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Ramasawmy P, Gamboa Arana OL, Mai TT, Heim LC, Schumann SE, Fechner E, Jiang Y, Moschner O, Chakalov I, Bähr M, Petzke F, Antal A. No add-on therapeutic benefit of at-home anodal tDCS of the primary motor cortex to mindfulness meditation in patients with fibromyalgia. Clin Neurophysiol 2024; 164:168-179. [PMID: 38901112 DOI: 10.1016/j.clinph.2024.05.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/25/2024] [Accepted: 05/28/2024] [Indexed: 06/22/2024]
Abstract
OBJECTIVE This study investigated the efficacy of combining at-home anodal transcranial direct current stimulation (tDCS) of the left primary motor cortex (M1) with mindfulness meditation (MM) in fibromyalgia patients trained in mindfulness. METHODS Thirty-seven patients were allocated to receive ten daily sessions of MM paired with either anodal or sham tDCS over the primary motor cortex. Primary outcomes were pain intensity and quality of life. Secondary outcomes were psychological impairment, sleep quality, mood, affective pain, mindfulness level, and transcranial magnetic stimulation (TMS) measures of cortical excitability. Outcomes were analyzed pre- and post-treatment, with a one-month follow-up. RESULTS We found post-tDCS improvement in all clinical outcomes, including mindfulness level, except for positive affect and stress, in both groups without significant difference between active and sham conditions. No significant group*time interaction was found for all clinical and TMS outcomes. CONCLUSIONS Our findings demonstrate no synergistic or add-on efffect of anodal tDCS of the left M1 compared to the proper effect of MM in patients with fibromyalgia. SIGNIFICANCE Our findings challenge the potential of combining anodal tDCS of the left M1 and MM in fibromyalgia.
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Affiliation(s)
- Perianen Ramasawmy
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany.
| | | | - Thuy Tien Mai
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Luise Charlotte Heim
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Samuel Enrico Schumann
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Elisabeth Fechner
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Yong Jiang
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Oscar Moschner
- Institute of Computer and Communication Technology, Technische Hochschule Köln, Köln, Germany
| | - Ivan Chakalov
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany; Department of Anesthesiology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Mathias Bähr
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Frank Petzke
- Department of Anesthesiology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Andrea Antal
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
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Muccio M, Pilloni G, Walton Masters L, He P, Krupp L, Datta A, Bikson M, Charvet L, Ge Y. Simultaneous and cumulative effects of tDCS on cerebral metabolic rate of oxygen in multiple sclerosis. Front Hum Neurosci 2024; 18:1418647. [PMID: 39081842 PMCID: PMC11286420 DOI: 10.3389/fnhum.2024.1418647] [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: 04/16/2024] [Accepted: 07/01/2024] [Indexed: 08/02/2024] Open
Abstract
Introduction Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique with simultaneous (during stimulation) and cumulative effects (after repeated sessions) on blood flow and neuronal metabolism. These effects remain mostly unclear especially in multiple sclerosis (MS). This work aims to elucidate brain metabolic and hemodynamic underpinnings of tDCS and its potential therapeutic impact in MS patients using quantitative tDCS-MRI. Methods MS participants (n = 20; age = 45.4 ± 12.3 years, 7 males) underwent 3 T MRI scans before and after 20 daily sessions of dorsolateral prefrontal cortex (DLFPC) tDCS (2.0 mA, left anodal) paired with adaptive cognitive training (aCT). During both visits, imaging measurements of cerebral blood flow (CBF), cerebral venous blood oxygenation (Yv) and calculated cerebral metabolic rate of oxygen (CMRO2) were obtained at pre-tDCS, during-tDCS and post-tDCS. Results At baseline, significant increase from pre- to during-tDCS was observed in CMRO2 (7.6%; p = 0.002), CBF (11.0%; p < 0.0001) and Yv (1.9%; p = 0.006). At follow up, we observed an increase in pre-tDCS CMRO2 (140.59 ± 13.83 μmol/100 g/min) compared to baseline pre-tDCS levels (128.30 ± 14.00 μmol/100 g/min; p = 0.006). Sustained elevations in CMRO2 and CBF into post-tDCS were also observed (tDCS lingering effects). Cumulative tDCS effects were observed in the form of sustained elevations in CMRO2 and CBF in pre-tDCS follow up, reaching the magnitudes measured at baseline during-tDCS. Discussion TDCS induces an acute surge in metabolic activity persisting immediately after the stimulation is removed. Moreover, treatment composed of repeated tDCS-aCT paired sessions contributes to establishing long-lasting increases in neuronal activity.
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Affiliation(s)
- Marco Muccio
- Department of Radiology, NYU Grossman School of Medicine, New York, NY, United States
| | - Giuseppina Pilloni
- Department of Neurology, NYU Grossman School of Medicine, New York, NY, United States
| | | | - Peidong He
- Department of Radiology, NYU Grossman School of Medicine, New York, NY, United States
| | - Lauren Krupp
- Department of Neurology, NYU Grossman School of Medicine, New York, NY, United States
| | - Abhishek Datta
- Research and Development, Soterix Medical, Inc., Woodbridge, NJ, United States
| | - Marom Bikson
- Department of Biomedical Engineering, City College of New York, New York, NY, United States
| | - Leigh Charvet
- Department of Neurology, NYU Grossman School of Medicine, New York, NY, United States
| | - Yulin Ge
- Department of Radiology, NYU Grossman School of Medicine, New York, NY, United States
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Diedrich L, Kolhoff HI, Bergmann C, Bähr M, Antal A. Boosting working memory in the elderly: driving prefrontal theta-gamma coupling via repeated neuromodulation. GeroScience 2024:10.1007/s11357-024-01272-3. [PMID: 38992335 DOI: 10.1007/s11357-024-01272-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 06/27/2024] [Indexed: 07/13/2024] Open
Abstract
The escalating global burden of age-related neurodegenerative diseases and associated healthcare costs necessitates innovative interventions to stabilize or enhance cognitive functions. Deficits in working memory (WM) are linked to alterations in prefrontal theta-gamma cross-frequency coupling. Low-intensity transcranial alternating current stimulation (tACS) has emerged as a non-invasive, low-cost approach capable of modulating ongoing oscillations in targeted brain areas through entrainment. This study investigates the impact of multi-session peak-coupled theta-gamma cross-frequency tACS administered to the dorsolateral prefrontal cortex (DLPFC) on WM performance in older adults. In a randomized, sham-controlled, triple-blinded design, 77 participants underwent 16 stimulation sessions over six weeks while performing n-back tasks. Signal detection measures revealed increased 2-back sensitivity and robust modulations of response bias, indicating improved WM and decision-making adaptations, respectively. No effects were observed in the 1-back condition, emphasizing dependencies on cognitive load. Repeated tACS reinforces behavioral changes, indicated by increasing effect sizes. This study supports prior research correlating prefrontal theta-gamma coupling with WM processes and provides unique insights into the neurocognitive benefits of repeated tACS intervention. The well-tolerated and highly effective multi-session tACS intervention among the elderly underscores its therapeutic potential in vulnerable populations.
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Affiliation(s)
- Lukas Diedrich
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany.
| | - Hannah I Kolhoff
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Clara Bergmann
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Mathias Bähr
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Andrea Antal
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
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Meinzer M, Shahbabaie A, Antonenko D, Blankenburg F, Fischer R, Hartwigsen G, Nitsche MA, Li SC, Thielscher A, Timmann D, Waltemath D, Abdelmotaleb M, Kocataş H, Caisachana Guevara LM, Batsikadze G, Grundei M, Cunha T, Hayek D, Turker S, Schlitt F, Shi Y, Khan A, Burke M, Riemann S, Niemann F, Flöel A. Investigating the neural mechanisms of transcranial direct current stimulation effects on human cognition: current issues and potential solutions. Front Neurosci 2024; 18:1389651. [PMID: 38957187 PMCID: PMC11218740 DOI: 10.3389/fnins.2024.1389651] [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: 02/21/2024] [Accepted: 05/15/2024] [Indexed: 07/04/2024] Open
Abstract
Transcranial direct current stimulation (tDCS) has been studied extensively for its potential to enhance human cognitive functions in healthy individuals and to treat cognitive impairment in various clinical populations. However, little is known about how tDCS modulates the neural networks supporting cognition and the complex interplay with mediating factors that may explain the frequently observed variability of stimulation effects within and between studies. Moreover, research in this field has been characterized by substantial methodological variability, frequent lack of rigorous experimental control and small sample sizes, thereby limiting the generalizability of findings and translational potential of tDCS. The present manuscript aims to delineate how these important issues can be addressed within a neuroimaging context, to reveal the neural underpinnings, predictors and mediators of tDCS-induced behavioral modulation. We will focus on functional magnetic resonance imaging (fMRI), because it allows the investigation of tDCS effects with excellent spatial precision and sufficient temporal resolution across the entire brain. Moreover, high resolution structural imaging data can be acquired for precise localization of stimulation effects, verification of electrode positions on the scalp and realistic current modeling based on individual head and brain anatomy. However, the general principles outlined in this review will also be applicable to other imaging modalities. Following an introduction to the overall state-of-the-art in this field, we will discuss in more detail the underlying causes of variability in previous tDCS studies. Moreover, we will elaborate on design considerations for tDCS-fMRI studies, optimization of tDCS and imaging protocols and how to assure high-level experimental control. Two additional sections address the pressing need for more systematic investigation of tDCS effects across the healthy human lifespan and implications for tDCS studies in age-associated disease, and potential benefits of establishing large-scale, multidisciplinary consortia for more coordinated tDCS research in the future. We hope that this review will contribute to more coordinated, methodologically sound, transparent and reproducible research in this field. Ultimately, our aim is to facilitate a better understanding of the underlying mechanisms by which tDCS modulates human cognitive functions and more effective and individually tailored translational and clinical applications of this technique in the future.
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Affiliation(s)
- Marcus Meinzer
- Department of Neurology, University Medicine Greifswald, Greifswald, Germany
| | - Alireza Shahbabaie
- Department of Neurology, University Medicine Greifswald, Greifswald, Germany
| | - Daria Antonenko
- Department of Neurology, University Medicine Greifswald, Greifswald, Germany
| | - Felix Blankenburg
- Neurocomputation and Neuroimaging Unit, Department of Education and Psychology, Freie Universität Berlin, Berlin, Germany
| | - Rico Fischer
- Department of Psychology, University of Greifswald, Greifswald, Germany
| | - Gesa Hartwigsen
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
- Wilhelm Wundt Institute for Psychology, Leipzig University, Leipzig, Germany
| | - Michael A. Nitsche
- Department of Psychology and Neurosciences, Leibniz Research Centre for Working Environment and Human Factors at TU Dortmund, Dortmund, Germany
- German Center for Mental Health (DZPG), Bochum, Germany
- Bielefeld University, University Hospital OWL, Protestant Hospital of Bethel Foundation, University Clinic of Psychiatry and Psychotherapy, Bielefeld, Germany
| | - Shu-Chen Li
- Chair of Lifespan Developmental Neuroscience, Faculty of Psychology, Technische Universität Dresden, Dresden, Germany
| | - Axel Thielscher
- Section for Magnetic Resonance, Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Copenhagen, Denmark
| | - Dagmar Timmann
- Department of Neurology and Center for Translational Neuro- and Behavioral Sciences (C-TNBS), Essen University Hospital, University of Duisburg-Essen, Essen, Germany
| | - Dagmar Waltemath
- Core Unit Data Integration Center, University Medicine Greifswald, Greifswald, Germany
| | | | - Harun Kocataş
- Department of Neurology, University Medicine Greifswald, Greifswald, Germany
| | | | - Giorgi Batsikadze
- Department of Neurology and Center for Translational Neuro- and Behavioral Sciences (C-TNBS), Essen University Hospital, University of Duisburg-Essen, Essen, Germany
| | - Miro Grundei
- Neurocomputation and Neuroimaging Unit, Department of Education and Psychology, Freie Universität Berlin, Berlin, Germany
| | - Teresa Cunha
- Section for Magnetic Resonance, Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Dayana Hayek
- Department of Neurology, University Medicine Greifswald, Greifswald, Germany
| | - Sabrina Turker
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
- Wilhelm Wundt Institute for Psychology, Leipzig University, Leipzig, Germany
| | - Frederik Schlitt
- Department of Neurology and Center for Translational Neuro- and Behavioral Sciences (C-TNBS), Essen University Hospital, University of Duisburg-Essen, Essen, Germany
| | - Yiquan Shi
- Chair of Lifespan Developmental Neuroscience, Faculty of Psychology, Technische Universität Dresden, Dresden, Germany
| | - Asad Khan
- Department of Psychology and Neurosciences, Leibniz Research Centre for Working Environment and Human Factors at TU Dortmund, Dortmund, Germany
| | - Michael Burke
- Department of Psychology and Neurosciences, Leibniz Research Centre for Working Environment and Human Factors at TU Dortmund, Dortmund, Germany
| | - Steffen Riemann
- Department of Neurology, University Medicine Greifswald, Greifswald, Germany
| | - Filip Niemann
- Department of Neurology, University Medicine Greifswald, Greifswald, Germany
| | - Agnes Flöel
- Department of Neurology, University Medicine Greifswald, Greifswald, Germany
- German Center for Neurodegenerative Diseases (DZNE Site Greifswald), Greifswald, Germany
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Diedrich L, Kolhoff HI, Chakalov I, Vékony T, Németh D, Antal A. Prefrontal theta-gamma transcranial alternating current stimulation improves non-declarative visuomotor learning in older adults. Sci Rep 2024; 14:4955. [PMID: 38418511 PMCID: PMC10901881 DOI: 10.1038/s41598-024-55125-2] [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: 08/29/2023] [Accepted: 02/20/2024] [Indexed: 03/01/2024] Open
Abstract
The rise in the global population of older adults underscores the significance to investigate age-related cognitive disorders and develop early treatment modalities. Previous research suggests that non-invasive transcranial Alternating Current Stimulation (tACS) can moderately improve cognitive decline in older adults. However, non-declarative cognition has received relatively less attention. This study investigates whether repeated (16-day) bilateral theta-gamma cross-frequency tACS targeting the Dorsolateral Prefrontal Cortex (DLPFC) enhances non-declarative memory. Computerized cognitive training was applied alongside stimulation to control for the state-of-the-brain. The Alternating Serial Reaction Time (ASRT) task was employed to assess non-declarative functions such as visuomotor skill and probabilistic sequence learning. Results from 35 participants aged 55-82 indicated that active tACS led to more substantial improvements in visuomotor skills immediately after treatment, which persisted 3 months later, compared to sham tACS. Treatment benefit was more pronounced in older adults of younger age and those with pre-existing cognitive decline. However, neither intervention group exhibited modulation of probabilistic sequence learning. These results suggest that repeated theta-gamma tACS can selectively improve distinct non-declarative cognitive aspects when targeting the DLPFC. Our findings highlight the therapeutic potential of tACS in addressing deficits in learning and retaining general skills, which could have a positive impact on the quality of life for cognitively impaired older individuals by preserving independence in daily activities.
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Affiliation(s)
- Lukas Diedrich
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany.
| | - Hannah I Kolhoff
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Ivan Chakalov
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
- Department of Anesthesiology, University Medical Center Göttingen, Göttingen, Germany
| | - Teodóra Vékony
- Centre de Recherche en Neurosciences de Lyon CRNL U1028 UMR5292, INSERM, CNRS, Université Claude Bernard Lyon 1, Bron, France
- Department of Education and Psychology, Faculty of Social Sciences, University of Atlántico Medio, Las Palmas de Gran Canaria, Spain
| | - Dezső Németh
- Centre de Recherche en Neurosciences de Lyon CRNL U1028 UMR5292, INSERM, CNRS, Université Claude Bernard Lyon 1, Bron, France
- BML-NAP Research Group, Institute of Psychology, Eötvös Loránd University and Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Budapest, Hungary
- Department of Education and Psychology, Faculty of Social Sciences, University of Atlántico Medio, Las Palmas de Gran Canaria, Spain
| | - Andrea Antal
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
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Chen Y, Lyu D, Wang F, Huang Q, Yang W, Zhang M, Wei Z, Shi S, Kong S, Chen S, He S, Yang V, Fang Y, Douiri A, Hong W. Adjunctive duration-doubled transcranial direct current stimulation for the treatment of depressive patients with suicidal ideation: study protocol for a double-blind, randomized, sham-controlled trial. Trials 2024; 25:15. [PMID: 38167178 PMCID: PMC10759703 DOI: 10.1186/s13063-023-07858-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 12/08/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND The problem of suicide has become increasingly common in individuals with major depressive disorder (MDD). Transcranial direct current stimulation (tDCS) is an effective treatment for MDD with 2 milliamperes (mA) for at least 30 min per day for 2 weeks. This study aims to investigate the efficacy of daily duration-doubled tDCS as an adjunctive intervention for rapidly reducing suicidal ideation and improving depression in MDD patients. METHODS In this double-blind, randomized, sham-controlled study, 76 MDD patients with suicidal ideation are randomly assigned to either active (n=38) or sham (n=38) tDCS group. The anode and cathode are placed over the scalp areas corresponding to left and right dorsolateral prefrontal cortex (DLPFC), respectively, and each stimulation lasts for 60 min. The primary outcome is defined as change of Beck Scale for Suicide Ideation (BSI) after 5 and 10 sessions. The change of other clinical assessments, blood biomarkers related to suicidal ideation and depressive sumptoms are defined as secondary outcomes. Blood biomarkers related to suicidal ideation are collected at baseline and after 10 sessions. DISCUSSION This study suggests the adjunctive duration-doubled tDCS might be a novel method to rapidly reduce suicidal ideation and improve depressive symptom. The variation of biomarkers could be potential predictive models of suicide risk. TRIAL REGISTRATION The trial protocol is registered with ClinicalTrials.gov under protocol registration number NCT05555927. Registered on September 25, 2022.
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Affiliation(s)
- Yiming Chen
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Dongbin Lyu
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fan Wang
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qinte Huang
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | | | - Mengke Zhang
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zheyi Wei
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuxiang Shi
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuqi Kong
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shentse Chen
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuang He
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Vivien Yang
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yiru Fang
- Department of Psychiatry & Affective Disorders Center, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai, China
- CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai, China
- Hunan Second People's Hospital (Hunan Brain Hospital), Hunan, China
| | - Abdel Douiri
- King's College London, School of Life Course & Population Sciences, London, UK.
- National Institute for Health Research Biomedical Research Centre (BRC), Guy's and St Thomas' NHS Foundation Trust and King's College London, London, UK.
| | - Wu Hong
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai, China.
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El Jamal C, Harrie A, Rahman-Filipiak A, Iordan AD, DaSilva AF, Ploutz-Snyder R, Khadr L, Vesia M, Bikson M, Hampstead BM. Tolerability and blinding of high-definition transcranial direct current stimulation among older adults at intensities of up to 4 mA per electrode. Brain Stimul 2023; 16:1328-1335. [PMID: 37660936 PMCID: PMC11218548 DOI: 10.1016/j.brs.2023.08.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/29/2023] [Accepted: 08/31/2023] [Indexed: 09/05/2023] Open
Abstract
BACKGROUND Few studies have investigated tolerability, blinding, and double-blinding of High-Definition transcranial Direct Current Stimulation (HD-tDCS) at amplitudes above 2 milliamps (mA). OBJECTIVE We examined a) tolerability of HD-tDCS during stimulation sessions and b) blinding and double blinding of participants and study team members. METHODS Data from a mixed neurologic sample of 292 older adults were pooled from 3046 HD-tDCS sessions (2329 active; 717 sham). Per electrode amplitudes ranged from 1 mA to 4 mA with total currents up to 10 mA. Participants completed a standardized sensation (tolerability) questionnaire after each session. Participants and study team members stated whether the participant received active or sham stimulation at the end of various sessions. Data were collapsed into the presence/absence of a symptom due to low rates of positive responding and were analyzed for both differences and bioequivalency. RESULTS There were no safety-related adverse events. HD-tDCS was well tolerated with mostly no ("none") or "mild" sensations reported across sessions, regardless of active or sham condition and in both stimulation naïve and experienced participants. There were no significant differences in side effects between active and sham, with some achieving bioequivalence. Tingling and itching were significantly more common after lower (<2 mA) than higher (≥3 mA) amplitude active sessions, while skin redness was significantly more common after higher amplitudes. Blinding was effective at the participant and study team levels. CONCLUSIONS HD-tDCS was well tolerated with center electrode amplitudes up to 4 mA. The bimodal ramp-up/down format of the sham was effective for blinding. These results support higher scalp-based amplitudes that enable greater brain-based current intensities in older adults.
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Affiliation(s)
- Carine El Jamal
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Ashley Harrie
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Annalise Rahman-Filipiak
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Alexandru D Iordan
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Alexandre F DaSilva
- Headache & Orofacial Pain Effort (H.O.P.E.), Biologic & Materials Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Robert Ploutz-Snyder
- Applied Biostatistics Laboratory, School of Nursing, University of Michigan, Ann Arbor, MI, USA
| | - Lara Khadr
- Applied Biostatistics Laboratory, School of Nursing, University of Michigan, Ann Arbor, MI, USA
| | - Michael Vesia
- Brain Behavior Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI, USA
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
| | - Benjamin M Hampstead
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA; Mental Health Service, VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
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Klees-Themens G, Théoret H. The effects of transcranial direct current stimulation on corticospinal excitability: A systematic review of nonsignificant findings. Eur J Neurosci 2023; 58:3074-3097. [PMID: 37407275 DOI: 10.1111/ejn.16073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 06/05/2023] [Accepted: 06/12/2023] [Indexed: 07/07/2023]
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that can modulate brain activity through the application of low-intensity electrical currents. Based on its reported effects on corticospinal excitability (CSE), tDCS has been used to study cognition in healthy individuals and reduce symptoms in a variety of clinical conditions. Despite its increasing popularity as a research and clinical tool, high interindividual variability has been reported in the response to protocols using transcranial magnetic stimulation (TMS) to assess tDCS-induced changes in CSE leading to several nonsignificant findings. In this systematic review, studies that reported no significant modulation of CSE following tDCS were identified from PubMed and Embase (Ovid) databases. Forty-three articles were identified where demographic, TMS and tDCS parameters were extracted. Overall, stimulation parameters, CSE measurements and participant characteristics were similar to those described in studies reporting positive results and were likewise heterogeneous between studies. Small sample sizes and inadequate blinding were notable features of the reviewed studies. This systematic review suggests that studies reporting nonsignificant findings do not markedly differ from those reporting significant modulation of CSE.
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Affiliation(s)
| | - Hugo Théoret
- Department of Psychology, Université de Montréal, Montreal, Québec, Canada
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Boscutti A, Murphy N, Cho R, Selvaraj S. Noninvasive Brain Stimulation Techniques for Treatment-Resistant Depression: Transcranial Magnetic Stimulation and Transcranial Direct Current Stimulation. Psychiatr Clin North Am 2023; 46:307-329. [PMID: 37149347 DOI: 10.1016/j.psc.2023.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Transcranial magnetic stimulation is a safe, effective, and well-tolerated intervention for depression; it is currently approved for treatment-resistant depression. This article summarizes the mechanism of action, evidence of clinical efficacy, and the clinical aspects of this intervention, including patient evaluation, stimulation parameters selection, and safety considerations. Transcranial direct current stimulation is another neuromodulation treatment for depression; although promising, the technique is not currently approved for clinical use in the United States. The final section outlines the open challenges and future directions of the field.
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Affiliation(s)
- Andrea Boscutti
- Louis. A. Faillace, MD, Department of Psychiatry and Behavioral Sciences, The University of Texas Health Science Center at Houston, Houston, TX, USA; Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Nicholas Murphy
- Baylor College of Medicine, Menninger Department of Psychiatry and Behavioral Sciences, Houston, TX, USA; The Menninger Clinic, Houston, TX, USA
| | - Raymond Cho
- Baylor College of Medicine, Menninger Department of Psychiatry and Behavioral Sciences, Houston, TX, USA; The Menninger Clinic, Houston, TX, USA
| | - Sudhakar Selvaraj
- Louis. A. Faillace, MD, Department of Psychiatry and Behavioral Sciences, The University of Texas Health Science Center at Houston, Houston, TX, USA.
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10
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Nawani H, Mittner M, Csifcsák G. Modulation of mind wandering using transcranial direct current stimulation: A meta-analysis based on electric field modeling. Neuroimage 2023; 272:120051. [PMID: 36965860 DOI: 10.1016/j.neuroimage.2023.120051] [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: 11/16/2022] [Revised: 03/03/2023] [Accepted: 03/22/2023] [Indexed: 03/27/2023] Open
Abstract
Mind wandering (MW) is a heterogeneous construct involving task-unrelated thoughts. Recently, the interest in modulating MW propensity via non-invasive brain stimulation techniques has increased. Single-session transcranial direct current stimulation (tDCS) in healthy controls has led to mixed results in modulating MW propensity, possibly due to methodological heterogeneity. Therefore, our aim was to conduct a systematic meta-analysis to examine the influence of left dorsolateral prefrontal cortex (lDLPFC) and right inferior parietal lobule (rIPL) targeted tDCS on MW propensity. Importantly, by computational modeling of tDCS-induced electric fields, we accounted for differences in tDCS-dose across studies that varied strongly in their applied methodology. Fifteen single-session, sham-controlled tDCS studies published until October 2021 were included. All studies involved healthy adult participants and used cognitive tasks combined with MW thought-probes. Heterogeneity in tDCS electrode placement, stimulation polarity and intensity were controlled for by means of electric field simulations, while overall methodological quality was assessed via an extended risk of bias (RoB) assessment. We found that RoB was the strongest predictor of study outcomes. Moreover, the rIPL was the most promising cortical area for influencing MW, with stronger anodal electric fields in this region being negatively associated with MW propensity. Electric field strength in the lDLPFC was not related to MW propensity. We identified several severe methodological problems that could have contributed to overestimated effect sizes in this literature, an issue that needs urgent attention in future research in this area. Overall, there is no reliable evidence for tDCS influencing MW in the healthy. However, the analysis also revealed that increasing neural excitability in the rIPL via tDCS might be associated with reduced MW propensity. In an exploratory approach, we also found some indication that targeting prefrontal regions outside the lDLPFC with tDCS could lead to increased MW propensity.
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Affiliation(s)
- Hema Nawani
- Institute for Psychology, UiT The Arctic University of Norway.
| | | | - Gábor Csifcsák
- Institute for Psychology, UiT The Arctic University of Norway.
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11
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Therrien-Blanchet JM, Ferland MC, Badri M, Rousseau MA, Merabtine A, Boucher E, Hofmann LH, Lepage JF, Théoret H. The neurophysiological aftereffects of brain stimulation in human primary motor cortex: a Sham-controlled comparison of three protocols. Cereb Cortex 2023:7030623. [PMID: 36749004 DOI: 10.1093/cercor/bhad021] [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: 10/03/2022] [Revised: 01/14/2023] [Accepted: 01/15/2023] [Indexed: 02/08/2023] Open
Abstract
Paired associative stimulation (PAS), transcranial direct current stimulation (tDCS), and transcranial alternating current stimulation (tACS) are non-invasive brain stimulation methods that are used to modulate cortical excitability. Whether one technique is superior to the others in achieving this outcome and whether individuals that respond to one intervention are more likely to respond to another remains largely unknown. In the present study, the neurophysiological aftereffects of three excitatory neurostimulation protocols were measured with transcranial magnetic stimulation (TMS). Twenty minutes of PAS at an ISI of 25 ms, anodal tDCS, 20-Hz tACS, and Sham stimulation were administered to 31 healthy adults in a repeated measures design. Compared with Sham, none of the stimulation protocols significantly modulated corticospinal excitability (input/ouput curve and slope, TMS stimulator intensity required to elicit MEPs of 1-mV amplitude) or intracortical excitability (short- and long-interval intracortical inhibition, intracortical facilitation, cortical silent period). Sham-corrected responder analysis estimates showed that an average of 41 (PAS), 39 (tDCS), and 39% (tACS) of participants responded to the interventions with an increase in corticospinal excitability. The present data show that three stimulation protocols believed to increase cortical excitability are associated with highly heterogenous and variable aftereffects that may explain a lack of significant group effects.
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Affiliation(s)
| | | | - Meriem Badri
- Département de psychologie, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | | | - Amira Merabtine
- Département de psychologie, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Emelie Boucher
- Département de psychologie, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Lydia Helena Hofmann
- Department of Psychology and Neuroscience, Maastricht University, Maastricht 6229, The Netherlands
| | - Jean-François Lepage
- Département de Pédiatrie, Faculté de Médecine et des Sciences de la Santé de l'Université de Sherbrooke, Centre de Recherche du CHU Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Hugo Théoret
- Département de psychologie, Université de Montréal, Montréal, QC H3C 3J7, Canada
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12
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Hanoglu L, Velioglu HA, Hanoglu T, Yulug B. Neuroimaging-Guided Transcranial Magnetic and Direct Current Stimulation in MCI: Toward an Individual, Effective and Disease-Modifying Treatment. Clin EEG Neurosci 2023; 54:82-90. [PMID: 34751037 DOI: 10.1177/15500594211052815] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The therapeutic approaches currently applied in Alzheimer's disease (AD) and similar neurodegenerative diseases are essentially based on pharmacological strategies. However, despite intensive research, the effectiveness of these treatments is limited to transient symptomatic effects, and they are still far from exhibiting a true therapeutic effect capable of altering prognosis. The lack of success of such pharmacotherapy-based protocols may be derived from the cases in the majority of trials being too advanced to benefit significantly in therapeutic terms at the clinical level. For neurodegenerative diseases, mild cognitive impairment (MCI) may be an early stage of the disease continuum, including Alzheimer's. Noninvasive brain stimulation (NIBS) techniques have been developed to modulate plasticity in the human cortex in the last few decades. NIBS techniques have made it possible to obtain unique findings concerning brain functions, and design novel approaches to treat various neurological and psychiatric conditions. In addition, its synaptic and cellular neurobiological effects, NIBS is an attractive treatment option in the early phases of neurodegenerative diseases, such as MCI, with its beneficial modifying effects on cellular neuroplasticity. However, there is still insufficient evidence about the potential positive clinical effects of NIBS on MCI. Furthermore, the huge variability of the clinical effects of NIBS limits its use. In this article, we reviewed the combined approach of NIBS with various neuroimaging and electrophysiological methods. Such methodologies may provide a new horizon to the path for personalized treatment, including a more individualized pathophysiology approach which might even define new specific targets for specific symptoms of neurodegenerations.
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Affiliation(s)
- Lutfu Hanoglu
- 218502Istanbul Medipol University School of Medicine, Istanbul, Turkey
| | - Halil Aziz Velioglu
- 218502Istanbul Medipol University, Health Sciences and Technology Research Institute (SABITA), Regenerative and Restorative Medicine Research Center (REMER), functional Imaging and Cognitive-Affective Neuroscience Lab (fINCAN), Istanbul, Turkey
| | - Taha Hanoglu
- 218502Istanbul Medipol University, Health Sciences and Technology Research Institute (SABITA), Regenerative and Restorative Medicine Research Center (REMER), functional Imaging and Cognitive-Affective Neuroscience Lab (fINCAN), Istanbul, Turkey
| | - Burak Yulug
- 450199Alanya Alaaddin Keykubat University School of Medicine, Alanya/Antalya, Turkey
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13
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Chen Y, Lyu D, Wang F, Huang Q, Yang W, Zhang M, Wei Z, Shi S, Kong S, Chen S, He S, Yang V, Fang Y, Hong W. Efficacy of adjunctive intensive transcranial direct current stimulation of different cortices in treatment-resistant depression: a study protocol for a randomized double-blinded sham-controlled trial. BMC Psychiatry 2022; 22:802. [PMID: 36536362 PMCID: PMC9762018 DOI: 10.1186/s12888-022-04465-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 12/09/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Treatment-resistant depression (TRD) carries a high economic burden worldwide. Transcranial direct current stimulation (tDCS) is advantageous for improving cognition and can be safely used in the treatment of depression. The effectiveness of tDCS of the left and right orbitofrontal cortex (OFC) as adjuvant treatment in patients with TRD has rarely been explored. Therefore, the objective of this trial is to evaluate the effectiveness there of when administering left dorsolateral prefrontal cortex (DLPFC) positive stimulation or OFC negative stimulation in patients with TRD. METHODS Ninety eligible participants will be recruited to receive intervention at Shanghai Mental Health Center. Treatment will be randomly assigned in a double-blind fashion. Participants will receive either DLPFC (n = 30), OFC (n = 30), or sham (n = 30) tDCS, while continuing their usual pharmacotherapy at a stable dosage for at least 2 weeks before enrollment and throughout the stimulation period. All participants will receive 20 weekday stimulation sessions of 60 minutes duration each. Participants in the active group will be stimulated at 2 mA throughout the session, whereas the sham group will receive only a brief period of stimulation to mimic the sensation. After 20 stimulation sessions, no further treatment will be administered. Measurements will be conducted at regular points throughout and at 8 weeks after trial completion. The primary outcome is the change in the 17-item Hamilton Depression Rating Scale (HAMD-17) score after 20 sessions. Secondary outcomes were defined as changes in other measurement scales, cognitive function, resting-state functional magnetic resonance imaging (rs-fMRI), and serum biomarkers. DISCUSSION We hypothesize that, in contrast to the sham group, both the active DLPFC and OFC tDCS groups will show superiority in HAMD-17 score reduction after 5, 10, and 20 sessions. Moreover, associations of the improvement of depressive symptoms with variations in rs-fMRI and TRD-related biomarkers will be evaluated. Our study may suggest that adjunctive intensive tDCS with left DLPFC positive stimulation or right OFC negative stimulation may be effective as a novel method to relieve depressive symptoms in patients with TRD. The variation of rs-fMRI, biomarkers could be used as a potential prediction model of treatment efficacy in TRD. TRIAL REGISTRATION The trial protocol is registered with www.chictr.org.cn under protocol registration number ChiCTR2200058030. Date of registration: March 27, 2022. Recruitment started in September 2022 and is ongoing.
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Affiliation(s)
- Yiming Chen
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Dongbin Lyu
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fan Wang
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qinte Huang
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Weichieh Yang
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Mengke Zhang
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zheyi Wei
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuxiang Shi
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuqi Kong
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shentse Chen
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuang He
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Vivien Yang
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yiru Fang
- grid.16821.3c0000 0004 0368 8293Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China ,grid.415630.50000 0004 1782 6212Shanghai Key Laboratory of Psychotic Disorders, Shanghai, China ,grid.507732.4CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai, China
| | - Wu Hong
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China. .,Shanghai Key Laboratory of Psychotic Disorders, Shanghai, China.
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14
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Coulborn S, Fernández-Espejo D. Prefrontal tDCS is unable to modulate mind wandering propensity or underlying functional or effective brain connectivity. Sci Rep 2022; 12:18021. [PMID: 36289366 PMCID: PMC9606118 DOI: 10.1038/s41598-022-22893-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 10/20/2022] [Indexed: 01/24/2023] Open
Abstract
There is conflicting evidence over the ability to modulate mind-wandering propensity with anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (prefrontal tDCS). Here, 20 participants received 20-min of active and sham prefrontal tDCS while in the MRI scanner, in two separate sessions (counterbalanced). In each session, they completed two runs of a sustained attention to response task (before and during tDCS), which included probes recording subjective responses of mind-wandering. We assessed the effects of tDCS on behavioural responses as well as functional and effective dynamics, via dynamic functional network connectivity (dFNC) and dynamic causal modelling analyses over regions of the default mode, salience and executive control networks. Behavioural results provided substantial evidence in support of no effect of tDCS on task performance nor mind-wandering propensity. Similarly, we found no effect of tDCS on frequency (how often) or dwell time (time spent) of underlying brain states nor effective connectivity. Overall, our results suggest that prefrontal tDCS is unable to modulate mind-wandering propensity or influence underlying brain function. This expands previous behavioural replication failures in suggesting that prefrontal tDCS may not lead to even subtle (i.e., under a behavioural threshold) changes in brain activity during self-generated cognition.
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Affiliation(s)
- Sean Coulborn
- grid.6572.60000 0004 1936 7486School of Psychology, University of Birmingham, Birmingham, UK ,grid.6572.60000 0004 1936 7486Centre for Human Brain Health, University of Birmingham, Birmingham, UK ,grid.47840.3f0000 0001 2181 7878University of California, Berkeley, USA
| | - Davinia Fernández-Espejo
- grid.6572.60000 0004 1936 7486School of Psychology, University of Birmingham, Birmingham, UK ,grid.6572.60000 0004 1936 7486Centre for Human Brain Health, University of Birmingham, Birmingham, UK
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15
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Ramasawmy P, Khalid S, Petzke F, Antal A. Pain reduction in fibromyalgia syndrome through pairing transcranial direct current stimulation and mindfulness meditation: A randomized, double-blinded, sham-controlled pilot clinical trial. Front Med (Lausanne) 2022; 9:908133. [PMID: 36314032 PMCID: PMC9596988 DOI: 10.3389/fmed.2022.908133] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 08/23/2022] [Indexed: 11/13/2022] Open
Abstract
Background This double-blinded, randomized and sham-controlled pilot clinical trial aimed to investigate the preliminary clinical efficacy and feasibility of combining mindfulness meditation (MM) and transcranial direct current stimulation (tDCS) for pain and associated symptoms in patients with fibromyalgia syndrome (FMS). Methods Included FMS patients (age: 33 to 70) were randomized to three different groups to receive either ten daily sessions of anodal tDCS over the left primary motor cortex paired with MM for 20 min (active + MM, n = 10), sham tDCS combined with MM (sham + MM, n = 10) or no intervention (NoT, n = 10). Patients in the bimodal therapy groups received a week of training in MM prior to the stimulation. Participants reported pain intensity, the primary outcome, by filling in a pain diary daily throughout the whole study. They were also evaluated for quality of life, pressure pain sensitivity, psychological wellbeing, sleep quality and sleep quantity. Assessments were performed at three time points (baseline, immediately after treatment and one-month follow-up). Results Participants in the active + MM group did not exhibit reduced pain intensity following the bimodal therapy compared to controls. Patients in active group demonstrated clinically meaningful and significantly higher quality of life following the therapeutic intervention than other groups. There was no significant difference among groups regarding pressure pain sensitivity, sleep parameters and psychological scales. The combined treatment was well tolerated among participants, with no serious adverse effects. Conclusion This study was the first to pair these two effective non-pharmacological therapies for pain management in FMS. In the light of an underpowered sample size, repetitive anodal tDCS combined with MM did not improve pain or FMS-associated symptoms. However, patients in the active + MM group reported higher quality of life than the control groups. Studies with more participants and longer follow-ups are required to confirm our findings. Clinical trial registration [www.drks.de], identifier [DRKS00023490].
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Affiliation(s)
- Perianen Ramasawmy
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Sarah Khalid
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Frank Petzke
- Department of Anesthesiology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Andrea Antal
- Department of Neurology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
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16
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Smits FM, Geuze E, de Kort GJ, Kouwer K, Geerlings L, van Honk J, Schutter DJ. Effects of Multisession Transcranial Direct Current Stimulation on Stress Regulation and Emotional Working Memory: A Randomized Controlled Trial in Healthy Military Personnel. Neuromodulation 2022:S1094-7159(22)00721-8. [DOI: 10.1016/j.neurom.2022.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 05/02/2022] [Accepted: 05/02/2022] [Indexed: 10/16/2022]
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17
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Gordon MS, Seeto JXW, Dux PE, Filmer HL. Intervention is a better predictor of tDCS mind-wandering effects than subjective beliefs about experimental results. Sci Rep 2022; 12:13110. [PMID: 35908042 PMCID: PMC9338927 DOI: 10.1038/s41598-022-16545-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 07/12/2022] [Indexed: 11/29/2022] Open
Abstract
Blinding in non-invasive brain stimulation research is a topic of intense debate, especially regarding the efficacy of sham-controlled methods for transcranial direct current stimulation (tDCS). A common approach to assess blinding success is the inclusion of correct guess rate. However, this method cannot provide insight into the effect of unblinding on observed stimulation outcomes. Thus, the implementation of measures to systematically evaluate subjective expectation regarding stimulation is needed. Previous work evaluated subjective effects in an earlier study which reported a mind-wandering and tDCS data set and concluded that subjective belief drove the pattern of results observed. Here we consider the subjective and objective intervention effects in a key contrast from that data set-2 mA vs. sham-which was not examined in the reanalysis. In addition, we examine another key contrast from a different tDCS mind-wandering study that employed similar methodology. Our findings support objective intervention as the strongest predictor of the observed effects of mind-wandering in both re-analyses, over and above that of subjective intervention. However, it is important to control for and understand the possible inadequacies of sham-controlled methods.
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Affiliation(s)
- Matilda S Gordon
- School of Psychology, The University of Queensland, McElwain Building (24A), St Lucia, QLD, 4072, Australia.
| | - Jennifer X W Seeto
- School of Psychology, The University of Queensland, McElwain Building (24A), St Lucia, QLD, 4072, Australia
| | - Paul E Dux
- School of Psychology, The University of Queensland, McElwain Building (24A), St Lucia, QLD, 4072, Australia
| | - Hannah L Filmer
- School of Psychology, The University of Queensland, McElwain Building (24A), St Lucia, QLD, 4072, Australia
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18
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Blinding efficacy and adverse events following repeated transcranial alternating current, direct current, and random noise stimulation. Cortex 2022; 154:77-88. [PMID: 35759817 DOI: 10.1016/j.cortex.2022.05.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 04/10/2022] [Accepted: 05/03/2022] [Indexed: 11/22/2022]
Abstract
As transcranial electrical stimulation (tES) protocols advance, assumptions underlying the technique need to be retested to ensure they still hold. Whilst the safety of stimulation has been demonstrated mainly for a small number of sessions, and small sample size, adverse events (AEs) following multiple sessions remain largely untested. Similarly, whilst blinding procedures are typically assumed to be effective, the effect of multiple stimulation sessions on the efficacy of blinding procedures also remains under question. This is especially relevant in multisite projects where small unintentional variations in protocol could lead to inter-site difference. We report AE and blinding data from 1,019 participants who received up to 11 semi-consecutive sessions of active or sham transcranial alternating current stimulation (tACS), direct current stimulation (tDCS), and random noise stimulation (tRNS), at 4 sites in the UK and US. We found that AEs were often best predicted by factors other than tES, such as testing site or session number. Results from the blinding analysis suggested that blinding was less effective for tDCS and tACS than tRNS. The occurrence of AEs did not appear to be linked to tES despite the use of smaller electrodes or repeated delivery. However, blinding efficacy was impacted in tES conditions with higher cutaneous sensation, highlighting a need for alternative stimulation blinding protocols. This may be increasingly necessary in studies wishing to deliver stimulation with higher intensities.
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19
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The Effect of Transcranial Direct Current Stimulation on Error Rates in the Distractor-Induced Deafness Paradigm. Brain Sci 2022; 12:brainsci12060738. [PMID: 35741623 PMCID: PMC9220866 DOI: 10.3390/brainsci12060738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/16/2022] [Accepted: 06/02/2022] [Indexed: 11/16/2022] Open
Abstract
To further understand how consciousness emerges, certain paradigms inducing distractor-induced perceptual impairments are promising. Neuro-computational models explain the inhibition of conscious perception of targets with suppression of distractor information when the target and distractor share the same features. Because these gating mechanisms are controlled by the prefrontal cortex, transcranial direct current stimulation of this specific region is expected to alter distractor-induced effects depending on the presence and number of distractors. To this end, participants were asked to perform an auditory variant of the distractor-induced blindness paradigm under frontal transcranial direct current stimulation (tDCS). Results show the expected distractor-induced deafness effects in a reduction of target detection depending on the number of distractors. While tDCS had no significant effects on target detection per se, error rates due to missed cues are increased under stimulation. Thus, while our variant led to successful replication of behavioral deafness effects, the results under tDCS stimulation indicate that the chosen paradigm may have difficulty too low to respond to stimulation. That the error rates nevertheless led to a tDCS effect may be due to the divided attention between the visual cue and the auditory target.
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20
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Olgiati E, Malhotra PA. Using non-invasive transcranial direct current stimulation for neglect and associated attentional deficits following stroke. Neuropsychol Rehabil 2022; 32:732-763. [PMID: 32892712 DOI: 10.1080/09602011.2020.1805335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Neglect is a disabling neuropsychological syndrome that is frequently observed following right-hemispheric stroke. Affected individuals often present with multiple attentional deficits, ranging from reduced orienting towards contralesional space to a generalized impairment in maintaining attention over time. Although a degree of spontaneous recovery occurs in most patients, in some individuals this condition can be treatment-resistant with prominent ongoing non-spatial deficits. Further, there is a large inter-individual variability in response to different therapeutic approaches. Given its potential to alter neuronal excitability and affect neuroplasticity, non-invasive brain stimulation is a promising tool that could potentially be utilized to facilitate recovery. However, there are many outstanding questions regarding its implementation in this heterogeneous patient group. Here we provide a critical overview of the available evidence on the use of non-invasive electrical brain stimulation, focussing on transcranial direct current stimulation (tDCS), to improve neglect and associated attentional deficits after right-hemispheric stroke. At present, there is insufficient robust evidence supporting the clinical use of tDCS to alleviate symptoms of neglect. Future research would benefit from careful study design, enhanced precision of electrical montages, multi-modal approaches exploring predictors of response, tailored dose-control applications and increased efforts to evaluate standalone tDCS versus its incorporation into combination therapy.
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Affiliation(s)
- Elena Olgiati
- Department of Brain Sciences, Imperial College London, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Paresh A Malhotra
- Department of Brain Sciences, Imperial College London, London, UK.,Imperial College Healthcare NHS Trust, London, UK.,UK Dementia Research Institute, Care Research & Technology Centre, Imperial College London and University of Surrey, London, UK
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21
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Inter-Individual Variability in tDCS Effects: A Narrative Review on the Contribution of Stable, Variable, and Contextual Factors. Brain Sci 2022; 12:brainsci12050522. [PMID: 35624908 PMCID: PMC9139102 DOI: 10.3390/brainsci12050522] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 04/08/2022] [Accepted: 04/14/2022] [Indexed: 01/27/2023] Open
Abstract
Due to its safety, portability, and cheapness, transcranial direct current stimulation (tDCS) use largely increased in research and clinical settings. Despite tDCS’s wide application, previous works pointed out inconsistent and low replicable results, sometimes leading to extreme conclusions about tDCS’s ineffectiveness in modulating behavioral performance across cognitive domains. Traditionally, this variability has been linked to significant differences in the stimulation protocols across studies, including stimulation parameters, target regions, and electrodes montage. Here, we reviewed and discussed evidence of heterogeneity emerging at the intra-study level, namely inter-individual differences that may influence the response to tDCS within each study. This source of variability has been largely neglected by literature, being results mainly analyzed at the group level. Previous research, however, highlighted that only a half—or less—of studies’ participants could be classified as responders, being affected by tDCS in the expected direction. Stable and variable inter-individual differences, such as morphological and genetic features vs. hormonal/exogenous substance consumption, partially account for this heterogeneity. Moreover, variability comes from experiments’ contextual elements, such as participants’ engagement/baseline capacity and individual task difficulty. We concluded that increasing knowledge on inter-dividual differences rather than undermining tDCS effectiveness could enhance protocols’ efficiency and reproducibility.
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22
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Mind-wandering: mechanistic insights from lesion, tDCS, and iEEG. Trends Cogn Sci 2022; 26:268-282. [PMID: 35086725 PMCID: PMC9166901 DOI: 10.1016/j.tics.2021.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 01/04/2023]
Abstract
Cognitive neuroscience has witnessed a surge of interest in investigating the neural correlates of the mind when it drifts away from an ongoing task and the external environment. To that end, functional neuroimaging research has consistently implicated the default mode network (DMN) and frontoparietal control network (FPCN) in mind-wandering. Yet, it remains unknown which subregions within these networks are necessary and how they facilitate mind-wandering. In this review, we synthesize evidence from lesion, transcranial direct current stimulation (tDCS), and intracranial electroencephalogram (iEEG) studies demonstrating the causal relevance of brain regions, and providing insights into the neuronal mechanism underlying mind-wandering. We propose that the integration of complementary approaches is the optimal strategy to establish a comprehensive understanding of the neural basis of mind-wandering.
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23
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Zeng D, Yan X, Deng H, Li J, Xiao J, Yuan J, Huang J, Xu N, Fu W, Jianhua L. Placebo response vary between different types of sham acupuncture: A randomized double-blind trial in neck pain patients. Eur J Pain 2022; 26:1006-1020. [PMID: 35129852 PMCID: PMC9305463 DOI: 10.1002/ejp.1924] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 08/31/2021] [Accepted: 02/05/2022] [Indexed: 11/06/2022]
Abstract
Background In prospective experimental studies of neck pain patients, it is difficult to determine whether responses to sham acupuncture differ from responses to real acupuncture due to the heterogeneous methodologies in control/sham interventions. Here we aim to compare the specific and nonspecific effects of electroacupuncture with four types of sham acupuncture. Methods In this double‐blind, sham‐controlled study, we randomly assigned 175 patients with neck pain to receive 10 sessions of electroacupuncture, shallow puncture, nonacupoint deep puncture, nonacupoint shallow puncture, or nonpenetration acupuncture. We used the Northwick Park Neck Pain Questionnaire (NPQ) as our primary outcome, and Short‐form McGill Pain Questionnaire, visual analog scale (VAS), and Pain Threshold as secondary outcomes to measure the changes from baseline to a 3‐month follow up. Results All groups, except nonacupoint shallow puncture, had significant improvement in all outcome measurements. Electroacupuncture only showed superior improvements than the shallow puncture, nonacupoint shallow puncture, and nonpenetration groups when compared using the NPQ and VAS scale (*p < 0.001). Interestingly, the nonacupoint shallow puncture produced even less placebo response than nonpenetration acupuncture. Conclusion Our study demonstrates the high variability of placebo response among different types of sham controls depending on the depth of needle insertion and the puncture location. An important implication of our results is nonacupoint deep puncture produced similar analgesic effects as electroacupuncture. Our study may shed a new light on the predominant underlying mechanisms among different types of sham acupuncture controls, which can help with interpreting the effect of acupuncture in other studies. Trial registration Chinese clinical trial registry (ChiCTR‐IOR‐15006886). Significance This study compared the observed specific and nonspecific analgesia effect in four different types of sham acupuncture stimulation with neck pain patients, assessed by four outcomes. Although all of the sham controls produced significant reduction in neck pain, electroacupuncture had superior significant improvement. Importantly, placebo responses differed significantly between the sham controls and responses were inconsistent according to different outcome assessments. This study emphasizes the importance of taking into consideration which sham control and method of outcome measurement were used in a pain research study when evaluating its results.
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Affiliation(s)
- Dian Zeng
- Acupuncture Research Team, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xiaoxia Yan
- Acupuncture Research Team, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Hongmei Deng
- Acupuncture Research Team, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jiemei Li
- Acupuncture Research Team, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jiaxin Xiao
- Acupuncture Research Team, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jiawei Yuan
- Acupuncture Research Team, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jianpeng Huang
- Acupuncture Research Team, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Nenggui Xu
- South China Research Center for Acupuncture, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wenbin Fu
- Acupuncture Research Team, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Liu Jianhua
- Acupuncture Research Team, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
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No effects of transcranial direct current stimulation on visual evoked potential and peak gamma frequency. Cogn Process 2022; 23:235-254. [PMID: 35099659 DOI: 10.1007/s10339-022-01076-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 01/12/2022] [Indexed: 11/03/2022]
Abstract
Evidence suggests that the visual evoked potential (VEP) and gamma oscillations elicited by visual stimuli reflect the balance of excitatory and inhibitory (E-I) cortical processes. As tDCS has been shown to modulate E-I balance, the current study investigated whether amplitudes of VEP components (N1 and P2) and peak gamma frequency are modulated by transcranial direct current stimulation (tDCS). Healthy adults underwent two electroencephalography (EEG) recordings while viewing stimuli designed to elicit a robust visual response. Between the two recordings, participants were randomly assigned to three tDCS conditions (anodal-, cathodal-, and sham-tDCS) or received no-tDCS. tDCS electrodes were placed over the occipital cortex (Oz) and the left cheek with an intensity of 2 mA for 10 min. Data of 39 participants were analysed for VEP amplitudes and peak gamma frequency using mixed-model ANOVAs. The results showed no main effects of tDCS in any metric. Possible explanations for the absence of tDCS effects are discussed.
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Ward N, Hussey E, Wooten T, Marfeo E, Brunyé TT. Modulating Cognitive–Motor Multitasking with Commercial-off-the-Shelf Non-Invasive Brain Stimulation. Brain Sci 2022; 12:brainsci12020180. [PMID: 35203943 PMCID: PMC8870640 DOI: 10.3390/brainsci12020180] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 01/26/2022] [Accepted: 01/28/2022] [Indexed: 02/04/2023] Open
Abstract
One growing area of multitasking research involves a focus on performing cognitive and motor tasks in tandem. In these situations, increasing either cognitive or motor demands has implications for performance in both tasks, an effect which is thought to be due to competing neural resources. Separate research suggests that non-invasive brain stimulation may offer a means to mitigate performance decrements experienced during multitasking. In the present study, we investigated the degree to which a commercially available non-invasive brain stimulation device (Halo Sport) alters balance performance in the presence of different types of cognitive demands. Specifically, we tested if performing a secondary cognitive task impacts postural sway in healthy young adults and if we could mitigate this impact using transcranial direct current stimulation (tDCS) applied over the primary motor cortex. Furthermore, we included conditions of unstable and stable surfaces and found that lower surface stability increased postural sway. In addition, we found that cognitive load impacted postural sway but in the opposite pattern we had anticipated, with higher sway found in the single-task control condition compared to executive function conditions. Finally, we found a small but significant effect of tDCS on balance with decreased sway for active (compared to sham) tDCS.
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Affiliation(s)
- Nathan Ward
- Department of Psychology, Tufts University, Medford, MA 02155, USA;
- Correspondence:
| | - Erika Hussey
- Defense Innovation Unit, Mountain View, CA 94043, USA;
| | - Thomas Wooten
- Department of Psychology, Tufts University, Medford, MA 02155, USA;
| | - Elizabeth Marfeo
- Department of Occupational Therapy, Tufts University, Medford, MA 02155, USA;
| | - Tad T. Brunyé
- U.S. Army DEVCOM Soldier Center, Natick, MA 01760, USA;
- Center for Applied Brain & Cognitive Sciences, Tufts University, Medford, MA 02155, USA
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26
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Stanković M, Živanović M, Bjekić J, Filipović SR. Blinding in tDCS Studies: Correct End-of-Study Guess Does Not Moderate the Effects on Associative and Working Memory. Brain Sci 2021; 12:brainsci12010058. [PMID: 35053802 PMCID: PMC8773753 DOI: 10.3390/brainsci12010058] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/27/2021] [Accepted: 12/27/2021] [Indexed: 11/16/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) has become a valuable tool in cognitive neuroscience research as it enables causal inferences about neural underpinnings of cognition. However, studies using tDCS to modulate cognitive functions often yield inconsistent findings. Hence, there is an increasing interest in factors that may moderate the effects, one of which is the participants’ beliefs of the tDCS condition (i.e., real or sham) they received. Namely, whether participants’ correct guessing of sham condition may lead to false-positive tDCS effects. In this study, we aimed to explore if participants’ beliefs about received stimulation type (i.e., the success of blinding) impacted their task performance in tDCS experiments on associative (AM) and working memory (WM). We analyzed data from four within-subject, sham-controlled tDCS memory experiments (N = 83) to check if the correct end-of-study guess of sham condition moderated tDCS effects. We found no evidence that sham guessing moderated post-tDCS memory performance in experiments in which tDCS effects were observed as well as in experiments that showed null effects of tDCS. The results suggest that the correct sham guessing (i.e., placebo-like effect) is unlikely to influence the results in tDCS memory experiments. We discuss the results in light of the growing debate about the relevance and effectiveness of blinding in brain stimulation research.
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Affiliation(s)
- Marija Stanković
- Human Neuroscience Group, Institute for Medical Research, University of Belgrade, 11000 Belgrade, Serbia; (M.S.); (S.R.F.)
| | - Marko Živanović
- Institute of Psychology and Laboratory for Research of Individual Differences, Department of Psychology, Faculty of Philosophy, University of Belgrade, 11000 Belgrade, Serbia;
| | - Jovana Bjekić
- Human Neuroscience Group, Institute for Medical Research, University of Belgrade, 11000 Belgrade, Serbia; (M.S.); (S.R.F.)
- Correspondence:
| | - Saša R. Filipović
- Human Neuroscience Group, Institute for Medical Research, University of Belgrade, 11000 Belgrade, Serbia; (M.S.); (S.R.F.)
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27
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The Role of Expectation and Beliefs on the Effects of Non-Invasive Brain Stimulation. Brain Sci 2021; 11:brainsci11111526. [PMID: 34827526 PMCID: PMC8615662 DOI: 10.3390/brainsci11111526] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/14/2021] [Accepted: 11/16/2021] [Indexed: 11/25/2022] Open
Abstract
Non-invasive brain stimulation (NIBS) techniques are used in clinical and cognitive neuroscience to induce a mild magnetic or electric field in the brain to modulate behavior and cortical activation. Despite the great body of literature demonstrating promising results, unexpected or even paradoxical outcomes are sometimes observed. This might be due either to technical and methodological issues (e.g., stimulation parameters, stimulated brain area), or to participants’ expectations and beliefs before and during the stimulation sessions. In this narrative review, we present some studies showing that placebo and nocebo effects, associated with positive and negative expectations, respectively, could be present in NIBS trials, both in experimental and in clinical settings. The lack of systematic evaluation of subjective expectations and beliefs before and after stimulation could represent a caveat that overshadows the potential contribution of placebo and nocebo effects in the outcome of NIBS trials.
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28
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Fietsam AC, Deters JR, Workman CD, Ponto LLB, Rudroff T. Alterations in Leg Muscle Glucose Uptake and Inter-Limb Asymmetry after a Single Session of tDCS in Four People with Multiple Sclerosis. Brain Sci 2021; 11:brainsci11101363. [PMID: 34679427 PMCID: PMC8533729 DOI: 10.3390/brainsci11101363] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/10/2021] [Accepted: 10/14/2021] [Indexed: 01/11/2023] Open
Abstract
Asymmetrical lower limb weakness is an early symptom and significant contributor to the progressive worsening of walking ability in people with multiple sclerosis (PwMS). Transcranial direct current stimulation (tDCS) may effectively increase neural drive to the more-affected lower limb and, therefore, increase symmetrical activation. Four PwMS (1 female, age range: 27–57) underwent one session each of 3 mA or SHAM tDCS over the motor cortex corresponding to their more-affected limb followed by 20 min of treadmill walking at a self-selected speed. Two min into the treadmill task, the subjects were injected with the glucose analog [18F]fluorodeoxyglucose (FDG). Immediately after treadmill walking, the subjects underwent whole-body positron emission tomography (PET) imaging. Glucose uptake (GU) values were compared between the legs, the spatial distribution of FDG was assessed to estimate glucose uptake heterogeneity (GUh), and GU asymmetry indices (AIs) were calculated. After tDCS, GU was altered, and GUh was decreased in various muscle groups in each subject. Additionally, AIs went from asymmetric to symmetric after tDCS in the subjects that demonstrated asymmetrical glucose uptake during SHAM. These results indicate that tDCS improved GU asymmetries, potentially from an increased neural drive and a more efficient muscle activation strategy of the lower limb in PwMS.
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Affiliation(s)
- Alexandra C. Fietsam
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA 52242, USA; (A.C.F.); (J.R.D.); (C.D.W.)
| | - Justin R. Deters
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA 52242, USA; (A.C.F.); (J.R.D.); (C.D.W.)
| | - Craig D. Workman
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA 52242, USA; (A.C.F.); (J.R.D.); (C.D.W.)
| | - Laura L. Boles Ponto
- Department of Radiology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA;
| | - Thorsten Rudroff
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA 52242, USA; (A.C.F.); (J.R.D.); (C.D.W.)
- Department of Neurology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA
- Correspondence: ; Tel.: +1-319-467-0363
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29
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Jo NG, Kim GW, Won YH, Park SH, Seo JH, Ko MH. Timing-Dependent Effects of Transcranial Direct Current Stimulation on Hand Motor Function in Healthy Individuals: A Randomized Controlled Study. Brain Sci 2021; 11:brainsci11101325. [PMID: 34679390 PMCID: PMC8534210 DOI: 10.3390/brainsci11101325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 09/30/2021] [Accepted: 09/30/2021] [Indexed: 11/18/2022] Open
Abstract
The timing of transcranial direct current stimulation (tDCS) is essential for enhancing motor skill learning. Previously, tDCS, before or concurrently, with motor training was evaluated in healthy volunteers or elderly patients, but the optimal timing of stimulation has not been determined. In this study, we aimed to optimize the existing tDCS protocols by exploring the timing-dependent stimulation effects on finger movements in healthy individuals. We conducted a single-center, prospective, randomized controlled trial. The study participants (n = 39) were randomly assigned into three groups: tDCS concurrently with finger tapping training (CON), tDCS prior to finger tapping training (PRI), and SHAM-tDCS simultaneously with finger tapping training (SHAM). In all groups, the subjects participated in five 40-min training sessions for one week. Motor performance was measured before and after treatment using the finger-tapping task (FTT), the grooved pegboard test (GPT), and hand strength tests. tDCS treatment prior to finger tapping training significantly improved motor skill learning, as indicated by the GPT and hand strength measurements. In all groups, the treatment improved the FTT performance. Our results indicate that applying tDCS before training could be optimal for enhancing motor skill learning. Further research is required to confirm these findings.
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Affiliation(s)
- Nam-Gyu Jo
- Department of Physical Medicine & Rehabilitation, Jeonbuk National University Medical School, Geonjiro 20, Deokjin-gu, Jeonju 54097, Korea; (N.-G.J.); (G.-W.K.); (Y.H.W.); (S.-H.P.); (J.-H.S.)
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Geonjiro 20, Deokjin-gu, Jeonju 54907, Korea
| | - Gi-Wook Kim
- Department of Physical Medicine & Rehabilitation, Jeonbuk National University Medical School, Geonjiro 20, Deokjin-gu, Jeonju 54097, Korea; (N.-G.J.); (G.-W.K.); (Y.H.W.); (S.-H.P.); (J.-H.S.)
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Geonjiro 20, Deokjin-gu, Jeonju 54907, Korea
| | - Yu Hui Won
- Department of Physical Medicine & Rehabilitation, Jeonbuk National University Medical School, Geonjiro 20, Deokjin-gu, Jeonju 54097, Korea; (N.-G.J.); (G.-W.K.); (Y.H.W.); (S.-H.P.); (J.-H.S.)
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Geonjiro 20, Deokjin-gu, Jeonju 54907, Korea
| | - Sung-Hee Park
- Department of Physical Medicine & Rehabilitation, Jeonbuk National University Medical School, Geonjiro 20, Deokjin-gu, Jeonju 54097, Korea; (N.-G.J.); (G.-W.K.); (Y.H.W.); (S.-H.P.); (J.-H.S.)
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Geonjiro 20, Deokjin-gu, Jeonju 54907, Korea
| | - Jeong-Hwan Seo
- Department of Physical Medicine & Rehabilitation, Jeonbuk National University Medical School, Geonjiro 20, Deokjin-gu, Jeonju 54097, Korea; (N.-G.J.); (G.-W.K.); (Y.H.W.); (S.-H.P.); (J.-H.S.)
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Geonjiro 20, Deokjin-gu, Jeonju 54907, Korea
| | - Myoung-Hwan Ko
- Department of Physical Medicine & Rehabilitation, Jeonbuk National University Medical School, Geonjiro 20, Deokjin-gu, Jeonju 54097, Korea; (N.-G.J.); (G.-W.K.); (Y.H.W.); (S.-H.P.); (J.-H.S.)
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Geonjiro 20, Deokjin-gu, Jeonju 54907, Korea
- Correspondence: ; Tel.: +82-63-250-1795; Fax: +82-63-254-4145
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30
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Friehs MA, Frings C, Hartwigsen G. Effects of single-session transcranial direct current stimulation on reactive response inhibition. Neurosci Biobehav Rev 2021; 128:749-765. [PMID: 34271027 DOI: 10.1016/j.neubiorev.2021.07.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 06/30/2021] [Accepted: 07/11/2021] [Indexed: 01/03/2023]
Abstract
Transcranial direct current stimulation (tDCS) is widely used to explore the role of various cortical regions for reactive response inhibition. In recent years, tDCS studies reported polarity-, time- and stimulation-site dependent effects on response inhibition. Given the large parameter space in which study designs, tDCS procedures and task procedures can differ, it is crucial to systematically explore the existing tDCS literature to increase the current understanding of potential modulatory effects and limitations of different approaches. We performed a systematic review on the modulatory effects of tDCS on response inhibition as measured by the Stop-Signal Task. The final dataset shows a large variation in methodology and heterogeneous effects of tDCS on performance. The most consistent result across studies is a performance enhancement due to anodal tDCS over the right prefrontal cortex. Partially sub-optimal choices in study design, methodology and lacking consistency in reporting procedures may impede valid conclusions and obscured the effects of tDCS on response inhibition in some previous studies. Finally, we outline future directions and areas to improve research.
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Affiliation(s)
| | - Christian Frings
- Trier University, Department of Cognitive Psychology and Methodology, Trier, Germany
| | - Gesa Hartwigsen
- Lise Meitner Research Group Cognition and Plasticity, Max Planck Institute for Human Cognitive Brain Sciences, Leipzig, Germany
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31
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Friehs MA, Greene C, Pastötter B. Transcranial direct current stimulation over the left anterior temporal lobe during memory retrieval differentially affects true and false recognition in the DRM task. Eur J Neurosci 2021; 54:4609-4620. [PMID: 34076917 DOI: 10.1111/ejn.15337] [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] [Received: 03/01/2021] [Revised: 05/06/2021] [Accepted: 05/24/2021] [Indexed: 01/13/2023]
Abstract
Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that has been used to modulate human brain activity and cognition. One area which has not yet been extensively explored using tDCS is the generation of false memories. In this study, we combined the Deese-Roediger-McDermott (DRM) task with stimulation of the left anterior temporal lobe (ATL) during retrieval. This area has been shown to be involved in semantic processing in general and retrieval of false memories in the DRM paradigm in particular. During stimulation, 0.7 mA were applied via a 9 cm² electrode over the left ATL, with the 35 cm² return electrode placed over the left deltoid. We contrasted the effects of cathodal, anodal, and sham stimulation, which were applied in the recognition phase of the experiment on a sample of 78 volunteers. Results showed impaired recognition of true memories after both anodal and cathodal stimulation in comparison to sham stimulation, suggesting a reduced signal-to-noise ratio. In addition, the results revealed enhanced false recognition of concept lure items during cathodal stimulation compared to anodal stimulation, indicating a polarity-dependent impact of tDCS on false memories in the DRM task. The pathway by which tDCS modulated false recognition remains unclear: stimulation may have changed the activation of irrelevant lures or affected the weighting and monitoring of lure activations. Nevertheless, these results are a first step towards using brain stimulation to decrease false memories. Practical implications of the findings for real-life settings, for example, in the courtroom, need to be addressed in future work.
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Affiliation(s)
| | - Ciara Greene
- School of Psychology, University College Dublin, Dublin, Ireland
| | - Bernhard Pastötter
- Department of Cognitive Psychology and Methodology, Trier University, Trier, Germany
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Quinlan C, Rattray B, Pryor D, Northey JM, Coxon J, Cherbuin N, Andrews SC. A Short-Term Intervention of High-Intensity Exercise and Anodal-tDCS on Motor Learning in Middle-Aged Adults: An RCT. Front Hum Neurosci 2021; 15:661079. [PMID: 34220470 PMCID: PMC8241928 DOI: 10.3389/fnhum.2021.661079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 05/21/2021] [Indexed: 11/23/2022] Open
Abstract
High-intensity exercise has enhanced motor learning in healthy young adults. Anodal-transcranial direct current stimulation (a-tDCS) may optimize these effects. This study aimed to determine the effects of a short-term high-intensity interval exercise intervention either with or without a-tDCS on the learning and retention of a novel motor task in middle-aged adults. Forty-two healthy middle-aged adults (age = 44.6 ± 6.3, female = 76%) were randomized into three groups: exercise and active a-tDCS, exercise and sham a-tDCS, and a non-exercise and sham a-tDCS control. Participants completed a baseline testing session, followed by three intervention sessions 48-h apart. The exercise groups completed 20-min of high-intensity exercise followed by a novel sequential visual isometric pinch task (SVIPT) while receiving 20-min of 1.5 mA a-tDCS, or sham tDCS. The control group completed 20-min of reading before receiving sham a-tDCS during the SVIPT. Learning was assessed by skill change within and between intervention sessions. Participants returned 5–7 days after the final intervention session and performed the SVIPT task to assess retention. All three groups showed evidence of learning on the SVIPT task. Neither group displayed enhanced overall learning or retention when compared to the control group. High-intensity exercise with or without a-tDCS did not improve learning or retention of a novel motor task in middle-aged adults. The methodological framework provides direction for future research to investigate the potential of differing exercise intensity effects on learning and retention.
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Affiliation(s)
- Clare Quinlan
- UC Research Institute for Sport and Exercise, University of Canberra, Canberra, ACT, Australia.,Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, Canberra, ACT, Australia
| | - Ben Rattray
- UC Research Institute for Sport and Exercise, University of Canberra, Canberra, ACT, Australia.,Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, Canberra, ACT, Australia.,Centre for Research on Ageing, Health and Wellbeing, Australian National University, Canberra, ACT, Australia
| | - Disa Pryor
- Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, Canberra, ACT, Australia
| | - Joseph M Northey
- UC Research Institute for Sport and Exercise, University of Canberra, Canberra, ACT, Australia.,Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, Canberra, ACT, Australia.,Centre for Research on Ageing, Health and Wellbeing, Australian National University, Canberra, ACT, Australia
| | - James Coxon
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Nicolas Cherbuin
- Centre for Research on Ageing, Health and Wellbeing, Australian National University, Canberra, ACT, Australia
| | - Sophie C Andrews
- Centre for Research on Ageing, Health and Wellbeing, Australian National University, Canberra, ACT, Australia.,Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia.,Neuroscience Research Australia, Randwick, NSW, Australia.,School of Psychology, University of New South Wales, Sydney, NSW, Australia
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33
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Stevens CE, Lausen MA, Wagstaff LE, McRae TR, Pittman BR, Amthor FR, Boggiano MM. Effect of transcranial direct current stimulation (tDCS) on food craving and eating when using a control method that minimizes guessing of the real vs. control condition. Eat Weight Disord 2021; 26:1669-1674. [PMID: 32748372 DOI: 10.1007/s40519-020-00970-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 07/24/2020] [Indexed: 02/04/2023] Open
Abstract
PURPOSE Validation of transcranial direct current stimulation (tDCS) to treat obesity is hampered by evidence that participants can distinguish real from the traditional-control condition. Correctly guessing the real condition precludes knowing if it is neuromodulation or expectation that suppresses food craving and eating. Therefore, this study tested the putative efficacy of tDCS to the dorsolateral prefrontal cortex (DLPFC) to reduce food craving and eating when an alternative control condition was used that would be difficult to distinguish from the real condition. METHODS N = 28 adults with a 26-50 BMI range received a typical 20-min 2 mA current session of tDCS targeting the DLPFC as the real condition and a same duration/current tDCS session targeting the sensorimotor cortex (SMC), a region not expected to affect appetite, as the control. Food image craving ratings, in-lab food consumption, and momentary ratings of physical sensations were measured. RESULTS DLPFC failed to reduce food craving and consumption compared to SMC stimulation. When interviewed, 71% of participants were unable to guess real from control conditions. Those who guessed DLPFC tDCS as real attributed their guess to increased number and frequency of sensations. However, their sensation ratings during tDCS did not differ between conditions. CONCLUSIONS The results question if tDCS suppresses craving and eating at all, or if the DLPFC is the best target to do so. The results also indicate that alternate-site constant stimulation as the control method may strengthen the scientific evaluation of tDCS to treat obesity. LEVEL OF EVIDENCE Level I, experimental study.
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Affiliation(s)
- Carl E Stevens
- Department of Psychology, The University of Alabama at Birmingham, 415 Campbell Hall, 1300 University Blvd., Birmingham, AL, 35294-1170, USA
| | - Marissa A Lausen
- Department of Psychology, The University of Alabama at Birmingham, 415 Campbell Hall, 1300 University Blvd., Birmingham, AL, 35294-1170, USA
| | - Laura E Wagstaff
- Department of Psychology, The University of Alabama at Birmingham, 415 Campbell Hall, 1300 University Blvd., Birmingham, AL, 35294-1170, USA
| | - Tommy R McRae
- Department of Psychology, The University of Alabama at Birmingham, 415 Campbell Hall, 1300 University Blvd., Birmingham, AL, 35294-1170, USA
| | - Bethany R Pittman
- Department of Psychology, The University of Alabama at Birmingham, 415 Campbell Hall, 1300 University Blvd., Birmingham, AL, 35294-1170, USA
| | - Franklin R Amthor
- Department of Psychology, The University of Alabama at Birmingham, 415 Campbell Hall, 1300 University Blvd., Birmingham, AL, 35294-1170, USA
| | - Mary M Boggiano
- Department of Psychology, The University of Alabama at Birmingham, 415 Campbell Hall, 1300 University Blvd., Birmingham, AL, 35294-1170, USA.
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The impact of transcranial Direct Current stimulation on rumination: A systematic review of the sham-controlled studies in healthy and clinical samples. Compr Psychiatry 2021; 106:152226. [PMID: 33581448 DOI: 10.1016/j.comppsych.2021.152226] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 12/16/2020] [Accepted: 12/20/2020] [Indexed: 01/27/2023] Open
Abstract
INTRODUCTION Broadly considered a transdiagnostic feature of psychological disorders, rumination is associated with lower treatment response, slower recovery rates, and higher relapse rates. Accordingly, research has focused on the development of interventions to alleviate rumination. Recently, transcranial Direct Current Stimulation (tDCS) has emerged as a promising tool to do so. METHODS We performed a systematic review of sham-controlled tDCS studies targeting rumination among healthy participants or patients with psychiatric disorders, investigating the effectiveness of tDCS in reducing rumination, and assessing the research quality of this nascent field. RESULTS We identified nine studies, with five reporting a significant impact of tDCS on rumination. We also outlined a few tDCS parameters (e.g., stimulation duration, electrode size) and research methods' features (e.g., within- versus between-research designs) characterizing those positive-finding studies. However, these studies were characterized by substantial heterogeneity (e.g., methodological flaws, lack of open science practices), precluding any definite statement about the best way to target rumination via tDCS. Moreover, several strong methodological limitations were also present across those studies. DISCUSSION Although our systematic review identifies the strengths and weaknesses of the available research about the impact of tDCS on rumination, it calls for strong efforts to improve this nascent field's current methodological caveats. We discuss how open science practices can help to usher this field forward.
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Suleman R, Tucker BV, Dursun SM, Demas ML. The Neurostimulation of the Brain in Depression Trial: Protocol for a Randomized Controlled Trial of Transcranial Direct Current Stimulation in Treatment-Resistant Depression. JMIR Res Protoc 2021; 10:e22805. [PMID: 33729165 PMCID: PMC8088846 DOI: 10.2196/22805] [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] [Received: 07/28/2020] [Revised: 01/20/2021] [Accepted: 02/18/2021] [Indexed: 01/28/2023] Open
Abstract
Background Major depressive disorder (MDD) is the second highest cause of disability worldwide. Standard treatments for MDD include medicine and talk therapy; however, approximately 1 in 5 Canadians fail to respond to these approaches and must consider alternatives. Transcranial direct current stimulation (tDCS) is a safe, noninvasive method that uses electrical stimulation to change the activation pattern of different brain regions. By targeting those regions known to be affected in MDD, tDCS may be useful in ameliorating treatment-resistant depression. Objective The objective of the Neurostimulation of the Brain in Depression trial is to compare the effectiveness of active versus sham tDCS in treating patients with ultraresistant MDD. The primary outcome will be the improvement in depressive symptoms, as measured by the change on the Mongtomery-Asberg Depression Rating Scale. Secondary outcomes will include changes in the Quick Inventory of Depressive Symptomatology Scale (subjective assessment), the World Health Organization Disability Assessment Schedule 2.0 (functional assessment), and the Screen for Cognitive Impairment in Psychiatry (cognitive assessment). Adverse events will be captured using the Young Mania Rating Scale; tDCS Adverse Events Questionnaire; Frequency, Intensity, and Burden of Side Effects Rating Scale; and Patient-Rated Inventory of Side Effects Scale. A parallel component of the study will involve assaying for baseline language function and the effect of treatment on language using an exploratory acoustic and semantic corpus analysis on recorded interviews. Participant accuracy and response latency on an auditory lexical decision task will also be evaluated. Methods We will recruit inpatients and outpatients in the city of Edmonton, Alberta, and will deliver the study interventions at the Grey Nuns and University of Alberta Hospitals. Written informed consent will be obtained from all participants before enrollment. Eligible participants will be randomly assigned, in a double-blinded fashion, to receive active or sham tDCS, and they will continue receiving their usual pharmacotherapy and psychotherapy throughout the trial. In both groups, participants will receive 30 weekday stimulation sessions, each session being 30 minutes in length, with the anode over the left dorsolateral prefrontal cortex and the cathode over the right. Participants in the active group will be stimulated at 2 mA throughout, whereas the sham group will receive only a brief period of stimulation to mimic skin sensations felt in the active group. Measurements will be conducted at regular points throughout the trial and 30 days after trial completion. Results The trial has been approved by the University of Alberta Research Ethics Board and is scheduled to commence in June 2021. The target sample size is 60 participants. Conclusions This is a protocol for a multicenter, double-blinded, randomized controlled superiority trial comparing active versus sham tDCS in patients with treatment-resistant MDD. Trial Registration ClinicalTrials.gov NCT04159012; http://clinicaltrials.gov/ct2/show/NCT04159012. International Registered Report Identifier (IRRID) PRR1-10.2196/22805
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Affiliation(s)
- Raheem Suleman
- Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Benjamin V Tucker
- Department of Linguistics, Faculty of Arts, University of Alberta, Edmonton, AB, Canada
| | - Serdar M Dursun
- Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.,Grey Nuns Community Hospital, Edmonton, AB, Canada
| | - Michael L Demas
- Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.,Grey Nuns Community Hospital, Edmonton, AB, Canada
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Garofalo S, Battaglia S, Starita F, di Pellegrino G. Modulation of cue-guided choices by transcranial direct current stimulation. Cortex 2021; 137:124-137. [PMID: 33609898 DOI: 10.1016/j.cortex.2021.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 11/13/2020] [Accepted: 01/13/2021] [Indexed: 10/22/2022]
Abstract
Environmental cues may anticipate the availability of rewards, thus acting as a guide towards a specific choice (i.e., cue-guided choices). Despite the lateral prefrontal cortex having a critical role in using past learning and flexibly selecting relevant information to guide behavior, the literature on the neural basis of human cue-guided choice mainly focused on the subcortical brain structures implicated, while the specific role of cortical areas remained unclear. The present study aimed to provide causal evidence for the involvement of the lateral prefrontal cortex in two forms of human cue-guided choice, namely outcome-specific and general. To do this, 2 mA cathodal, anodal or sham transcranial direct current stimulation was applied over the lateral prefrontal cortex (with the posterior parietal cortex serving as control region) in three separate groups performing a Pavlovian-to-Instrumental Transfer task. Results showed, for the first time, a dissociation in the cortical structures involved in human cue-guided choice. Cathodal stimulation of the lateral prefrontal cortex reduced the outcome-specific transfer. In striking contrast, there was no influence on the general transfer. These results argue in favor of the presence of at least two possible neural pathways underlying cue-guided choices.
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Affiliation(s)
- Sara Garofalo
- Department of Psychology, University of Bologna, Cesena, Italy.
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Boayue NM, Csifcsák G, Kreis IV, Schmidt C, Finn I, Hovde Vollsund AE, Mittner M. The interplay between executive control, behavioural variability and mind wandering: Insights from a high-definition transcranial direct-current stimulation study. Eur J Neurosci 2020; 53:1498-1516. [PMID: 33220131 DOI: 10.1111/ejn.15049] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 11/05/2020] [Accepted: 11/15/2020] [Indexed: 12/23/2022]
Abstract
While the involvement of executive processes in mind wandering is largely undebated, their exact relationship is subject to an ongoing debate and rarely studied dynamically within-subject. Several brain-stimulation studies using transcranial direct current stimulation (tDCS) have attempted to modulate mind-wandering propensity by stimulating the left dorsolateral prefrontal cortex (DLPFC) which is an important hub in the prefrontal control network. In a series of three studies testing a total of N = 100 participants, we develop a novel task that allows to study the dynamic interplay of mind wandering, behavioural varibility and the flexible recruitment of executive resources as indexed by the randomness (entropy) of movement sequences generated by our participants. We consistently find that behavioural variability is increased and randomness is decreased during periods of mind wandering. Interestingly, we also find that behavioural variability interacts with the entropy-MW effect, opening up the possibility to detect distinct states of off-focus cognition. When applying a high-definition transcranial direct-current stimulation (HD-tDCS) montage to the left DLPFC, we find that propensity to mind wander is reduced relative to a group receiving sham stimulation.
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Affiliation(s)
- Nya M Boayue
- Institute for Psychology, UiT The Arctic University of Norway, Tromsø, Norway
| | - Gábor Csifcsák
- Institute for Psychology, UiT The Arctic University of Norway, Tromsø, Norway
| | - Isabel V Kreis
- Institute for Psychology, UiT The Arctic University of Norway, Tromsø, Norway
| | - Carole Schmidt
- Institute for Psychology, UiT The Arctic University of Norway, Tromsø, Norway
| | - Iselin Finn
- Institute for Psychology, UiT The Arctic University of Norway, Tromsø, Norway
| | | | - Matthias Mittner
- Institute for Psychology, UiT The Arctic University of Norway, Tromsø, Norway
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Workman CD, Fietsam AC, Kamholz J, Rudroff T. Women report more severe sensations from 2 mA and 4 mA transcranial direct current stimulation than men. Eur J Neurosci 2020; 53:2696-2702. [PMID: 33259084 DOI: 10.1111/ejn.15070] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/24/2020] [Accepted: 11/25/2020] [Indexed: 01/29/2023]
Abstract
Interest in transcranial direct current stimulation (tDCS) to alter cortical excitability, facilitate neural plasticity, and improve performance is increasing. Subjects often report temporary stimulation-related sensations, which might distract from the task being performed or compromise blinding. tDCS is also prone to high outcome irregularity and one potential variability source is the biological sex of the subject. The purpose of this study was to re-analyze existing tolerability data to ascertain any sex differences in sensation severity and blinding guesses from tDCS at 2 mA and 4 mA. Each subject underwent tDCS at three randomly ordered intensities (sham, 2 mA, 4 mA), reported the severity sensations experienced, and guessed which tDCS condition they underwent (blinding). Women reported higher sensation severities than men from 2 mA and 4 mA tDCS and higher severities with increasing intensity (sham < 2 mA < 4 mA). Men reported similar severities in all stimulation conditions. Both sexes distinguished sham from 2 mA and 4 mA, and neither were able to discriminate between 2 mA from 4 mA. This study highlights differences in severity reports between women and men and adds to the growing body of literature, indicating that current sham methodologies might be inadequate to maintain blinding.
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Affiliation(s)
- Craig D Workman
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA, USA
| | - Alexandra C Fietsam
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA, USA
| | - John Kamholz
- Department of Neurology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
| | - Thorsten Rudroff
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA, USA.,Department of Neurology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
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Khadka N, Bikson M. Role of skin tissue layers and ultra-structure in transcutaneous electrical stimulation including tDCS. Phys Med Biol 2020; 65:225018. [PMID: 32916670 DOI: 10.1088/1361-6560/abb7c1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND During transcranial electrical stimulation (tES), including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), current density concentration around the electrode edges that is predicted by simplistic skin models does not match experimental observations of erythema, heating, or other adverse events. We hypothesized that enhancing models to include skin anatomical details, would alter predicted current patterns to align with experimental observations. METHOD We develop a high-resolution multi-layer skin model (epidermis, dermis, and fat), with or without additional ultra-structures (hair follicles, sweat glands, and blood vessels). Current flow patterns across each layer and within ultra-structures were predicted using finite element methods considering a broad range of modeled tissue parameters including 78 combinations of skin layer conductivities (S m-1): epidermis (standard: 1.05 × 10-5; range: 1.05 × 10-6 to 0.465); dermis (standard: 0.23; range: 0.0023 to 23), fat (standard: 2 × 10-4; range: 0.02 to 2 × 10-5). The impact of each ultra-structures in isolation and combination was evaluated with varied basic geometries. An integrated final model is then developed. RESULTS Consistent with prior models, current flow through homogenous skin was annular (concentrated at the electrode edges). In multi-layer skin, reducing epidermis conductivity and/or increasing dermis conductivity decreased current near electrode edges, however no realistic tissue layer parameters produced non-annular current flow at both epidermis and dermis. Addition of just hair follicles, sweat glands, or blood vessels resulted in current peaks around each ultrastructure, irrespective of proximity to electrode edges. Addition of only sweat glands was the most effective approach in reducing overall current concentration near electrode edges. Representation of blood vessels resulted in a uniform current flow across the vascular network. Finally, we ran the first realistic model of current flow across the skin. CONCLUSION We confirm prior models exhibiting current concentration near hair follicles or sweat glands, but also exhibit that an overall annular pattern of current flow remains for realistic tissue parameters. We model skin blood vessels for the first time and show that this robustly distributes current across the vascular network, consistent with experimental erythema patterns. Only a state-of-the-art precise model of skin current flow predicts lack of current concentration near electrode edges across all skin layers.
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Affiliation(s)
- Niranjan Khadka
- Department of Biomedical Engineering, The City College of New York, CUNY, New York, NY 10031, United States of America
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Turner C, Jackson C, Learmonth G. Is the "end-of-study guess" a valid measure of sham blinding during transcranial direct current stimulation? Eur J Neurosci 2020; 53:1592-1604. [PMID: 33098709 PMCID: PMC8048983 DOI: 10.1111/ejn.15018] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 09/30/2020] [Accepted: 10/16/2020] [Indexed: 11/28/2022]
Abstract
Studies using transcranial direct current stimulation (tDCS) typically incorporate a fade‐in, short‐stimulation, fade‐out sham (placebo) protocol, which is assumed to be indistinct from a 10–30 min active protocol on the scalp. However, many studies report that participants can dissociate active stimulation from sham, even during low‐intensity 1 mA currents. We recently identified differences in the perception of an active (10 min of 1 mA) and a sham (20 s of 1 mA) protocol that lasted for 5 min after the cessation of sham. In the present study we assessed whether delivery of a higher‐intensity 2 mA current would exacerbate these differences. Two protocols were delivered to 32 adults in a double‐blinded, within‐subjects design (active: 10 min of 2 mA, and sham: 20 s of 2 mA), with the anode over the left primary motor cortex and the cathode on the right forehead. Participants were asked “Is the stimulation on?” and “How sure are you?” at 30 s intervals during and after stimulation. The differences between active and sham were more consistent and sustained during 2 mA than during 1 mA. We then quantified how well participants were able to track the presence and absence of stimulation (i.e. their sensitivity) during the experiment using cross‐correlations. Current strength was a good classifier of sensitivity during active tDCS, but exhibited only moderate specificity during sham. The accuracy of the end‐of‐study guess was no better than chance at predicting sensitivity. Our results indicate that the traditional end‐of‐study guess poorly reflects the sensitivity of participants to stimulation, and may not be a valid method of assessing sham blinding.
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Affiliation(s)
| | | | - Gemma Learmonth
- School of Psychology, University of Glasgow, Glasgow, UK.,Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
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Firouzi M, Van Herk K, Kerckhofs E, Swinnen E, Baeken C, Van Overwalle F, Deroost N. Transcranial direct‐current stimulation enhances implicit motor sequence learning in persons with Parkinson's disease with mild cognitive impairment. J Neuropsychol 2020; 15:363-378. [DOI: 10.1111/jnp.12231] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 10/07/2020] [Indexed: 01/17/2023]
Affiliation(s)
- Mahyar Firouzi
- Brain, Body and Cognition Department of Psychology and Educational Sciences Vrije Universiteit Brussel Belgium
- Rehabilitation Research Department of Physiotherapy Human Physiology and Anatomy Vrije Universiteit Brussel Belgium
- Center for Neurosciences (C4N) Vrije Universiteit Brussel Belgium
| | - Karlijn Van Herk
- Rehabilitation Research Department of Physiotherapy Human Physiology and Anatomy Vrije Universiteit Brussel Belgium
| | - Eric Kerckhofs
- Brain, Body and Cognition Department of Psychology and Educational Sciences Vrije Universiteit Brussel Belgium
- Rehabilitation Research Department of Physiotherapy Human Physiology and Anatomy Vrije Universiteit Brussel Belgium
- Center for Neurosciences (C4N) Vrije Universiteit Brussel Belgium
| | - Eva Swinnen
- Rehabilitation Research Department of Physiotherapy Human Physiology and Anatomy Vrije Universiteit Brussel Belgium
- Center for Neurosciences (C4N) Vrije Universiteit Brussel Belgium
| | - Chris Baeken
- Brain, Body and Cognition Department of Psychology and Educational Sciences Vrije Universiteit Brussel Belgium
- Center for Neurosciences (C4N) Vrije Universiteit Brussel Belgium
- Department of Psychiatry and Medical Psychology Ghent University University Hospital Ghent Belgium
- Department of Psychiatry Faculty of Medicine and Pharmacy Vrije Universiteit Brussel University Hospital Brussel Belgium
| | - Frank Van Overwalle
- Brain, Body and Cognition Department of Psychology and Educational Sciences Vrije Universiteit Brussel Belgium
- Center for Neurosciences (C4N) Vrije Universiteit Brussel Belgium
| | - Natacha Deroost
- Brain, Body and Cognition Department of Psychology and Educational Sciences Vrije Universiteit Brussel Belgium
- Rehabilitation Research Department of Physiotherapy Human Physiology and Anatomy Vrije Universiteit Brussel Belgium
- Center for Neurosciences (C4N) Vrije Universiteit Brussel Belgium
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Individual Cerebral Blood Flow Responses to Transcranial Direct Current Stimulation at Various Intensities. Brain Sci 2020; 10:brainsci10110855. [PMID: 33202753 PMCID: PMC7697831 DOI: 10.3390/brainsci10110855] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/03/2020] [Accepted: 11/11/2020] [Indexed: 12/12/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) has been shown to alter cortical excitability. However, it is increasingly accepted that tDCS has high inter- and intra-subject response variability, which currently limits broad application and has prompted some to doubt if the current can reach the brain. This study reports individual cerebral blood flow responses in people with multiple sclerosis and neurologically healthy subjects that experienced 5 min of anodal tDCS at 1 mA, 2 mA, 3 mA, and 4 mA over either the dorsolateral prefrontal cortex (DLPFC) or the primary motor cortex (M1). The most notable results indicated anticipated changes in regional cerebral blood flow (rCBF) in two regions of one DLPFC subject (2 mA condition), and expected changes in one M1 subject in the 2 mA and 4 mA conditions and in another M1 subject in the 2 mA condition. There were also changes contrary to the expected direction in one DLPFC subject and in two M1 subjects. These data suggest the effects of tDCS might be site-specific and highlight the high variability and individualized responses increasingly reported in tDCS literature. Future studies should use longer stimulation durations and image at various time points after stimulation cessation when exploring the effects of tDCS on cerebral blood flow (CBF).
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Klaus J, Hartwigsen G. Failure to Improve Verbal Fluency with Transcranial Direct Current Stimulation. Neuroscience 2020; 449:123-133. [DOI: 10.1016/j.neuroscience.2020.09.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 08/28/2020] [Accepted: 09/01/2020] [Indexed: 10/23/2022]
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Wagner J, Lo Monaco S, Contò F, Parrott D, Battelli L, Rusconi E. Effects of transcranial direct current stimulation over the posterior parietal cortex on novice X-ray screening performance. Cortex 2020; 132:1-14. [PMID: 32911230 DOI: 10.1016/j.cortex.2020.08.002] [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] [Received: 03/31/2020] [Revised: 07/08/2020] [Accepted: 08/03/2020] [Indexed: 10/23/2022]
Abstract
Existing theories of visual search are generally deduced from lab-based studies involving the identification of a target object among similar distractors. The role of the right parietal cortex in visual search is well-established. However, less is known about real-world visual search tasks, such as X-ray screening, which require targets to be disembedded from their background. Research has shown variations in the cognitive abilities required for these tasks and typical lab-based visual search tasks. Thus, the findings of traditional visual search studies do not always transfer into the applied domain. Although brain imaging studies have offered insights into visual search tasks involving disembedding, highlighting an association between the left parietal cortex and disembedding performance, no causal link has yet been established. To this end, we carried out a pilot study (n = 34, between-subjects) administering non-invasive brain stimulation over the posterior parietal cortex (PPC) prior to completing a security X-ray screening task. The findings suggested that anodal left PPC tDCS enhanced novice performance in X-ray screening over that of sham stimulation, in line with brain imaging findings. However, the efficacy of tDCS is under question, with a growing number of failed replications. With this in mind, this study aims to re-test our original hypothesis by examining the effects of left-side parietal stimulation on novice X-ray screener performance and comparing them to those of sham stimulation and of stimulation on a control site (right PPC). As such, this within-subjects study comprised three sessions (2 mA left PPC, 2 mA right PPC, low-intensity sham stimulation left PPC), to investigate effects of anodal tDCS on X-ray screening performance. The pre-registered analysis did not detect any significant differences between left PPC tDCS and sham tDCS or left PPC tDCS and right PPC tDCS on novice performance (d') in X-ray screening. Further exploratory analyses detected no effects of left PPC tDCS on any other indices of performance in the X-ray security screening task (c, RTs and accuracy), or a disembedding control task (RTs and accuracy). The use of alternative stimulation techniques, with replicable behavioural effects on the parietal lobe (or a multi-technique approach), and well-powered studies with a systematic variation of stimulation parameters, could help to choose between two possible interpretations: that neither left nor right PPC are causally related to either tasks or that tDCS was ineffective. Finally, low-intensity sham stimulation (.016 mA), previously shown to outperform other sham conditions in between-subjects designs, was found to be ineffective for blinding participants in a within-subjects design. Our findings raise concerns for the current lack of optimal control conditions and add to the growing literature highlighting the need for replication in the field.
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Affiliation(s)
| | - Silvia Lo Monaco
- Department of Psychology and Cognitive Sciences, University of Trento, Rovereto, Italy
| | - Federica Contò
- Center for Neuroscience and Cognitive Systems@UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - Danielle Parrott
- Center for Neuroscience and Cognitive Systems@UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - Lorella Battelli
- Center for Neuroscience and Cognitive Systems@UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy; Department of Neurology, Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, USA
| | - Elena Rusconi
- Department of Psychology and Cognitive Sciences, University of Trento, Rovereto, Italy.
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Turi Z, Mittner M, Lehr A, Bürger H, Antal A, Paulus W. θ-γ Cross-Frequency Transcranial Alternating Current Stimulation over the Trough Impairs Cognitive Control. eNeuro 2020; 7:ENEURO.0126-20.2020. [PMID: 32764077 PMCID: PMC7540931 DOI: 10.1523/eneuro.0126-20.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/15/2020] [Accepted: 07/15/2020] [Indexed: 01/16/2023] Open
Abstract
Cognitive control is a mental process, which underlies adaptive goal-directed decisions. Previous studies have linked cognitive control to electrophysiological fluctuations in the θ band and θ-γ cross-frequency coupling (CFC) arising from the cingulate and frontal cortices. However, to date, the behavioral consequences of different forms of θ-γ CFC remain elusive. Here, we studied the behavioral effects of the θ-γ CFC via transcranial alternating current stimulation (tACS) designed to stimulate the frontal and cingulate cortices in humans. Using a double-blind, randomized, repeated measures study design, 24 healthy participants were subjected to three active and one control CFC-tACS conditions. In the active conditions, 80-Hz γ tACS was coupled to 4-Hz θ tACS. Specifically, in two of the active conditions, short γ bursts were coupled to the delivered θ cycle to coincide with either its peaks or troughs. In the third active condition, the phase of a θ cycle modulated the amplitude of the γ oscillation. In the fourth, control protocol, 80-Hz tACS was continuously superimposed over the 4-Hz tACS, therefore lacking any phase specificity in the CFC. During the 20 min of stimulation, the participants performed a Go/NoGo monetary reward-based and punishment-based instrumental learning task. A Bayesian hierarchical logistic regression analysis revealed that relative to the control, the peak-coupled tACS had no effects on the behavioral performance, whereas the trough-coupled tACS and, to a lesser extent, amplitude-modulated tACS reduced performance in conflicting trials. Our results suggest that cognitive control depends on the phase specificity of the θ-γ CFC.
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Affiliation(s)
- Zsolt Turi
- Department of Clinical Neurophysiology, University Medical Center Göttingen, Göttingen 37073, Germany
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany
| | - Matthias Mittner
- Department of Psychology, UiT The Arctic University of Norway, 9037
| | - Albert Lehr
- Department of Clinical Neurophysiology, University Medical Center Göttingen, Göttingen 37073, Germany
| | - Hannah Bürger
- Department of Clinical Neurophysiology, University Medical Center Göttingen, Göttingen 37073, Germany
| | - Andrea Antal
- Department of Clinical Neurophysiology, University Medical Center Göttingen, Göttingen 37073, Germany
| | - Walter Paulus
- Department of Clinical Neurophysiology, University Medical Center Göttingen, Göttingen 37073, Germany
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Enhancing cognitive control training with transcranial direct current stimulation: a systematic parameter study. Brain Stimul 2020; 13:1358-1369. [DOI: 10.1016/j.brs.2020.07.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 06/18/2020] [Accepted: 07/13/2020] [Indexed: 12/31/2022] Open
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Different Effects of Transcranial Direct Current Stimulation on Leg Muscle Glucose Uptake Asymmetry in Two Women with Multiple Sclerosis. Brain Sci 2020; 10:brainsci10080549. [PMID: 32823504 PMCID: PMC7465960 DOI: 10.3390/brainsci10080549] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 12/17/2022] Open
Abstract
Asymmetrical lower limb strength is a significant contributor to impaired walking abilities in people with multiple sclerosis (PwMS). Transcranial direct current stimulation (tDCS) may be an effective technique to enhance cortical excitability and increase neural drive to more-affected lower limbs. A sham-controlled, randomized, cross-over design was employed. Two women with MS underwent two 20 min sessions of either 3 mA tDCS or Sham before 20 min of treadmill walking at a self-selected speed. During walking, the participants were injected with the glucose analogue, [18F] fluorodeoxyglucose (FDG). Participants were then imaged to examine glucose metabolism and uptake asymmetries in the legs. Standardized uptake values (SUVs) were compared between the legs and asymmetry indices were calculated. Subject 2 was considered physically active (self-reported participating in at least 30 min of moderate-intensity physical activity on at least three days of the week for the last three months), while Subject 1 was physically inactive. In Subject 1, there was a decrease in SUVs at the left knee flexors, left upper leg, left and right plantar flexors, and left and right lower legs and SUVs in the knee extensors and dorsiflexors were considered symmetric after tDCS compared to Sham. Subject 2 showed an increase in SUVs at the left and right upper legs, right plantar flexors, and right lower leg with no muscle group changing asymmetry status. This study demonstrates that tDCS may increase neural drive to leg muscles and decrease glucose uptake during walking in PwMS with low physical activity levels.
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Stonsaovapak C, Hemrungroj S, Terachinda P, Piravej K. Effect of Anodal Transcranial Direct Current Stimulation at the Right Dorsolateral Prefrontal Cortex on the Cognitive Function in Patients With Mild Cognitive Impairment: A Randomized Double-Blind Controlled Trial. Arch Phys Med Rehabil 2020; 101:1279-1287. [DOI: 10.1016/j.apmr.2020.03.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 03/12/2020] [Accepted: 03/17/2020] [Indexed: 12/20/2022]
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Razza LB, Palumbo P, Moffa AH, Carvalho AF, Solmi M, Loo CK, Brunoni AR. A systematic review and meta-analysis on the effects of transcranial direct current stimulation in depressive episodes. Depress Anxiety 2020; 37:594-608. [PMID: 32101631 DOI: 10.1002/da.23004] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 01/28/2020] [Accepted: 02/04/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Transcranial direct current stimulation (tDCS) has shown mixed results for depression treatment. OBJECTIVE To perform a systematic review and meta-analysis of trials using tDCS to improve depressive symptoms. METHODS A systematic review was performed from the first date available to January 06, 2020 in PubMed, EMBASE, Cochrane Library, and additional sources. We included randomized, sham-controlled clinical trials (RCTs) enrolling participants with an acute depressive episode and compared the efficacy of active versus sham tDCS, including association with other interventions. The primary outcome was the Hedges' g for continuous depression scores; secondary outcomes included odds ratios (ORs) and number needed to treat (NNT) for response, remission, and acceptability. Random effects models were employed. Sources of heterogeneity were explored via metaregression, sensitivity analyses, subgroup analyses, and bias assessment. RESULTS We included 23 RCTs (25 datasets, 1,092 participants), most (57%) presenting a low risk of bias. Active tDCS was superior to sham regarding endpoint depression scores (k = 25, g = 0.46, 95% confidence interval [CI]: 0.22-0.70), and also achieved superior response (k = 18, 33.3% vs. 16.56%, OR = 2.28 [1.52-3.42], NNT = 6) and remission (k = 18, 19.12% vs. 9.78%, OR = 2.12 [1.42-3.16], NNT = 10.7) rates. Moreover, active tDCS was as acceptable as sham. No risk of publication bias was identified. Cumulative meta-analysis showed that effect sizes are basically unchanged since total sample reached 439 participants. CONCLUSIONS TDCS is modestly effective in treating depressive episodes. Further well-designed, large-scale RCTs are warranted.
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Affiliation(s)
- Lais B Razza
- Laboratory of Neurosciences (LIM-27), Instituto Nacional de Biomarcadores em Neuropsiquiatria (INBioN), Department and Institute of Psychiatry, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.,Department of Internal Medicine, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Priscila Palumbo
- Laboratory of Neurosciences (LIM-27), Instituto Nacional de Biomarcadores em Neuropsiquiatria (INBioN), Department and Institute of Psychiatry, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.,Department of Internal Medicine, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Adriano H Moffa
- Black Dog Institute, School of Psychiatry, University of New South Wales, Sydney, New South Wales, Australia
| | - Andre F Carvalho
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.,Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Marco Solmi
- Department of Neurosciences, University of Padova, Padova, Italy.,Padova Neuroscience Center, University of Padova, Padova, Italy
| | - Colleen K Loo
- Black Dog Institute, School of Psychiatry, University of New South Wales, Sydney, New South Wales, Australia
| | - Andre Russowsky Brunoni
- Laboratory of Neurosciences (LIM-27), Instituto Nacional de Biomarcadores em Neuropsiquiatria (INBioN), Department and Institute of Psychiatry, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.,Department of Internal Medicine, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.,Hospital Universitário, Universidade de São Paulo, São Paulo, Brazil
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Bergmann TO, Hartwigsen G. Inferring Causality from Noninvasive Brain Stimulation in Cognitive Neuroscience. J Cogn Neurosci 2020; 33:195-225. [PMID: 32530381 DOI: 10.1162/jocn_a_01591] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Noninvasive brain stimulation (NIBS) techniques, such as transcranial magnetic stimulation or transcranial direct and alternating current stimulation, are advocated as measures to enable causal inference in cognitive neuroscience experiments. Transcending the limitations of purely correlative neuroimaging measures and experimental sensory stimulation, they allow to experimentally manipulate brain activity and study its consequences for perception, cognition, and eventually, behavior. Although this is true in principle, particular caution is advised when interpreting brain stimulation experiments in a causal manner. Research hypotheses are often oversimplified, disregarding the underlying (implicitly assumed) complex chain of causation, namely, that the stimulation technique has to generate an electric field in the brain tissue, which then evokes or modulates neuronal activity both locally in the target region and in connected remote sites of the network, which in consequence affects the cognitive function of interest and eventually results in a change of the behavioral measure. Importantly, every link in this causal chain of effects can be confounded by several factors that have to be experimentally eliminated or controlled to attribute the observed results to their assumed cause. This is complicated by the fact that many of the mediating and confounding variables are not directly observable and dose-response relationships are often nonlinear. We will walk the reader through the chain of causation for a generic cognitive neuroscience NIBS study, discuss possible confounds, and advise appropriate control conditions. If crucial assumptions are explicitly tested (where possible) and confounds are experimentally well controlled, NIBS can indeed reveal cause-effect relationships in cognitive neuroscience studies.
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Affiliation(s)
| | - Gesa Hartwigsen
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
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