating current stimulation (tDCS/tACS). Action potentials can be indeed elicited when applied (supra-threshold) electric fields are in the 10-100 V/m range, while lower (subthreshold) electric fields result in more limited and subtler membrane polarization effects. In this review, we address the question of the mechanisms underlying the immediate effects (also referred to as acute, concurrent or short-term) and the lasting effects (also referred to as long-term or aftereffects) of low-level electric fields on brain tissue. We review recent evidence at the in vitro and in vivo (animal and human) level, and also present mechanistic insights gained from in silico models, which are still few but have received increased attention over the recent past years. We highlight the convergent evidence towards potential mechanisms, and also discuss discrepancies between in vitro studies and human tDCS/tACS studies that require further investigation to bridge the gap between the single-cell and large-scale network level. Possible novel avenues of research are discussed.
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de Souza Nicolau E, de Alvarenga KAF, Tenza-Ferrer H, Nogueira MCA, Rezende FD, Nicolau NF, Collodetti M, de Miranda DM, Magno LAV, Romano-Silva MA. Transcranial Direct Current Stimulation (tDCS) in Mice. J Vis Exp 2018. [PMID: 30295664 DOI: 10.3791/58517] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique proposed as an alternative or complementary treatment for several neuropsychiatric diseases. The biological effects of tDCS are not fully understood, which is in part explained due to the difficulty in obtaining human brain tissue. This protocol describes a tDCS mouse model that uses a chronically implanted electrode allowing the study of the long-lasting biological effects of tDCS. In this experimental model, tDCS changes the cortical gene expression and offers a prominent contribution to the understanding of the rationale for its therapeutic use.
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Affiliation(s)
- Eduardo de Souza Nicolau
- Centro de Tecnologia em Medicina Molecular (CTMM), Faculdade de Medicina, Universidade Federal de Minas Gerais
| | | | - Helia Tenza-Ferrer
- Centro de Tecnologia em Medicina Molecular (CTMM), Faculdade de Medicina, Universidade Federal de Minas Gerais
| | | | - Fernanda Donizete Rezende
- Centro de Tecnologia em Medicina Molecular (CTMM), Faculdade de Medicina, Universidade Federal de Minas Gerais
| | - Nycolle Ferreira Nicolau
- Centro de Tecnologia em Medicina Molecular (CTMM), Faculdade de Medicina, Universidade Federal de Minas Gerais
| | - Mélcar Collodetti
- Centro de Tecnologia em Medicina Molecular (CTMM), Faculdade de Medicina, Universidade Federal de Minas Gerais
| | - Débora Marques de Miranda
- Centro de Tecnologia em Medicina Molecular (CTMM), Faculdade de Medicina, Universidade Federal de Minas Gerais
| | - Luiz Alexandre Viana Magno
- Centro de Tecnologia em Medicina Molecular (CTMM), Faculdade de Medicina, Universidade Federal de Minas Gerais
| | - Marco Aurélio Romano-Silva
- Centro de Tecnologia em Medicina Molecular (CTMM), Faculdade de Medicina, Universidade Federal de Minas Gerais;
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Sánchez-León CA, Sánchez-López Á, Ammann C, Cordones I, Carretero-Guillén A, Márquez-Ruiz J. Exploring new transcranial electrical stimulation strategies to modulate brain function in animal models. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2018; 8:7-13. [PMID: 30272042 DOI: 10.1016/j.cobme.2018.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Transcranial electrical stimulation (tES) refers to a group of non-invasive brain stimulation techniques to induce changes in the excitability of cortical neurons in humans. In recent years, studies in animal models have been shown to be essential for disentangling the neuromodulatory effects of tES, defining safety limits, and exploring potential therapeutic applications in neurological and neuropsychiatric disorders. Testing in animal models is valuable for the development of new unconventional protocols intended to improve tES administration and optimize the desired effects by increasing its focality and enabling deep-brain stimulation. Successful and controlled application of tES in humans relies on the knowledge acquired from studies meticulously performed in animal models.
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Affiliation(s)
- Carlos A Sánchez-León
- Department of Physiology, Anatomy and Cell Biology, Pablo de Olavide University, 41013-Seville, Spain
| | - Álvaro Sánchez-López
- Department of Physiology, Anatomy and Cell Biology, Pablo de Olavide University, 41013-Seville, Spain
| | - Claudia Ammann
- CINAC, University Hospital HM Puerta del Sur, CEU - San Pablo University, 28938-Móstoles, Madrid, Spain
| | - Isabel Cordones
- Department of Physiology, Anatomy and Cell Biology, Pablo de Olavide University, 41013-Seville, Spain
| | | | - Javier Márquez-Ruiz
- Department of Physiology, Anatomy and Cell Biology, Pablo de Olavide University, 41013-Seville, Spain
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Abstract
Direct current stimulation is a neuromodulatory noninvasive brain stimulation tool, which was first introduced in animal and human experiments in the 1950s, and added to the standard arsenal of methods to alter brain physiology as well as psychological, motor, and behavioral processes and clinical symptoms in neurological and psychiatric diseases about 20 years ago. In contrast to other noninvasive brain stimulation tools, such as transcranial magnetic stimulation, it does not directly induce cerebral activity, but rather alters spontaneous brain activity and excitability by subthreshold modulation of neuronal membranes. Beyond acute effects on brain functions, specific protocols are suited to induce long-lasting alterations of cortical excitability and activity, which share features with long-term potentiation and depression. These neuroplastic processes are important foundations for various cognitive functions such as learning and memory formation and are pathologically altered in numerous neurological and psychiatric diseases. This explains the increasing interest to investigate transcranial direct current stimulation (tDCS) as a therapeutic tool. However, for tDCS to be used effectively, it is crucial to be informed about physiological mechanisms of action. These have been increasingly elucidated during the last years. This review gives an overview of the current knowledge available regarding physiological mechanisms of tDCS, spanning from acute regional effects, over neuroplastic effects to its impact on cerebral networks. Although knowledge about the physiological effects of tDCS is still not complete, this might help to guide applications on a scientifically sound foundation.
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Affiliation(s)
| | - Andrea Antal
- Department of Clinical Neurophysiology, University Medical Center Göttingen, University of Göttingen, Göttingen
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63
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Abstract
Transcranial direct current stimulation (tDCS) devices apply direct current through electrodes on the scalp with the intention to modulate brain function for experimental or clinical purposes. All tDCS devices include a current controlled stimulator, electrodes that include a disposable electrolyte, and headgear to position the electrodes on the scalp. Transcranial direct current stimulation dose can be defined by the size and position of electrodes and the duration and intensity of current applied across electrodes. Electrode design and preparation are important for reproducibility and tolerability. High-definition tDCS uses smaller electrodes that can be arranged in arrays to optimize brain current flow. When intended to be used at home, tDCS devices require specific device design considerations. Computational models of current flow have been validated and support optimization and hypothesis testing. Consensus on the safety and tolerability of tDCS is protocol specific, but medical-grade tDCS devices minimize risk.
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Kantrowitz JT, Swerdlow NR, Dunn W, Vinogradov S. Auditory System Target Engagement During Plasticity-Based Interventions in Schizophrenia: A Focus on Modulation of N-Methyl-D-Aspartate-Type Glutamate Receptor Function. BIOLOGICAL PSYCHIATRY. COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2018; 3:581-590. [PMID: 29656951 PMCID: PMC6062454 DOI: 10.1016/j.bpsc.2018.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 01/24/2018] [Accepted: 02/12/2018] [Indexed: 12/31/2022]
Abstract
Cognitive deficits are predictive of long-term social and occupational functional deficits in schizophrenia but are currently without gold-standard treatments. In particular, augmentation of auditory cortical neuroplasticity may represent a rate-limiting first step before addressing higher-order cognitive deficits. We review the rationale for N-methyl-d-aspartate-type glutamate receptor (NMDAR) modulators as treatments for auditory plasticity deficits in schizophrenia, along with potential serum and electroencephalographic target engagement biomarkers for NMDAR function. Several recently published NMDAR-modulating treatment studies are covered, involving D-serine, memantine, and transcranial direct current stimulation. While all three interventions appear to modulate auditory plasticity, direct agonists (D-serine) appear to have the largest and most consistent effects on plasticity, at least acutely. We hypothesize that there may be synergistic effects of combining procognitive NMDAR-modulating approaches with auditory cortical neuroplasticity cognitive training interventions. Future studies should assess biomarkers for target engagement and patient stratification, along with head-to-head studies comparing putative interventions and potential long-term versus acute effects.
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Affiliation(s)
- Joshua T Kantrowitz
- Schizophrenia Research Center, Nathan Kline Institute for Psychiatric Research, Orangeburg, New York; Division of Experimental Therapeutics, Department of Psychiatry, Columbia University, New York, New York.
| | - Neal R Swerdlow
- Department of Psychiatry, University of California, San Diego, La Jolla
| | - Walter Dunn
- Department of Psychiatry, University of California, Los Angeles, Los Angeles, California
| | - Sophia Vinogradov
- Department of Psychiatry, University of Minnesota Medical School, Minneapolis, Minnesota
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65
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Bikson M, Brunoni AR, Charvet LE, Clark VP, Cohen LG, Deng ZD, Dmochowski J, Edwards DJ, Frohlich F, Kappenman ES, Lim KO, Loo C, Mantovani A, McMullen DP, Parra LC, Pearson M, Richardson JD, Rumsey JM, Sehatpour P, Sommers D, Unal G, Wassermann EM, Woods AJ, Lisanby SH. Rigor and reproducibility in research with transcranial electrical stimulation: An NIMH-sponsored workshop. Brain Stimul 2018; 11:465-480. [PMID: 29398575 PMCID: PMC5997279 DOI: 10.1016/j.brs.2017.12.008] [Citation(s) in RCA: 137] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 12/01/2017] [Accepted: 12/21/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Neuropsychiatric disorders are a leading source of disability and require novel treatments that target mechanisms of disease. As such disorders are thought to result from aberrant neuronal circuit activity, neuromodulation approaches are of increasing interest given their potential for manipulating circuits directly. Low intensity transcranial electrical stimulation (tES) with direct currents (transcranial direct current stimulation, tDCS) or alternating currents (transcranial alternating current stimulation, tACS) represent novel, safe, well-tolerated, and relatively inexpensive putative treatment modalities. OBJECTIVE This report seeks to promote the science, technology and effective clinical applications of these modalities, identify research challenges, and suggest approaches for addressing these needs in order to achieve rigorous, reproducible findings that can advance clinical treatment. METHODS The National Institute of Mental Health (NIMH) convened a workshop in September 2016 that brought together experts in basic and human neuroscience, electrical stimulation biophysics and devices, and clinical trial methods to examine the physiological mechanisms underlying tDCS/tACS, technologies and technical strategies for optimizing stimulation protocols, and the state of the science with respect to therapeutic applications and trial designs. RESULTS Advances in understanding mechanisms, methodological and technological improvements (e.g., electronics, computational models to facilitate proper dosing), and improved clinical trial designs are poised to advance rigorous, reproducible therapeutic applications of these techniques. A number of challenges were identified and meeting participants made recommendations made to address them. CONCLUSIONS These recommendations align with requirements in NIMH funding opportunity announcements to, among other needs, define dosimetry, demonstrate dose/response relationships, implement rigorous blinded trial designs, employ computational modeling, and demonstrate target engagement when testing stimulation-based interventions for the treatment of mental disorders.
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Affiliation(s)
- Marom Bikson
- Department of Biomedical Engineering, The City College of the City University of New York, United States
| | - Andre R Brunoni
- Laboratory of Neurosciences (LIM-27), Department and Institute of Psychiatry, University of Sao Paulo, Sao Paulo, Brazil
| | - Leigh E Charvet
- Department of Neurology, New York University School of Medicine, New York, NY, United States
| | - Vincent P Clark
- Department of Psychology, University of New Mexico, Albuquerque, NM, United States
| | - Leonardo G Cohen
- Human Cortical Physiology and Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD, United States
| | - Zhi-De Deng
- Experimental Therapeutics and Pathophysiology Branch, National Institute of Mental Health, Bethesda, MD, United States
| | - Jacek Dmochowski
- Department of Biomedical Engineering, The City College of the City University of New York, United States
| | - Dylan J Edwards
- Non-invasive Brain Stimulation and Human Motor Control Laboratory, Burke Rehabilitation and Research, Burke-Cornell Medical Research Facility, White Plains, New York and School of Medicine and Health Sciences, Edith Cowan University, Perth, Australia
| | - Flavio Frohlich
- Department of Psychiatry, Cell Biology and Physiology, Biomedical Engineering, and Neurology, Carolina Center for Neurostimulation, University of North Carolina School of Medicine, Chapel Hill, NC, United States
| | - Emily S Kappenman
- Department of Psychology, San Diego State University, San Diego, CA, United States
| | - Kelvin O Lim
- Department of Psychiatry, University of Minnesota, Minneapolis Veterans Administration Health Care System, and Defense Veterans Brain Injury Center, Minneapolis, MN, United States
| | - Colleen Loo
- School of Psychiatry and Black Dog Institute, University of New South Wales, Sydney, Australia
| | - Antonio Mantovani
- Department of Physiology, Pharmacology and Neuroscience, City College of the City University of New York, New York, NY, United States
| | - David P McMullen
- Division of Translational Research, National Institute of Mental Health, Bethesda, MD, United States
| | - Lucas C Parra
- Department of Biomedical Engineering, The City College of the City University of New York, United States
| | - Michele Pearson
- Division of Translational Research, National Institute of Mental Health, Bethesda, MD, United States
| | - Jessica D Richardson
- Department of Speech and Hearing Sciences, University of New Mexico, Albuquerque, NM, United States
| | - Judith M Rumsey
- Division of Translational Research, National Institute of Mental Health, Bethesda, MD, United States.
| | - Pejman Sehatpour
- Department of Psychiatry, Columbia University, New York, NY, United States
| | - David Sommers
- Scientific Review Branch, National Institute of Mental Health, Bethesda, MD, United States
| | - Gozde Unal
- Department of Biomedical Engineering, The City College of the City University of New York, United States
| | - Eric M Wassermann
- Behavioral Neurology Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, United States
| | - Adam J Woods
- Department of Clinical and Health Psychology, Center for Cognitive Aging and Memory, McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Sarah H Lisanby
- Division of Translational Research, National Institute of Mental Health, Bethesda, MD, United States
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Giboin LS, Gruber M. Anodal and cathodal transcranial direct current stimulation can decrease force output of knee extensors during an intermittent MVC fatiguing task in young healthy male participants. J Neurosci Res 2018; 96:1600-1609. [PMID: 29696675 DOI: 10.1002/jnr.24254] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/13/2018] [Accepted: 04/13/2018] [Indexed: 11/09/2022]
Abstract
Transcranial direct current stimulation (tDCS) has the capacity to enhance force output during a short-lasting maximal voluntary contraction (MVC) as well as during a long-lasting submaximal voluntary contraction until task failure. However, its effect on an intermittent maximal effort is not known. We hypothesized that anodal tDCS applied during or before a maximal fatigue task increases the amplitude of maximal voluntary contraction (aMVC) and voluntary activation (VA) in young healthy male participants. We measured VA, potentiated twitch at rest (Ptw), root mean square electromyogram (EMG), and aMVC during a fatiguing task that consisted of 35 × 5 s MVC of knee extensors and was performed during tDCS or 10 min after the end of tDCS (sham, anodal, or cathodal treatments). No effect of tDCS was detected on the first MVC but, when compared to sham tDCS, both anodal tDCS and cathodal tDCS reduced aMVC when tDCS was applied during the task (p < .001) and only anodal tDCS reduced aMVC when applied 10 min before the task (p = .03). The reductions in aMVC were accompanied by reductions in EMG of M. vastus lateralis for both tDCS treatments as well as in Ptw only during anodal tDCS and in VA only during cathodal tDCS. Both cathodal tDCS and anodal tDCS impaired force production during an intermittent fatiguing MVC task. The detrimental effects were stronger when tDCS was applied during the task. Here, cathodal and anodal tDCS specifically affected Ptw and VA indicating different underlying mechanisms.
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Affiliation(s)
| | - Markus Gruber
- Sensorimotor Performance Lab, Universität Konstanz, Konstanz, Germany
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Sánchez-León CA, Ammann C, Medina JF, Márquez-Ruiz J. Using animal models to improve the design and application of transcranial electrical stimulation in humans. Curr Behav Neurosci Rep 2018; 5:125-135. [PMID: 30013890 DOI: 10.1007/s40473-018-0149-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Purpose of Review Transcranial electrical stimulation (tES) is a non-invasive stimulation technique used for modulating brain function in humans. To help tES reach its full therapeutic potential, it is necessary to address a number of critical gaps in our knowledge. Here, we review studies that have taken advantage of animal models to provide invaluable insight about the basic science behind tES. Recent Findings Animal studies are playing a key role in elucidating the mechanisms implicated in tES, defining safety limits, validating computational models, inspiring new stimulation protocols, enhancing brain function and exploring new therapeutic applications. Summary Animal models provide a wealth of information that can facilitate the successful utilization of tES for clinical interventions in human subjects. To this end, tES experiments in animals should be carefully designed to maximize opportunities for applying discoveries to the treatment of human disease.
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Affiliation(s)
| | - Claudia Ammann
- CINAC, University Hospital HM Puerta del Sur, CEU - San Pablo University, 28938-Móstoles, Madrid, Spain
| | - Javier F Medina
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
| | - Javier Márquez-Ruiz
- Division of Neurosciences, Pablo de Olavide University, 41013-Seville, Spain
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68
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Li W, Papilloud A, Lozano-Montes L, Zhao N, Ye X, Zhang X, Sandi C, Rainer G. Stress Impacts the Regulation Neuropeptides in the Rat Hippocampus and Prefrontal Cortex. Proteomics 2018; 18:e1700408. [PMID: 29406625 DOI: 10.1002/pmic.201700408] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/10/2018] [Indexed: 11/05/2022]
Abstract
Adverse life experiences increase the lifetime risk to several stress-related psychopathologies, such as anxiety or depressive-like symptoms following stress in adulthood. However, the neurochemical modulations triggered by stress have not been fully characterized. Neuropeptides play an important role as signaling molecules that contribute to physiological regulation and have been linked to neurological and psychiatric diseases. However, little is known about the influence of stress on neuropeptide regulation in the brain. Here, we have performed an exploratory study of how neuropeptide expression at adulthood is modulated by experiencing a period of multiple stressful experiences. We have targeted hippocampus and prefrontal cortex (PFC) brain areas, which have previously been shown to be modulated by stressors, employing a targeted liquid chromatography-mass spectrometry (LC-MS) based approach that permits broad peptide coverage with high sensitivity. We found that in the hippocampus, Met-enkephalin, Met-enkephalin-Arg-Phe, and Met-enkephalin-Arg-Gly-Leu were upregulated, while Leu-enkephalin and Little SAAS were downregulated after stress. In the PFC area, Met-enkephalin-Arg-Phe, Met-enkephalin-Arg-Gly-Leu, peptide PHI-27, somatostatin-28 (AA1-12), and Little SAAS were all downregulated. This systematic evaluation of neuropeptide alterations in the hippocampus and PFC suggests that stressors impact neuropeptides and that neuropeptide regulation is brain-area specific. These findings suggest several potential peptide candidates, which warrant further investigations in terms of correlation with depression-associated behaviors.
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Affiliation(s)
- Wenxue Li
- Department of Medicine, University of Fribourg, Fribourg, Switzerland
| | - Aurelie Papilloud
- Laboratory of Behavioral Genetics, Brain Mind Institute, School of Life Science, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland
| | | | - Nan Zhao
- Division of Biological Technology, Chinese Academy of Science, Dalian Institute of Chemical Physics, Dalian, P. R. China
| | - Xueting Ye
- Division of Biological Technology, Chinese Academy of Science, Dalian Institute of Chemical Physics, Dalian, P. R. China
| | - Xiaozhe Zhang
- Division of Biological Technology, Chinese Academy of Science, Dalian Institute of Chemical Physics, Dalian, P. R. China
| | - Carmen Sandi
- Laboratory of Behavioral Genetics, Brain Mind Institute, School of Life Science, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland
| | - Gregor Rainer
- Department of Medicine, University of Fribourg, Fribourg, Switzerland
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Souza A, Martins DF, Medeiros LF, Nucci-Martins C, Martins TC, Siteneski A, Caumo W, dos Santos ARS, Torres IL. Neurobiological mechanisms of antiallodynic effect of transcranial direct current stimulation (tDCS) in a mice model of neuropathic pain. Brain Res 2018; 1682:14-23. [DOI: 10.1016/j.brainres.2017.12.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 09/14/2017] [Accepted: 12/08/2017] [Indexed: 01/07/2023]
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Koo H, Kim MS, Han SW, Paulus W, Nitche MA, Kim YH, Kim HI, Ko SH, Shin YI. After-effects of anodal transcranial direct current stimulation on the excitability of the motor cortex in rats. Restor Neurol Neurosci 2018; 34:859-68. [PMID: 27567759 DOI: 10.3233/rnn-160664] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE Transcranial direct current stimulation (tDCS) is increasingly seen as a useful tool for noninvasive cortical neuromodulation. A number of studies in humans have shown that when tDCS is applied to the motor cortex it can modulate cortical excitability. It is especially interesting to note that when applied with sufficient duration and intensity, tDCS can enable long-lasting neuroplastic effects. However, the mechanism by which tDCS exerts its effects on the cortex is not fully understood. We investigated the effects of anodal tDCS under urethane anesthesia on field potentials in in vivo rats. METHODS These were measured on the skull over the right motor cortex of rats immediately after stimulating the left corpus callosum. RESULTS Evoked field potentials in the motor cortex were gradually increased for more than one hour after anodal tDCS. To induce these long-lasting effects, a sufficient duration of stimulation (20 minutes or more) was found to may be required rather than high stimulation intensity. CONCLUSION We propose that anodal tDCS with a sufficient duration of stimulation may modulate transcallosal plasticity.
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Affiliation(s)
- Ho Koo
- Department of Physiology, Wonkwang University College of Medicine, Iksan, South Korea
| | - Min Sun Kim
- Department of Physiology, Wonkwang University College of Medicine, Iksan, South Korea
| | - Sang Who Han
- Department of Physiology, Wonkwang University College of Medicine, Iksan, South Korea
| | - Walter Paulus
- University Medical Center, Department Clinical Neurophysiology, Georg-August-University, Goettingen, Germany
| | - Michael A Nitche
- University Medical Center, Department 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
| | - Yun-Hee Kim
- Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Hyoung-Ihl Kim
- Department of Medical System Engineering & Department of Mechatronics, Gwangju Institute of Science and Technology, Gwangju, South Korea
| | - Sung-Hwa Ko
- Department of Rehabilitation Medicine, Pusan National University School of Medicine, Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, South Korea
| | - Yong-Il Shin
- Department of Rehabilitation Medicine, Pusan National University School of Medicine, Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, South Korea
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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: 135] [Impact Index Per Article: 16.9] [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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Nazario LR, da Silva RS, Bonan CD. Targeting Adenosine Signaling in Parkinson's Disease: From Pharmacological to Non-pharmacological Approaches. Front Neurosci 2017; 11:658. [PMID: 29217998 PMCID: PMC5703841 DOI: 10.3389/fnins.2017.00658] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 11/10/2017] [Indexed: 12/29/2022] Open
Abstract
Parkinson's disease (PD) is one of the most prevalent neurodegenerative disease displaying negative impacts on both the health and social ability of patients and considerable economical costs. The classical anti-parkinsonian drugs based in dopaminergic replacement are the standard treatment, but several motor side effects emerge during long-term use. This mini-review presents the rationale to several efforts from pre-clinical and clinical studies using adenosine receptor antagonists as a non-dopaminergic therapy. As several studies have indicated that the monotherapy with adenosine receptor antagonists reaches limited efficacy, the usage as a co-adjuvant appeared to be a promising strategy. The formulation of multi-targeted drugs, using adenosine receptor antagonists and other neurotransmitter systems than the dopaminergic one as targets, have been receiving attention since Parkinson's disease presents a complex biological impact. While pharmacological approaches to cure or ameliorate the conditions of PD are the leading strategy in this area, emerging positive aspects have arisen from non-pharmacological approaches and adenosine function inhibition appears to improve both strategies.
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Affiliation(s)
- Luiza R Nazario
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Rosane S da Silva
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Carla D Bonan
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
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Krause MR, Zanos TP, Csorba BA, Pilly PK, Choe J, Phillips ME, Datta A, Pack CC. Transcranial Direct Current Stimulation Facilitates Associative Learning and Alters Functional Connectivity in the Primate Brain. Curr Biol 2017; 27:3086-3096.e3. [PMID: 29033331 DOI: 10.1016/j.cub.2017.09.020] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 07/19/2017] [Accepted: 09/11/2017] [Indexed: 01/12/2023]
Abstract
There has been growing interest in transcranial direct current stimulation (tDCS), a non-invasive technique purported to modulate neural activity via weak, externally applied electric fields. Although some promising preliminary data have been reported for applications ranging from stroke rehabilitation to cognitive enhancement, little is known about how tDCS affects the human brain, and some studies have concluded that it may have no effect at all. Here, we describe a macaque model of tDCS that allows us to simultaneously examine the effects of tDCS on brain activity and behavior. We find that applying tDCS to right prefrontal cortex improves monkeys' performance on an associative learning task. While firing rates do not change within the targeted area, tDCS does induce large low-frequency oscillations in the underlying tissue. These oscillations alter functional connectivity, both locally and between distant brain areas, and these long-range changes correlate with tDCS's effects on behavior. Together, these results are consistent with the idea that tDCS leads to widespread changes in brain activity and suggest that it may be a valuable method for cheaply and non-invasively altering functional connectivity in humans.
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Affiliation(s)
- Matthew R Krause
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | | | - Bennett A Csorba
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Praveen K Pilly
- Information and Systems Sciences Laboratory, HRL Laboratories, LLC, Malibu, CA 90265, USA.
| | - Jaehoon Choe
- Information and Systems Sciences Laboratory, HRL Laboratories, LLC, Malibu, CA 90265, USA
| | - Matthew E Phillips
- Information and Systems Sciences Laboratory, HRL Laboratories, LLC, Malibu, CA 90265, USA
| | | | - Christopher C Pack
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada.
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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: 2.4] [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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Caffeine has no effect on eyeblink conditioning in mice. Behav Brain Res 2017; 337:252-255. [PMID: 28893553 DOI: 10.1016/j.bbr.2017.09.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 08/29/2017] [Accepted: 09/01/2017] [Indexed: 11/20/2022]
Abstract
Caffeine is one of the most widely used drugs in the world. In the brain, caffeine acts as an antagonist for the adenosine A1 and A2B receptors. Since A1 receptors are highly concentrated in the cortex of the cerebellum, we hypothesized that caffeine could potentially affect learning tasks that require the cerebellar cortex, such as eyeblink conditioning. To test this hypothesis, we examined the effect of low (5mg/kg) and high (50mg/kg) doses of caffeine, injected intraperitoneally before training, on eyeblink conditioning in mice. The results show that, at the dosages we used, caffeine affects neither the rate of acquisition, nor the timing of the onset or peak of the conditioned blink responses. Therefore, we conclude that caffeine neither improves nor worsens performance on eyeblink conditioning.
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77
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Transcranial direct current stimulation as a motor neurorehabilitation tool: an empirical review. Biomed Eng Online 2017; 16:76. [PMID: 28830433 PMCID: PMC5568608 DOI: 10.1186/s12938-017-0361-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The present review collects the most relevant empirical evidence available in the literature until date regarding the effects of transcranial direct current stimulation (tDCS) on the human motor function. tDCS in a non-invasive neurostimulation technique that delivers a weak current through the brain scalp altering the cortical excitability on the target brain area. The electrical current modulates the resting membrane potential of a variety of neuronal population (as pyramidal and gabaergic neurons); raising or dropping the firing rate up or down, depending on the nature of the electrode and the applied intensity. These local changes additionally have shown long-lasting effects, evidenced by its promotion of the brain-derived neurotrophic factor. Due to its easy and safe application and its neuromodulatory effects, tDCS has attracted a big attention in the motor neurorehabilitation field among the last years. Therefore, the present manuscript updates the knowledge available about the main concept of tDCS, its practical use, safety considerations, and its underlying mechanisms of action. Moreover, we will focus on the empirical data obtained by studies regarding the application of tDCS on the motor function of healthy and clinical population, comprising motor deficiencies of a variety of pathologies as Parkinson's disease, stroke, multiple sclerosis and cerebral palsy, among others. Finally, we will discuss the main current issues and future directions of tDCS as a motor neurorehabilitation tool.
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Das S, Spoor M, Sibindi TM, Holland P, Schonewille M, De Zeeuw CI, Frens MA, Donchin O. Impairment of Long-Term Plasticity of Cerebellar Purkinje Cells Eliminates the Effect of Anodal Direct Current Stimulation on Vestibulo-Ocular Reflex Habituation. Front Neurosci 2017; 11:444. [PMID: 28824366 PMCID: PMC5541059 DOI: 10.3389/fnins.2017.00444] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 07/20/2017] [Indexed: 11/13/2022] Open
Abstract
Anodal direct current stimulation (DCS) of the cerebellum facilitates adaptation tasks, but the mechanism underlying this effect is poorly understood. We have evaluated whether the effects of DCS effects depend on plasticity of cerebellar Purkinje cells (PCs). Here, we have successfully developed a mouse model of cerebellar DCS, allowing us to present the first demonstration of cerebellar DCS driven behavioral changes in rodents. We have utilized a simple gain down vestibulo-ocular reflex (VOR) adaptation paradigm, that stabilizes a visual image on the retina during brief head movements, as behavioral tool. Our results provide evidence that anodal stimulation has an acute post-stimulation effect on baseline gain reduction of VOR (VOR gain in sham, anodal and cathodal groups are 0.75 ± 0.12, 0.68 ± 0.1, and 0.78 ± 0.05, respectively). Moreover, this anodal induced decrease in VOR gain is directly dependent on the PP2B medicated synaptic long-term potentiation (LTP) and intrinsic plasticity pathways of PCs.
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Affiliation(s)
- Suman Das
- Department of Biomedical Engineering and Zlotowski Center for Neuroscience, Ben Gurion University of the NegevBe'er Sheva, Israel.,Department of Neuroscience, Erasmus Medical CenterRotterdam, Netherlands.,Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit AmsterdamAmsterdam, Netherlands
| | - Marcella Spoor
- Department of Neuroscience, Erasmus Medical CenterRotterdam, Netherlands
| | - Tafadzwa M Sibindi
- Department of Neuroscience, Erasmus Medical CenterRotterdam, Netherlands
| | - Peter Holland
- Department of Biomedical Engineering and Zlotowski Center for Neuroscience, Ben Gurion University of the NegevBe'er Sheva, Israel.,Department of Neuroscience, Erasmus Medical CenterRotterdam, Netherlands
| | | | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus Medical CenterRotterdam, Netherlands.,Netherlands Institute for NeuroscienceAmsterdam, Netherlands
| | - Maarten A Frens
- Department of Neuroscience, Erasmus Medical CenterRotterdam, Netherlands.,Faculty of Social and Behavioral Sciences, Erasmus University College, Erasmus UniversityRotterdam, Netherlands
| | - Opher Donchin
- Department of Biomedical Engineering and Zlotowski Center for Neuroscience, Ben Gurion University of the NegevBe'er Sheva, Israel.,Department of Neuroscience, Erasmus Medical CenterRotterdam, Netherlands
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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: 7.0] [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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80
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Jankowska E. Spinal control of motor outputs by intrinsic and externally induced electric field potentials. J Neurophysiol 2017; 118:1221-1234. [PMID: 28539396 DOI: 10.1152/jn.00169.2017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/22/2017] [Accepted: 05/22/2017] [Indexed: 12/13/2022] Open
Abstract
Despite numerous studies on spinal neuronal systems, several issues regarding their role in motor behavior remain unresolved. One of these issues is how electric fields associated with the activity of spinal neurons influence the operation of spinal neuronal networks and how effects of these field potentials are combined with other means of modulating neuronal activity. Another closely related issue is how external electric field potentials affect spinal neurons and how they can be used for therapeutic purposes such as pain relief or recovery of motor functions by transspinal direct current stimulation. Nevertheless, progress in our understanding of the spinal effects of electric fields and their mechanisms has been made over the last years, and the aim of the present review is to summarize the recent findings in this field.
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Affiliation(s)
- Elzbieta Jankowska
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
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81
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Rahman A, Lafon B, Parra LC, Bikson M. Direct current stimulation boosts synaptic gain and cooperativity in vitro. J Physiol 2017; 595:3535-3547. [PMID: 28436038 DOI: 10.1113/jp273005] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 02/13/2017] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS Direct current stimulation (DCS) polarity specifically modulates synaptic efficacy during a continuous train of presynaptic inputs, despite synaptic depression. DCS polarizes afferent axons and postsynaptic neurons, boosting cooperativity between synaptic inputs. Polarization of afferent neurons in upstream brain regions may modulate activity in the target brain region during transcranial DCS (tDCS). A statistical theory of coincident activity predicts that the diffuse and weak profile of current flow can be advantageous in enhancing connectivity between co-active brain regions. ABSTRACT Transcranial direct current stimulation (tDCS) produces sustained and diffuse current flow in the brain with effects that are state dependent and outlast stimulation. A mechanistic explanation for tDCS should capture these spatiotemporal features. It remains unclear how sustained DCS affects ongoing synaptic dynamics and how modulation of afferent inputs by diffuse stimulation changes synaptic activity at the target brain region. We tested the effect of acute DCS (10-20 V m-1 for 3-5 s) on synaptic dynamics with constant rate (5-40 Hz) and Poisson-distributed (4 Hz mean) trains of presynaptic inputs. Across tested frequencies, sustained synaptic activity was modulated by DCS with polarity-specific effects. Synaptic depression attenuates the sensitivity to DCS from 1.1% per V m-1 to 0.55%. DCS applied during synaptic activity facilitates cumulative neuromodulation, potentially reversing endogenous synaptic depression. We establish these effects are mediated by both postsynaptic membrane polarization and afferent axon fibre polarization, which boosts cooperativity between synaptic inputs. This potentially extends the locus of neuromodulation from the nominal target to afferent brain regions. Based on these results we hypothesized the polarization of afferent neurons in upstream brain regions may modulate activity in the target brain region during tDCS. A multiscale model of transcranial electrical stimulation including a finite element model of brain current flow, numerical simulations of neuronal activity, and a statistical theory of coincident activity predicts that the diffuse and weak profile of current flow can be advantageous. Thus, we propose that specifically because tDCS is diffuse, weak and sustained it can boost connectivity between co-active brain regions.
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Affiliation(s)
- Asif Rahman
- Department of Biomedical Engineering, The City College of The City University of New York, Steinman Hall, 160 Convent Ave, New York, NY, 10031, USA
| | - Belen Lafon
- Department of Biomedical Engineering, The City College of The City University of New York, Steinman Hall, 160 Convent Ave, New York, NY, 10031, USA
| | - Lucas C Parra
- Department of Biomedical Engineering, The City College of The City University of New York, Steinman Hall, 160 Convent Ave, New York, NY, 10031, USA
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of The City University of New York, Steinman Hall, 160 Convent Ave, New York, NY, 10031, USA
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82
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Giordano J, Bikson M, Kappenman ES, Clark VP, Coslett HB, Hamblin MR, Hamilton R, Jankord R, Kozumbo WJ, McKinley RA, Nitsche MA, Reilly JP, Richardson J, Wurzman R, Calabrese E. Mechanisms and Effects of Transcranial Direct Current Stimulation. Dose Response 2017; 15:1559325816685467. [PMID: 28210202 PMCID: PMC5302097 DOI: 10.1177/1559325816685467] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The US Air Force Office of Scientific Research convened a meeting of researchers in the fields of neuroscience, psychology, engineering, and medicine to discuss most pressing issues facing ongoing research in the field of transcranial direct current stimulation (tDCS) and related techniques. In this study, we present opinions prepared by participants of the meeting, focusing on the most promising areas of research, immediate and future goals for the field, and the potential for hormesis theory to inform tDCS research. Scientific, medical, and ethical considerations support the ongoing testing of tDCS in healthy and clinical populations, provided best protocols are used to maximize safety. Notwithstanding the need for ongoing research, promising applications include enhancing vigilance/attention in healthy volunteers, which can accelerate training and support learning. Commonly, tDCS is used as an adjunct to training/rehabilitation tasks with the goal of leftward shift in the learning/treatment effect curves. Although trials are encouraging, elucidating the basic mechanisms of tDCS will accelerate validation and adoption. To this end, biomarkers (eg, clinical neuroimaging and findings from animal models) can support hypotheses linking neurobiological mechanisms and behavioral effects. Dosage can be optimized using computational models of current flow and understanding dose–response. Both biomarkers and dosimetry should guide individualized interventions with the goal of reducing variability. Insights from other applied energy domains, including ionizing radiation, transcranial magnetic stimulation, and low-level laser (light) therapy, can be prudently leveraged.
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Affiliation(s)
- James Giordano
- Department of Neurology and Biochemistry, Neuroethics Studies Program, Pellegrino Center for Clinical Bioethics, Georgetown University Medical Center, Washington, DC, USA
| | - Marom Bikson
- Biomedical Engineering, City College of New York, CUNY, New York, NY, USA
| | - Emily S Kappenman
- San Diego State University, Department of Psychology, San Diego, CA, USA
| | - Vincent P Clark
- Psychology Clinical Neuroscience Center, Department of Psychology, University of New Mexico, Albuquerque, NM, USA
| | - H Branch Coslett
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael R Hamblin
- Wellman Center for Photomedicine, Massachusetts General Hospital and Department of Dermatology, Harvard Medical School, Boston, MA, USA
| | - Roy Hamilton
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ryan Jankord
- United States Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA
| | | | - R Andrew McKinley
- United States Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA
| | - Michael A Nitsche
- Department Psychology and Neurosciences, Leibniz Research Center for Working Environmental and Human Factors, Dortmund, Germany
| | | | - Jessica Richardson
- Department of Speech and Hearing Sciences, University of New Mexico, Albuquerque, NM, USA
| | - Rachel Wurzman
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Edward Calabrese
- Environmental Health Sciences, University of Massachusetts, Amherst, MA, USA
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83
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Beyer L, Batsikadze G, Timmann D, Gerwig M. Cerebellar tDCS Effects on Conditioned Eyeblinks using Different Electrode Placements and Stimulation Protocols. Front Hum Neurosci 2017; 11:23. [PMID: 28203151 PMCID: PMC5285376 DOI: 10.3389/fnhum.2017.00023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 01/11/2017] [Indexed: 11/13/2022] Open
Abstract
There is good evidence that the human cerebellum is involved in the acquisition and timing of classically conditioned eyeblink responses (CRs). Animal studies suggest that the cerebellum is also important in CR extinction and savings. Cerebellar transcranial direct current stimulation (tDCS) was reported to modulate CR acquisition and timing in a polarity dependent manner. To extent previous findings three experiments were conducted using standard delay eyeblink conditioning. In a between-group design, effects of tDCS were assessed with stimulation over the right cerebellar hemisphere ipsilaterally to the unconditioned stimulus (US). An extracephalic reference electrode was used in Experiment 1 and a cephalic reference in Experiment 2. In both parts the influence on unconditioned eyeblink responses (UR) was investigated by starting stimulation in the second half of the pseudoconditioning phase lasting throughout the first half of paired trials. In a third experiment, effects of cerebellar tDCS during 40 extinction trials were assessed on extinction and reacquisition on the next day. In each experiment, 30 subjects received anodal, cathodal or sham stimulation in a double-blinded fashion. Using the extracephalic reference electrode, no significant effects on CR incidences comparing stimulation groups were observed. Using the cephalic reference anodal as well as cathodal cerebellar tDCS increased CR acquisition compared to sham only on a trend level. Analysis of timing parameters did not reveal significant effects on CR onset and peaktime latencies nor on UR timing. In the third experiment, cerebellar tDCS during extinction trials had no significant effect on extinction and savings on the next day. The present study did not reveal clear polarity dependent effects of cerebellar tDCS on CR acquisition and timing as previously described. Weaker effects may be explained by start of tDCS before the learning phase i.e., offline, individual thresholds and current flow based on individual anatomy may also play role. Likewise cerebellar tDCS during extinction did not modulate extinction or reacquisition. Further studies are needed in larger subject populations to determine parameters of stimulation and learning paradigms yielding robust cerebellar tDCS effects.
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Affiliation(s)
- Linda Beyer
- Department of Neurology, University of Duisburg-EssenEssen, Germany
| | | | - Dagmar Timmann
- Department of Neurology, University of Duisburg-EssenEssen, Germany
| | - Marcus Gerwig
- Department of Neurology, University of Duisburg-EssenEssen, Germany
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84
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Transcriptomic Modification in the Cerebral Cortex following Noninvasive Brain Stimulation: RNA-Sequencing Approach. Neural Plast 2016; 2016:5942980. [PMID: 28119786 PMCID: PMC5227175 DOI: 10.1155/2016/5942980] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/27/2016] [Accepted: 11/14/2016] [Indexed: 11/18/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) has been shown to modulate neuroplasticity. Beneficial effects are observed in patients with psychiatric disorders and enhancement of brain performance in healthy individuals has been observed following tDCS. However, few studies have attempted to elucidate the underlying molecular mechanisms of tDCS in the brain. This study was conducted to assess the impact of tDCS on gene expression within the rat cerebral cortex. Anodal tDCS was applied at 3 different intensities followed by RNA-sequencing and analysis. In each current intensity, approximately 1,000 genes demonstrated statistically significant differences compared to the sham group. A variety of functional pathways, biological processes, and molecular categories were found to be modified by tDCS. The impact of tDCS on gene expression was dependent on current intensity. Results show that inflammatory pathways, antidepressant-related pathways (GTP signaling, calcium ion binding, and transmembrane/signal peptide pathways), and receptor signaling pathways (serotonergic, adrenergic, GABAergic, dopaminergic, and glutamate) were most affected. Of the gene expression profiles induced by tDCS, some changes were observed across multiple current intensities while other changes were unique to a single stimulation intensity. This study demonstrates that tDCS can modify the expression profile of various genes in the cerebral cortex and that these tDCS-induced alterations are dependent on the current intensity applied.
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85
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Ammann C, Spampinato D, Márquez-Ruiz J. Modulating Motor Learning through Transcranial Direct-Current Stimulation: An Integrative View. Front Psychol 2016; 7:1981. [PMID: 28066300 PMCID: PMC5179543 DOI: 10.3389/fpsyg.2016.01981] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 12/05/2016] [Indexed: 02/05/2023] Open
Abstract
Motor learning consists of the ability to improve motor actions through practice playing a major role in the acquisition of skills required for high-performance sports or motor function recovery after brain lesions. During the last decades, it has been reported that transcranial direct-current stimulation (tDCS), consisting in applying weak direct current through the scalp, is able of inducing polarity-specific changes in the excitability of cortical neurons. This low-cost, painless and well-tolerated portable technique has found a wide-spread use in the motor learning domain where it has been successfully applied to enhance motor learning in healthy individuals and for motor recovery after brain lesion as well as in pathological states associated to motor deficits. The main objective of this mini-review is to offer an integrative view about the potential use of tDCS for human motor learning modulation. Furthermore, we introduce the basic mechanisms underlying immediate and long-term effects associated to tDCS along with important considerations about its limitations and progression in recent years.
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Affiliation(s)
- Claudia Ammann
- Department of Physical Medicine and Rehabilitation, Johns Hopkins Medical Institution Baltimore, MD, USA
| | - Danny Spampinato
- Department of Physical Medicine and Rehabilitation, Johns Hopkins Medical Institution Baltimore, MD, USA
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86
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Lee C, Jung YJ, Lee SJ, Im CH. COMETS2: An advanced MATLAB toolbox for the numerical analysis of electric fields generated by transcranial direct current stimulation. J Neurosci Methods 2016; 277:56-62. [PMID: 27989592 DOI: 10.1016/j.jneumeth.2016.12.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 12/12/2016] [Accepted: 12/13/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND Since there is no way to measure electric current generated by transcranial direct current stimulation (tDCS) inside the human head through in vivo experiments, numerical analysis based on the finite element method has been widely used to estimate the electric field inside the head. In 2013, we released a MATLAB toolbox named COMETS, which has been used by a number of groups and has helped researchers to gain insight into the electric field distribution during stimulation. The aim of this study was to develop an advanced MATLAB toolbox, named COMETS2, for the numerical analysis of the electric field generated by tDCS. NEW METHOD COMETS2 can generate any sizes of rectangular pad electrodes on any positions on the scalp surface. To reduce the large computational burden when repeatedly testing multiple electrode locations and sizes, a new technique to decompose the global stiffness matrix was proposed. RESULTS As examples of potential applications, we observed the effects of sizes and displacements of electrodes on the results of electric field analysis. The proposed mesh decomposition method significantly enhanced the overall computational efficiency. COMPARISON WITH EXISTING METHODS We implemented an automatic electrode modeler for the first time, and proposed a new technique to enhance the computational efficiency. CONCLUSIONS In this paper, an efficient toolbox for tDCS analysis is introduced (freely available at http://www.cometstool.com). It is expected that COMETS2 will be a useful toolbox for researchers who want to benefit from the numerical analysis of electric fields generated by tDCS.
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Affiliation(s)
- Chany Lee
- Department of Biomedical Engineering, Hanyang University, Seoul, Republic of Korea
| | - Young-Jin Jung
- Department of Radiological Science, Dongseo University, Busan, Republic of Korea
| | - Sang Jun Lee
- Department of Biomedical Engineering, Hanyang University, Seoul, Republic of Korea
| | - Chang-Hwan Im
- Department of Biomedical Engineering, Hanyang University, Seoul, Republic of Korea.
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87
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Abstract
PURPOSE OF REVIEW The review aims at highlighting the additional benefit that can be gained from combining noninvasive brain stimulation as well as repetitive sensory stimulation protocols with MRI techniques to account for the intersubject variability observed in those treatments. Potentially, this should help to identify predictive patterns in the individual receptiveness to the treatment. RECENT FINDINGS Knowledge about the underlying physiological principles of excitability changes as induced by noninvasive brain stimulation or repetitive sensory stimulation is accumulating, revealing strong associations with plasticity processes at the synaptic level. In this context, MRI techniques, such as magnetic resonance spectroscopy and functional MRI, emerged as valuable tools for the qualitative assessment of baseline states and induced changes. Those physiological readouts can help explain the interindividual heterogeneity found in behavioural and/or clinical responses to the specific stimulation protocols. This knowledge will eventually translate, first, into the preliminary classification of study participants into treatment groups according to their neurophysiological baseline state and expected responses to a particular stimulation. Subsequently, this should also aid the optimization of stimulation protocols according to the classification outcome, resulting in retuned protocols for particular groups of study participants. SUMMARY The consistent MRI-based monitoring of stimulation effects in the neural network promises a considerable gain for the customization of intervention protocols with improved therapeutic potential and rehabilitative predictions.
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88
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Jackson MP, Rahman A, Lafon B, Kronberg G, Ling D, Parra LC, Bikson M. Animal models of transcranial direct current stimulation: Methods and mechanisms. Clin Neurophysiol 2016; 127:3425-3454. [PMID: 27693941 PMCID: PMC5083183 DOI: 10.1016/j.clinph.2016.08.016] [Citation(s) in RCA: 204] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 08/05/2016] [Accepted: 08/08/2016] [Indexed: 12/28/2022]
Abstract
The objective of this review is to summarize the contribution of animal research using direct current stimulation (DCS) to our understanding of the physiological effects of transcranial direct current stimulation (tDCS). We comprehensively address experimental methodology in animal studies, broadly classified as: (1) transcranial stimulation; (2) direct cortical stimulation in vivo and (3) in vitro models. In each case advantages and disadvantages for translational research are discussed including dose translation and the overarching "quasi-uniform" assumption, which underpins translational relevance in all animal models of tDCS. Terminology such as anode, cathode, inward current, outward current, current density, electric field, and uniform are defined. Though we put key animal experiments spanning decades in perspective, our goal is not simply an exhaustive cataloging of relevant animal studies, but rather to put them in context of ongoing efforts to improve tDCS. Cellular targets, including excitatory neuronal somas, dendrites, axons, interneurons, glial cells, and endothelial cells are considered. We emphasize neurons are always depolarized and hyperpolarized such that effects of DCS on neuronal excitability can only be evaluated within subcellular regions of the neuron. Findings from animal studies on the effects of DCS on plasticity (LTP/LTD) and network oscillations are reviewed extensively. Any endogenous phenomena dependent on membrane potential changes are, in theory, susceptible to modulation by DCS. The relevance of morphological changes (galvanotropy) to tDCS is also considered, as we suggest microscopic migration of axon terminals or dendritic spines may be relevant during tDCS. A majority of clinical studies using tDCS employ a simplistic dose strategy where excitability is singularly increased or decreased under the anode and cathode, respectively. We discuss how this strategy, itself based on classic animal studies, cannot account for the complexity of normal and pathological brain function, and how recent studies have already indicated more sophisticated approaches are necessary. One tDCS theory regarding "functional targeting" suggests the specificity of tDCS effects are possible by modulating ongoing function (plasticity). Use of animal models of disease are summarized including pain, movement disorders, stroke, and epilepsy.
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Affiliation(s)
- Mark P Jackson
- Department of Biomedical Engineering, The City College of The City University of New York, NY, USA
| | - Asif Rahman
- Department of Biomedical Engineering, The City College of The City University of New York, NY, USA
| | - Belen Lafon
- Department of Biomedical Engineering, The City College of The City University of New York, NY, USA
| | - Gregory Kronberg
- Department of Biomedical Engineering, The City College of The City University of New York, NY, USA
| | - Doris Ling
- Department of Biomedical Engineering, The City College of The City University of New York, NY, USA
| | - Lucas C Parra
- Department of Biomedical Engineering, The City College of The City University of New York, NY, USA
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of The City University of New York, NY, USA.
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89
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Kronberg G, Bridi M, Abel T, Bikson M, Parra LC. Direct Current Stimulation Modulates LTP and LTD: Activity Dependence and Dendritic Effects. Brain Stimul 2016; 10:51-58. [PMID: 28104085 DOI: 10.1016/j.brs.2016.10.001] [Citation(s) in RCA: 245] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 08/15/2016] [Accepted: 10/03/2016] [Indexed: 10/20/2022] Open
Abstract
BACKGROUND Transcranial direct current stimulation (tDCS) has been reported to improve various forms of learning in humans. Stimulation is often applied during training, producing lasting enhancements that are specific to the learned task. These learning effects are thought to be mediated by altered synaptic plasticity. However, the effects of DCS during the induction of endogenous synaptic plasticity remain largely unexplored. OBJECTIVE/HYPOTHESIS Here we are interested in the effects of DCS applied during synaptic plasticity induction. METHODS To model endogenous plasticity we induced long-term potentiation (LTP) and depression (LTD) at Schaffer collateral synapses in CA1 of rat hippocampal slices. Anodal and cathodal DCS at 20 V/m were applied throughout plasticity induction in both apical and basal dendritic compartments. RESULTS When DCS was paired with concurrent plasticity induction, the resulting plasticity was biased towards potentiation, such that LTP was enhanced and LTD was reduced. Remarkably, both anodal and cathodal stimulation can produce this bias, depending on the dendritic location and type of plasticity induction. Cathodal DCS enhanced LTP in apical dendrites while anodal DCS enhanced LTP in basal dendrites. Both anodal and cathodal DCS reduced LTD in apical dendrites. DCS did not affect synapses that were weakly active or when NMDA receptors were blocked. CONCLUSIONS These results highlight the role of DCS as a modulator, rather than inducer of synaptic plasticity, as well as the dependence of DCS effects on the spatial and temporal properties of endogenous synaptic activity. The relevance of the present results to human tDCS should be validated in future studies.
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Affiliation(s)
- Greg Kronberg
- Department of Biomedical Engineering, The City College of New York, New York, NY 10031, USA.
| | - Morgan Bridi
- Laboratory of Neural Circuits and Behavior, Hussman Institute for Autism, Baltimore, MD 21201, USA
| | - Ted Abel
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York, New York, NY 10031, USA
| | - Lucas C Parra
- Department of Biomedical Engineering, The City College of New York, New York, NY 10031, USA
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90
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Direct Current Stimulation Alters Neuronal Input/Output Function. Brain Stimul 2016; 10:36-45. [PMID: 27717601 DOI: 10.1016/j.brs.2016.08.014] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 08/16/2016] [Accepted: 08/30/2016] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Direct current stimulation (DCS) affects both neuronal firing rate and synaptic efficacy. The neuronal input/output (I/O) function determines the likelihood that a neuron elicits an action potential in response to synaptic input of a given strength. Changes of the neuronal I/O function by DCS may underlie previous observations in animal models and human testing, yet have not been directly assessed. OBJECTIVE Test if the neuronal input/output function is affected by DCS METHODS: Using rat hippocampal brain slices and computational modeling, we provide evidence for how DCS modulates the neuronal I/O function. RESULTS We show for the first time that DCS modulates the likelihood of neuronal firing for a given and fixed synaptic input. Opposing polarization of soma and dendrite may have a synergistic effect for anodal stimulation, increasing the driving force of synaptic activity while simultaneously increasing spiking probability at the soma. For cathodal stimulation, however, the opposing effects tend to cancel. This results in an asymmetry in the strength of the effects of stimulation for opposite polarities. CONCLUSIONS Our results may explain the asymmetries observed in acute and long term effects of transcranial direct current stimulation.
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91
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Luu P, Essaki Arumugam EM, Anderson E, Gunn A, Rech D, Turovets S, Tucker DM. Slow-Frequency Pulsed Transcranial Electrical Stimulation for Modulation of Cortical Plasticity Based on Reciprocity Targeting with Precision Electrical Head Modeling. Front Hum Neurosci 2016. [PMID: 27531976 DOI: 10.3339/fnhum.2016.00377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In pain management as well as other clinical applications of neuromodulation, it is important to consider the timing parameters influencing activity-dependent plasticity, including pulsed versus sustained currents, as well as the spatial action of electrical currents as they polarize the complex convolutions of the cortical mantle. These factors are of course related; studying temporal factors is not possible when the spatial resolution of current delivery to the cortex is so uncertain to make it unclear whether excitability is increased or decreased with anodal vs. cathodal current flow. In the present study we attempted to improve the targeting of specific cortical locations by applying current through flexible source-sink configurations of 256 electrodes in a geodesic array. We constructed a precision electric head model for 12 healthy individuals. Extraction of the individual's cortical surface allowed computation of the component of the induced current that is normal to the target cortical surface. In an effort to replicate the long-term depression (LTD) induced with pulsed protocols in invasive animal research and transcranial magnetic stimulation studies, we applied 100 ms pulses at 1.9 s intervals either in cortical-surface-anodal or cortical-surface-cathodal directions, with a placebo (sham) control. The results showed significant LTD of the motor evoked potential as a result of the cortical-surface-cathodal pulses in contrast to the placebo control, with a smaller but similar LTD effect for anodal pulses. The cathodal LTD after-effect was sustained over 90 min following current injection. These results support the feasibility of pulsed protocols with low total charge in non-invasive neuromodulation when the precision of targeting is improved with a dense electrode array and accurate head modeling.
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Affiliation(s)
- Phan Luu
- Electrical Geodesics, Inc., EugeneOR, USA; Department of Psychology, University of Oregon, EugeneOR, USA
| | | | | | | | | | - Sergei Turovets
- Electrical Geodesics, Inc., EugeneOR, USA; NeuroInformatics Center, University of Oregon, EugeneOR, USA
| | - Don M Tucker
- Electrical Geodesics, Inc., EugeneOR, USA; Department of Psychology, University of Oregon, EugeneOR, USA
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92
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Luu P, Essaki Arumugam EM, Anderson E, Gunn A, Rech D, Turovets S, Tucker DM. Slow-Frequency Pulsed Transcranial Electrical Stimulation for Modulation of Cortical Plasticity Based on Reciprocity Targeting with Precision Electrical Head Modeling. Front Hum Neurosci 2016; 10:377. [PMID: 27531976 PMCID: PMC4969286 DOI: 10.3389/fnhum.2016.00377] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 07/12/2016] [Indexed: 12/16/2022] Open
Abstract
In pain management as well as other clinical applications of neuromodulation, it is important to consider the timing parameters influencing activity-dependent plasticity, including pulsed versus sustained currents, as well as the spatial action of electrical currents as they polarize the complex convolutions of the cortical mantle. These factors are of course related; studying temporal factors is not possible when the spatial resolution of current delivery to the cortex is so uncertain to make it unclear whether excitability is increased or decreased with anodal vs. cathodal current flow. In the present study we attempted to improve the targeting of specific cortical locations by applying current through flexible source-sink configurations of 256 electrodes in a geodesic array. We constructed a precision electric head model for 12 healthy individuals. Extraction of the individual's cortical surface allowed computation of the component of the induced current that is normal to the target cortical surface. In an effort to replicate the long-term depression (LTD) induced with pulsed protocols in invasive animal research and transcranial magnetic stimulation studies, we applied 100 ms pulses at 1.9 s intervals either in cortical-surface-anodal or cortical-surface-cathodal directions, with a placebo (sham) control. The results showed significant LTD of the motor evoked potential as a result of the cortical-surface-cathodal pulses in contrast to the placebo control, with a smaller but similar LTD effect for anodal pulses. The cathodal LTD after-effect was sustained over 90 min following current injection. These results support the feasibility of pulsed protocols with low total charge in non-invasive neuromodulation when the precision of targeting is improved with a dense electrode array and accurate head modeling.
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Affiliation(s)
- Phan Luu
- Electrical Geodesics, Inc., EugeneOR, USA; Department of Psychology, University of Oregon, EugeneOR, USA
| | | | | | | | | | - Sergei Turovets
- Electrical Geodesics, Inc., EugeneOR, USA; NeuroInformatics Center, University of Oregon, EugeneOR, USA
| | - Don M Tucker
- Electrical Geodesics, Inc., EugeneOR, USA; Department of Psychology, University of Oregon, EugeneOR, USA
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93
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Hämmerer D, Bonaiuto J, Klein-Flügge M, Bikson M, Bestmann S. Selective alteration of human value decisions with medial frontal tDCS is predicted by changes in attractor dynamics. Sci Rep 2016; 6:25160. [PMID: 27146700 PMCID: PMC4857193 DOI: 10.1038/srep25160] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 03/04/2016] [Indexed: 02/02/2023] Open
Abstract
During value-based decision making, ventromedial prefrontal cortex (vmPFC) is thought to support choices by tracking the expected gain from different outcomes via a competition-based process. Using a computational neurostimulation approach we asked how perturbing this region might alter this competition and resulting value decisions. We simulated a perturbation of neural dynamics in a biophysically informed model of decision-making through in silico depolarization at the level of neuronal ensembles. Simulated depolarization increased baseline firing rates of pyramidal neurons, which altered their susceptibility to background noise, and thereby increased choice stochasticity. These behavioural predictions were compared to choice behaviour in healthy participants performing similar value decisions during transcranial direct current stimulation (tDCS), a non-invasive brain stimulation technique. We placed the soma depolarizing electrode over medial frontal PFC. In line with model predictions, this intervention resulted in more random choices. By contrast, no such effect was observed when placing the depolarizing electrode over lateral PFC. Using a causal manipulation of ventromedial and lateral prefrontal function, these results provide support for competition-based choice dynamics in human vmPFC, and introduce computational neurostimulation as a mechanistic assay for neurostimulation studies of cognition.
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Affiliation(s)
- D. Hämmerer
- Institute of Cognitive Neuroscience, London, United Kingdom
- Lifespan Psychology, MPI for Human Development, Berlin, Germany
| | - J. Bonaiuto
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London, United Kingdom
| | - M. Klein-Flügge
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London, United Kingdom
- Department of Experimental Psychology, Oxford, United Kingdom
| | - M. Bikson
- Department for Biomedical Engineering, The City University of New York, New York, NY, USA
| | - S. Bestmann
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London, United Kingdom
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94
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Furlong M, McLoughlin F, McGilloway S, Geary D. Interventions to improve mathematical performance for children with mathematical learning difficulties (MLD). Hippokratia 2016. [DOI: 10.1002/14651858.cd012130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Mairead Furlong
- Maynooth University Department of Psychology; National University of Ireland Maynooth; Maynooth Ireland
| | - Fergal McLoughlin
- Health Service Executive (HSE) Dublin Mid-Leinster Region; Mullingar Ireland
| | - Sinead McGilloway
- Maynooth University Department of Psychology (Mental Health and Social Research Unit); National University of Ireland Maynooth; Maynooth Ireland
| | - David Geary
- Department of Psychological Sciences; University of Missouri; Columbia USA
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95
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Vaseghi B, Zoghi M, Jaberzadeh S. Unihemispheric concurrent dual-site cathodal transcranial direct current stimulation: the effects on corticospinal excitability. Eur J Neurosci 2016; 43:1161-72. [PMID: 26946332 DOI: 10.1111/ejn.13229] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 02/20/2016] [Accepted: 03/01/2016] [Indexed: 11/30/2022]
Abstract
We aimed to assess the effects of concurrent cathodal transcranial direct current stimulation (c-tDCS) of two targets in a hemisphere, termed unihemispheric concurrent dual-site cathodal tDCS (c-tDCSUHCDS ), on the size of M1 corticospinal excitability and its lasting effect. Secondary aims were to identify the mechanisms behind the efficacy of c-tDCSUHCDS and to evaluate the side effects of this new technique. Twelve healthy volunteers received 20 min c-tDCS under five conditions in a random order: M1 c-tDCS, c-tDCSUHCDS of M1-dorsolateral prefrontal cortex (DLPFC), M1-primary sensory cortex (S1), M1-primary visual cortex (V1) and sham. The M1 corticospinal excitability of the first dorsal interossei muscle was assessed before, immediately after, and 30 min, 60 min and 24 h after the interventions. Short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) were also assessed, using a paired-pulse paradigm. Compared to conventional M1 c-tDCS, corticospinal excitability significantly increased following c-tDCSUHCDS of M1-DLPFC and M1-V1 for up to 24 h (P = 0.001). Significant increases in ICF were observed following c-tDCSUHCDS of M1-DLPFC (P = 0.005) and M1-V1 (P = 0.002). Compared to baseline values, ICF and SICI increased significantly at T60 (P < 0.001) and T24 h (P < 0.001) following the concurrent c-tDCS of M1 and V1. Sham c-tDCSUHCDS did not induce any significant alteration. The corticospinal excitability increase was mainly accompanied by ICF increase, which indirectly indicates the activity of glutamergic mechanisms. The findings may help us to more fully understand the brain function and develop future motor learning studies. No significant excitability change induced by sham c-tDCSUHCDS suggests that there is no placebo effect associated with this new tDCS technique.
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Affiliation(s)
- Bita Vaseghi
- Department of Physiotherapy, School of Primary Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Building B, Frankston 3199, Melbourne, Vic., Australia
| | - Maryam Zoghi
- Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Melbourne, Vic., Australia
| | - Shapour Jaberzadeh
- Department of Physiotherapy, School of Primary Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Building B, Frankston 3199, Melbourne, Vic., Australia
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96
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Calcium imaging reveals glial involvement in transcranial direct current stimulation-induced plasticity in mouse brain. Nat Commun 2016; 7:11100. [PMID: 27000523 PMCID: PMC4804173 DOI: 10.1038/ncomms11100] [Citation(s) in RCA: 269] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 02/19/2016] [Indexed: 02/06/2023] Open
Abstract
Transcranical direct current stimulation (tDCS) is a treatment known to ameliorate various neurological conditions and enhance memory and cognition in humans. tDCS has gained traction for its potential therapeutic value; however, little is known about its mechanism of action. Using a transgenic mouse expressing G-CaMP7 in astrocytes and a subpopulation of excitatory neurons, we find that tDCS induces large-amplitude astrocytic Ca2+ surges across the entire cortex with no obvious changes in the local field potential. Moreover, sensory evoked cortical responses are enhanced after tDCS. These enhancements are dependent on the alpha-1 adrenergic receptor and are not observed in IP3R2 (inositol trisphosphate receptor type 2) knockout mice, in which astrocytic Ca2+ surges are absent. Together, we propose that tDCS changes the metaplasticity of the cortex through astrocytic Ca2+/IP3 signalling. While transcranical direct current stimulation (tDCS) is used in clinical setting, its cellular mechanism of action is unclear. Here, Hajime Hirase and colleagues visualize cellular response in mouse brain to tDCS and show robust astrocyte activation that coincide with plasticity changes.
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97
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Krause V, Meier A, Dinkelbach L, Pollok B. Beta Band Transcranial Alternating (tACS) and Direct Current Stimulation (tDCS) Applied After Initial Learning Facilitate Retrieval of a Motor Sequence. Front Behav Neurosci 2016; 10:4. [PMID: 26834593 PMCID: PMC4722123 DOI: 10.3389/fnbeh.2016.00004] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 01/04/2016] [Indexed: 11/15/2022] Open
Abstract
The primary motor cortex (M1) contributes to the acquisition and early consolidation of a motor sequence. Although the relevance of M1 excitability for motor learning has been supported, the significance of M1 oscillations remains an open issue. This study aims at investigating to what extent retrieval of a newly learned motor sequence can be differentially affected by motor-cortical transcranial alternating (tACS) and direct current stimulation (tDCS). Alpha (10 Hz), beta (20 Hz) or sham tACS was applied in 36 right-handers. Anodal or cathodal tDCS was applied in 30 right-handers. Participants learned an eight-digit serial reaction time task (SRTT; sequential vs. random) with the right hand. Stimulation was applied to the left M1 after SRTT acquisition at rest for 10 min. Reaction times were analyzed at baseline, end of acquisition, retrieval immediately after stimulation and reacquisition after eight further sequence repetitions. Reaction times during retrieval were significantly faster following 20 Hz tACS as compared to 10 Hz and sham tACS indicating a facilitation of early consolidation. tDCS yielded faster reaction times, too, independent of polarity. No significant differences between 20 Hz tACS and tDCS effects on retrieval were found suggesting that 20 Hz effects might be associated with altered motor-cortical excitability. Based on the behavioral modulation yielded by tACS and tDCS one might speculate that altered motor-cortical beta oscillations support early motor consolidation possibly associated with neuroplastic reorganization.
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Affiliation(s)
- Vanessa Krause
- Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine-University Duesseldorf Duesseldorf, Germany
| | - Anna Meier
- Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine-University Duesseldorf Duesseldorf, Germany
| | - Lars Dinkelbach
- Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine-University Duesseldorf Duesseldorf, Germany
| | - Bettina Pollok
- Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine-University Duesseldorf Duesseldorf, Germany
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98
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Synthetic tactile perception induced by transcranial alternating-current stimulation can substitute for natural sensory stimulus in behaving rabbits. Sci Rep 2016; 6:19753. [PMID: 26790614 PMCID: PMC4726368 DOI: 10.1038/srep19753] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 12/16/2015] [Indexed: 11/10/2022] Open
Abstract
The use of brain-derived signals for controlling external devices has long attracted the attention from neuroscientists and engineers during last decades. Although much effort has been dedicated to establishing effective brain-to-computer communication, computer-to-brain communication feedback for “closing the loop” is now becoming a major research theme. While intracortical microstimulation of the sensory cortex has already been successfully used for this purpose, its future application in humans partly relies on the use of non-invasive brain stimulation technologies. In the present study, we explore the potential use of transcranial alternating-current stimulation (tACS) for synthetic tactile perception in alert behaving animals. More specifically, we determined the effects of tACS on sensory local field potentials (LFPs) and motor output and tested its capability for inducing tactile perception using classical eyeblink conditioning in the behaving animal. We demonstrated that tACS of the primary somatosensory cortex vibrissa area could indeed substitute natural stimuli during training in the associative learning paradigm.
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99
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Abstract
UNLABELLED Investigations into the use of transcranial direct current stimulation (tDCS) in relieving symptoms of neurological disorders and enhancing cognitive or motor performance have exhibited promising results. However, the mechanisms by which tDCS effects brain function remain under scrutiny. We have demonstrated that in vivo tDCS in rats produced a lasting effect on hippocampal synaptic plasticity, as measured using extracellular recordings. Ex vivo preparations of hippocampal slices from rats that have been subjected to tDCS of 0.10 or 0.25 mA for 30 min followed by 30 min of recovery time displayed a robust twofold enhancement in long-term potentiation (LTP) induction accompanied by a 30% increase in paired-pulse facilitation (PPF). The magnitude of the LTP effect was greater with 0.25 mA compared with 0.10 mA stimulations, suggesting a dose-dependent relationship between tDCS intensity and its effect on synaptic plasticity. To test the persistence of these observed effects, animals were stimulated in vivo for 30 min at 0.25 mA and then allowed to return to their home cage for 24 h. Observation of the enhanced LTP induction, but not the enhanced PPF, continued 24 h after completion of 0.25 mA of tDCS. Addition of the NMDA blocker AP-5 abolished LTP in both control and stimulated rats but maintained the PPF enhancement in stimulated rats. The observation of enhanced LTP and PPF after tDCS demonstrates that non-invasive electrical stimulation is capable of modifying synaptic plasticity. SIGNIFICANCE STATEMENT Researchers have used brain stimulation such as transcranial direct current stimulation on human subjects to alleviate symptoms of neurological disorders and enhance their performance. Here, using rats, we have investigated the potential mechanisms of how in vivo brain stimulation can produce such effect. We recorded directly on viable brain slices from rats after brain stimulation to detect lasting changes in pattern of neuronal activity. Our results showed that 30 min of brain stimulation in rats induced a robust enhancement in synaptic plasticity, a neuronal process critical for learning and memory. Understanding such molecular effects will lead to a better understanding of the mechanisms by which brain stimulation produces its effects on cognition and performance.
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100
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Shpektor A, Bartrés-Faz D, Feurra M. Commentary: Duration-dependent effects of the BDNF Val66Met polymorphism on anodal tDCS induced motor cortex plasticity in older adults: a group and individual perspective. Front Aging Neurosci 2015; 7:183. [PMID: 26441642 PMCID: PMC4585066 DOI: 10.3389/fnagi.2015.00183] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 09/07/2015] [Indexed: 01/24/2023] Open
Affiliation(s)
- Anna Shpektor
- School of Psychology, Centre for Cognition and Decision Making, National Research University Higher School of Economics Moscow, Russia
| | - David Bartrés-Faz
- Department of Psychiatry and Clinical Psychobiology, University of Barcelona Barcelona, Spain
| | - Matteo Feurra
- School of Psychology, Centre for Cognition and Decision Making, National Research University Higher School of Economics Moscow, Russia ; Unit of Neurology and Clinical Neurophysiology, Brain Investigation and Neuromodulation laboratory (Si-BIN Lab), Department of Medicine, Surgery and Neuroscience, Azienda Ospedaliera Universitaria of Siena Siena, Italy
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