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Sánchez-León CA, Campos GSG, Fernández M, Sánchez-López A, Medina JF, Márquez-Ruiz J. Somatodendritic orientation determines tDCS-induced neuromodulation of Purkinje cell activity in awake mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.02.18.529047. [PMID: 36824866 PMCID: PMC9949160 DOI: 10.1101/2023.02.18.529047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Transcranial direct-current stimulation (tDCS) of the cerebellum is a promising non-invasive neuromodulatory technique being proposed for the treatment of neurological and neuropsychiatric disorders. However, there is a lack of knowledge about how externally applied currents affect neuronal spiking activity in cerebellar circuits in vivo. We investigated how Cb-tDCS affects the firing rate of Purkinje cells (PC) and non-PC in the mouse cerebellar cortex to understand the underlying mechanisms behind the polarity-dependent modulation of neuronal activity induced by tDCS. Mice (n = 9) were prepared for the chronic recording of LFPs to assess the actual electric field gradient imposed by Cb-tDCS in our experimental design. Single-neuron extracellular recording of PCs in awake (n = 24) and anesthetized (n = 27) mice was combined with juxtacellular recordings and subsequent staining of PC with neurobiotin under anesthesia (n = 8) to correlate their neuronal orientation with their response to Cb-tDCS. Finally, a high-density Neuropixels recording system was used to demonstrate the relevance of neuronal orientation during the application of Cb-tDCS in awake mice (n = 6). In this study, we observe that Cb-tDCS induces a heterogeneous polarity-dependent modulation of the firing rate of Purkinje cells (PC) and non-PC in the mouse cerebellar cortex. We demonstrate that the apparently heterogeneous effects of tDCS on PC activity can be explained by taking into account the somatodendritic orientation relative to the electric field. Our findings highlight the need to consider neuronal orientation and morphology to improve tDCS computational models, enhance stimulation protocol reliability, and optimize effects in both basic and clinical applications.
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Affiliation(s)
- Carlos A Sánchez-León
- Department of Physiology, Anatomy and Cell Biology, Pablo de Olavide University, Ctra. de Utrera, km. 1, 41013, Seville, Spain
- Department of Neurology and Neurobiology, University of California Los Angeles, Los Angeles 90095, USA
| | | | - Marta Fernández
- Department of Psychiatry, University of California Los Angeles, Los Angeles 90095, USA
- Department of Pharmacology, University of the Basque Country (UPV/EHU), Leioa 48940, Spain
| | | | - Javier F Medina
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Javier Márquez-Ruiz
- Department of Physiology, Anatomy and Cell Biology, Pablo de Olavide University, Ctra. de Utrera, km. 1, 41013, Seville, Spain
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Kim KM, Needle AR, Kim JS, An YW, Cruz-Díaz D, Taube W. What interventions can treat arthrogenic muscle inhibition in patients with chronic ankle instability? A systematic review with meta-analysis. Disabil Rehabil 2024; 46:241-256. [PMID: 36650898 DOI: 10.1080/09638288.2022.2161643] [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: 04/04/2022] [Accepted: 12/18/2022] [Indexed: 01/19/2023]
Abstract
PURPOSE To identify, critically appraise, and synthesize the existing evidence regarding the effects of therapeutic interventions on arthrogenic muscle inhibition (AMI) in patients with chronic ankle instability (CAI). MATERIALS AND METHODS Two reviewers independently performed exhaustive database searches in Web of Science, PubMed, Medline, CINAHL, and SPORTDiscus. RESULTS Nine studies were finally included. Five types of disinhibitory interventions were identified: focal ankle joint cooling (FAJC), manual therapy, fibular reposition taping (FRT), whole-body vibration (WBV), and transcranial direct current stimulation (tDCS). There were moderate effects of FAJC on spinal excitability in ankle muscles (g = 0.55, 95% CI = 0.03-1.08, p = 0.040 for the soleus and g = 0.54, 95% CI = 0.01-1.07, p = 0.046 for the fibularis longus). In contrast, manual therapy, FRT, WBV were not effective. Finally, 4 weeks of tDCS combined with eccentric exercise showed large effects on corticospinal excitability in 2 weeks after the intervention (g = 0.99, 95% CI = 0.14-1.85 for the fibularis longus and g = 1.02, 95% CI = 0.16-1.87 for the tibialis anterior). CONCLUSIONS FAJC and tDCS may be effective in counteracting AMI. However, the current evidence of mainly short-term studies to support the use of disinhibitory interventions is too limited to draw definitive conclusions.
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Affiliation(s)
- Kyung-Min Kim
- Department of Sport Science, Sungkyunkwan University, Suwon-si, Korea
- Department of Kinesiology and Sport Sciences, University of Miami, Coral Gables, FL, USA
| | - Alan R Needle
- Department of Public Health & Exercise Science, Appalachian State University, Boone, NC, USA
- Department of Rehabilitation Sciences, Appalachian State University, Boone, NC, USA
| | - Joo-Sung Kim
- Department of Kinesiology and Sport Sciences, University of Miami, Coral Gables, FL, USA
| | - Yong Woo An
- Department of Health and Human Sciences, Loyola Marymount University, Los Angeles, CA, USA
| | - David Cruz-Díaz
- Department of Health Sciences, Faculty of Health Sciences, University of Jaén, Jaén, Spain
| | - Wolfgang Taube
- Department of Neurosciences and Movement Sciences, University of Fribourg, Fribourg, Switzerland
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Hemmerich K, Lupiáñez J, Luna FG, Martín-Arévalo E. The mitigation of the executive vigilance decrement via HD-tDCS over the right posterior parietal cortex and its association with neural oscillations. Cereb Cortex 2023:6988102. [PMID: 36646467 DOI: 10.1093/cercor/bhac540] [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: 07/21/2022] [Revised: 12/22/2022] [Accepted: 12/23/2022] [Indexed: 01/18/2023] Open
Abstract
Vigilance-maintaining a prolonged state of preparation to detect and respond to specific yet unpredictable environmental changes-usually decreases across prolonged tasks, causing potentially severe real-life consequences, which could be mitigated through transcranial direct current stimulation (tDCS). The present study aimed at replicating previous mitigatory effects observed with anodal high-definition tDCS (HD-tDCS) over the right posterior parietal cortex (rPPC) while extending the analyses on electrophysiological measures associated with vigilance. In sum, 60 participants completed the ANTI-Vea task while receiving anodal (1.5 mA, n = 30) or sham (0 mA, n = 30) HD-tDCS over the rPPC for ~ 28 min. EEG recordings were completed before and after stimulation. Anodal HD-tDCS specifically mitigated executive vigilance (EV) and reduced the alpha power increment across time-on-task while increasing the gamma power increment. To further account for the observed behavioral and physiological outcomes, a new index of Alphaparietal/Gammafrontal is proposed. Interestingly, the increment of this Alphaparietal/Gammafrontal Index with time-on-task is associated with a steeper EV decrement in the sham group, which was mitigated by anodal HD-tDCS. We highlight the relevance of replicating mitigatory effects of tDCS and the need to integrate conventional and novel physiological measures to account for how anodal HD-tDCS can be used to modulate cognitive performance.
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Affiliation(s)
- Klara Hemmerich
- Department of Experimental Psychology, and Mind, Brain, and Behavior Research Center (CIMCYC), University of Granada, Granada 18071, Spain
| | - Juan Lupiáñez
- Department of Experimental Psychology, and Mind, Brain, and Behavior Research Center (CIMCYC), University of Granada, Granada 18071, Spain
| | - Fernando G Luna
- Instituto de Investigaciones Psicológicas (IIPsi, CONICET-UNC), Facultad de Psicología, Universidad Nacional de Córdoba, Córdoba 5010, Argentina
| | - Elisa Martín-Arévalo
- Department of Experimental Psychology, and Mind, Brain, and Behavior Research Center (CIMCYC), University of Granada, Granada 18071, Spain
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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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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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Elsner B, Kugler J, Pohl M, Mehrholz J. Transcranial direct current stimulation (tDCS) for improving activities of daily living, and physical and cognitive functioning, in people after stroke. Cochrane Database Syst Rev 2020; 11:CD009645. [PMID: 33175411 PMCID: PMC8095012 DOI: 10.1002/14651858.cd009645.pub4] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Stroke is one of the leading causes of disability worldwide. Functional impairment, resulting in poor performance in activities of daily living (ADL) among stroke survivors is common. Current rehabilitation approaches have limited effectiveness in improving ADL performance, function, muscle strength, and cognitive abilities (including spatial neglect) after stroke, with improving cognition being the number one research priority in this field. A possible adjunct to stroke rehabilitation might be non-invasive brain stimulation by transcranial direct current stimulation (tDCS) to modulate cortical excitability, and hence to improve these outcomes in people after stroke. OBJECTIVES To assess the effects of tDCS on ADL, arm and leg function, muscle strength and cognitive abilities (including spatial neglect), dropouts and adverse events in people after stroke. SEARCH METHODS We searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE, Embase and seven other databases in January 2019. In an effort to identify further published, unpublished, and ongoing trials, we also searched trials registers and reference lists, handsearched conference proceedings, and contacted authors and equipment manufacturers. SELECTION CRITERIA This is the update of an existing review. In the previous version of this review, we focused on the effects of tDCS on ADL and function. In this update, we broadened our inclusion criteria to compare any kind of active tDCS for improving ADL, function, muscle strength and cognitive abilities (including spatial neglect) versus any kind of placebo or control intervention. DATA COLLECTION AND ANALYSIS Two review authors independently assessed trial quality and risk of bias, extracted data, and applied GRADE criteria. If necessary, we contacted study authors to ask for additional information. We collected information on dropouts and adverse events from the trial reports. MAIN RESULTS We included 67 studies involving a total of 1729 patients after stroke. We also identified 116 ongoing studies. The risk of bias did not differ substantially for different comparisons and outcomes. The majority of participants had ischaemic stroke, with mean age between 43 and 75 years, in the acute, postacute, and chronic phase after stroke, and level of impairment ranged from severe to less severe. Included studies differed in terms of type, location and duration of stimulation, amount of current delivered, electrode size and positioning, as well as type and location of stroke. We found 23 studies with 781 participants examining the effects of tDCS versus sham tDCS (or any other passive intervention) on our primary outcome measure, ADL after stroke. Nineteen studies with 686 participants reported absolute values and showed evidence of effect regarding ADL performance at the end of the intervention period (standardised mean difference (SMD) 0.28, 95% confidence interval (CI) 0.13 to 0.44; random-effects model; moderate-quality evidence). Four studies with 95 participants reported change scores, and showed an effect (SMD 0.48, 95% CI 0.02 to 0.95; moderate-quality evidence). Six studies with 269 participants assessed the effects of tDCS on ADL at the end of follow-up and provided absolute values, and found improved ADL (SMD 0.31, 95% CI 0.01 to 0.62; moderate-quality evidence). One study with 16 participants provided change scores and found no effect (SMD -0.64, 95% CI -1.66 to 0.37; low-quality evidence). However, the results did not persist in a sensitivity analysis that included only trials with proper allocation concealment. Thirty-four trials with a total of 985 participants measured upper extremity function at the end of the intervention period. Twenty-four studies with 792 participants that presented absolute values found no effect in favour of tDCS (SMD 0.17, 95% CI -0.05 to 0.38; moderate-quality evidence). Ten studies with 193 participants that presented change values also found no effect (SMD 0.33, 95% CI -0.12 to 0.79; low-quality evidence). Regarding the effects of tDCS on upper extremity function at the end of follow-up, we identified five studies with a total of 211 participants (absolute values) without an effect (SMD -0.00, 95% CI -0.39 to 0.39; moderate-quality evidence). Three studies with 72 participants presenting change scores found an effect (SMD 1.07; 95% CI 0.04 to 2.11; low-quality evidence). Twelve studies with 258 participants reported outcome data for lower extremity function and 18 studies with 553 participants reported outcome data on muscle strength at the end of the intervention period, but there was no effect (high-quality evidence). Three studies with 156 participants reported outcome data on muscle strength at follow-up, but there was no evidence of an effect (moderate-quality evidence). Two studies with 56 participants found no evidence of effect of tDCS on cognitive abilities (low-quality evidence), but one study with 30 participants found evidence of effect of tDCS for improving spatial neglect (very low-quality evidence). In 47 studies with 1330 participants, the proportions of dropouts and adverse events were comparable between groups (risk ratio (RR) 1.25, 95% CI 0.74 to 2.13; random-effects model; moderate-quality evidence). AUTHORS' CONCLUSIONS: There is evidence of very low to moderate quality on the effectiveness of tDCS versus control (sham intervention or any other intervention) for improving ADL outcomes after stroke. However, the results did not persist in a sensitivity analyses including only trials with proper allocation concealment. Evidence of low to high quality suggests that there is no effect of tDCS on arm function and leg function, muscle strength, and cognitive abilities in people after stroke. Evidence of very low quality suggests that there is an effect on hemispatial neglect. There was moderate-quality evidence that adverse events and numbers of people discontinuing the treatment are not increased. Future studies should particularly engage with patients who may benefit the most from tDCS after stroke, but also should investigate the effects in routine application. Therefore, further large-scale randomised controlled trials with a parallel-group design and sample size estimation for tDCS are needed.
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Affiliation(s)
- Bernhard Elsner
- Department of Public Health, Dresden Medical School, Technical University Dresden, Dresden, Germany
- Department of Physiotherapy, SRH Hochschule für Gesundheit Gera, 07548 Gera, Germany
| | - Joachim Kugler
- Department of Public Health, Dresden Medical School, Technical University Dresden, Dresden, Germany
| | - Marcus Pohl
- Neurological Rehabilitation, Helios Klinik Schloss Pulsnitz, Pulsnitz, Germany
| | - Jan Mehrholz
- Department of Public Health, Dresden Medical School, Technical University Dresden, Dresden, Germany
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Cerreta AGB, Mruczek REB, Berryhill ME. Predicting Working Memory Training Benefits From Transcranial Direct Current Stimulation Using Resting-State fMRI. Front Psychol 2020; 11:570030. [PMID: 33154728 PMCID: PMC7591503 DOI: 10.3389/fpsyg.2020.570030] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 09/09/2020] [Indexed: 12/14/2022] Open
Abstract
The effects of transcranial direct current stimulation (tDCS) on working memory (WM) performance are promising but variable and contested. In particular, designs involving one session of tDCS are prone to variable outcomes with notable effects of individual differences. Some participants benefit, whereas others are impaired by the same tDCS protocol. In contrast, protocols including multiple sessions of tDCS more consistently report WM improvement across participants. The objective of the current project was to test whether differences in resting-state connectivity between stimulation site and two WM-relevant networks [default mode network (DMN) and central executive network (CEN)] could account for initial and longitudinal responses to tDCS. Healthy young adults completed 5 days of visual WM training during sham or anodal right frontal tDCS. The behavioral data showed that only the active tDCS group significantly improved over the visual WM training period. There were no significant correlations between initial response to tDCS and resting-state activity. DMN activity in the anterior cingulate cortex significantly correlated with WM training slope. These data underscore the importance of sampling in studies applying tDCS; homogeneity (e.g., of gender, special population, and WM capacity) may produce more consistent data in a single experiment with limited power, whereas heterogeneity is important in determining the mechanism(s) and potential for tDCS-linked protocols. This issue is a limitation in tDCS findings that continues to hamper its optimization and translational value.
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Affiliation(s)
- Adelle G B Cerreta
- Program in Cognitive and Brain Sciences, Program in Integrative Neuroscience, Department of Psychology, University of Nevada, Reno, NV, United States
| | - Ryan E B Mruczek
- Department of Psychology, College of the Holy Cross, Worcester, MA, United States
| | - Marian E Berryhill
- Program in Cognitive and Brain Sciences, Program in Integrative Neuroscience, Department of Psychology, University of Nevada, Reno, NV, United States
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Schroeder PA, Schwippel T, Wolz I, Svaldi J. Meta-analysis of the effects of transcranial direct current stimulation on inhibitory control. Brain Stimul 2020; 13:1159-1167. [DOI: 10.1016/j.brs.2020.05.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 04/17/2020] [Accepted: 05/04/2020] [Indexed: 01/18/2023] Open
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The Role of the Left and Right Anterior Temporal Poles in People Naming and Recognition. Neuroscience 2020; 440:175-185. [DOI: 10.1016/j.neuroscience.2020.05.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 05/21/2020] [Accepted: 05/23/2020] [Indexed: 01/27/2023]
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Workman CD, Fietsam AC, Rudroff T. Different Effects of 2 mA and 4 mA Transcranial Direct Current Stimulation on Muscle Activity and Torque in a Maximal Isokinetic Fatigue Task. Front Hum Neurosci 2020; 14:240. [PMID: 32714170 PMCID: PMC7344304 DOI: 10.3389/fnhum.2020.00240] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 06/02/2020] [Indexed: 12/13/2022] Open
Abstract
Studies investigating the effects of transcranial direct current stimulation (tDCS) on fatigue and muscle activity have elicited measurable improvements using stimulation intensities ≤2 mA and submaximal effort tasks. The purpose of this study was to determine the effects of 2 mA and 4 mA anodal tDCS over the primary motor cortex (M1) on performance fatigability and electromyographic (EMG) activity of the leg muscles during a maximal isokinetic task in healthy young adults. A double-blind, randomized, sham-controlled crossover study design was applied. Twenty-seven active young adults completed four sessions, each spaced by 5-8 days. During session 1, dominance was verified with isokinetic strength testing, and subjects were familiarized with the fatigue task (FT). The FT protocol included 40 continuous maximum isokinetic contractions of the knee extensors and flexors (120°/s, concentric/concentric). During Sessions 2-4, tDCS was applied for 20 min with one of three randomly assigned intensities (sham, 2 mA or 4 mA) and the FT was repeated. The anode and cathode of the tDCS device were placed over C3 and the contralateral supraorbital area, respectively. A wireless EMG system collected muscle activity during the FT. The 2 mA tDCS condition had significantly less torque (65.9 ± 32.7 Nm) during the FT than both the sham (68.4 ± 33.9 Nm, p < 0.001) and 4 mA conditions (68.4 ± 33.9 Nm, p = 0.001). Furthermore, the 2 mA condition (33.8 ± 11.7%) had significantly less EMG activity during the FT than both the sham (39.7 ± 10.6%, p < 0.001) and 4 mA conditions (40.5 ± 13.4%, p = 0.001). Contrary to previous submaximal isometric fatigue investigations, the 2 mA tDCS condition significantly reduced torque production and EMG activity of the leg extensors during a maximal isokinetic FT compared with the sham and 4 mA conditions. Also, torque production and EMG activity in the 4 mA condition were not significantly different from sham. Thus, the effects of tDCS, and the underlying mechanisms, might not be the same for different tasks and warrants more investigation.
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Affiliation(s)
- Craig David Workman
- Department of Health and Human Physiology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA, United States
| | - Alexandra C Fietsam
- Department of Health and Human Physiology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA, United States
| | - Thorsten Rudroff
- Department of Health and Human Physiology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA, United States.,Department of Neurology, Carver College of Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, United States
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Placebo Brain Stimulation Affects Subjective but Not Neurocognitive Measures of Error Processing. JOURNAL OF COGNITIVE ENHANCEMENT 2020. [DOI: 10.1007/s41465-020-00172-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
AbstractThe aim of this preregistered EEG study was to show how expectations about enhanced or impaired performance through transcranial stimulation affect feelings of agency and error processing. Using a single-blind experimental design, participants (N = 57) were attached to a transcranial direct current stimulation (tDCS) device, and in different blocks, they were verbally instructed to expect enhanced or impaired cognitive performance, or no effects of the brain stimulation. In all cases, but unbeknownst to the participants, we used an inert sham tDCS protocol. Subsequently, we measured their response to errors on a cognitive control task. Our expectancy manipulation was successful: participants reported improved subjective performance in the enhancement compared with the impairment condition—even though objective performance was kept at a constant level across conditions. Participants reported the highest feelings of agency over their task performance in the control condition, and lowest feelings of agency in the impairment condition. The expectancy manipulation did not affect the error-related negativity (ERN) in association with incorrect responses. During the induction phase, expecting impaired versus enhanced performance increased frontal theta power, potentially reflecting a process of increased cognitive control allocation. Our findings show that verbally induced manipulations can affect subjective performance on a cognitive control task, but that stronger manipulations (e.g., through conditioning) are necessary to induce top-down effects on neural error processing.
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Imaging Transcranial Direct Current Stimulation (tDCS) with Positron Emission Tomography (PET). Brain Sci 2020; 10:brainsci10040236. [PMID: 32326515 PMCID: PMC7226010 DOI: 10.3390/brainsci10040236] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/06/2020] [Accepted: 04/13/2020] [Indexed: 12/11/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) is a form of non-invasive neuromodulation that is increasingly being utilized to examine and modify several cognitive and motor functions. Although tDCS holds great potential, it is difficult to determine optimal treatment procedures to accommodate configurations, the complex shapes, and dramatic conductivity differences among various tissues. Furthermore, recent demonstrations showed that up to 75% of the tDCS current applied to rodents and human cadavers was shunted by the scalp, subcutaneous tissue, and muscle, bringing the effects of tDCS on the cortex into question. Consequently, it is essential to combine tDCS with human neuroimaging to complement animal and cadaver studies and clarify if and how tDCS can affect neural function. One viable approach is positron emission tomography (PET) imaging. PET has unique potential for examining the effects of tDCS within the central nervous system in vivo, including cerebral metabolism, neuroreceptor occupancy, and neurotransmitter activity/binding. The focus of this review is the emerging role of PET and potential PET radiotracers for studying tDCS-induced functional changes in the human brain.
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Benussi A, Pascual-Leone A, Borroni B. Non-Invasive Cerebellar Stimulation in Neurodegenerative Ataxia: A Literature Review. Int J Mol Sci 2020; 21:ijms21061948. [PMID: 32178459 PMCID: PMC7139863 DOI: 10.3390/ijms21061948] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/08/2020] [Accepted: 03/11/2020] [Indexed: 12/16/2022] Open
Abstract
Cerebellar ataxias are a heterogenous group of degenerative disorders for which we currently lack effective and disease-modifying interventions. The field of non-invasive brain stimulation has made much progress in the development of specific stimulation protocols to modulate cerebellar excitability and try to restore the physiological activity of the cerebellum in patients with ataxia. In light of limited evidence-based pharmacologic and non-pharmacologic treatment options for patients with ataxia, several different non-invasive brain stimulation protocols have emerged, particularly employing repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS) techniques. In this review, we summarize the most relevant rTMS and tDCS therapeutic trials and discuss their implications in the care of patients with degenerative ataxias.
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Affiliation(s)
- Alberto Benussi
- Neurology Unit, Department of Clinical and Experimental Sciences, University of Brescia, 25123 Brescia, Italy;
| | - Alvaro Pascual-Leone
- Arthur and Hinda Marcus Institute for Aging Brain, Hebrew SeniorLife and Department of Neurology, Harvard Medical School, Boston, MA 02131, USA;
- Guttmann Brain Health Institute, Institute Guttmann, Universitat Autonoma, 08027 Barcelona, Spain
| | - Barbara Borroni
- Neurology Unit, Department of Clinical and Experimental Sciences, University of Brescia, 25123 Brescia, Italy;
- Correspondence: ; Tel.: +39-030-3995632
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Freidle M, Nilsson J, Lebedev AV, Lövdén M. No evidence for any effect of multiple sessions of frontal transcranial direct stimulation on mood in healthy older adults. Neuropsychologia 2020; 137:107325. [PMID: 31877311 DOI: 10.1016/j.neuropsychologia.2019.107325] [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: 05/23/2019] [Revised: 12/06/2019] [Accepted: 12/20/2019] [Indexed: 11/28/2022]
Abstract
The dorsolateral prefrontal cortex (DLPFC) is part of a network important for emotional regulation and the possibility of modulating activity in this region with transcranial direct current stimulation (TDCS) to change mood has gained great interest, particularly for application in clinical populations. Whilst results in major depressive disorder have been promising, less is known about the effects of TDCS on mood in non-clinical populations. We hypothesized that multiple sessions of anodal TDCS applied over the left DLPFC would enhance mood, primarily as measured by the Profile of Mood States questionnaire, in healthy older adults. In addition, in an exploratory analysis, we examined the potentially moderating role of working memory training. Working memory, just like emotional regulation, taxes the DLPFC, which suggests that engaging in a working memory task whilst receiving TDCS may have a different effect on activity in this region and consequently mood. A total of 123 participants between 65 and 75 years of age were randomly assigned to receive either 20 sessions of TDCS, with or without working memory training, or 20 sessions sham stimulation, with or without working memory training. We found no support for enhancement of mood due to TDCS in healthy older adults, with or without cognitive training and conclude that the TDCS protocol used is unlikely to improve mood in non-depressed older individuals.
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Affiliation(s)
- Malin Freidle
- Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet and Stockholm University, Stockholm, Sweden.
| | - Jonna Nilsson
- Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet and Stockholm University, Stockholm, Sweden
| | - Alexander V Lebedev
- Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet and Stockholm University, Stockholm, Sweden; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Martin Lövdén
- Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet and Stockholm University, Stockholm, Sweden
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Fernández-Corazza M, Turovets S, Muravchik CH. Unification of optimal targeting methods in transcranial electrical stimulation. Neuroimage 2019; 209:116403. [PMID: 31862525 PMCID: PMC7110419 DOI: 10.1016/j.neuroimage.2019.116403] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 11/11/2019] [Accepted: 11/24/2019] [Indexed: 12/22/2022] Open
Abstract
One of the major questions in high-density transcranial electrical stimulation (TES) is: given a region of interest (ROI) and electric current limits for safety, how much current should be delivered by each electrode for optimal targeting of the ROI? Several solutions, apparently unrelated, have been independently proposed depending on how "optimality" is defined and on how this optimization problem is stated mathematically. The least squares (LS), weighted LS (WLS), or reciprocity-based approaches are the simplest ones and have closed-form solutions. An extended optimization problem can be stated as follows: maximize the directional intensity at the ROI, limit the electric fields at the non-ROI, and constrain total injected current and current per electrode for safety. This problem requires iterative convex or linear optimization solvers. We theoretically prove in this work that the LS, WLS and reciprocity-based closed-form solutions are specific solutions to the extended directional maximization optimization problem. Moreover, the LS/WLS and reciprocity-based solutions are the two extreme cases of the intensity-focality trade-off, emerging under variation of a unique parameter of the extended directional maximization problem, the imposed constraint to the electric fields at the non-ROI. We validate and illustrate these findings with simulations on an atlas head model. The unified approach we present here allows a better understanding of the nature of the TES optimization problem and helps in the development of advanced and more effective targeting strategies.
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Affiliation(s)
- Mariano Fernández-Corazza
- LEICI Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales, Universidad Nacional de La Plata, CONICET, Argentina.
| | - Sergei Turovets
- NeuroInformatics Center, University of Oregon, Eugene, OR, USA
| | - Carlos Horacio Muravchik
- LEICI Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales, Universidad Nacional de La Plata, CONICET, Argentina; Comisión de Investigaciones Científicas, CICPBA, Provincia de Buenos Aires, Argentina
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Wertheim J, Colzato LS, Nitsche MA, Ragni M. Enhancing spatial reasoning by anodal transcranial direct current stimulation over the right posterior parietal cortex. Exp Brain Res 2019; 238:181-192. [DOI: 10.1007/s00221-019-05699-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 11/22/2019] [Indexed: 01/18/2023]
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Patel R, Ashcroft J, Patel A, Ashrafian H, Woods AJ, Singh H, Darzi A, Leff DR. The Impact of Transcranial Direct Current Stimulation on Upper-Limb Motor Performance in Healthy Adults: A Systematic Review and Meta-Analysis. Front Neurosci 2019; 13:1213. [PMID: 31803003 PMCID: PMC6873898 DOI: 10.3389/fnins.2019.01213] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 10/28/2019] [Indexed: 11/25/2022] Open
Abstract
Background: Transcranial direct current stimulation (tDCS) has previously been reported to improve facets of upper limb motor performance such as accuracy and strength. However, the magnitude of motor performance improvement has not been reviewed by contemporaneous systematic review or meta-analysis of sham vs. active tDCS. Objective: To systematically review and meta-analyse the existing evidence regarding the benefits of tDCS on upper limb motor performance in healthy adults. Methods: A systematic search was conducted to obtain relevant articles from three databases (MEDLINE, EMBASE, and PsycINFO) yielding 3,200 abstracts. Following independent assessment by two reviewers, a total of 86 articles were included for review, of which 37 were deemed suitable for meta-analysis. Results: Meta-analyses were performed for four outcome measures, namely: reaction time (RT), execution time (ET), time to task failure (TTF), and force. Further qualitative review was performed for accuracy and error. Statistically significant improvements in RT (effect size −0.01; 95% CI −0.02 to 0.001, p = 0.03) and ET (effect size −0.03; 95% CI −0.05 to −0.01, p = 0.017) were demonstrated compared to sham. In exercise tasks, increased force (effect size 0.10; 95% CI 0.08 to 0.13, p < 0.001) and a trend towards improved TTF was also observed. Conclusions: This meta-analysis provides evidence attesting to the impact of tDCS on upper limb motor performance in healthy adults. Improved performance is demonstrable in reaction time, task completion time, elbow flexion tasks and accuracy. Considerable heterogeneity exists amongst the literature, further confirming the need for a standardised approach to reporting tDCS studies.
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Affiliation(s)
- Ronak Patel
- Department of Surgery & Cancer, Imperial College London, London, United Kingdom
| | - James Ashcroft
- Department of Surgery & Cancer, Imperial College London, London, United Kingdom
| | - Ashish Patel
- Department of Surgery & Cancer, Imperial College London, London, United Kingdom
| | - Hutan Ashrafian
- Department of Surgery & Cancer, Imperial College London, London, United Kingdom
| | - Adam J Woods
- Department of Clinical and Health Psychology, Center for Cognitive Aging and Memory, McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Harsimrat Singh
- Department of Surgery & Cancer, Imperial College London, London, United Kingdom
| | - Ara Darzi
- Department of Surgery & Cancer, Imperial College London, London, United Kingdom
| | - Daniel Richard Leff
- Department of Surgery & Cancer, Imperial College London, London, United Kingdom
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Sommer IE, Hugdahl K. Auditory hallucinations in schizophrenia: Where are we now and where do we go from here? A personal commentary. Schizophr Res 2019; 212:1-3. [PMID: 31383513 DOI: 10.1016/j.schres.2019.07.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 06/05/2019] [Accepted: 07/11/2019] [Indexed: 11/25/2022]
Affiliation(s)
- Iris E Sommer
- Rijks Universiteit Groningen, Department of Biomedical Sciences of Cells and Systems, Department of Psychiatry, University Medical Center Groningen the Netherlands; Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.
| | - Kenneth Hugdahl
- Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway; Division of Psychiatry, Haukeland University Hospital, Bergen, Norway
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Rabipour S, Vidjen PS, Remaud A, Davidson PSR, Tremblay F. Examining the Interactions Between Expectations and tDCS Effects on Motor and Cognitive Performance. Front Neurosci 2019; 12:999. [PMID: 30666182 PMCID: PMC6330301 DOI: 10.3389/fnins.2018.00999] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 12/11/2018] [Indexed: 11/13/2022] Open
Abstract
Background: Despite a growing literature and commercial market, the effectiveness of transcranial direct current stimulation (tDCS) remains questionable. Notably, studies rarely examine factors such as expectations of outcomes, which may influence tDCS response through placebo-like effects. Here we sought to determine whether expectations could influence the behavioral outcomes of a tDCS intervention. Methods: Through an initial study and self-replication, we recruited 121 naïve young adults 18-34 years of age (M = 21.14, SD = 3.58; 88 women). We evaluated expectations of tDCS and of motor and cognitive performance at three times: (i) at baseline; (ii) after being primed to have High or Low expectations of outcomes; and (iii) after a single session of sham-controlled anodal tDCS over the left or right motor cortex. Before and after stimulation, participants performed the Grooved Pegboard Test and a choice reaction time task as measures of motor dexterity, response time, and response inhibition. Results: Repeated measures ANOVA revealed that participants had varying, largely uncertain, expectations regarding tDCS effectiveness at baseline. Expectation ratings significantly increased or decreased in response to High or Low priming, respectively, and decreased following the intervention. Response times and accuracy on motor and cognitive measures were largely unaffected by expectation or stimulation conditions. Overall, our analysis revealed no effect attributable to baseline expectations, belief of group assignment, or experimental condition on behavioral outcomes. Subjective experience did not differ based on expectation or stimulation condition. Conclusions: Our results suggest no clear effects of tDCS or of expectations on our performance measures, highlighting the need for further investigations of such stimulation methods.
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Affiliation(s)
- Sheida Rabipour
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | | | - Anthony Remaud
- Bruyère Research Institute, Bruyère Continuing Care, Ottawa, ON, Canada
| | - Patrick S. R. Davidson
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
- Bruyère Research Institute, Bruyère Continuing Care, Ottawa, ON, Canada
| | - François Tremblay
- Bruyère Research Institute, Bruyère Continuing Care, Ottawa, ON, Canada
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Fonteneau C, Mondino M, Arns M, Baeken C, Bikson M, Brunoni AR, Burke MJ, Neuvonen T, Padberg F, Pascual-Leone A, Poulet E, Ruffini G, Santarnecchi E, Sauvaget A, Schellhorn K, Suaud-Chagny MF, Palm U, Brunelin J. Sham tDCS: A hidden source of variability? Reflections for further blinded, controlled trials. Brain Stimul 2019; 12:668-673. [PMID: 30639235 DOI: 10.1016/j.brs.2018.12.977] [Citation(s) in RCA: 113] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 12/20/2018] [Accepted: 12/29/2018] [Indexed: 11/26/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique increasingly used to modulate neural activity in the living brain. In order to establish the neurophysiological, cognitive or clinical effects of tDCS, most studies compare the effects of active tDCS to those observed with a sham tDCS intervention. In most cases, sham tDCS consists in delivering an active stimulation for a few seconds to mimic the sensations observed with active tDCS and keep participants blind to the intervention. However, to date, sham-controlled tDCS studies yield inconsistent results, which might arise in part from sham inconsistencies. Indeed, a multiplicity of sham stimulation protocols is being used in the tDCS research field and might have different biological effects beyond the intended transient sensations. Here, we seek to enlighten the scientific community to this possible confounding factor in order to increase reproducibility of neurophysiological, cognitive and clinical tDCS studies.
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Affiliation(s)
- Clara Fonteneau
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Psychiatric Disorders: from Resistance to Response Team, F-69000, France; University Lyon 1, Villeurbanne, F-69000, France; Centre Hospitalier Le Vinatier, Lyon, F-69000, France
| | - Marine Mondino
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Psychiatric Disorders: from Resistance to Response Team, F-69000, France; University Lyon 1, Villeurbanne, F-69000, France; Centre Hospitalier Le Vinatier, Lyon, F-69000, France
| | - Martijn Arns
- neuroCare Group GmbH, Munich, Germany; Research Institute Brainclinics, Nijmegen, the Netherlands
| | - Chris Baeken
- Department of Psychiatry and Medical Psychology, Ghent University Hospital, Ghent University, Ghent, Belgium; Department of Psychiatry, University Hospital UZBrussel, Brussels, Belgium; Ghent Experimental Psychiatry (GHEP) Lab, Ghent, Belgium
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York, New York City, NY, USA
| | - Andre R Brunoni
- Department of Psychiatry and Psychotherapy, University Hospital, LMU, Munich, Germany; Service of Interdisciplinary Neuromodulation (SIN), Laboratory of Neuroscience (LIM27) and National Institute of Biomarkers in Neuropsychiatry (INBioN), Department and Institute of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil
| | - Matthew J Burke
- Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | | | - Frank Padberg
- Department of Psychiatry and Psychotherapy, University Hospital, LMU, Munich, Germany
| | - Alvaro Pascual-Leone
- Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Emmanuel Poulet
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Psychiatric Disorders: from Resistance to Response Team, F-69000, France; University Lyon 1, Villeurbanne, F-69000, France; Centre Hospitalier Le Vinatier, Lyon, F-69000, France
| | - Giulio Ruffini
- Neuroelectrics Corporation, 210 Broadway, 02139, Cambridge, MA, USA
| | - Emiliano Santarnecchi
- Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Anne Sauvaget
- CHU de Nantes, Psychiatric Neuromodulation Unit, Addictology and Liaison-Psychiatry Department, Nantes, France; Laboratory "Movement, Interactions, Performance" (E.A. 4334), Faculty of Sport Sciences, University of Nantes, Nantes, France
| | | | - Marie-Françoise Suaud-Chagny
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Psychiatric Disorders: from Resistance to Response Team, F-69000, France; University Lyon 1, Villeurbanne, F-69000, France; Centre Hospitalier Le Vinatier, Lyon, F-69000, France
| | - Ulrich Palm
- Department of Psychiatry and Psychotherapy, University Hospital, LMU, Munich, Germany
| | - Jérome Brunelin
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Psychiatric Disorders: from Resistance to Response Team, F-69000, France; University Lyon 1, Villeurbanne, F-69000, France; Centre Hospitalier Le Vinatier, Lyon, F-69000, France.
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Jongkees BJ, Loseva AA, Yavari FB, Nitsche MA, Colzato LS. The COMT Val 158 Met polymorphism does not modulate the after-effect of tDCS on working memory. Eur J Neurosci 2019; 49:263-274. [PMID: 30402947 PMCID: PMC6590637 DOI: 10.1111/ejn.14261] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 09/25/2018] [Accepted: 10/29/2018] [Indexed: 01/12/2023]
Abstract
Transcranial direct current stimulation (tDCS) can alter cortical excitability, neural plasticity, and cognitive-behavioral performance; however, its effects are known to vary across studies. A partial account of this variability relates to individual differences in dopamine function. Indeed, dopaminergic manipulations alter the physiological and cognitive-behavioral effects of tDCS, and gene polymorphisms related to dopamine have predicted individual response to online tDCS (i.e., stimulation overlapping with the critical task). Notably, the role of individual differences in dopamine has not yet been properly assessed in the effect of offline tDCS (i.e., stimulation prior to the critical task). We investigated if and how the COMT Val158 Met polymorphism (rs4680) modulates the after-effect of prefrontal tDCS on verbal working memory (WM). One hundred and thirty-nine participants were genotyped for the COMT Val158 Met polymorphism and received anodal-over-left, cathodal-over-right (AL-CR), cathodal-over-left, anodal-over-right (CL-AR), or sham stimulation over the dorsolateral prefrontal cortex in a between-subjects, pretest-posttest study design. WM was assessed using the N-back task. The results provide no evidence that the COMT polymorphism impacts the after-effect of prefrontal tDCS on WM. Taken together with previous findings on dopamine and tDCS interactions, the results of the present study suggest that (a) indirect markers of dopamine (such as COMT) are differently related to online and offline effects of tDCS, and (b) findings from studies involving pharmacological manipulation should be generalized with caution to findings of inter-individual differences. In sum, we argue that state (i.e., a manipulation of) and trait (i.e., baseline) differences in dopamine may exert different effects on online and offline tDCS.
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Affiliation(s)
- Bryant J. Jongkees
- Cognitive Psychology Unit & Leiden Institute for Brain and CognitionLeiden UniversityLeidenThe Netherlands
| | - Alexandra A. Loseva
- Cognitive Psychology Unit & Leiden Institute for Brain and CognitionLeiden UniversityLeidenThe Netherlands
| | - Fatemeh B. Yavari
- Leibniz Research Centre for Working Environment and Human FactorsDortmundGermany
| | - Michael A. Nitsche
- Leibniz Research Centre for Working Environment and Human FactorsDortmundGermany
- Department of Clinical NeurophysiologyGeorg‐August University GöttingenGöttingenGermany
- Department of NeurologyUniversity Medical Hospital BergmannsheilBochumGermany
| | - Lorenza S. Colzato
- Cognitive Psychology Unit & Leiden Institute for Brain and CognitionLeiden UniversityLeidenThe Netherlands
- Department of Cognitive PsychologyFaculty of PsychologyInstitute of Cognitive NeuroscienceRuhr University BochumBochumGermany
- Institute for Sports and Sport ScienceUniversity of KasselKasselGermany
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Would the Use of Safe, Cost-Effective tDCS Tackle Rather than Cause Unfairness in Sports? JOURNAL OF COGNITIVE ENHANCEMENT 2018. [DOI: 10.1007/s41465-018-0113-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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den Uyl TE, Gladwin TE, Lindenmeyer J, Wiers RW. A Clinical Trial with Combined Transcranial Direct Current Stimulation and Attentional Bias Modification in Alcohol-Dependent Patients. Alcohol Clin Exp Res 2018; 42:1961-1969. [PMID: 30025152 PMCID: PMC6175348 DOI: 10.1111/acer.13841] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 07/12/2018] [Indexed: 11/30/2022]
Abstract
BACKGROUND Modifying attentional processes with attentional bias modification (ABM) might be a relevant add-on to treatment in addiction. This study investigated whether influencing cortical plasticity with transcranial direct current stimulation (tDCS) could increase training effects. tDCS could also help alcohol-dependent patients to overcome craving and reduce relapse, independent of training. These approaches were combined to investigate effects in the treatment of alcoholism. METHODS Ninety-eight patients (analytical sample = 83) were randomly assigned to 4 groups in a 2-by-2 factorial design. Patients received 4 sessions of ABM (control or real training) combined with 2 mA tDCS (active: 20 minutes or sham: 30 seconds) over the left dorsolateral prefrontal cortex. Alcohol bias and craving were assessed, and treatment outcome was measured as relapse after 1 year. RESULTS Attentional bias scores indicated that during the training only the group with active tDCS and real ABM displayed an overall avoidance bias (p < 0.05). From pre- to postassessment, there were no main or interaction effects of tDCS and ABM on the bias scores, craving, or relapse (p > 0.2). However, effects on relapse after active tDCS were in the expected direction. CONCLUSIONS There was no evidence of a beneficial effect of tDCS or ABM or the combination. Whether the absence of effect was due to issues with the outcome measurements (e.g., lack of craving, high dropout, and unreliable measurements) or aspects of the intervention should be further investigated.
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Affiliation(s)
- Tess E. den Uyl
- Addiction, Development and Psychopathology (ADAPT) LabDepartment of PsychologyUniversity of AmsterdamAmsterdamThe Netherlands
- Amsterdam Brain & Cognition (ABC)University of AmsterdamAmsterdamThe Netherlands
| | | | | | - Reinout W. Wiers
- Addiction, Development and Psychopathology (ADAPT) LabDepartment of PsychologyUniversity of AmsterdamAmsterdamThe Netherlands
- Amsterdam Brain & Cognition (ABC)University of AmsterdamAmsterdamThe Netherlands
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Attenuating anger and aggression with neuromodulation of the vmPFC: A simultaneous tDCS-fMRI study. Cortex 2018; 109:156-170. [PMID: 30343211 DOI: 10.1016/j.cortex.2018.09.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 08/20/2018] [Accepted: 09/13/2018] [Indexed: 12/22/2022]
Abstract
Angry outbursts during interpersonal provocations may lead to violence and prevails in numerous pathological conditions. In the anger-infused Ultimatum Game (aiUG), unfair monetary offers accompanied by written provocations induce anger. Rejection of such offers relates to aggression, whereas acceptance to anger regulation. We previously demonstrated the involvement of the ventro-medial prefrontal cortex (vmPFC) in accepting unfair offers and attenuating anger during an aiUG, suggestive of its role in anger regulation. Here, we aimed to enhance anger regulation by facilitating vmPFC activity during anger induction, using anodal transcranial direct current stimulation (tDCS) and simultaneously with functional Magnetic Resonance Imaging to validate modulation of vmPFC activity. In a cross-over, sham-controlled, double-blind study, participants (N = 25) were each scanned twice, counterbalancing sham and active tDCS applied during administration of the aiUG. Outcome measures included the effect of active versus sham stimulation on vmPFC activity, unfair offers' acceptance rates, self-reported anger, and aggressive behavior in a subsequent reactive aggression paradigm. Results indicate that active stimulation led to increased vmPFC activity during the processing of unfair offers, increased acceptance rates of these offers, and mitigated the increase in self-reported anger following the aiUG. We also noted a decrease in subsequent aggressive behavior following active stimulation, but only when active stimulation was conducted in the first experimental session. Finally, an exploratory finding indicated that participants with a stronger habitual tendency to use suppression as an emotion regulation strategy, reported less anger following the aiUG in the active compared to sham stimulation conditions. Findings support a potential causal link between vmPFC functionality and the experience and expression of anger, supporting vmPFC's role in anger regulation, and providing a promising avenue for reducing angry and aggressive outbursts during interpersonal provocations in various psychiatric and medical conditions.
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Cognitive effects of transcranial direct current stimulation combined with working memory training in fibromyalgia: a randomized clinical trial. Sci Rep 2018; 8:12477. [PMID: 30127510 PMCID: PMC6102237 DOI: 10.1038/s41598-018-30127-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 07/17/2018] [Indexed: 12/20/2022] Open
Abstract
Cognitive dysfunction in fibromyalgia has been reported, especially memory. Anodal transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) has been effective in enhancing this function. We tested the effects of eight sessions of tDCS and cognitive training on immediate and delayed memory, verbal fluency and working memory and its association with brain-derived neurotrophic factor (BDNF) levels. Forty females with fibromyalgia were randomized to receive eight sessions of active or sham tDCS. Anodal stimulation (2 mA) was applied over the DLPFC and online combined with a working memory training (WMT) for 20 minutes. Pre and post-treatment neurocognitive tests were administered. Data analysis on deltas considering years of education and BDNF as covariates, indicated active-tDCS + WMT significantly increased immediate memory indexed by Rey Auditory Verbal Learning Test score when compared to sham. This effect was dependent on basal BDNF levels. In addition, the model showed active stimulation increased orthographic and semantic verbal fluency scores (Controlled Oral Word Association Test) and short-term memory (Forward Digit Span). The combination of both techniques seemed to produce effects on specific cognitive functions related to short-term and long-term episodic memory and executive functions, which has clinical relevance for top-down treatment approaches in FM.
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Payne JS, Tainturier MJ. tDCS Facilitation of Picture Naming: Item-Specific, Task General, or Neither? Front Neurosci 2018; 12:549. [PMID: 30147643 PMCID: PMC6095956 DOI: 10.3389/fnins.2018.00549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/20/2018] [Indexed: 11/22/2022] Open
Abstract
The aim of the present study was to clarify the conditions under which anodal tDCS applied to left hemisphere language sites may facilitate picture naming latencies in healthy young adults. We built upon previous studies by directly testing for item-specific and generalized effects of tDCS through manipulation of item-familiarization and through testing for both online and offline effects of stimulation, in the same paradigm. In addition, we tested for the robustness of these effects by comparing two left hemisphere sites critical for lexical retrieval. Twenty-eight healthy young adults completed two testing sessions receiving either anodal (1.5 mA, 20 min) or sham stimulation (1.5 mA, 30 s) in each session. Half of the participants received tDCS over the left inferior frontal region and the other half over the left posterior superior temporal region. All participants were asked to a name a set of pictures and their response latencies were compared at three time points (before, during, and after the end of stimulation). The stimulus set was constructed so that some items were presented at all time points, some before and after stimulation, and some during stimulation only. A parsimonious linear mixed effects model (LMM) revealed robust repetition priming effects as latencies were reliably faster for previously named items in all conditions. However, active tDCS did not produce any additional facilitation in relation to sham, and even led to slower performance in the IFG group when the stimulated items differed from those tested at baseline and post-test. Our findings add to the present debate about the efficacy of single-session tDCS for modulation of lexical retrieval in healthy young adults. We conclude that future research should take a more systematic, step-wise approach to the application of tDCS to the study of language and that more sensitive experimental paradigms, which include a training element, are more adapted to the study of cognitive processes in populations with optimal levels of cortical excitability.
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Affiliation(s)
- Joshua S Payne
- Bilingual Aphasia Lab, School of Psychology, Bangor University, Bangor, United Kingdom.,Centre for Research on Bilingualism, Bangor University, Bangor, United Kingdom
| | - Marie-Josèphe Tainturier
- Bilingual Aphasia Lab, School of Psychology, Bangor University, Bangor, United Kingdom.,Centre for Research on Bilingualism, Bangor University, Bangor, United Kingdom
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Abend R, Sar-El R, Gonen T, Jalon I, Vaisvaser S, Bar-Haim Y, Hendler T. Modulating Emotional Experience Using Electrical Stimulation of the Medial-Prefrontal Cortex: A Preliminary tDCS-fMRI Study. Neuromodulation 2018; 22:884-893. [PMID: 29741803 DOI: 10.1111/ner.12787] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 03/23/2018] [Accepted: 03/26/2018] [Indexed: 12/28/2022]
Abstract
OBJECTIVES Implicit regulation of emotions involves medial-prefrontal cortex (mPFC) regions exerting regulatory control over limbic structures. Diminished regulation relates to aberrant mPFC functionality and psychopathology. Establishing means of modulating mPFC functionality could benefit research on emotion and its dysregulation. Here, we tested the capacity of transcranial direct current stimulation (tDCS) targeting mPFC to modulate subjective emotional states by facilitating implicit emotion regulation. MATERIALS AND METHODS Stimulation was applied concurrently with functional magnetic resonance imaging to validate its neurobehavioral effect. Sixteen participants were each scanned twice, counterbalancing active and sham tDCS application, while undergoing negative mood induction (clips featuring negative vs. neutral contents). Effects of stimulation on emotional experience were assessed using subjective and neural measures. RESULTS Subjectively, active stimulation led to significant reduction in reported intensity of experienced emotions to negatively valenced (p = 0.005) clips but not to neutral clips (p > 0.99). Active stimulation further mitigated a rise in stress levels from pre- to post-induction (sham: p = 0.004; active: p = 0.15). Neurally, stimulation increased activation in mPFC regions associated with implicit emotion regulation (ventromedial-prefrontal cortex; subgenual anterior-cingulate cortex, sgACC), and in ventral striatum, a core limbic structure (all ps < 0.05). Stimulation also altered functional connectivity (assessed using whole-brain psycho-physiological interaction) between these regions, and with additional limbic regions. Stimulation-induced sgACC activation correlated with reported emotion intensity and depressive symptoms (rs > 0.64, ps < 0.018), suggesting individual differences in stimulation responsivity. CONCLUSIONS Results of this study indicate the potential capacity of tDCS to facilitate brain activation in mPFC regions underlying implicit regulation of emotion and accordingly modulate subjective emotional experiences.
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Affiliation(s)
- Rany Abend
- School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel.,Functional Brain Center, Wohl Institute for Advanced Imaging, Sourasky Medical Center, Tel Aviv, Israel.,Section on Development and Affective Neuroscience, National Institute of Mental Health, Bethesda, MD, USA
| | - Roy Sar-El
- Functional Brain Center, Wohl Institute for Advanced Imaging, Sourasky Medical Center, Tel Aviv, Israel.,Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Tal Gonen
- Functional Brain Center, Wohl Institute for Advanced Imaging, Sourasky Medical Center, Tel Aviv, Israel
| | - Itamar Jalon
- Functional Brain Center, Wohl Institute for Advanced Imaging, Sourasky Medical Center, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Sharon Vaisvaser
- Functional Brain Center, Wohl Institute for Advanced Imaging, Sourasky Medical Center, Tel Aviv, Israel
| | - Yair Bar-Haim
- School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Talma Hendler
- School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel.,Functional Brain Center, Wohl Institute for Advanced Imaging, Sourasky Medical Center, Tel Aviv, Israel.,Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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29
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Sung K, Gordon B. Transcranial direct current stimulation (tDCS) facilitates overall visual search response times but does not interact with visual search task factors. PLoS One 2018; 13:e0194640. [PMID: 29558513 PMCID: PMC5860774 DOI: 10.1371/journal.pone.0194640] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 03/07/2018] [Indexed: 11/18/2022] Open
Abstract
Whether transcranial direct current stimulation (tDCS) affects mental functions, and how any such effects arise from its neural effects, continue to be debated. We investigated whether tDCS applied over the visual cortex (Oz) with a vertex (Cz) reference might affect response times (RTs) in a visual search task. We also examined whether any significant tDCS effects would interact with task factors (target presence, discrimination difficulty, and stimulus brightness) that are known to selectively influence one or the other of the two information processing stages posited by current models of visual search. Based on additive factor logic, we expected that the pattern of interactions involving a significant tDCS effect could help us colocalize the tDCS effect to one (or both) of the processing stages. In Experiment 1 (n = 12), anodal tDCS improved RTs significantly; cathodal tDCS produced a nonsignificant trend toward improvement. However, there were no interactions between the anodal tDCS effect and target presence or discrimination difficulty. In Experiment 2 (n = 18), we manipulated stimulus brightness along with target presence and discrimination difficulty. Anodal and cathodal tDCS both produced significant improvements in RTs. Again, the tDCS effects did not interact with any of the task factors. In Experiment 3 (n = 16), electrodes were placed at Cz and on the upper arm, to test for a possible effect of incidental stimulation of the motor regions under Cz. No effect of tDCS on RTs was found. These findings strengthen the case for tDCS having real effects on cerebral information processing. However, these effects did not clearly arise from either of the two processing stages of the visual search process. We suggest that this is because tDCS has a DIFFUSE, pervasive action across the task-relevant neuroanatomical region(s), not a discrete effect in terms of information processing stages.
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Affiliation(s)
- Kyongje Sung
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Barry Gordon
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Cognitive Science Department, The Johns Hopkins University, Baltimore, Maryland, United States of America
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30
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Abstract
Transcranial magnetic and electric stimulation of the brain are novel and highly promising techniques currently employed in both research and clinical practice. Improving or rehabilitating brain functions by modulating excitability with these noninvasive tools is an exciting new area in neuroscience. Since the cerebellum is closely connected with the cerebral regions subserving motor, associative, and affective functions, the cerebello-thalamo-cortical pathways are an interesting target for these new techniques. Targeting the cerebellum represents a novel way to modulate the excitability of remote cortical regions and their functions. This review brings together the studies that have applied cerebellar stimulation, magnetic and electric, and presents an overview of the current knowledge and unsolved issues. Some recommendations for future research are implemented as well.
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31
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Polanía R, Nitsche MA, Ruff CC. Studying and modifying brain function with non-invasive brain stimulation. Nat Neurosci 2018; 21:174-187. [PMID: 29311747 DOI: 10.1038/s41593-017-0054-4] [Citation(s) in RCA: 496] [Impact Index Per Article: 82.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 11/22/2017] [Indexed: 12/12/2022]
Abstract
In the past three decades, our understanding of brain-behavior relationships has been significantly shaped by research using non-invasive brain stimulation (NIBS) techniques. These methods allow non-invasive and safe modulation of neural processes in the healthy brain, enabling researchers to directly study how experimentally altered neural activity causally affects behavior. This unique property of NIBS methods has, on the one hand, led to groundbreaking findings on the brain basis of various aspects of behavior and has raised interest in possible clinical and practical applications of these methods. On the other hand, it has also triggered increasingly critical debates about the properties and possible limitations of these methods. In this review, we discuss these issues, clarify the challenges associated with the use of currently available NIBS techniques for basic research and practical applications, and provide recommendations for studies using NIBS techniques to establish brain-behavior relationships.
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Affiliation(s)
- Rafael Polanía
- Laboratory for Social and Neural Systems Research (SNS-Lab), Department of Economics, University of Zurich, Zurich, Switzerland.
| | - Michael A Nitsche
- Leibniz Research Center for Working Environment and Human Factors, Department of Psychology and Neurosciences, TU Dortmund, Dortmund, Germany.,Department of Neurology, University Medical Hospital Bergmannsheil, Bochum, Germany
| | - Christian C Ruff
- Laboratory for Social and Neural Systems Research (SNS-Lab), Department of Economics, University of Zurich, Zurich, Switzerland.
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32
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Learmonth G, Felisatti F, Siriwardena N, Checketts M, Benwell CSY, Märker G, Thut G, Harvey M. No Interaction between tDCS Current Strength and Baseline Performance: A Conceptual Replication. Front Neurosci 2017; 11:664. [PMID: 29249932 PMCID: PMC5717015 DOI: 10.3389/fnins.2017.00664] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 11/15/2017] [Indexed: 01/05/2023] Open
Abstract
Several recent studies have reported non-linear effects of transcranial direct current stimulation (tDCS), which has been attributed to an interaction between the stimulation parameters (e.g., current strength, duration) and the neural state of the cortex being stimulated (e.g., indexed by baseline performance ability, age) (see Fertonani and Miniussi, 2016). We have recently described one such non-linear interaction between current strength and baseline performance on a visuospatial attention (landmark) task (Benwell et al., 2015). In this previous study, we induced a small overall rightward shift of spatial attention across 38 participants using bi-hemispheric tDCS applied for 20 min (concurrent left posterior parietal (P5) anode and right posterior parietal (P6) cathode) relative to a sham protocol. Importantly, this shift in bias was driven by a state-dependent interaction between current intensity and the discrimination sensitivity of the participant at baseline (pre-stimulation) for the landmark task. Individuals with high discrimination sensitivity (HDS) shifted rightward in response to low- (1 mA) but not high-intensity (2 mA) tDCS, whereas individuals with low discrimination sensitivity (LDS) shifted rightward with high- but not low-intensity stimulation. However, in Benwell et al. (2015) current strength was applied as a between-groups factor, where half of the participants received 1 mA and half received 2 mA tDCS, thus we were unable to compare high and low-intensity tDCS directly within each individual. Here we aimed to replicate these findings using a within-group design. Thirty young adults received 15 min of 1 and 2 mA tDCS, and a sham protocol, each on different days, to test the concept of an interaction between baseline performance and current strength. We found no overall rightward shift of spatial attention with either current strength, and no interaction between performance and current strength. These results provide further evidence of low replicability of non-invasive brain stimulation protocols, and the need for further attempts to replicate the key experimental findings within this field.
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Affiliation(s)
- Gemma Learmonth
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom.,School of Psychology, University of Glasgow, Glasgow, United Kingdom
| | | | | | - Matthew Checketts
- School of Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Christopher S Y Benwell
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom.,School of Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Gesine Märker
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom.,School of Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Gregor Thut
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Monika Harvey
- School of Psychology, University of Glasgow, Glasgow, United Kingdom
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33
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tDCS effects on word production: Limited by design? Comment on Westwood et al. (2017). Cortex 2017; 96:137-142. [DOI: 10.1016/j.cortex.2017.06.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 06/14/2017] [Indexed: 11/18/2022]
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34
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den Uyl TE, Gladwin TE, Rinck M, Lindenmeyer J, Wiers RW. A clinical trial with combined transcranial direct current stimulation and alcohol approach bias retraining. Addict Biol 2017; 22:1632-1640. [PMID: 27790791 DOI: 10.1111/adb.12463] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 09/12/2016] [Accepted: 09/12/2016] [Indexed: 12/20/2022]
Abstract
Two studies showed an improvement in clinical outcomes after alcohol approach bias retraining, a form of Cognitive Bias Modification (CBM). We investigated whether transcranial direct current stimulation (tDCS) could enhance effects of CBM. TDCS is a neuromodulation technique that can increase neuroplasticity and has previously been found to reduce craving. One hundred alcohol-dependent inpatients (91 used for analysis) were randomized into three experimental groups in a double-blind parallel design. The experimental group received four sessions of CBM while receiving 2 mA of anodal tDCS over the dorsolateral prefrontal cortex (DLPFC). There were two control groups: One received sham stimulation during training and one received active stimulation at a different moment. Treatment outcomes were abstinence duration (primary) and relapse after 3 and 12 months, craving and approach bias (secondary). Craving and approach bias scores decreased over time; there were no significant interactions with experimental condition. There was no effect on abstinence duration after three months (χ2(2) = 3.53, p = 0.77). However, a logistic regression on relapse rates after one year (standard outcome in the clinic, but not-preregistered) showed a trend when relevant predictors were included; relapse was lower in the condition receiving active stimulation during CBM only when comparing to sham stimulation (B = 1.52, S.E. = .836, p = .07, without predictors: p = .19). No strong evidence for a specific enhancement effect of tDCS on CBM was found. However, in a post-hoc analysis, tDCS combined with CBM showed a promising trend on treatment outcome. Important limitations are discussed, and replication is necessary to find more reliable effects.
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Affiliation(s)
- Tess E. den Uyl
- Addiction, Development and Psychopathology (ADAPT) lab, Department of Psychology; University of Amsterdam; The Netherlands
- Amsterdam Brain and Cognition (ABC); University of Amsterdam; The Netherlands
| | - Thomas E. Gladwin
- Addiction, Development and Psychopathology (ADAPT) lab, Department of Psychology; University of Amsterdam; The Netherlands
- Research Centre-Military Mental Health; Ministry of Defense; The Netherlands
| | - Mike Rinck
- Behavioural Science Institute; Radboud University Nijmegen; The Netherlands
| | | | - Reinout W. Wiers
- Addiction, Development and Psychopathology (ADAPT) lab, Department of Psychology; University of Amsterdam; The Netherlands
- Amsterdam Brain and Cognition (ABC); University of Amsterdam; The Netherlands
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35
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Bikson M, Paneri B, Mourdoukoutas A, Esmaeilpour Z, Badran BW, Azzam R, Adair D, Datta A, Fang XH, Wingeier B, Chao D, Alonso-Alonso M, Lee K, Knotkova H, Woods AJ, Hagedorn D, Jeffery D, Giordano J, Tyler WJ. Limited output transcranial electrical stimulation (LOTES-2017): Engineering principles, regulatory statutes, and industry standards for wellness, over-the-counter, or prescription devices with low risk. Brain Stimul 2017; 11:134-157. [PMID: 29122535 DOI: 10.1016/j.brs.2017.10.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 09/16/2017] [Accepted: 10/15/2017] [Indexed: 01/17/2023] Open
Abstract
We present device standards for low-power non-invasive electrical brain stimulation devices classified as limited output transcranial electrical stimulation (tES). Emerging applications of limited output tES to modulate brain function span techniques to stimulate brain or nerve structures, including transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial pulsed current stimulation (tPCS), have engendered discussion on how access to technology should be regulated. In regards to legal regulations and manufacturing standards for comparable technologies, a comprehensive framework already exists, including quality systems (QS), risk management, and (inter)national electrotechnical standards (IEC). In Part 1, relevant statutes are described for medical and wellness application. While agencies overseeing medical devices have broad jurisdiction, enforcement typically focuses on those devices with medical claims or posing significant risk. Consumer protections regarding responsible marketing and manufacture apply regardless. In Part 2 of this paper, we classify the electrical output performance of devices cleared by the United States Food and Drug Administration (FDA) including over-the-counter (OTC) and prescription electrostimulation devices, devices available for therapeutic or cosmetic purposes, and devices indicated for stimulation of the body or head. Examples include iontophoresis devices, powered muscle stimulators (PMS), cranial electrotherapy stimulation (CES), and transcutaneous electrical nerve stimulation (TENS) devices. Spanning over 13 FDA product codes, more than 1200 electrical stimulators have been cleared for marketing since 1977. The output characteristics of conventional tDCS, tACS, and tPCS techniques are well below those of most FDA cleared devices, including devices that are available OTC and those intended for stimulation on the head. This engineering analysis demonstrates that with regard to output performance and standing regulation, the availability of tDCS, tACS, or tPCS to the public would not introduce risk, provided such devices are responsibly manufactured and legally marketed. In Part 3, we develop voluntary manufacturer guidance for limited output tES that is aligned with current regulatory standards. Based on established medical engineering and scientific principles, we outline a robust and transparent technical framework for ensuring limited output tES devices are designed to minimize risks, while also supporting access and innovation. Alongside applicable medical and government activities, this voluntary industry standard (LOTES-2017) further serves an important role in supporting informed decisions by the public.
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Affiliation(s)
- Marom Bikson
- The City College of New York, Department of Biomedical Engineering, New York, NY 10031, USA.
| | - Bhaskar Paneri
- The City College of New York, Department of Biomedical Engineering, New York, NY 10031, USA
| | - Andoni Mourdoukoutas
- The City College of New York, Department of Biomedical Engineering, New York, NY 10031, USA
| | - Zeinab Esmaeilpour
- The City College of New York, Department of Biomedical Engineering, New York, NY 10031, USA
| | - Bashar W Badran
- U.S. Army Research Laboratory, Aberdeen Proving Ground, MD, USA; Department of Psychology, University of New Mexico, Albuquerque, NM, USA
| | | | - Devin Adair
- The City College of New York, Department of Biomedical Engineering, New York, NY 10031, USA
| | | | - Xiao Hui Fang
- The City College of New York, Department of Biomedical Engineering, New York, NY 10031, USA
| | | | - Daniel Chao
- Halo Neuroscience Inc., San Francisco, CA 94103, USA
| | - Miguel Alonso-Alonso
- Harvard Medical School, Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Boston, MA, USA
| | - Kiwon Lee
- Ybrain Inc., Sampyeong-dong, Seongnam-si, South Korea
| | - Helena Knotkova
- MJHS Institute for Innovation in Palliative Care, New York, NY, USA; Department of Family and Social Medicine, Albert Einstein College of Medicine, The Bronx, NY, USA
| | - Adam J Woods
- Center for Cognitive Aging and Memory, McKnight Brain Institute, Department of Clinical and Health Psychology, University of Florida, USA
| | | | | | - James Giordano
- Department of Neurology and Neuroethics Studies Program, Pellegrino Center for Clinical Bioethics, Georgetown University Medical Center, Washington, DC, USA
| | - William J Tyler
- Arizona State University, School of Biological and Health Systems Engineering, Tempe, AZ 85287, USA
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36
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Krause MR, Zanos TP, Csorba BA, Pilly PK, Choe J, Phillips ME, Datta A, Pack CC. Transcranial Direct Current Stimulation Facilitates Associative Learning and Alters Functional Connectivity in the Primate Brain. Curr Biol 2017; 27:3086-3096.e3. [PMID: 29033331 DOI: 10.1016/j.cub.2017.09.020] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 07/19/2017] [Accepted: 09/11/2017] [Indexed: 01/12/2023]
Abstract
There has been growing interest in transcranial direct current stimulation (tDCS), a non-invasive technique purported to modulate neural activity via weak, externally applied electric fields. Although some promising preliminary data have been reported for applications ranging from stroke rehabilitation to cognitive enhancement, little is known about how tDCS affects the human brain, and some studies have concluded that it may have no effect at all. Here, we describe a macaque model of tDCS that allows us to simultaneously examine the effects of tDCS on brain activity and behavior. We find that applying tDCS to right prefrontal cortex improves monkeys' performance on an associative learning task. While firing rates do not change within the targeted area, tDCS does induce large low-frequency oscillations in the underlying tissue. These oscillations alter functional connectivity, both locally and between distant brain areas, and these long-range changes correlate with tDCS's effects on behavior. Together, these results are consistent with the idea that tDCS leads to widespread changes in brain activity and suggest that it may be a valuable method for cheaply and non-invasively altering functional connectivity in humans.
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Affiliation(s)
- Matthew R Krause
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | | | - Bennett A Csorba
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Praveen K Pilly
- Information and Systems Sciences Laboratory, HRL Laboratories, LLC, Malibu, CA 90265, USA.
| | - Jaehoon Choe
- Information and Systems Sciences Laboratory, HRL Laboratories, LLC, Malibu, CA 90265, USA
| | - Matthew E Phillips
- Information and Systems Sciences Laboratory, HRL Laboratories, LLC, Malibu, CA 90265, USA
| | | | - Christopher C Pack
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada.
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37
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Almeida J, Martins AR, Bergström F, Amaral L, Freixo A, Ganho-Ávila A, Kristensen S, Lee D, Nogueira J, Ruttorf M. Polarity-specific transcranial direct current stimulation effects on object-selective neural responses in the inferior parietal lobe. Cortex 2017; 94:176-181. [DOI: 10.1016/j.cortex.2017.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 04/03/2017] [Accepted: 07/03/2017] [Indexed: 10/19/2022]
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38
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Transcranial direct current stimulation (tDCS) modulation of picture naming and word reading: A meta-analysis of single session tDCS applied to healthy participants. Neuropsychologia 2017; 104:234-249. [DOI: 10.1016/j.neuropsychologia.2017.07.031] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 06/17/2017] [Accepted: 07/25/2017] [Indexed: 12/21/2022]
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39
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Zoefel B, Davis MH. Transcranial electric stimulation for the investigation of speech perception and comprehension. LANGUAGE, COGNITION AND NEUROSCIENCE 2017; 32:910-923. [PMID: 28670598 PMCID: PMC5470108 DOI: 10.1080/23273798.2016.1247970] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 10/04/2016] [Indexed: 05/24/2023]
Abstract
Transcranial electric stimulation (tES), comprising transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), involves applying weak electrical current to the scalp, which can be used to modulate membrane potentials and thereby modify neural activity. Critically, behavioural or perceptual consequences of this modulation provide evidence for a causal role of neural activity in the stimulated brain region for the observed outcome. We present tES as a tool for the investigation of which neural responses are necessary for successful speech perception and comprehension. We summarise existing studies, along with challenges that need to be overcome, potential solutions, and future directions. We conclude that, although standardised stimulation parameters still need to be established, tES is a promising tool for revealing the neural basis of speech processing. Future research can use this method to explore the causal role of brain regions and neural processes for the perception and comprehension of speech.
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40
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Sellaro R, Nitsche MA, Colzato LS. The stimulated social brain: effects of transcranial direct current stimulation on social cognition. Ann N Y Acad Sci 2017; 1369:218-39. [PMID: 27206250 DOI: 10.1111/nyas.13098] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Transcranial direct current stimulation (tDCS) is an increasingly popular noninvasive neuromodulatory tool in the fields of cognitive and clinical neuroscience and psychiatry. It is an inexpensive, painless, and safe brain-stimulation technique that has proven to be effective in modulating cognitive and sensory-perceptual functioning in healthy individuals and clinical populations. Importantly, recent findings have shown that tDCS may also be an effective and promising tool for probing the neural mechanisms of social cognition. In this review, we present the state-of-the-art of the field of tDCS research in social cognition. By doing so, we aim to gather knowledge of the potential of tDCS to modulate social functioning and social decision making in healthy humans, and to inspire future research investigations.
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Affiliation(s)
- Roberta Sellaro
- Cognitive Psychology Unit & Leiden Institute for Brain and Cognition, Leiden University, the Netherlands
| | - Michael A Nitsche
- Department of Clinical Neurophysiology, Georg-August University Göttingen, Germany.,Leibniz Research Centre for Working Environment and Human Resources, Dortmund, Germany.,Department of Neurology, University Medical Hospital Bergmannsheil, Bochum, Germany
| | - Lorenza S Colzato
- Cognitive Psychology Unit & Leiden Institute for Brain and Cognition, Leiden University, the Netherlands
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41
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Frontoparietal neurostimulation modulates working memory training benefits and oscillatory synchronization. Brain Res 2017; 1667:28-40. [PMID: 28502585 DOI: 10.1016/j.brainres.2017.05.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 05/01/2017] [Accepted: 05/03/2017] [Indexed: 11/24/2022]
Abstract
There is considerable interest in maintaining working memory (WM) because it is essential to accomplish most cognitive tasks, and it is correlated with fluid intelligence and ecologically valid measures of daily living. Toward this end, WM training protocols aim to improve WM capacity and extend improvements to unpracticed domains, yet success is limited. One emerging approach is to couple WM training with transcranial direct current stimulation (tDCS). This pairing of WM training with tDCS in longitudinal designs promotes behavioral improvement and evidence of transfer of performance gains to untrained WM tasks. However, the mechanism(s) underlying tDCS-linked training benefits remain unclear. Our goal was to gain purchase on this question by recording high-density EEG before and after a weeklong WM training+tDCS study. Participants completed four sessions of frontoparietal tDCS (active anodal or sham) during which they performed a visuospatial WM change detection task. Participants who received active anodal tDCS demonstrated significant improvement on the WM task, unlike those who received sham stimulation. Importantly, this pattern was mirrored by neural correlates in spectral and phase synchrony analyses of the HD-EEG data. Notably, the behavioral interaction was echoed by interactions in frontal-posterior alpha band power, and theta and low alpha oscillations. These findings indicate that one mechanism by which paired tDCS+WM training operates is to enhance cortical efficiency and connectivity in task-relevant networks.
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42
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Jongkees BJ, Sellaro R, Beste C, Nitsche MA, Kühn S, Colzato LS. l -Tyrosine administration modulates the effect of transcranial direct current stimulation on working memory in healthy humans. Cortex 2017; 90:103-114. [DOI: 10.1016/j.cortex.2017.02.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 12/01/2016] [Accepted: 02/18/2017] [Indexed: 10/20/2022]
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43
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Giordano J, Bikson M, Kappenman ES, Clark VP, Coslett HB, Hamblin MR, Hamilton R, Jankord R, Kozumbo WJ, McKinley RA, Nitsche MA, Reilly JP, Richardson J, Wurzman R, Calabrese E. Mechanisms and Effects of Transcranial Direct Current Stimulation. Dose Response 2017; 15:1559325816685467. [PMID: 28210202 PMCID: PMC5302097 DOI: 10.1177/1559325816685467] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The US Air Force Office of Scientific Research convened a meeting of researchers in the fields of neuroscience, psychology, engineering, and medicine to discuss most pressing issues facing ongoing research in the field of transcranial direct current stimulation (tDCS) and related techniques. In this study, we present opinions prepared by participants of the meeting, focusing on the most promising areas of research, immediate and future goals for the field, and the potential for hormesis theory to inform tDCS research. Scientific, medical, and ethical considerations support the ongoing testing of tDCS in healthy and clinical populations, provided best protocols are used to maximize safety. Notwithstanding the need for ongoing research, promising applications include enhancing vigilance/attention in healthy volunteers, which can accelerate training and support learning. Commonly, tDCS is used as an adjunct to training/rehabilitation tasks with the goal of leftward shift in the learning/treatment effect curves. Although trials are encouraging, elucidating the basic mechanisms of tDCS will accelerate validation and adoption. To this end, biomarkers (eg, clinical neuroimaging and findings from animal models) can support hypotheses linking neurobiological mechanisms and behavioral effects. Dosage can be optimized using computational models of current flow and understanding dose–response. Both biomarkers and dosimetry should guide individualized interventions with the goal of reducing variability. Insights from other applied energy domains, including ionizing radiation, transcranial magnetic stimulation, and low-level laser (light) therapy, can be prudently leveraged.
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Affiliation(s)
- James Giordano
- Department of Neurology and Biochemistry, Neuroethics Studies Program, Pellegrino Center for Clinical Bioethics, Georgetown University Medical Center, Washington, DC, USA
| | - Marom Bikson
- Biomedical Engineering, City College of New York, CUNY, New York, NY, USA
| | - Emily S Kappenman
- San Diego State University, Department of Psychology, San Diego, CA, USA
| | - Vincent P Clark
- Psychology Clinical Neuroscience Center, Department of Psychology, University of New Mexico, Albuquerque, NM, USA
| | - H Branch Coslett
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael R Hamblin
- Wellman Center for Photomedicine, Massachusetts General Hospital and Department of Dermatology, Harvard Medical School, Boston, MA, USA
| | - Roy Hamilton
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ryan Jankord
- United States Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA
| | | | - R Andrew McKinley
- United States Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA
| | - Michael A Nitsche
- Department Psychology and Neurosciences, Leibniz Research Center for Working Environmental and Human Factors, Dortmund, Germany
| | | | - Jessica Richardson
- Department of Speech and Hearing Sciences, University of New Mexico, Albuquerque, NM, USA
| | - Rachel Wurzman
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Edward Calabrese
- Environmental Health Sciences, University of Massachusetts, Amherst, MA, USA
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Interventions aimed at automatic processes in addiction: considering necessary conditions for efficacy. Curr Opin Behav Sci 2017. [DOI: 10.1016/j.cobeha.2016.08.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Buch ER, Santarnecchi E, Antal A, Born J, Celnik PA, Classen J, Gerloff C, Hallett M, Hummel FC, Nitsche MA, Pascual-Leone A, Paulus WJ, Reis J, Robertson EM, Rothwell JC, Sandrini M, Schambra HM, Wassermann EM, Ziemann U, Cohen LG. Effects of tDCS on motor learning and memory formation: A consensus and critical position paper. Clin Neurophysiol 2017; 128:589-603. [PMID: 28231477 DOI: 10.1016/j.clinph.2017.01.004] [Citation(s) in RCA: 215] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 01/05/2017] [Accepted: 01/11/2017] [Indexed: 01/05/2023]
Abstract
Motor skills are required for activities of daily living. Transcranial direct current stimulation (tDCS) applied in association with motor skill learning has been investigated as a tool for enhancing training effects in health and disease. Here, we review the published literature investigating whether tDCS can facilitate the acquisition, retention or adaptation of motor skills. Work in multiple laboratories is underway to develop a mechanistic understanding of tDCS effects on different forms of learning and to optimize stimulation protocols. Efforts are required to improve reproducibility and standardization. Overall, reproducibility remains to be fully tested, effect sizes with present techniques vary over a wide range, and the basis of observed inter-individual variability in tDCS effects is incompletely understood. It is recommended that future studies explicitly state in the Methods the exploratory (hypothesis-generating) or hypothesis-driven (confirmatory) nature of the experimental designs. General research practices could be improved with prospective pre-registration of hypothesis-based investigations, more emphasis on the detailed description of methods (including all pertinent details to enable future modeling of induced current and experimental replication), and use of post-publication open data repositories. A checklist is proposed for reporting tDCS investigations in a way that can improve efforts to assess reproducibility.
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Affiliation(s)
- Ethan R Buch
- Human Cortical Physiology and Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Emiliano Santarnecchi
- Berenson-Allen Center for Non-Invasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Medical Center, Harvard Medical School, Boston, MA, USA
| | - Andrea Antal
- Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Göttingen, Germany
| | - Jan Born
- Institute for Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany; Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany
| | - Pablo A Celnik
- Department of Physical Medicine and Rehabilitation, Johns Hopkins Medical Institution, Baltimore, MD, USA; Department of Neuroscience, Johns Hopkins Medical Institution, Baltimore, MD, USA
| | - Joseph Classen
- Department of Neurology, University of Leipzig, Leipzig, Germany
| | - Christian Gerloff
- Brain Imaging and NeuroStimulation (BINS) Laboratory, Department of Neurology University Medical Center Hamburg-Eppendorf Martinistr, Hamburg, Germany
| | - Mark Hallett
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Friedhelm C Hummel
- Brain Imaging and NeuroStimulation (BINS) Laboratory, Department of Neurology University Medical Center Hamburg-Eppendorf Martinistr, Hamburg, Germany
| | - Michael A Nitsche
- Department of Psychology and Neuroscience, Leibniz Research Center for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Alvaro Pascual-Leone
- Berenson-Allen Center for Non-Invasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Medical Center, Harvard Medical School, Boston, MA, USA
| | - Walter J Paulus
- Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Göttingen, Germany
| | - Janine Reis
- Department of Neurology, Albert Ludwigs University, Freiburg, Germany
| | - Edwin M Robertson
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | | | - Marco Sandrini
- Department of Psychology, University of Roehampton, London, UK
| | - Heidi M Schambra
- Department of Rehabilitation and Regenerative Medicine, Columbia University, New York, NY, USA
| | - Eric M Wassermann
- Behavioral Neurology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Ulf Ziemann
- Department of Neurology & Stroke, and Hertie Institute for Clinical Brain Research, Eberhard Karls University, Tübingen, Germany
| | - Leonardo G Cohen
- Human Cortical Physiology and Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
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Westwood SJ, Olson A, Miall RC, Nappo R, Romani C. Limits to tDCS effects in language: Failures to modulate word production in healthy participants with frontal or temporal tDCS. Cortex 2017; 86:64-82. [PMID: 27912107 PMCID: PMC5264390 DOI: 10.1016/j.cortex.2016.10.016] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 10/19/2016] [Accepted: 10/25/2016] [Indexed: 01/19/2023]
Abstract
Transcranial direct current stimulation (tDCS) is a method of non-invasive brain stimulation widely used to modulate cognitive functions. Recent studies, however, suggests that effects are unreliable, small and often non-significant at least when stimulation is applied in a single session to healthy individuals. We examined the effects of frontal and temporal lobe anodal tDCS on naming and reading tasks and considered possible interactions with linguistic activation and selection mechanisms as well as possible interactions with item difficulty and participant individual variability. Across four separate experiments (N, Exp 1A = 18; 1B = 20; 1C = 18; 2 = 17), we failed to find any difference between real and sham stimulation. Moreover, we found no evidence of significant effects limited to particular conditions (i.e., those requiring suppression of semantic interference), to a subset of participants or to longer RTs. Our findings sound a cautionary note on using tDCS as a means to modulate cognitive performance. Consistent effects of tDCS may be difficult to demonstrate in healthy participants in reading and naming tasks, and be limited to cases of pathological neurophysiology and/or to the use of learning paradigms.
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Affiliation(s)
| | - Andrew Olson
- Behavioural Brain Sciences Centre, School of Psychology, University of Birmingham, UK
| | - R Chris Miall
- Behavioural Brain Sciences Centre, School of Psychology, University of Birmingham, UK
| | - Raffaele Nappo
- Aston University, Life & Health Sciences, Birmingham, UK
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Reinhart RMG, Cosman JD, Fukuda K, Woodman GF. Using transcranial direct-current stimulation (tDCS) to understand cognitive processing. Atten Percept Psychophys 2017; 79:3-23. [PMID: 27804033 PMCID: PMC5539401 DOI: 10.3758/s13414-016-1224-2] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Noninvasive brain stimulation methods are becoming increasingly common tools in the kit of the cognitive scientist. In particular, transcranial direct-current stimulation (tDCS) is showing great promise as a tool to causally manipulate the brain and understand how information is processed. The popularity of this method of brain stimulation is based on the fact that it is safe, inexpensive, its effects are long lasting, and you can increase the likelihood that neurons will fire near one electrode and decrease the likelihood that neurons will fire near another. However, this method of manipulating the brain to draw causal inferences is not without complication. Because tDCS methods continue to be refined and are not yet standardized, there are reports in the literature that show some striking inconsistencies. Primary among the complications of the technique is that the tDCS method uses two or more electrodes to pass current and all of these electrodes will have effects on the tissue underneath them. In this tutorial, we will share what we have learned about using tDCS to manipulate how the brain perceives, attends, remembers, and responds to information from our environment. Our goal is to provide a starting point for new users of tDCS and spur discussion of the standardization of methods to enhance replicability.
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Affiliation(s)
- Robert M G Reinhart
- Department of Psychological and Brain Sciences, Center for Research in Sensory Communications and Neural Technology, Center for Systems Neuroscience, Boston University, Boston, MA, 02215, USA.
| | - Josh D Cosman
- Department of Translational Medicine, Pfizer Inc., Cambridge, MA, 02215, USA
| | - Keisuke Fukuda
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
| | - Geoffrey F Woodman
- Department of Psychology, Center for Integrative and Cognitive Neuroscience, Vanderbilt Vision Research Center, Vanderbilt University, Nashville, TN, 37240, USA.
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Effects of HD-tDCS on memory and metamemory for general knowledge questions that vary by difficulty. Brain Stimul 2016; 10:231-241. [PMID: 27876306 DOI: 10.1016/j.brs.2016.10.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 10/24/2016] [Accepted: 10/28/2016] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND The ability to monitor one's own memory is an important feature of normal memory and is an aspect of 'metamemory'. Lesion studies have shown dissociations between memory and metamemory, but only single dissociations have been shown using transcranial direct current stimulation (tDCS). One potential reason that only single dissociations have been shown is that tDCS effects may be moderated by task difficulty. OBJECTIVE/HYPOTHESIS We used high definition (HD) tDCS to test for dissociable roles of the dorsolateral prefrontal cortex (DLPFC) and anterior temporal lobe (ATL) in semantic long-term memory and metamemory tasks. We also tested whether general knowledge question difficulty moderated the effects of HD-tDCS. METHODS Across 3 sessions, participants received active HD-tDCS over the left DLPFC or left ATL, or sham HD-tDCS during general knowledge recall and recognition tests, and a 'feeling-of-knowing' metamemory task. General knowledge questions were blocked by difficulty. Repeated measures ANOVAs were used to examine the effects of HD-tDCS on memory and metamemory tasks by memory question difficulty. RESULTS HD-tDCS over the ATL led to improved recall compared to DLPFC and sham HD-tDCS, and this occurred only for medium difficulty questions. In contrast, for non-recalled questions, HD-tDCS over the DLPFC led to improved recognition accuracy and improved feeling-of-knowing accuracy compared to ATL and sham HD-tDCS, and this was not moderated by memory question difficulty. CONCLUSION (S) HD-tDCS can be used to dissociate the roles of the ATL and DLPFC in different memory and 'metamemory' tasks. The effects of HD-tDCS on task may be moderated by task difficulty, depending on the nature of the task and site of stimulation.
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Seyed Majidi N, Verhage MC, Donchin O, Holland P, Frens MA, van der Geest JN. Cerebellar tDCS does not improve performance in probabilistic classification learning. Exp Brain Res 2016; 235:421-428. [PMID: 27766351 PMCID: PMC5272892 DOI: 10.1007/s00221-016-4800-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 10/11/2016] [Indexed: 11/20/2022]
Abstract
In this study, the role of the cerebellum in a cognitive learning task using transcranial direct current stimulation (tDCS) was investigated. Using a weather prediction task, subjects had to learn the probabilistic associations between a stimulus (a combination of cards) and an outcome (sun or rain). This task is a variant of a probabilistic classification learning task, for which it has been reported that prefrontal tDCS enhances performance. Using a between-subject design, all 30 subjects learned to improve their performance with increasing accuracies and shortened response times over a series of 500 trials. Subjects also became more confident in their prediction during the experiment. However, no differences in performance and learning were observed between subjects receiving sham stimulation (n = 10) or anodal stimulation (2 mA for 20 min) over either the right cerebellum (n = 10) or the left prefrontal cortex (n = 10). This suggests that stimulating the brain with cerebellar tDCS does not readily influence probabilistic classification performances, probably due to the rather complex nature of this cognitive task.
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Affiliation(s)
- N Seyed Majidi
- Department of Neuroscience (Ee1202), Erasmus MC, P.O. Box 2040, 3000, CA, Rotterdam, The Netherlands
| | - M C Verhage
- Department of Neuroscience (Ee1202), Erasmus MC, P.O. Box 2040, 3000, CA, Rotterdam, The Netherlands
| | - O Donchin
- Department of Biomedical Engineering, Zlotowski Centre for Neuroscience, Ben-Gurion University, Beer-Sheva, Israel
| | - P Holland
- Department of Neuroscience (Ee1202), Erasmus MC, P.O. Box 2040, 3000, CA, Rotterdam, The Netherlands.,Department of Biomedical Engineering, Zlotowski Centre for Neuroscience, Ben-Gurion University, Beer-Sheva, Israel
| | - M A Frens
- Department of Neuroscience (Ee1202), Erasmus MC, P.O. Box 2040, 3000, CA, Rotterdam, The Netherlands.,Erasmus University College, Rotterdam, The Netherlands
| | - J N van der Geest
- Department of Neuroscience (Ee1202), Erasmus MC, P.O. Box 2040, 3000, CA, Rotterdam, The Netherlands.
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