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Evans C, Johnstone A, Zich C, Lee JSA, Ward NS, Bestmann S. The impact of brain lesions on tDCS-induced electric fields. Sci Rep 2023; 13:19430. [PMID: 37940660 PMCID: PMC10632455 DOI: 10.1038/s41598-023-45905-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 10/25/2023] [Indexed: 11/10/2023] Open
Abstract
Transcranial direct current stimulation (tDCS) can enhance motor and language rehabilitation after stroke. Though brain lesions distort tDCS-induced electric field (E-field), systematic accounts remain limited. Using electric field modelling, we investigated the effect of 630 synthetic lesions on E-field magnitude in the region of interest (ROI). Models were conducted for two tDCS montages targeting either primary motor cortex (M1) or Broca's area (BA44). Absolute E-field magnitude in the ROI differed by up to 42% compared to the non-lesioned brain depending on lesion size, lesion-ROI distance, and lesion conductivity value. Lesion location determined the sign of this difference: lesions in-line with the predominant direction of current increased E-field magnitude in the ROI, whereas lesions located in the opposite direction decreased E-field magnitude. We further explored how individualised tDCS can control lesion-induced effects on E-field. Lesions affected the individualised electrode configuration needed to maximise E-field magnitude in the ROI, but this effect was negligible when prioritising the maximisation of radial inward current. Lesions distorting tDCS-induced E-field, is likely to exacerbate inter-individual variability in E-field magnitude. Individualising electrode configuration and stimulator output can minimise lesion-induced variability but requires improved estimates of lesion conductivity. Individualised tDCS is critical to overcome E-field variability in lesioned brains.
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Affiliation(s)
- Carys Evans
- Department for Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, University College London, London, UK.
| | - Ainslie Johnstone
- Department for Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Catharina Zich
- Department for Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, University College London, London, UK
- Nuffield Department of Clinical Neurosciences, FMRIB, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
| | - Jenny S A Lee
- Department for Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Nick S Ward
- Department for Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, University College London, London, UK
- The National Hospital for Neurology and Neurosurgery, London, UK
- UCLP Centre for Neurorehabilitation, London, UK
| | - Sven Bestmann
- Department for Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, University College London, London, UK
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, UK
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2
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Pan R, Ye S, Zhong Y, Chen Q, Cai Y. Transcranial alternating current stimulation for the treatment of major depressive disorder: from basic mechanisms toward clinical applications. Front Hum Neurosci 2023; 17:1197393. [PMID: 37731669 PMCID: PMC10507344 DOI: 10.3389/fnhum.2023.1197393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/22/2023] [Indexed: 09/22/2023] Open
Abstract
Non-pharmacological treatment is essential for patients with major depressive disorder (MDD) that is medication resistant or who are unable to take medications. Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation method that manipulates neural oscillations. In recent years, tACS has attracted substantial attention for its potential as an MDD treatment. This review summarizes the latest advances in tACS treatment for MDD and outlines future directions for promoting its clinical application. We first introduce the neurophysiological mechanism of tACS and its novel developments. In particular, two well-validated tACS techniques have high application potential: high-definition tACS targeting local brain oscillations and bifocal tACS modulating interarea functional connectivity. Accordingly, we summarize the underlying mechanisms of tACS modulation for MDD. We sort out the local oscillation abnormalities within the reward network and the interarea oscillatory synchronizations among multiple MDD-related networks in MDD patients, which provide potential modulation targets of tACS interventions. Furthermore, we review the latest clinical studies on tACS treatment for MDD, which were based on different modulation mechanisms and reported alleviations in MDD symptoms. Finally, we discuss the main challenges of current tACS treatments for MDD and outline future directions to improve intervention target selection, tACS implementation, and clinical validations.
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Affiliation(s)
- Ruibo Pan
- Department of Psychiatry, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Shengfeng Ye
- Department of Psychology and Behavioral Science, Zhejiang University, Hangzhou, China
| | - Yun Zhong
- Department of Psychology and Behavioral Science, Zhejiang University, Hangzhou, China
| | - Qiaozhen Chen
- Department of Psychiatry, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Medical Molecular Imaging of Zhejiang Province, Hangzhou, China
| | - Ying Cai
- Department of Psychology and Behavioral Science, Zhejiang University, Hangzhou, China
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3
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Pérez-Benítez JA, Martínez-Ortiz P, Aguila-Muñoz J. A Review of Formulations, Boundary Value Problems and Solutions for Numerical Computation of Transcranial Magnetic Stimulation Fields. Brain Sci 2023; 13:1142. [PMID: 37626498 PMCID: PMC10452852 DOI: 10.3390/brainsci13081142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 07/22/2023] [Accepted: 07/24/2023] [Indexed: 08/27/2023] Open
Abstract
Since the inception of the transcranial magnetic stimulation (TMS) technique, it has become imperative to numerically compute the distribution of the electric field induced in the brain. Various models of the coil-brain system have been proposed for this purpose. These models yield a set of formulations and boundary conditions that can be employed to calculate the induced electric field. However, the literature on TMS simulation presents several of these formulations, leading to potential confusion regarding the interpretation and contribution of each source of electric field. The present study undertakes an extensive compilation of widely utilized formulations, boundary value problems and numerical solutions employed in TMS fields simulations, analyzing the advantages and disadvantages associated with each used formulation and numerical method. Additionally, it explores the implementation strategies employed for their numerical computation. Furthermore, this work provides numerical expressions that can be utilized for the numerical computation of TMS fields using the finite difference and finite element methods. Notably, some of these expressions are deduced within the present study. Finally, an overview of some of the most significant results obtained from numerical computation of TMS fields is presented. The aim of this work is to serve as a guide for future research endeavors concerning the numerical simulation of TMS.
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Affiliation(s)
- J. A. Pérez-Benítez
- Laboratorio de Bio-Electromagnetismo, ESIME-SEPI, Edif. Z-4, Instituto Politécnico Nacional, Mexico City 07738, CDMX, Mexico;
| | - P. Martínez-Ortiz
- Laboratorio de Bio-Electromagnetismo, ESIME-SEPI, Edif. Z-4, Instituto Politécnico Nacional, Mexico City 07738, CDMX, Mexico;
| | - J. Aguila-Muñoz
- CONAHCYT—Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, km 107 Carretera Tijuana-Ensenada, Apartado Postal 14, Ensenada 22800, BC, Mexico
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4
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Evancho A, Tyler WJ, McGregor K. A review of combined neuromodulation and physical therapy interventions for enhanced neurorehabilitation. Front Hum Neurosci 2023; 17:1151218. [PMID: 37545593 PMCID: PMC10400781 DOI: 10.3389/fnhum.2023.1151218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 06/30/2023] [Indexed: 08/08/2023] Open
Abstract
Rehabilitation approaches for individuals with neurologic conditions have increasingly shifted toward promoting neuroplasticity for enhanced recovery and restoration of function. This review focuses on exercise strategies and non-invasive neuromodulation techniques that target neuroplasticity, including transcranial magnetic stimulation (TMS), vagus nerve stimulation (VNS), and peripheral nerve stimulation (PNS). We have chosen to focus on non-invasive neuromodulation techniques due to their greater potential for integration into routine clinical practice. We explore and discuss the application of these interventional strategies in four neurological conditions that are frequently encountered in rehabilitation settings: Parkinson's Disease (PD), Traumatic Brain Injury (TBI), stroke, and Spinal Cord Injury (SCI). Additionally, we discuss the potential benefits of combining non-invasive neuromodulation with rehabilitation, which has shown promise in accelerating recovery. Our review identifies studies that demonstrate enhanced recovery through combined exercise and non-invasive neuromodulation in the selected patient populations. We primarily focus on the motor aspects of rehabilitation, but also briefly address non-motor impacts of these conditions. Additionally, we identify the gaps in current literature and barriers to implementation of combined approaches into clinical practice. We highlight areas needing further research and suggest avenues for future investigation, aiming to enhance the personalization of the unique neuroplastic responses associated with each condition. This review serves as a resource for rehabilitation professionals and researchers seeking a comprehensive understanding of neuroplastic exercise interventions and non-invasive neuromodulation techniques tailored for specific diseases and diagnoses.
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Affiliation(s)
- Alexandra Evancho
- Department of Physical Therapy, School of Health Professions, University of Alabama at Birmingham, Birmingham, AL, United States
| | - William J. Tyler
- Department of Biomedical Engineering, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Department of Physical Medicine and Rehabilitation, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Keith McGregor
- Department of Clinical and Diagnostic Studies, School of Health Professions, University of Alabama at Birmingham, Birmingham, AL, United States
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5
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Alawi M, Lee PF, Deng ZD, Goh YK, Croarkin PE. Modelling the differential effects of age on transcranial magnetic stimulation induced electric fields. J Neural Eng 2023; 20. [PMID: 36240726 DOI: 10.1088/1741-2552/ac9a76] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 10/14/2022] [Indexed: 11/11/2022]
Abstract
Objective. The therapeutic application of noninvasive brain stimulation modalities such as transcranial magnetic stimulation (TMS) has expanded in terms of indications and patient populations. Often neurodevelopmental and neurodegenerative changes are not considered in research studies and clinical applications. This study sought to examine TMS dosing across time points in the life cycle.Approach. TMS induced electric fields with a figure-of-eight coil was simulated at left dorsolateral prefrontal cortex regions and taken in vertex as a control region. Realistic magnetic resonance imaging-based head models (N= 48) were concurrently examined in a cross-sectional study of three different age groups (children, adults, and elderlies).Main results. Age had a negative correlation with electric field peaks in white matter, grey matter and cerebrospinal fluid (P< 0.001). Notably, the electric field map in children displayed the widest cortical surface spread of TMS induced electric fields.Significance. Age-related anatomical geometry beneath the coil stimulation site had a significant impact on the TMS induced electric fields for different age groups. Safety considerations for TMS applications and protocols in children are warranted based on the present electric field findings.
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Affiliation(s)
- Mansour Alawi
- Lee Kong Chian Faculty of Engineering & Science, University Tunku Abdul Rahman, Kajang, Malaysia
| | - Poh Foong Lee
- Lee Kong Chian Faculty of Engineering & Science, University Tunku Abdul Rahman, Kajang, Malaysia
| | - Zhi-De Deng
- Noninvasive Neuromodulation Unit, National Institute of Mental Health, NIH, Bethesda, MD, United States of America
| | - Yong Kheng Goh
- Lee Kong Chian Faculty of Engineering & Science, University Tunku Abdul Rahman, Kajang, Malaysia
| | - Paul E Croarkin
- Department of Psychiatry and Psychology, Mayo Clinic, Minnesota, MN, United States of America
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6
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Romanella SM, Sprugnoli G, Ruffini G, Seyedmadani K, Rossi S, Santarnecchi E. Noninvasive Brain Stimulation & Space Exploration: Opportunities and Challenges. Neurosci Biobehav Rev 2020; 119:294-319. [PMID: 32937115 PMCID: PMC8361862 DOI: 10.1016/j.neubiorev.2020.09.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 05/22/2020] [Accepted: 09/03/2020] [Indexed: 01/11/2023]
Abstract
As NASA prepares for longer space missions aiming for the Moon and Mars, astronauts' health and performance are becoming a central concern due to the threats associated with galactic cosmic radiation, unnatural gravity fields, and life in extreme environments. In space, the human brain undergoes functional and structural changes related to fluid shift and changes in intracranial pressure. Behavioral abnormalities, such as cognitive deficits, sleep disruption, and visuomotor difficulties, as well as psychological effects, are also an issue. We discuss opportunities and challenges of noninvasive brain stimulation (NiBS) methods - including transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES) - to support space exploration in several ways. NiBS includes safe and portable techniques already applied in a wide range of cognitive and motor domains, as well as therapeutically. NiBS could be used to enhance in-flight performance, supporting astronauts during pre-flight Earth-based training, as well as to identify biomarkers of post-flight brain changes for optimization of rehabilitation/compensatory strategies. We review these NiBS techniques and their effects on brain physiology, psychology, and cognition.
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Affiliation(s)
- S M Romanella
- Siena Brain Investigation & Neuromodulation Lab (Si-BIN Lab), Department of Medicine, Surgery and Neuroscience, Neurology and Clinical Neurophysiology Section, University of Siena, Italy
| | - G Sprugnoli
- Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; Radiology Unit, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - G Ruffini
- Neuroelectrics Corporation, Cambridge, MA, USA
| | - K Seyedmadani
- University Space Research Association NASA Johnson Space Center, Houston, TX, USA; Ann and H.J. Smead Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - S Rossi
- Siena Brain Investigation & Neuromodulation Lab (Si-BIN Lab), Department of Medicine, Surgery and Neuroscience, Neurology and Clinical Neurophysiology Section, University of Siena, Italy; Human Physiology Section, Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy
| | - E Santarnecchi
- Siena Brain Investigation & Neuromodulation Lab (Si-BIN Lab), Department of Medicine, Surgery and Neuroscience, Neurology and Clinical Neurophysiology Section, University of Siena, Italy; Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
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7
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Ciullo V, Spalletta G, Caltagirone C, Banaj N, Vecchio D, Piras F, Piras F. Transcranial Direct Current Stimulation and Cognition in Neuropsychiatric Disorders: Systematic Review of the Evidence and Future Directions. Neuroscientist 2020; 27:285-309. [PMID: 32644874 DOI: 10.1177/1073858420936167] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Transcranial direct current stimulation (tDCS) has been implemented in neuropsychiatric disorders characterized by cognitive impairment. However, methodological heterogeneity challenges conclusive remarks. Through a critical analysis of previous conflicting findings and in the light of current neurobiological models of pathophysiology, we qualitatively assessed the effects of tDCS in neuropsychiatric disorders that share neurobiological underpinnings, as to evaluate whether stimulation can improve cognitive deficits in patients' cohorts. We performed a systematic review of tDCS studies targeting cognitive functions in mental disorders and pathological cognitive aging. Data from 41 studies, comprising patients with diagnosis of mood disorders, schizophrenia-spectrum disorders, Alzheimer's disease (AD), and mild cognitive impairment (MCI), were included. Results indicate that tDCS has the capacity to enhance processing speed, working memory, and executive functions in patients with mood and schizophrenia-spectrum disorders. The evidence of a positive effect on general cognitive functioning and memory is either inconclusive in AD, or weak in MCI. Future directions are discussed for developing standardized stimulation protocols and for translating the technique therapeutic potential into effective clinical practice.
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Affiliation(s)
- Valentina Ciullo
- Neuropsychiatry Laboratory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Gianfranco Spalletta
- Neuropsychiatry Laboratory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy.,Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA
| | - Carlo Caltagirone
- Neuropsychiatry Laboratory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Nerisa Banaj
- Neuropsychiatry Laboratory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Daniela Vecchio
- Neuropsychiatry Laboratory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Fabrizio Piras
- Neuropsychiatry Laboratory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Federica Piras
- Neuropsychiatry Laboratory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
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8
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Bashir S, Aisha D, Hamza A, Al-Hussain F, Yoo WK. Effects of transcranial direct current stimulation on cortex modulation by stimulation of the primary motor cortex and parietal cortex in humans. Int J Neurosci 2020; 131:1107-1114. [PMID: 32462947 DOI: 10.1080/00207454.2020.1775594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
AIM OF THE STUDY Transcranial magnetic stimulation (TMS) is used to measure corticospinal excitability (CSE) from the primary motor cortex (M1) in humans through motor-evoked potentials (MEPs). The variability of CSE responses to transcranial direct current stimulation (tDCS) protocols is high and needs to be reproduced in the healthy population. The M1 and posterior parietal cortex (PPC) are anatomically and functionally connected and could play a role in understanding the variability in CSE responses. We tested the individual MEPs following a common cathodal (ctDCS) protocol over the M1 and PPC. MATERIALS AND METHODS Twenty-eight healthy subjects were randomized for a ctDCS stimulation over the left M1 and PPC for 20 min on a separate days. The first dorsal interosseous muscle (FDI) contralateral stimulation of the left M1 was used as the resting motor threshold (RMT), while 15 single pulses 4-8 s apart at an intensity of 120% RMT were used to determine the baseline MEP amplitude and at T0, 5, 10, 20, 30, 40, 50, and 60 min after ctDCS stimulation in both sessions. RESULTS A 20 min duration of ctDCS stimulation significantly deceased the CSE only at T0 (p = 0.046 at M1, p = 0.010 at PPC). CONCLUSION Our results suggested that PPC stimulation can modulate M1 excitability and PPC-M1 connectivity, but a significant effect is only observed immediately post ctDCS. The tDCS showed variability in response to the tDCS protocol is consistent with other non-invasive brain stimulation studies.
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Affiliation(s)
- Shahid Bashir
- Neuroscience Center, King Fahad Specialist Hospital Dammam, Dammam, Saudi Arabia
| | - Dowihi Aisha
- Neuroscience Center, King Fahad Specialist Hospital Dammam, Dammam, Saudi Arabia
| | - Ali Hamza
- Department of Electrical Engineering, National University of Computer and Emerging Sciences, Lahore, Pakistan
| | - Fawaz Al-Hussain
- Division of Neurology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Woo-Kyoung Yoo
- Department of Physical Medicine and Rehabilitation, Hallym University College of Medicine, Anyang, South Korea.,Department of Physical Medicine and Rehabilitation, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, South Korea
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9
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Herpich F, Contò F, van Koningsbruggen M, Battelli L. Modulating the excitability of the visual cortex using a stimulation priming paradigm. Neuropsychologia 2018; 119:165-171. [PMID: 30107155 DOI: 10.1016/j.neuropsychologia.2018.08.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 08/08/2018] [Accepted: 08/10/2018] [Indexed: 11/29/2022]
Abstract
BACKGROUND Transcranial random noise stimulation (tRNS) can cause long term increase of corticospinal excitability when used to prime the motor cortex, before measuring the motor response in the hand muscles with TMS (Terney et al., 2008). In cognitive studies, tRNS has been used to improve visual attention and mathematical skills, an enhancement effect that might suggest sustained cortical plasticity changes (Cappelletti et al., 2013; Snowball et al., 2013). However, while the behavioral evidence of increased performance is becoming substantiated by empirical data, it still remains unclear whether tRNS over visual areas causes an increase in cortical excitability similar to what has been found in the motor cortex, and if that increase could be a potential physiological explanation for behavioral improvements found in visual tasks. OBJECTIVE/HYPOTHESIS In the present study, we aimed to investigate whether priming the visual cortex with tRNS leads to increased and sustained excitability as measured with visual phosphenes. METHODS We measured phosphene thresholds (PTs) using an objective staircase method to quantify the magnitude of cortical excitability changes. Single-pulse TMS was used to elicit phosphenes before, immediately after, and every 10 min up to one hour after the end of 20 min tRNS, anodal tDCS (a-tDCS) or sham. RESULTS Results showed that phosphene thresholds were significantly reduced up to 60 min post stimulation relative to baseline after tRNS, a behavioral marker of increased excitability of the visual cortex, while a-tDCS had no effect. This result is very similar in magnitude and duration to what has been found in the motor cortex. CONCLUSIONS Our findings demonstrate promising potential of tRNS as a tool to increase and sustain cortical excitability to promote improvement of cognitive functions.
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Affiliation(s)
- Florian Herpich
- Center for Neuroscience and Cognitive Systems@UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy; Center for Mind/Brain Sciences - CIMeC, University of Trento, 38122 Trento, Italy
| | - Federica Contò
- Center for Neuroscience and Cognitive Systems@UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy; Center for Mind/Brain Sciences - CIMeC, University of Trento, 38122 Trento, Italy
| | | | - Lorella Battelli
- Center for Neuroscience and Cognitive Systems@UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy; Berenson-Allen Center for Noninvasive Brain Stimulation and Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA; Department of Psychology, Harvard University, Cambridge, MA 02138, USA.
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10
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Kuck A, Stegeman DF, van der Kooij H, van Asseldonk EHF. Changes in H-Reflex Recruitment After Trans-Spinal Direct Current Stimulation With Multiple Electrode Configurations. Front Neurosci 2018; 12:151. [PMID: 29643759 PMCID: PMC5882846 DOI: 10.3389/fnins.2018.00151] [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: 07/15/2017] [Accepted: 02/26/2018] [Indexed: 01/11/2023] Open
Abstract
Trans-spinal direct current stimulation (tsDCS) is an electro-modulatory tool with possible application in the rehabilitation of spinal cord injury. TsDCS generates a small electric field, aiming to induce lasting, functional neuromodulation in the targeted neuronal networks. Earlier studies have shown significant modulatory effects after application of lumbar tsDCS. However, for clinical application, a better understanding of application specific factors is required. Our goal was to investigate the effect of different electrode configurations using lumbar spinal tsDCS on spinal excitability. We applied tsDCS (2.5 mA, 15 min) in 10 healthy subjects with three different electrode configurations: (1) Anode and cathode placed over vertebra T11, and the posterior left shoulder respectively (LSC-S) (one polarity), and (2) Both electrodes placed in equal distance (ED) (7 cm) above and below vertebra T11, investigated for two polarities (ED-Anodal/Cathodal). The soleus H-Reflex is measured before, during and after tsDCS in either electrode configuration or a sham condition. To account for genetic predispositions in response to direct current stimulation, subject BDNF genotype was assessed. Stimulation in configuration ED-Cathodal induced an amplitude reduction of the H-reflex, 30 min after tsDCS with respect to baseline, whereas none of the other configurations led to significant post intervention effects. BDNF genotype did not correlate with post intervention effects. Furthermore, we failed to replicate effects shown by a previous study, which highlights the need for a better understanding of methodological and subject specific influences on tsDCS outcome. The H-reflex depression after tsDCS (Config. ED-Cathodal) provides new insights and may foster our understanding of the working mechanism of tsDCS.
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Affiliation(s)
- Alexander Kuck
- Laboratory of Biomechanical Engineering, Department of Engineering Technology, University of Twente, Enschede, Netherlands.,Neuronal Rhythms in Movement Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
| | - Dick F Stegeman
- Department of Neurology/Clinical Neurophysiology, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behavior, Nijmegen, Netherlands
| | - Herman van der Kooij
- Laboratory of Biomechanical Engineering, Department of Engineering Technology, University of Twente, Enschede, Netherlands.,Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, Netherlands
| | - Edwin H F van Asseldonk
- Laboratory of Biomechanical Engineering, Department of Engineering Technology, University of Twente, Enschede, Netherlands
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Antal A, Alekseichuk I, Bikson M, Brockmöller J, Brunoni AR, Chen R, Cohen LG, Dowthwaite G, Ellrich J, Flöel A, Fregni F, George MS, Hamilton R, Haueisen J, Herrmann CS, Hummel FC, Lefaucheur JP, Liebetanz D, Loo CK, McCaig CD, Miniussi C, Miranda PC, Moliadze V, Nitsche MA, Nowak R, Padberg F, Pascual-Leone A, Poppendieck W, Priori A, Rossi S, Rossini PM, Rothwell J, Rueger MA, Ruffini G, Schellhorn K, Siebner HR, Ugawa Y, Wexler A, Ziemann U, Hallett M, Paulus W. Low intensity transcranial electric stimulation: Safety, ethical, legal regulatory and application guidelines. Clin Neurophysiol 2017; 128:1774-1809. [PMID: 28709880 PMCID: PMC5985830 DOI: 10.1016/j.clinph.2017.06.001] [Citation(s) in RCA: 643] [Impact Index Per Article: 91.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/29/2017] [Accepted: 06/06/2017] [Indexed: 12/11/2022]
Abstract
Low intensity transcranial electrical stimulation (TES) in humans, encompassing transcranial direct current (tDCS), transcutaneous spinal Direct Current Stimulation (tsDCS), transcranial alternating current (tACS), and transcranial random noise (tRNS) stimulation or their combinations, appears to be safe. No serious adverse events (SAEs) have been reported so far in over 18,000 sessions administered to healthy subjects, neurological and psychiatric patients, as summarized here. Moderate adverse events (AEs), as defined by the necessity to intervene, are rare, and include skin burns with tDCS due to suboptimal electrode-skin contact. Very rarely mania or hypomania was induced in patients with depression (11 documented cases), yet a causal relationship is difficult to prove because of the low incidence rate and limited numbers of subjects in controlled trials. Mild AEs (MAEs) include headache and fatigue following stimulation as well as prickling and burning sensations occurring during tDCS at peak-to-baseline intensities of 1-2mA and during tACS at higher peak-to-peak intensities above 2mA. The prevalence of published AEs is different in studies specifically assessing AEs vs. those not assessing them, being higher in the former. AEs are frequently reported by individuals receiving placebo stimulation. The profile of AEs in terms of frequency, magnitude and type is comparable in healthy and clinical populations, and this is also the case for more vulnerable populations, such as children, elderly persons, or pregnant women. Combined interventions (e.g., co-application of drugs, electrophysiological measurements, neuroimaging) were not associated with further safety issues. Safety is established for low-intensity 'conventional' TES defined as <4mA, up to 60min duration per day. Animal studies and modeling evidence indicate that brain injury could occur at predicted current densities in the brain of 6.3-13A/m2 that are over an order of magnitude above those produced by tDCS in humans. Using AC stimulation fewer AEs were reported compared to DC. In specific paradigms with amplitudes of up to 10mA, frequencies in the kHz range appear to be safe. In this paper we provide structured interviews and recommend their use in future controlled studies, in particular when trying to extend the parameters applied. We also discuss recent regulatory issues, reporting practices and ethical issues. These recommendations achieved consensus in a meeting, which took place in Göttingen, Germany, on September 6-7, 2016 and were refined thereafter by email correspondence.
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Affiliation(s)
- A Antal
- Department of Clinical Neurophysiology, University Medical Center Göttingen, Georg August University, Göttingen, Germany.
| | - I Alekseichuk
- Department of Clinical Neurophysiology, University Medical Center Göttingen, Georg August University, Göttingen, Germany
| | - M Bikson
- Department of Biomedical Engineering, The City College of New York, New York, USA
| | - J Brockmöller
- Department of Clinical Pharmacology, University Medical Center Goettingen, Germany
| | - A R Brunoni
- Service of Interdisciplinary Neuromodulation, Department and Institute of Psychiatry, Laboratory of Neurosciences (LIM-27) and Interdisciplinary Center for Applied Neuromodulation University Hospital, University of São Paulo, São Paulo, Brazil
| | - R Chen
- Division of Neurology, Department of Medicine, University of Toronto and Krembil Research Institute, Toronto, Ontario, Canada
| | - L G Cohen
- Human Cortical Physiology and Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke NIH, Bethesda, USA
| | | | - J Ellrich
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark; Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany; EBS Technologies GmbH, Europarc Dreilinden, Germany
| | - A Flöel
- Universitätsmedizin Greifswald, Klinik und Poliklinik für Neurologie, Greifswald, Germany
| | - F Fregni
- Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, MA, USA
| | - M S George
- Brain Stimulation Division, Medical University of South Carolina, and Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC, USA
| | - R Hamilton
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - J Haueisen
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Germany
| | - C S Herrmann
- Experimental Psychology Lab, Department of Psychology, European Medical School, Carl von Ossietzky Universität, Oldenburg, Germany
| | - F C Hummel
- Defitech Chair of Clinical Neuroengineering, Centre of Neuroprosthetics (CNP) and Brain Mind Institute, Swiss Federal Institute of Technology (EPFL), Geneva, Switzerland; Defitech Chair of Clinical Neuroengineering, Clinique Romande de Réadaptation, Swiss Federal Institute of Technology (EPFL Valais), Sion, Switzerland
| | - J P Lefaucheur
- Department of Physiology, Henri Mondor Hospital, Assistance Publique - Hôpitaux de Paris, and EA 4391, Nerve Excitability and Therapeutic Team (ENT), Faculty of Medicine, Paris Est Créteil University, Créteil, France
| | - D Liebetanz
- Department of Clinical Neurophysiology, University Medical Center Göttingen, Georg August University, Göttingen, Germany
| | - C K Loo
- School of Psychiatry & Black Dog Institute, University of New South Wales, Sydney, Australia
| | - C D McCaig
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, Scotland, UK
| | - C Miniussi
- Center for Mind/Brain Sciences CIMeC, University of Trento, Rovereto, Italy; Cognitive Neuroscience Section, IRCCS Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - P C Miranda
- Institute of Biophysics and Biomedical Engineering, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - V Moliadze
- Institute of Medical Psychology and Medical Sociology, University Hospital of Schleswig-Holstein (UKSH), Campus Kiel, Christian-Albrechts-University, Kiel, Germany
| | - M A Nitsche
- Department of Psychology and Neurosciences, Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany; Department of Neurology, University Hospital Bergmannsheil, Bochum, Germany
| | - R Nowak
- Neuroelectrics, Barcelona, Spain
| | - F Padberg
- Department of Psychiatry and Psychotherapy, Munich Center for Brain Stimulation, Ludwig-Maximilian University Munich, Germany
| | - A Pascual-Leone
- Division of Cognitive Neurology, Harvard Medical Center and Berenson-Allen Center for Noninvasive Brain Stimulation at Beth Israel Deaconess Medical Center, Boston, USA
| | - W Poppendieck
- Department of Information Technology, Mannheim University of Applied Sciences, Mannheim, Germany
| | - A Priori
- Center for Neurotechnology and Experimental Brain Therapeutich, Department of Health Sciences, University of Milan Italy; Deparment of Clinical Neurology, University Hospital Asst Santi Paolo E Carlo, Milan, Italy
| | - S Rossi
- Department of Medicine, Surgery and Neuroscience, Human Physiology Section and Neurology and Clinical Neurophysiology Section, Brain Investigation & Neuromodulation Lab, University of Siena, Italy
| | - P M Rossini
- Area of Neuroscience, Institute of Neurology, University Clinic A. Gemelli, Catholic University, Rome, Italy
| | | | - M A Rueger
- Department of Neurology, University Hospital of Cologne, Germany
| | | | | | - H R Siebner
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Department of Neurology, Copenhagen University Hospital Bispebjerg, Copenhagen, Denmark
| | - Y Ugawa
- Department of Neurology, Fukushima Medical University, Fukushima, Japan; Fukushima Global Medical Science Center, Advanced Clinical Research Center, Fukushima Medical University, Japan
| | - A Wexler
- Department of Science, Technology & Society, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - U Ziemann
- Department of Neurology & Stroke, and Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - M Hallett
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - W Paulus
- Department of Clinical Neurophysiology, University Medical Center Göttingen, Georg August University, Göttingen, Germany
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12
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Kuck A, Stegeman DF, van Asseldonk EHF. Modeling trans-spinal direct current stimulation for the modulation of the lumbar spinal motor pathways. J Neural Eng 2017. [PMID: 28631619 DOI: 10.1088/1741-2552/aa7960] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVE Trans-spinal direct current stimulation (tsDCS) is a potential new technique for the treatment of spinal cord injury (SCI). TsDCS aims to facilitate plastic changes in the neural pathways of the spinal cord with a positive effect on SCI recovery. To establish tsDCS as a possible treatment option for SCI, it is essential to gain a better understanding of its cause and effects. We seek to understand the acute effect of tsDCS, including the generated electric field (EF) and its polarization effect on the spinal circuits, to determine a cellular target. We further ask how these findings can be interpreted to explain published experimental results. APPROACH We use a realistic full body finite element volume conductor model to calculate the EF of a 2.5 mA direct current for three different electrode configurations. We apply the calculated electric field to realistic motoneuron models to investigate static changes in membrane resting potential. The results are combined with existing knowledge about the theoretical effect on a neuronal level and implemented into an existing lumbar spinal network model to simulate the resulting changes on a network level. MAIN RESULTS Across electrode configurations, the maximum EF inside the spinal cord ranged from 0.47 V m-1 to 0.82 V m-1. Axon terminal polarization was identified to be the dominant cellular target. Also, differences in electrode placement have a large influence on axon terminal polarization. Comparison between the simulated acute effects and the electrophysiological long-term changes observed in human tsDCS studies suggest an inverse relationship between the two. SIGNIFICANCE We provide methods and knowledge for better understanding the effects of tsDCS and serve as a basis for a more targeted and optimized application of tsDCS.
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Affiliation(s)
- A Kuck
- University of Twente, Drienerlolaan 5, 7522 NB Enschede, Netherlands
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13
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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: 186] [Impact Index Per Article: 23.3] [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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14
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Adaptive Plasticity in the Healthy Language Network: Implications for Language Recovery after Stroke. Neural Plast 2016; 2016:9674790. [PMID: 27830094 PMCID: PMC5088318 DOI: 10.1155/2016/9674790] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/18/2016] [Accepted: 09/25/2016] [Indexed: 12/27/2022] Open
Abstract
Across the last three decades, the application of noninvasive brain stimulation (NIBS) has substantially increased the current knowledge of the brain's potential to undergo rapid short-term reorganization on the systems level. A large number of studies applied transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) in the healthy brain to probe the functional relevance and interaction of specific areas for different cognitive processes. NIBS is also increasingly being used to induce adaptive plasticity in motor and cognitive networks and shape cognitive functions. Recently, NIBS has been combined with electrophysiological techniques to modulate neural oscillations of specific cortical networks. In this review, we will discuss recent advances in the use of NIBS to modulate neural activity and effective connectivity in the healthy language network, with a special focus on the combination of NIBS and neuroimaging or electrophysiological approaches. Moreover, we outline how these results can be transferred to the lesioned brain to unravel the dynamics of reorganization processes in poststroke aphasia. We conclude with a critical discussion on the potential of NIBS to facilitate language recovery after stroke and propose a phase-specific model for the application of NIBS in language rehabilitation.
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15
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Huang Y, Parra LC, Haufe S. The New York Head-A precise standardized volume conductor model for EEG source localization and tES targeting. Neuroimage 2016; 140:150-62. [PMID: 26706450 PMCID: PMC5778879 DOI: 10.1016/j.neuroimage.2015.12.019] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 10/12/2015] [Accepted: 12/12/2015] [Indexed: 12/01/2022] Open
Abstract
In source localization of electroencephalograpic (EEG) signals, as well as in targeted transcranial electric current stimulation (tES), a volume conductor model is required to describe the flow of electric currents in the head. Boundary element models (BEM) can be readily computed to represent major tissue compartments, but cannot encode detailed anatomical information within compartments. Finite element models (FEM) can capture more tissue types and intricate anatomical structures, but with the higher precision also comes the need for semi-automated segmentation, and a higher computational cost. In either case, adjusting to the individual human anatomy requires costly magnetic resonance imaging (MRI), and thus head modeling is often based on the anatomy of an 'arbitrary' individual (e.g. Colin27). Additionally, existing reference models for the human head often do not include the cerebro-spinal fluid (CSF), and their field of view excludes portions of the head and neck-two factors that demonstrably affect current-flow patterns. Here we present a highly detailed FEM, which we call ICBM-NY, or "New York Head". It is based on the ICBM152 anatomical template (a non-linear average of the MRI of 152 adult human brains) defined in MNI coordinates, for which we extended the field of view to the neck and performed a detailed segmentation of six tissue types (scalp, skull, CSF, gray matter, white matter, air cavities) at 0.5mm(3) resolution. The model was solved for 231 electrode locations. To evaluate its performance, additional FEMs and BEMs were constructed for four individual subjects. Each of the four individual FEMs (regarded as the 'ground truth') is compared to its BEM counterpart, the ICBM-NY, a BEM of the ICBM anatomy, an 'individualized' BEM of the ICBM anatomy warped to the individual head surface, and FEMs of the other individuals. Performance is measured in terms of EEG source localization and tES targeting errors. Results show that the ICBM-NY outperforms FEMs of mismatched individual anatomies as well as the BEM of the ICBM anatomy according to both criteria. We therefore propose the New York Head as a new standard head model to be used in future EEG and tES studies whenever an individual MRI is not available. We release all model data online at neuralengr.com/nyhead/ to facilitate broad adoption.
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Affiliation(s)
- Yu Huang
- Department of Biomedical Engineering, City College of the City University of New York, New York, NY 10031, USA
| | - Lucas C Parra
- Department of Biomedical Engineering, City College of the City University of New York, New York, NY 10031, USA.
| | - Stefan Haufe
- Laboratory for Intelligent Imaging and Neural Computing, Columbia University, New York, NY 10027, USA; Machine Learning Department, Technische Universität Berlin, 10587, Berlin, Germany.
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16
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Tseng P, Chang YT, Chang CF, Liang WK, Juan CH. The critical role of phase difference in gamma oscillation within the temporoparietal network for binding visual working memory. Sci Rep 2016; 6:32138. [PMID: 27573864 PMCID: PMC5004173 DOI: 10.1038/srep32138] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 08/03/2016] [Indexed: 11/09/2022] Open
Abstract
How does the brain enable us to remember two or more object representations in visual working memory (VWM) without confusing them? This "gluing" process, or feature binding, refers to the ability to join certain features together while keeping them segregated from others. Recent neuroimaging research has reported higher BOLD response in the left temporal and parietal cortex during a binding-VWM task. However, less is known about how the two regions work in synchrony to support such process. In this study, we applied transcranial alternating current stimulation (tACS) over the left temporal and parietal cortex in gamma and theta frequency, with a phase difference of either 0° (in-phase) or 180° (anti-phase) to account for the different ways through which neural synchronization may occur. We found no facilitatory or inhibitory effect from sham, theta, and in-phase gamma stimulation. Importantly, there was an enhancement effect from anti-phase gamma tACS that was binding-specific, and such effect was only apparent in low-performing individuals who had room for improvement. Together, these results demonstrate that binding-VWM is supported by a temporally-precise oscillatory mechanism within the gamma frequency range, and that the advantageous 180°-apart phase relationship also implies a possible temporal driver-to-receiver time-lag between the temporal and parietal cortex.
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Affiliation(s)
- Philip Tseng
- Graduate Institute of Humanities in Medicine, Taipei Medical University, Taiwan
- Brain & Consciousness Research Center, Shuang-Ho Hospital, Taipei Medical University, Taiwan
| | - Yu-Ting Chang
- Brain & Consciousness Research Center, Shuang-Ho Hospital, Taipei Medical University, Taiwan
- Institute of Cognitive Neuroscience, National Central University, Taiwan
| | - Chi-Fu Chang
- Institute of Cognitive Neuroscience, National Central University, Taiwan
| | - Wei-Kuang Liang
- Institute of Cognitive Neuroscience, National Central University, Taiwan
| | - Chi-Hung Juan
- Institute of Cognitive Neuroscience, National Central University, Taiwan
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17
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Zheng Y, Dong L, Gao Y, Qiu Q, Li ZY, Zhao Z, Chen RJ, Wang HQ. Simulation and experimental study of DC electric field distribution characteristics of rat hippocampal slices in vitro. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:064702. [PMID: 27370477 DOI: 10.1063/1.4953047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Direct current (DC) electric field is a noninvasive neuromodulation tool that can inhibit or facilitate excitability of neurons. Despite its efficacy, the dielectric constant of artificial cerebrospinal fluid and the position and direction of brain slices and other factors can affect the field intensity and distribution acting on the surface of rat hippocampus slices, thus causing errors. In this study, we describe a new analytical method optimized for DC electric fields acting on brain slices, and the design of an external DC electric field stimulator to allow scientific evaluation of brain slices. We investigated parameters regarding the uniformity of electric field distribution and identified the maximal parameters using the finite element method. Then, we selected and simplified slice images using magnetic resonance imaging data and calculated the electric field intensity of the original and simplified models. The electric field simulator induced action potential and excitatory postsynaptic current with intensities of 1, 5, and 10 V/m. This study describes the development of a new electric field stimulator and successfully demonstrates its practicability for scientific evaluation of tissue slices.
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Affiliation(s)
- Yu Zheng
- School of Electronics and Information Engineering, Tianjin polytechnic university, Tianjin 300387, China
| | - Lei Dong
- School of Electronics and Information Engineering, Tianjin polytechnic university, Tianjin 300387, China
| | - Yang Gao
- School of Electronics and Information Engineering, Tianjin polytechnic university, Tianjin 300387, China
| | - Qian Qiu
- School of Electronics and Information Engineering, Tianjin polytechnic university, Tianjin 300387, China
| | - Ze-Yan Li
- School of Electronics and Information Engineering, Tianjin polytechnic university, Tianjin 300387, China
| | - Zhe Zhao
- School of Electronics and Information Engineering, Tianjin polytechnic university, Tianjin 300387, China
| | - Rui-Juan Chen
- School of Electronics and Information Engineering, Tianjin polytechnic university, Tianjin 300387, China
| | - Hui-Quan Wang
- School of Electronics and Information Engineering, Tianjin polytechnic university, Tianjin 300387, China
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18
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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: 3.4] [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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19
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Klooster DCW, de Louw AJA, Aldenkamp AP, Besseling RMH, Mestrom RMC, Carrette S, Zinger S, Bergmans JWM, Mess WH, Vonck K, Carrette E, Breuer LEM, Bernas A, Tijhuis AG, Boon P. Technical aspects of neurostimulation: Focus on equipment, electric field modeling, and stimulation protocols. Neurosci Biobehav Rev 2016; 65:113-41. [PMID: 27021215 DOI: 10.1016/j.neubiorev.2016.02.016] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 02/05/2016] [Accepted: 02/17/2016] [Indexed: 12/31/2022]
Abstract
Neuromodulation is a field of science, medicine, and bioengineering that encompasses implantable and non-implantable technologies for the purpose of improving quality of life and functioning of humans. Brain neuromodulation involves different neurostimulation techniques: transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), vagus nerve stimulation (VNS), and deep brain stimulation (DBS), which are being used both to study their effects on cognitive brain functions and to treat neuropsychiatric disorders. The mechanisms of action of neurostimulation remain incompletely understood. Insight into the technical basis of neurostimulation might be a first step towards a more profound understanding of these mechanisms, which might lead to improved clinical outcome and therapeutic potential. This review provides an overview of the technical basis of neurostimulation focusing on the equipment, the present understanding of induced electric fields, and the stimulation protocols. The review is written from a technical perspective aimed at supporting the use of neurostimulation in clinical practice.
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Affiliation(s)
- D C W Klooster
- Kempenhaeghe Academic Center for Epileptology, P.O. Box 61, 5590 AB Heeze, The Netherlands; Department of Electrical Engineering, University of Technology Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
| | - A J A de Louw
- Kempenhaeghe Academic Center for Epileptology, P.O. Box 61, 5590 AB Heeze, The Netherlands; Department of Electrical Engineering, University of Technology Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Department of Neurology, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht, The Netherlands.
| | - A P Aldenkamp
- Kempenhaeghe Academic Center for Epileptology, P.O. Box 61, 5590 AB Heeze, The Netherlands; Department of Electrical Engineering, University of Technology Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Department of Neurology, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht, The Netherlands; School for Mental Health and Neuroscience, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands; Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
| | - R M H Besseling
- Department of Electrical Engineering, University of Technology Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
| | - R M C Mestrom
- Department of Electrical Engineering, University of Technology Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
| | - S Carrette
- Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
| | - S Zinger
- Kempenhaeghe Academic Center for Epileptology, P.O. Box 61, 5590 AB Heeze, The Netherlands; Department of Electrical Engineering, University of Technology Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
| | - J W M Bergmans
- Department of Electrical Engineering, University of Technology Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
| | - W H Mess
- Departments of Clinical Neurophysiology, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht, The Netherlands.
| | - K Vonck
- Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
| | - E Carrette
- Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
| | - L E M Breuer
- Kempenhaeghe Academic Center for Epileptology, P.O. Box 61, 5590 AB Heeze, The Netherlands.
| | - A Bernas
- Department of Electrical Engineering, University of Technology Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
| | - A G Tijhuis
- Department of Electrical Engineering, University of Technology Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
| | - P Boon
- Kempenhaeghe Academic Center for Epileptology, P.O. Box 61, 5590 AB Heeze, The Netherlands; Department of Electrical Engineering, University of Technology Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
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20
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Baeken C, Brunelin J, Duprat R, Vanderhasselt MA. The application of tDCS in psychiatric disorders: a brain imaging view. SOCIOAFFECTIVE NEUROSCIENCE & PSYCHOLOGY 2016; 6:29588. [PMID: 26993785 PMCID: PMC4799388 DOI: 10.3402/snp.v6.29588] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/20/2015] [Accepted: 01/11/2016] [Indexed: 12/24/2022]
Abstract
Background Transcranial direct current stimulation (tDCS) is a non-invasive, non-convulsive technique for modulating brain function. In contrast to other non-invasive brain stimulation techniques, where costs, clinical applicability, and availability limit their large-scale use in clinical practices, the low-cost, portable, and easy-to-use tDCS devices may overcome these restrictions. Objective Despite numerous clinical applications in large numbers of patients suffering from psychiatric disorders, it is not quite clear how tDCS influences the mentally affected human brain. In order to decipher potential neural mechanisms of action of tDCS in patients with psychiatric conditions, we focused on the combination of tDCS with neuroimaging techniques. Design We propose a contemporary overview on the currently available neurophysiological and neuroimaging data where tDCS has been used as a research or treatment tool in patients with psychiatric disorders. Results Over a reasonably short period of time, tDCS has been broadly used as a research tool to examine neuronal processes in the healthy brain. tDCS has also commonly been applied as a treatment application in a variety of mental disorders, with to date no straightforward clinical outcome and not always accompanied by brain imaging techniques. Conclusion tDCS, as do other neuromodulation devices, clearly affects the underlying neuronal processes. However, research on these mechanisms in psychiatric patients is rather limited. A better comprehension of how tDCS modulates brain function will help us to define optimal parameters of stimulation in each indication and may result in the detection of biomarkers in favor of clinical response.
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Affiliation(s)
- Chris Baeken
- Department of Psychiatry and Medical Psychology, Ghent University Hospital, Ghent University, Ghent, Belgium.,Department of Psychiatry University Hospital (UZBrussel), Brussels, Belgium.,Ghent Experimental Psychiatry (GHEP) Lab, Ghent, Belgium;
| | - Jerome Brunelin
- INSERM U1028, CNRS UMR5292, PSYR2 Team, Lyon Neuroscience Research Center, Centre Hospitalier Le Vinatier, Université Claude Bernard Lyon 1, Villeurbanne, France.,CIRRIS-Centre Interdisciplinaire de Recherche en Réadaptation et en Intégration Sociale, Université Laval, Québec, Canada
| | - Romain Duprat
- Department of Psychiatry and Medical Psychology, Ghent University Hospital, Ghent University, Ghent, Belgium.,Ghent Experimental Psychiatry (GHEP) Lab, Ghent, Belgium
| | - Marie-Anne Vanderhasselt
- Department of Psychiatry and Medical Psychology, Ghent University Hospital, Ghent University, Ghent, Belgium.,Faculty of Medicine and Pharmacy, Free University Brussels, Brussels, Belgium
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21
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Galletta EE, Vogel-Eyny A. Translational treatment of aphasia combining neuromodulation and behavioral intervention for lexical retrieval: implications from a single case study. Front Hum Neurosci 2015; 9:447. [PMID: 26347634 PMCID: PMC4541259 DOI: 10.3389/fnhum.2015.00447] [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: 01/27/2015] [Accepted: 07/27/2015] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Transcranial direct current stimulation (tDCS), a non-invasive method of brain stimulation, is an adjunctive research-therapy for aphasia. The concept supporting translational application of tDCS is that brain plasticity, facilitated by language intervention, can be enhanced by non-invasive brain stimulation. This study combined tDCS with an ecologically focused behavioral approach that involved training nouns and verbs in sentences. METHOD PARTICIPANT A 43-year-old, right-handed male with fluent-anomic aphasia who sustained a single-left-hemisphere-temporal-parietal stroke was recruited. TREATMENT Instrumentation included the Soterix Medical 1 × 1 Device. Anodal tDCS was applied over Broca's area. Behavioral materials included: sentence production, naming in the sentence context, and implementation of a social-conversational-discourse treatment. DESIGN AND PROCEDURES The independent variable of this crossover case-study was tDCS, and the dependent variables were language and quality-of-life measures. In each session the subject received language treatment with the first 20 minutes additionally including tDCS. RESULTS Performance in naming nouns and verbs in single words and sentences were obtained. Verb production in the sentence context increased after active anodal tDCS and speech-language treatment. CONCLUSION Aphasia treatment that involves naming in the sentence context in conjunction with translational application of tDCS may be a promising approach for language-recovery post stroke.
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Affiliation(s)
- Elizabeth E. Galletta
- Speech-Language Pathology and Audiology, Hunter CollegeNew York, NY, USA
- Speech-Language-Hearing Sciences, Graduate Center, City University of New YorkNew York, NY, USA
| | - Amy Vogel-Eyny
- Speech-Language Pathology and Audiology, Hunter CollegeNew York, NY, USA
- Speech-Language-Hearing Sciences, Graduate Center, City University of New YorkNew York, NY, USA
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22
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Opitz A, Legon W, Mueller J, Barbour A, Paulus W, Tyler WJ. Is sham cTBS real cTBS? The effect on EEG dynamics. Front Hum Neurosci 2015; 8:1043. [PMID: 25620925 PMCID: PMC4287020 DOI: 10.3389/fnhum.2014.01043] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 12/14/2014] [Indexed: 11/28/2022] Open
Abstract
Increasing sensitivity of modern evaluation tools allows for the study of weaker electric stimulation effects on neural populations. In the current study we examined the effects of sham continuous theta burst (cTBS) transcranial magnetic stimulation to the left dorsolateral prefrontal cortex (DLPFC) upon somatosensory evoked potentials (SEP) and frontal-parietal phase coupling of alpha and beta bands. Sham TMS results in an induced electric field amplitude roughly 5% that of real TMS with a similar spatial extent in cortex. Both real and sham cTBS reduced the amplitude of the frontal P14-N30 SEP and increased local phase coupling in the alpha-beta frequency bands of left frontal cortex. In addition, both sham and real cTBS increased frontal-parietal phase coupling in the alpha-beta bands concomitant with an increase in amplitude of parietal P50-N70 complex. These data suggest that weak electric fields from sham cTBS can affect both local and downstream neuronal circuits, though in a different manner than high strength TMS.
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Affiliation(s)
- Alexander Opitz
- Department of Clinical Neurophysiology, Georg-August-University Göttingen, Germany ; Center for Biomedical Imaging and Neuromodulation, Nathan Kline Institute for Psychiatric Research Orangeburg, NY, USA ; Center for the Developing Brain, Child Mind Institute New York, NY, USA
| | - Wynn Legon
- Department of Physical Medicine and Rehabilitation, University of Minnesota Minneapolis, MN, USA
| | - Jerel Mueller
- School of Biomedical Engineering and Sciences, Virginia Tech Blacksburg, VA, USA
| | - Aaron Barbour
- Virginia Tech Carilion Research Institute Roanoke, VA, USA
| | - Walter Paulus
- Department of Clinical Neurophysiology, Georg-August-University Göttingen, Germany
| | - William J Tyler
- School of Biological and Health Systems Engineering, Arizona State University Tempe, AZ, USA
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23
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Eichelbaum S, Dannhauer M, Hlawitschka M, Brooks D, Knösche TR, Scheuermann G. Visualizing simulated electrical fields from electroencephalography and transcranial electric brain stimulation: a comparative evaluation. Neuroimage 2014; 101:513-30. [PMID: 24821532 PMCID: PMC4172355 DOI: 10.1016/j.neuroimage.2014.04.085] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 04/23/2014] [Accepted: 04/30/2014] [Indexed: 11/21/2022] Open
Abstract
Electrical activity of neuronal populations is a crucial aspect of brain activity. This activity is not measured directly but recorded as electrical potential changes using head surface electrodes (electroencephalogram - EEG). Head surface electrodes can also be deployed to inject electrical currents in order to modulate brain activity (transcranial electric stimulation techniques) for therapeutic and neuroscientific purposes. In electroencephalography and noninvasive electric brain stimulation, electrical fields mediate between electrical signal sources and regions of interest (ROI). These fields can be very complicated in structure, and are influenced in a complex way by the conductivity profile of the human head. Visualization techniques play a central role to grasp the nature of those fields because such techniques allow for an effective conveyance of complex data and enable quick qualitative and quantitative assessments. The examination of volume conduction effects of particular head model parameterizations (e.g., skull thickness and layering), of brain anomalies (e.g., holes in the skull, tumors), location and extent of active brain areas (e.g., high concentrations of current densities) and around current injecting electrodes can be investigated using visualization. Here, we evaluate a number of widely used visualization techniques, based on either the potential distribution or on the current-flow. In particular, we focus on the extractability of quantitative and qualitative information from the obtained images, their effective integration of anatomical context information, and their interaction. We present illustrative examples from clinically and neuroscientifically relevant cases and discuss the pros and cons of the various visualization techniques.
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Affiliation(s)
- Sebastian Eichelbaum
- Image and Signal Processing Group, Leipzig University, Augustusplatz 10-11, 04109 Leipzig, Germany.
| | - Moritz Dannhauer
- Scientific Computing and Imaging Institute, University of Utah, 72S. Central Campus Drive, 84112 Salt Lake City, UT, USA; Center for Integrative Biomedical Computing, University of Utah, 72S. Central Campus Drive, 84112, Salt Lake City, UT, USA.
| | - Mario Hlawitschka
- Scientific Visualization, Leipzig University, Augustusplatz 10-11, 04109 Leipzig, Germany.
| | - Dana Brooks
- Center for Integrative Biomedical Computing, University of Utah, 72S. Central Campus Drive, 84112, Salt Lake City, UT, USA; Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, USA.
| | - Thomas R Knösche
- Human Cognitive and Brain Sciences, Max Planck Institute, Stephanstraße 1a, 04103 Leipzig, Germany.
| | - Gerik Scheuermann
- Image and Signal Processing Group, Leipzig University, Augustusplatz 10-11, 04109 Leipzig, Germany.
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24
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Antal A, Ambrus GG, Chaieb L. The impact of electrical stimulation techniques on behavior. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2014; 5:649-659. [PMID: 26308871 DOI: 10.1002/wcs.1319] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 07/23/2014] [Accepted: 08/10/2014] [Indexed: 12/22/2022]
Abstract
UNLABELLED Low-intensity transcranial electrical stimulation (tES) methods are a group of noninvasive brain stimulation techniques, whereby currents are applied with intensities typically ranging between 1 and 2 mA, through the human scalp. These techniques have been shown to induce changes in cortical excitability and activity during and after the stimulation in a reversible manner. They include transcranial direct current simulation (tDCS), transcranial alternating current simulation (tACS), and transcranial random noise stimulation (tRNS). Currently, an increasing number of studies have been published regarding the effects of tES on cognitive performance and behavior. Processes of learning and increases in cognitive performance are accompanied by changes in cortical plasticity. tES can impact upon these processes and is able to affect task execution. Many studies have been based on the accepted idea that by increasing cortical excitability (e.g., by applying anodal tDCS) or coherence of oscillatory activity (e.g., by applying tACS) an increase in performance should be detected; however, a number of studies now suggest that the basic knowledge of the mechanisms of action is insufficient to predict the outcome of applied stimulation on the execution of a cognitive or behavioral task, and so far no standard paradigms for increasing cortical plasticity changes during learning or cognitive tasks have been established. The aim of this review is to summarize recent findings with regard to the effects of tES on behavior concentrating on the motor and visual areas. WIREs Cogn Sci 2014, 5:649-659. doi: 10.1002/wcs.1319 For further resources related to this article, please visit the WIREs website. CONFLICT OF INTEREST The authors have declared no conflicts of interest for this article.
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Affiliation(s)
- Andrea Antal
- Department of Clinical Neurophysiology, University Medical Center, University of Göttingen, Göttingen, Germany
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25
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Truong DQ, Hüber M, Xie X, Datta A, Rahman A, Parra LC, Dmochowski JP, Bikson M. Clinician accessible tools for GUI computational models of transcranial electrical stimulation: BONSAI and SPHERES. Brain Stimul 2014; 7:521-4. [PMID: 24776786 DOI: 10.1016/j.brs.2014.03.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/17/2014] [Accepted: 03/24/2014] [Indexed: 10/25/2022] Open
Abstract
Computational models of brain current flow during transcranial electrical stimulation (tES), including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), are increasingly used to understand and optimize clinical trials. We propose that broad dissemination requires a simple graphical user interface (GUI) software that allows users to explore and design montages in real-time, based on their own clinical/experimental experience and objectives. We introduce two complimentary open-source platforms for this purpose: BONSAI and SPHERES. BONSAI is a web (cloud) based application (available at neuralengr.com/bonsai) that can be accessed through any flash-supported browser interface. SPHERES (available at neuralengr.com/spheres) is a stand-alone GUI application that allow consideration of arbitrary montages on a concentric sphere model by leveraging an analytical solution. These open-source tES modeling platforms are designed go be upgraded and enhanced. Trade-offs between open-access approaches that balance ease of access, speed, and flexibility are discussed.
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Affiliation(s)
- Dennis Q Truong
- Department of Biomedical Engineering, The City College of New York, City University of New York, New York, NY, USA.
| | - Mathias Hüber
- Department of Biomedical Engineering, The City College of New York, City University of New York, New York, NY, USA
| | - Xihe Xie
- Department of Biomedical Engineering, The City College of New York, City University of New York, New York, NY, USA
| | | | - Asif Rahman
- Department of Biomedical Engineering, The City College of New York, City University of New York, New York, NY, USA
| | - Lucas C Parra
- Department of Biomedical Engineering, The City College of New York, City University of New York, New York, NY, USA
| | - Jacek P Dmochowski
- Department of Biomedical Engineering, The City College of New York, City University of New York, New York, NY, USA
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York, City University of New York, New York, NY, USA
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26
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Rampersad SM, Janssen AM, Lucka F, Aydin Ü, Lanfer B, Lew S, Wolters CH, Stegeman DF, Oostendorp TF. Simulating transcranial direct current stimulation with a detailed anisotropic human head model. IEEE Trans Neural Syst Rehabil Eng 2014; 22:441-52. [PMID: 24760939 DOI: 10.1109/tnsre.2014.2308997] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique able to induce long-lasting changes in cortical excitability that can benefit cognitive functioning and clinical treatment. In order to both better understand the mechanisms behind tDCS and possibly improve the technique, finite element models are used to simulate tDCS of the human brain. With the detailed anisotropic head model presented in this study, we provide accurate predictions of tDCS in the human brain for six of the practically most-used setups in clinical and cognitive research, targeting the primary motor cortex, dorsolateral prefrontal cortex, inferior frontal gyrus, occipital cortex, and cerebellum. We present the resulting electric field strengths in the complete brain and introduce new methods to evaluate the effectivity in the target area specifically, where we have analyzed both the strength and direction of the field. For all cerebral targets studied, the currently accepted configurations produced sub-optimal field strengths. The configuration for cerebellum stimulation produced relatively high field strengths in its target area, but it needs higher input currents than cerebral stimulation does. This study suggests that improvements in the effects of transcranial direct current stimulation are achievable.
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27
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Ruffini G, Wendling F, Merlet I, Molaee-Ardekani B, Mekonnen A, Salvador R, Soria-Frisch A, Grau C, Dunne S, Miranda PC. Transcranial current brain stimulation (tCS): models and technologies. IEEE Trans Neural Syst Rehabil Eng 2014; 21:333-45. [PMID: 22949089 DOI: 10.1109/tnsre.2012.2200046] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this paper, we provide a broad overview of models and technologies pertaining to transcranial current brain stimulation (tCS), a family of related noninvasive techniques including direct current (tDCS), alternating current (tACS), and random noise current stimulation (tRNS). These techniques are based on the delivery of weak currents through the scalp (with electrode current intensity to area ratios of about 0.3-5 A/m2) at low frequencies (typically < 1 kHz) resulting in weak electric fields in the brain (with amplitudes of about 0.2-2 V/m). Here we review the biophysics and simulation of noninvasive, current-controlled generation of electric fields in the human brain and the models for the interaction of these electric fields with neurons, including a survey of in vitro and in vivo related studies. Finally, we outline directions for future fundamental and technological research.
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Affiliation(s)
- Giulio Ruffini
- Starlab Neuroscience Research, Starlab Barcelona, 08022 Barcelona, Spain.
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28
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Wagner S, Rampersad SM, Aydin Ü, Vorwerk J, Oostendorp TF, Neuling T, Herrmann CS, Stegeman DF, Wolters CH. Investigation of tDCS volume conduction effects in a highly realistic head model. J Neural Eng 2013; 11:016002. [PMID: 24310982 DOI: 10.1088/1741-2560/11/1/016002] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE We investigate volume conduction effects in transcranial direct current stimulation (tDCS) and present a guideline for efficient and yet accurate volume conductor modeling in tDCS using our newly-developed finite element (FE) approach. APPROACH We developed a new, accurate and fast isoparametric FE approach for high-resolution geometry-adapted hexahedral meshes and tissue anisotropy. To attain a deeper insight into tDCS, we performed computer simulations, starting with a homogenized three-compartment head model and extending this step by step to a six-compartment anisotropic model. MAIN RESULTS We are able to demonstrate important tDCS effects. First, we find channeling effects of the skin, the skull spongiosa and the cerebrospinal fluid compartments. Second, current vectors tend to be oriented towards the closest higher conducting region. Third, anisotropic WM conductivity causes current flow in directions more parallel to the WM fiber tracts. Fourth, the highest cortical current magnitudes are not only found close to the stimulation sites. Fifth, the median brain current density decreases with increasing distance from the electrodes. SIGNIFICANCE Our results allow us to formulate a guideline for volume conductor modeling in tDCS. We recommend to accurately model the major tissues between the stimulating electrodes and the target areas, while for efficient yet accurate modeling, an exact representation of other tissues is less important. Because for the low-frequency regime in electrophysiology the quasi-static approach is justified, our results should also be valid for at least low-frequency (e.g., below 100 Hz) transcranial alternating current stimulation.
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Affiliation(s)
- S Wagner
- Institute for Biomagnetism and Biosignal Analysis, University of Münster, Münster, Germany
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29
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Russell MJ, Goodman T, Pierson R, Shepherd S, Wang Q, Groshong B, Wiley DF. Individual differences in transcranial electrical stimulation current density. J Biomed Res 2013; 27:495-508. [PMID: 24285948 PMCID: PMC3841475 DOI: 10.7555/jbr.27.20130074] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/16/2013] [Accepted: 07/28/2013] [Indexed: 12/23/2022] Open
Abstract
Transcranial electrical stimulation (TCES) is effective in treating many conditions, but it has not been possible to accurately forecast current density within the complex anatomy of a given subject's head. We sought to predict and verify TCES current densities and determine the variability of these current distributions in patient-specific models based on magnetic resonance imaging (MRI) data. Two experiments were performed. The first experiment estimated conductivity from MRIs and compared the current density results against actual measurements from the scalp surface of 3 subjects. In the second experiment, virtual electrodes were placed on the scalps of 18 subjects to model simulated current densities with 2 mA of virtually applied stimulation. This procedure was repeated for 4 electrode locations. Current densities were then calculated for 75 brain regions. Comparison of modeled and measured external current in experiment 1 yielded a correlation of r = .93. In experiment 2, modeled individual differences were greatest near the electrodes (ten-fold differences were common), but simulated current was found in all regions of the brain. Sites that were distant from the electrodes (e.g. hypothalamus) typically showed two-fold individual differences. MRI-based modeling can effectively predict current densities in individual brains. Significant variation occurs between subjects with the same applied electrode configuration. Individualized MRI-based modeling should be considered in place of the 10-20 system when accurate TCES is needed.
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Salvador R, Ramirez F, V'yacheslavovna M, Miranda PC. Effects of tissue dielectric properties on the electric field induced in tDCS: a sensitivity analysis. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2012:787-90. [PMID: 23366010 DOI: 10.1109/embc.2012.6346049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Numerical modeling studies remain the only viable way to accurately predict the electric field (E-field) distribution in transcranial direct current stimulation (tDCS). Despite the existence of multiple studies of this kind, a wide range of different values and properties for the electrical conductivities of the tissues represented is employed. This makes it difficult to predict whether the changes observed between models are due to differences in the geometries of the volume conductors or to the different electrical properties of the tissues. In this study we used the finite element method to calculate the E-field distribution in several spherical head models whose tissues were represented with different isotropic and anisotropic conductivity profiles. Results show that the distribution of the E-field is especially sensitive to the conductivity of the skull, skin and GM. These results might help comparing numerical modeling studies that employ different conductivity values.
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Affiliation(s)
- R Salvador
- Institute of Biophysics and Biomedical Engineering, Faculty of Science, University of Lisbon, Campo-Grande, Lisbon, Portugal.
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31
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Bai S, Loo C, Dokos S. Effects of electroconvulsive therapy stimulus pulsewidth and amplitude computed with an anatomically-realistic head model. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2012:2559-62. [PMID: 23366447 DOI: 10.1109/embc.2012.6346486] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The efficacy and cognitive outcomes of electro-convulsive therapy (ECT) on psychiatric disorders have been shown to depend on variations in treatment technique. In order to investigate this, a high resolution finite element human head model was generated from MRI scans and implemented with tissue heterogeneity and an excitable ionic neural formulations in the brain. The model was used to compare the effects of altered ECT stimulus amplitude and pulse width on the spatial extent of directly activated brain regions. The results showed that decreases in both amplitude and pulse width could effectively lead to reductions in the size of activated brain regions.
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Affiliation(s)
- Siwei Bai
- Graduate School of Biomedical Engineering, Faculty of Engineering, University of New South Wales (UNSW), Sydney, Australia.
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32
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Mekonnen A, Salvador R, Ruffini G, Miranda PC. The relationship between transcranial current stimulation electrode montages and the effect of the skull orbital openings. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2012:831-4. [PMID: 23366021 DOI: 10.1109/embc.2012.6346060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Due to its low electric conductivity, the skull has a major impact on the electric field distribution in the brain in transcranial current stimulation (tCS). However, the skull has several openings that are filled with higher conductivity soft tissues, and through which a significant fraction of the injected current may pass. We show that current entering the brain via the orbital openings increases the electric field intensity in the cortical regions near the orbit. Furthermore, this depends on the how far electrodes are placed from the orbital openings.
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Affiliation(s)
- A Mekonnen
- Institute of Biophysics and Biomedical Engineering (IBEB), Faculty of Sciences, University of Lisbon, Lisbon, Portugal.
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33
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Metwally MK, Cho YS, Park HJ, Kim TS. Investigation of the electric field components of tDCS via anisotropically conductive gyri-specific finite element head models. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2012:5514-7. [PMID: 23367178 DOI: 10.1109/embc.2012.6347243] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Transcranial Direct Current Stimulation (tDCS) is considered as one of the promising techniques for noninvasive brain stimulation and brain disease therapy. In this study, we have investigated the effect of skull and white matter (WM) anisotropy on the induced electric field (EF) by tDCS in two different montages; one using a pair of clinically used rectangular pad electrodes and the other 4(cathodes)+1(anode) ring electrodes. Using a gyri-specific finite element (FE) head model, we simulated tDCS and investigated the radial and tangential components of the induced EF in terms of their distribution over the cortical surface besides the distribution of the transverse and longitudinal components within WM. The results show that the tangential component of the EF on the cortical surface seems to be the main cause of the cortical stimulation of tDCS. Also WM anisotropy seems to increase the dispersion of the transverse component of the EF that affects the dispersion of the EF magnitude within the WM region.
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Affiliation(s)
- Mohamed K Metwally
- Department of Biomedical Engineering, Kyung Hee University, Yongin, Gyeonggi, Republic of Korea
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34
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Hauser TU, Rotzer S, Grabner RH, Mérillat S, Jäncke L. Enhancing performance in numerical magnitude processing and mental arithmetic using transcranial Direct Current Stimulation (tDCS). Front Hum Neurosci 2013; 7:244. [PMID: 23761750 PMCID: PMC3674316 DOI: 10.3389/fnhum.2013.00244] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 05/17/2013] [Indexed: 12/30/2022] Open
Abstract
The ability to accurately process numerical magnitudes and solve mental arithmetic is of highest importance for schooling and professional career. Although impairments in these domains in disorders such as developmental dyscalculia (DD) are highly detrimental, remediation is still sparse. In recent years, transcranial brain stimulation methods such as transcranial Direct Current Stimulation (tDCS) have been suggested as a treatment for various neurologic and neuropsychiatric disorders. The posterior parietal cortex (PPC) is known to be crucially involved in numerical magnitude processing and mental arithmetic. In this study, we evaluated whether tDCS has a beneficial effect on numerical magnitude processing and mental arithmetic. Due to the unclear lateralization, we stimulated the left, right as well as both hemispheres simultaneously in two experiments. We found that left anodal tDCS significantly enhanced performance in a number comparison and a subtraction task, while bilateral and right anodal tDCS did not induce any improvements compared to sham. Our findings demonstrate that the left PPC is causally involved in numerical magnitude processing and mental arithmetic. Furthermore, we show that these cognitive functions can be enhanced by means of tDCS. These findings encourage to further investigate the beneficial effect of tDCS in the domain of mathematics in healthy and impaired humans.
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Affiliation(s)
- Tobias U Hauser
- Division Neuropsychology, Institute of Psychology, University of Zurich Zurich, Switzerland ; University Clinics for Child and Adolescent Psychiatry, University of Zurich Zurich, Switzerland ; Neuroscience Center Zurich, University of Zurich and ETH Zurich Zurich, Switzerland
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35
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Tecchio F, Cancelli A, Cottone C, Tomasevic L, Devigus B, Zito G, Ercolani M, Carducci F. Regional personalized electrodes to select transcranial current stimulation target. Front Hum Neurosci 2013; 7:131. [PMID: 23626529 PMCID: PMC3631708 DOI: 10.3389/fnhum.2013.00131] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 03/25/2013] [Indexed: 11/18/2022] Open
Abstract
Rationale: Personalizing transcranial stimulations promises to enhance beneficial effects for individual patients. Objective: To stimulate specific cortical regions by developing a procedure to bend and position custom shaped electrodes; to probe the effects on cortical excitability produced when the properly customized electrode is targeting different cortical areas. Method: An ad hoc neuronavigation procedure was developed to accurately shape and place the personalized electrodes on the basis of individual brain magnetic resonance images (MRI) on bilateral primary motor (M1) and somatosensory (S1) cortices. The transcranial alternating current stimulation (tACS) protocol published by Feurra et al. (2011b) was used to test the effects on cortical excitability of the personalized electrode when targeting S1 or M1. Results: Neuronal excitability as evaluated by tACS was different when targeting M1 or S1, with the General Estimating Equation model indicating a clear tCS Effect (p < 0.001), and post hoc comparisons showing solely M1 20 Hz tACS to reduce M1 excitability with respect to baseline and other tACS conditions. Conclusions: The present work indicates that specific cortical regions can be targeted by tCS properly shaping and positioning the stimulating electrode. Significance: Through multimodal brain investigations continuous efforts in understanding the neuronal changes related to specific neurological or psychiatric diseases become more relevant as our ability to build the compensating interventions improves. An important step forward on this path is the ability to target the specific cortical area of interest, as shown in the present pilot work.
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Affiliation(s)
- Franca Tecchio
- Laboratory of Electrophysiology for Translational neuroScience (LET'S) - ISTC - CNR, Department of Neuroscience, Fatebenefratelli Hospital Rome, Italy ; Department of Neuroimaging, IRCCS San Raffaele Pisana Rome, Italy
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Rahman A, Reato D, Arlotti M, Gasca F, Datta A, Parra LC, Bikson M. Cellular effects of acute direct current stimulation: somatic and synaptic terminal effects. J Physiol 2013; 591:2563-78. [PMID: 23478132 DOI: 10.1113/jphysiol.2012.247171] [Citation(s) in RCA: 364] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique to modulate cortical excitability. Although increased/decreased excitability under the anode/cathode electrode is nominally associated with membrane depolarization/hyperpolarization, which cellular compartments (somas, dendrites, axons and their terminals) mediate changes in cortical excitability remains unaddressed. Here we consider the acute effects of DCS on excitatory synaptic efficacy. Using multi-scale computational models and rat cortical brain slices, we show the following. (1) Typical tDCS montages produce predominantly tangential (relative to the cortical surface) direction currents (4-12 times radial direction currents), even directly under electrodes. (2) Radial current flow (parallel to the somatodendritic axis) modulates synaptic efficacy consistent with somatic polarization, with depolarization facilitating synaptic efficacy. (3) Tangential current flow (perpendicular to the somatodendritic axis) modulates synaptic efficacy acutely (during stimulation) in an afferent pathway-specific manner that is consistent with terminal polarization, with hyperpolarization facilitating synaptic efficacy. (4) Maximal polarization during uniform DCS is expected at distal (the branch length is more than three times the membrane length constant) synaptic terminals, independent of and two-three times more susceptible than pyramidal neuron somas. We conclude that during acute DCS the cellular targets responsible for modulation of synaptic efficacy are concurrently somata and axon terminals, with the direction of cortical current flow determining the relative influence.
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Affiliation(s)
- Asif Rahman
- Department of Biomedical Engineering, The City College of The City University of New York, Convent Avenue at 140th Street, Steinman Hall, 4th Floor, T-454, New York, NY 10031, USA.
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Merlet I, Birot G, Salvador R, Molaee-Ardekani B, Mekonnen A, Soria-Frish A, Ruffini G, Miranda PC, Wendling F. From oscillatory transcranial current stimulation to scalp EEG changes: a biophysical and physiological modeling study. PLoS One 2013; 8:e57330. [PMID: 23468970 PMCID: PMC3585369 DOI: 10.1371/journal.pone.0057330] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 01/21/2013] [Indexed: 11/19/2022] Open
Abstract
Both biophysical and neurophysiological aspects need to be considered to assess the impact of electric fields induced by transcranial current stimulation (tCS) on the cerebral cortex and the subsequent effects occurring on scalp EEG. The objective of this work was to elaborate a global model allowing for the simulation of scalp EEG signals under tCS. In our integrated modeling approach, realistic meshes of the head tissues and of the stimulation electrodes were first built to map the generated electric field distribution on the cortical surface. Secondly, source activities at various cortical macro-regions were generated by means of a computational model of neuronal populations. The model parameters were adjusted so that populations generated an oscillating activity around 10 Hz resembling typical EEG alpha activity. In order to account for tCS effects and following current biophysical models, the calculated component of the electric field normal to the cortex was used to locally influence the activity of neuronal populations. Lastly, EEG under both spontaneous and tACS-stimulated (transcranial sinunoidal tCS from 4 to 16 Hz) brain activity was simulated at the level of scalp electrodes by solving the forward problem in the aforementioned realistic head model. Under the 10 Hz-tACS condition, a significant increase in alpha power occurred in simulated scalp EEG signals as compared to the no-stimulation condition. This increase involved most channels bilaterally, was more pronounced on posterior electrodes and was only significant for tACS frequencies from 8 to 12 Hz. The immediate effects of tACS in the model agreed with the post-tACS results previously reported in real subjects. Moreover, additional information was also brought by the model at other electrode positions or stimulation frequency. This suggests that our modeling approach can be used to compare, interpret and predict changes occurring on EEG with respect to parameters used in specific stimulation configurations.
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38
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Imaging artifacts induced by electrical stimulation during conventional fMRI of the brain. Neuroimage 2012; 85 Pt 3:1040-7. [PMID: 23099102 DOI: 10.1016/j.neuroimage.2012.10.026] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 10/16/2012] [Accepted: 10/17/2012] [Indexed: 11/22/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) of brain activation during transcranial electrical stimulation is used to provide insight into the mechanisms of neuromodulation and targeting of particular brain structures. However, the passage of current through the body may interfere with the concurrent detection of blood oxygen level-dependent (BOLD) signal, which is sensitive to local magnetic fields. To test whether these currents can affect concurrent fMRI recordings we performed conventional gradient echo-planar imaging (EPI) during transcranial direct current (tDCS) and alternating current stimulation (tACS) on two post-mortem subjects. tDCS induced signals in both superficial and deep structures. The signal was specific to the electrode montage, with the strongest signal near cerebrospinal fluid (CSF) and scalp. The direction of change relative to non-stimulation reversed with tDCS stimulation polarity. For tACS there was no net effect of the MRI signal. High-resolution individualized modeling of current flow and induced static magnetic fields suggested a strong coincidence of the change EPI signal with regions of large current density and magnetic fields. These initial results indicate that (1) fMRI studies of tDCS must consider this potentially confounding interference from current flow and (2) conventional MRI imaging protocols can be potentially used to measure current flow during transcranial electrical stimulation. The optimization of current measurement and artifact correction techniques, including consideration of the underlying physics, remains to be addressed.
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Peterchev AV, Wagner TA, Miranda PC, Nitsche MA, Paulus W, Lisanby SH, Pascual-Leone A, Bikson M. Fundamentals of transcranial electric and magnetic stimulation dose: definition, selection, and reporting practices. Brain Stimul 2012; 5:435-53. [PMID: 22305345 PMCID: PMC3346863 DOI: 10.1016/j.brs.2011.10.001] [Citation(s) in RCA: 227] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 10/05/2011] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The growing use of transcranial electric and magnetic (EM) brain stimulation in basic research and in clinical applications necessitates a clear understanding of what constitutes the dose of EM stimulation and how it should be reported. METHODS This paper provides fundamental definitions and principles for reporting of dose that encompass any transcranial EM brain stimulation protocol. RESULTS The biologic effects of EM stimulation are mediated through an electromagnetic field injected (via electric stimulation) or induced (via magnetic stimulation) in the body. Therefore, transcranial EM stimulation dose ought to be defined by all parameters of the stimulation device that affect the electromagnetic field generated in the body, including the stimulation electrode or coil configuration parameters: shape, size, position, and electrical properties, as well as the electrode or coil current (or voltage) waveform parameters: pulse shape, amplitude, width, polarity, and repetition frequency; duration of and interval between bursts or trains of pulses; total number of pulses; and interval between stimulation sessions and total number of sessions. Knowledge of the electromagnetic field generated in the body may not be sufficient but is necessary to understand the biologic effects of EM stimulation. CONCLUSIONS We believe that reporting of EM stimulation dose should be guided by the principle of reproducibility: sufficient information about the stimulation parameters should be provided so that the dose can be replicated.
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Affiliation(s)
- Angel V Peterchev
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, North Carolina 27710, USA.
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40
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Bikson M, Rahman A, Datta A, Fregni F, Merabet L. High-resolution modeling assisted design of customized and individualized transcranial direct current stimulation protocols. Neuromodulation 2012; 15:306-15. [PMID: 22780230 DOI: 10.1111/j.1525-1403.2012.00481.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers low-intensity currents facilitating or inhibiting spontaneous neuronal activity. tDCS is attractive since dose is readily adjustable by simply changing electrode number, position, size, shape, and current. In the recent past, computational models have been developed with increased precision with the goal to help customize tDCS dose. The aim of this review is to discuss the incorporation of high-resolution patient-specific computer modeling to guide and optimize tDCS. METHODS In this review, we discuss the following topics: 1) The clinical motivation and rationale for models of transcranial stimulation is considered pivotal in order to leverage the flexibility of neuromodulation; 2) the protocols and the workflow for developing high-resolution models; 3) the technical challenges and limitations of interpreting modeling predictions; and 4) real cases merging modeling and clinical data illustrating the impact of computational models on the rational design of rehabilitative electrotherapy. CONCLUSIONS Though modeling for noninvasive brain stimulation is still in its development phase, it is predicted that with increased validation, dissemination, simplification, and democratization of modeling tools, computational forward models of neuromodulation will become useful tools to guide the optimization of clinical electrotherapy.
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Affiliation(s)
- Marom Bikson
- Department of Biomedical Engineering, The City College of New York of CUNY, New York, NY 10031, USA
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Lee WH, Deng ZD, Kim TS, Laine AF, Lisanby SH, Peterchev AV. Regional electric field induced by electroconvulsive therapy in a realistic finite element head model: influence of white matter anisotropic conductivity. Neuroimage 2012; 59:2110-23. [PMID: 22032945 PMCID: PMC3495594 DOI: 10.1016/j.neuroimage.2011.10.029] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Revised: 09/14/2011] [Accepted: 10/10/2011] [Indexed: 11/30/2022] Open
Abstract
We present the first computational study investigating the electric field (E-field) strength generated by various electroconvulsive therapy (ECT) electrode configurations in specific brain regions of interest (ROIs) that have putative roles in the therapeutic action and/or adverse side effects of ECT. This study also characterizes the impact of the white matter (WM) conductivity anisotropy on the E-field distribution. A finite element head model incorporating tissue heterogeneity and WM anisotropic conductivity was constructed based on structural magnetic resonance imaging (MRI) and diffusion tensor MRI data. We computed the spatial E-field distributions generated by three standard ECT electrode placements including bilateral (BL), bifrontal (BF), and right unilateral (RUL) and an investigational electrode configuration for focal electrically administered seizure therapy (FEAST). The key results are that (1) the median E-field strength over the whole brain is 3.9, 1.5, 2.3, and 2.6 V/cm for the BL, BF, RUL, and FEAST electrode configurations, respectively, which coupled with the broad spread of the BL E-field suggests a biophysical basis for observations of superior efficacy of BL ECT compared to BF and RUL ECT; (2) in the hippocampi, BL ECT produces a median E-field of 4.8 V/cm that is 1.5-2.8 times stronger than that for the other electrode configurations, consistent with the more pronounced amnestic effects of BL ECT; and (3) neglecting the WM conductivity anisotropy results in E-field strength error up to 18% overall and up to 39% in specific ROIs, motivating the inclusion of the WM conductivity anisotropy in accurate head models. This computational study demonstrates how the realistic finite element head model incorporating tissue conductivity anisotropy provides quantitative insight into the biophysics of ECT, which may shed light on the differential clinical outcomes seen with various forms of ECT, and may guide the development of novel stimulation paradigms with improved risk/benefit ratio.
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Affiliation(s)
- Won Hee Lee
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC 27710, USA
| | - Zhi-De Deng
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC 27710, USA
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA
| | - Tae-Seong Kim
- Department of Biomedical Engineering, Kyung Hee University, Yongin, Gyeonggi, Republic of Korea
| | - Andrew F. Laine
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
| | - Sarah H. Lisanby
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC 27710, USA
- Department of Psychology & Neuroscience, Duke University, Durham, NC 27710, USA
| | - Angel V. Peterchev
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC 27710, USA
- Department of Biomedical Engineering and Department of Electrical and Computer Engineering, Duke University, Durham, NC 27710, USA
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Datta A, Truong D, Minhas P, Parra LC, Bikson M. Inter-Individual Variation during Transcranial Direct Current Stimulation and Normalization of Dose Using MRI-Derived Computational Models. Front Psychiatry 2012; 3:91. [PMID: 23097644 PMCID: PMC3477710 DOI: 10.3389/fpsyt.2012.00091] [Citation(s) in RCA: 274] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 10/01/2012] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Transcranial Direct Current Stimulation (tDCS) is a non-invasive, versatile, and safe neuromodulation technology under investigation for the treatment of neuropsychiatric disorders, adjunct to rehabilitation, and cognitive enhancement in healthy adults. Despite promising results, there is variability in responsiveness. One potential source of variability is the intensity of current delivered to the brain which is a function of both the operator controlled tDCS dose (electrode montage and total applied current) and subject specific anatomy. We are interested in both the scale of this variability across anatomical typical adults and methods to normalize inter-individual variation by customizing tDCS dose. Computational FEM simulations are a standard technique to predict brain current flow during tDCS and can be based on subject specific anatomical MRI. OBJECTIVE To investigate this variability, we modeled multiple tDCS montages across three adults (ages 34-41, one female). RESULTS Conventional pad stimulation led to diffuse modulation with maximum current flow between the pads across all subjects. There was high current flow directly under the pad for one subject while the location of peak induced cortical current flow was variable. The High-Definition tDCS montage led to current flow restricted to within the ring perimeter across all subjects. The current flow profile across all subjects and montages was influenced by details in cortical gyri/sulci. CONCLUSION This data suggests that subject specific modeling can facilitate consistent and more efficacious tDCS.
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Affiliation(s)
- Abhishek Datta
- Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of City University of New York New York, NY, USA ; Soterix Medical New York, NY, USA
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Neuling T, Wagner S, Wolters CH, Zaehle T, Herrmann CS. Finite-Element Model Predicts Current Density Distribution for Clinical Applications of tDCS and tACS. Front Psychiatry 2012; 3:83. [PMID: 23015792 PMCID: PMC3449241 DOI: 10.3389/fpsyt.2012.00083] [Citation(s) in RCA: 161] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 09/04/2012] [Indexed: 11/13/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) has been applied in numerous scientific studies over the past decade. However, the possibility to apply tDCS in therapy of neuropsychiatric disorders is still debated. While transcranial magnetic stimulation (TMS) has been approved for treatment of major depression in the United States by the Food and Drug Administration (FDA), tDCS is not as widely accepted. One of the criticisms against tDCS is the lack of spatial specificity. Focality is limited by the electrode size (35 cm(2) are commonly used) and the bipolar arrangement. However, a current flow through the head directly from anode to cathode is an outdated view. Finite-element (FE) models have recently been used to predict the exact current flow during tDCS. These simulations have demonstrated that the current flow depends on tissue shape and conductivity. To face the challenge to predict the location, magnitude, and direction of the current flow induced by tDCS and transcranial alternating current stimulation (tACS), we used a refined realistic FE modeling approach. With respect to the literature on clinical tDCS and tACS, we analyzed two common setups for the location of the stimulation electrodes which target the frontal lobe and the occipital lobe, respectively. We compared lateral and medial electrode configuration with regard to their usability. We were able to demonstrate that the lateral configurations yielded more focused stimulation areas as well as higher current intensities in the target areas. The high resolution of our simulation allows one to combine the modeled current flow with the knowledge of neuronal orientation to predict the consequences of tDCS and tACS. Our results not only offer a basis for a deeper understanding of the stimulation sites currently in use for clinical applications but also offer a better interpretation of observed effects.
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Affiliation(s)
- Toralf Neuling
- Experimental Psychology Lab, University of Oldenburg Oldenburg, Germany
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Deng ZD, Lisanby SH, Peterchev AV. Electric field strength and focality in electroconvulsive therapy and magnetic seizure therapy: a finite element simulation study. J Neural Eng 2011; 8:016007. [PMID: 21248385 PMCID: PMC3903509 DOI: 10.1088/1741-2560/8/1/016007] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We present the first computational study comparing the electric field induced by various electroconvulsive therapy (ECT) and magnetic seizure therapy (MST) paradigms. Four ECT electrode configurations (bilateral, bifrontal, right unilateral, and focal electrically administered seizure therapy) and three MST coil configurations (circular, cap, and double cone) were modeled. The model incorporated a modality-specific neural activation threshold. ECT (0.3 ms pulse width) and MST induced the maximum electric field of 2.1-2.5 V cm⁻¹ and 1.1-2.2 V cm⁻¹ in the brain, corresponding to 6.2-7.2 times and 1.2-2.3 times the neural activation threshold, respectively. The MST electric field is more confined to the superficial cortex compared to ECT. The brain volume stimulated was much larger with ECT (up to 100%) than with MST (up to 8.2%). MST with the double-cone coil was the most focal, and bilateral ECT was the least focal. Our results suggest a possible biophysical explanation of the reduced side effects of MST compared to ECT. Our results also indicate that the conventional ECT pulse amplitude (800-900 mA) is much higher than necessary for seizure induction. Reducing the ECT pulse amplitude should be explored as a potential means of diminishing side effects.
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Affiliation(s)
- Zhi-De Deng
- Division of Brain Stimulation and Therapeutic Modulation, Department of Psychiatry, ColumbiaUniversity/New York State Psychiatric Institute, 1051 Riverside Drive, Unit 21, New York, NY 10032, USA
- Department of Electrical Engineering, Columbia University, 1300 S. W. Mudd, 500 West 120th Street, New York, NY 10027, USA
| | - Sarah H. Lisanby
- Division of Brain Stimulation and Therapeutic Modulation, Department of Psychiatry, ColumbiaUniversity/New York State Psychiatric Institute, 1051 Riverside Drive, Unit 21, New York, NY 10032, USA
- Department of Psychiatry and Behavioral Sciences, Duke University, Box 3950 DUMC, Durham, NC27710, USA
| | - Angel V. Peterchev
- Division of Brain Stimulation and Therapeutic Modulation, Department of Psychiatry, ColumbiaUniversity/New York State Psychiatric Institute, 1051 Riverside Drive, Unit 21, New York, NY 10032, USA
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Bai S, Loo C, Dokos S. Electroconvulsive therapy simulations using an anatomically-realistic head model. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2011; 2011:5484-5487. [PMID: 22255579 DOI: 10.1109/iembs.2011.6091399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Electroconvulsive therapy (ECT) is a highly effective treatment for severe depressive disorder. Efficacy and cognitive outcomes have been shown to depend on variations in treatment technique. A high resolution finite element model of a human head was generated from MRI scans and implemented with tissue heterogeneity and an excitable ionic neural model incorporated in the brain. The model was used to compare the effects of three common ECT electrode configurations, including the spatial profiles of electric field and excitation in the brain. The results showed that electrode placement has a significant effect in determining the spatial extent of activation in different brain regions, which would account for differences seen in clinical outcomes.
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Affiliation(s)
- Siwei Bai
- Faculty of Engineering, Graduate School of Biomedical Engineering, University of New South Wales, Australia.
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