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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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Hafezi S, Doustan M, Saemi E. The Effect of Brain Anodal and Cathodal Transcranial Direct Current Stimulation on Psychological Refractory Period at Different Stimulus-Onset Asynchrony in Non-Fatigue and Mental Fatigue Conditions. Brain Sci 2024; 14:477. [PMID: 38790455 PMCID: PMC11118837 DOI: 10.3390/brainsci14050477] [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: 04/08/2024] [Revised: 05/04/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
The psychological refractory period (PRP) effect occurs when two stimuli that require separate responses are presented sequentially, particularly with a short and variable time interval between them. Fatigue is a suboptimal psycho-physiological state that leads to changes in strategies. In recent years, numerous studies have investigated the effects of transcranial direct current stimulation (tDCS) on motor control. The present study aimed to investigate the effects of two tDCS methods, anodal and cathodal, on PRP in ten different conditions of stimulus-onset asynchronies (SOAs) under non-fatigue and mental fatigue conditions. The participants involved 39 male university students aged 19 to 25 years. In the pre-test, they were assessed using the PRP measurement tool under both non-fatigue and mental fatigue conditions. The mental fatigue was induced by a 30-min Stroop task. The test consisted of two stimuli with different SOAs (50, 75, 100, 150, 300, 400, 600, 900, 1200, and 1500 ms). The first was a visual stimulus with three choices (letters A, B, and C). After a random SOA, the second stimulus, a visual stimulus with three choices (colors red, yellow, and blue), was presented. Subsequently, participants were randomly assigned to the anodal, cathodal, and sham stimulation groups and underwent four consecutive sessions of tDCS stimulation. In the anodal and cathodal stimulation groups, 20 min of tDCS stimulation were applied to the PLPFC area in each session, while in the sham group, the stimulation was artificially applied. All participants were assessed using the same measurement tools as in the pre-test phase, in a post-test phase one day after the last stimulation session, and in a follow-up phase four days after that. Inferential statistics include mixed ANOVA, one-way ANOVA, independent, and dependent t-tests. The findings indicated that the response time to the second stimulus was longer at lower SOAs. However, there was no significant difference between the groups in this regard. Additionally, there was no significant difference in response time to the second stimulus between the fatigue and non-fatigue conditions, or between the groups. Therefore, tDCS had no significant effect. There was a significant difference between mental fatigue and non-fatigue conditions in the psychological refractory period. Moreover, at lower SOAs, the PRP was longer than at higher SOAs. In conditions of fatigue, the active stimulation groups (anodal and cathodal) performed better than the sham stimulation group at higher SOAs. Considering the difference in response to both stimuli at different SOAs, some central aspects of the response can be simultaneously parallel. Fatigue also affects parallel processing. This study supports the response integration phenomenon in PRP, which predicts that there will be an increase in response time to the first stimulus as the interval between the presentation of the two stimuli increases. This finding contradicts the bottleneck model. In this study, the effectiveness of cathodal and anodal tDCS on response time to the second stimulus and PRP was found to be very small.
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Affiliation(s)
| | - Mohammadreza Doustan
- Department of Motor Behavior and Sport Psychology, Faculty of Sport Sciences, Shahid Chamran University of Ahvaz, Ahvaz 6135783151, Iran; (S.H.); (E.S.)
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Hashemirad F, Zoghi M, Fitzgerald PB, Hashemirad M, Jaberzadeh S. Site Dependency of Anodal Transcranial Direct-Current Stimulation on Reaction Time and Transfer of Learning during a Sequential Visual Isometric Pinch Task. Brain Sci 2024; 14:408. [PMID: 38672057 PMCID: PMC11048073 DOI: 10.3390/brainsci14040408] [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: 03/05/2024] [Revised: 04/10/2024] [Accepted: 04/16/2024] [Indexed: 04/28/2024] Open
Abstract
Considering the advantages of brain stimulation techniques in detecting the role of different areas of the brain in human sensorimotor behaviors, we used anodal transcranial direct-current stimulation (a-tDCS) over three different brain sites of the frontoparietal cortex (FPC) in healthy participants to elucidate the role of these three brain areas of the FPC on reaction time (RT) during a sequential visual isometric pinch task (SVIPT). We also aimed to assess if the stimulation of these cortical sites affects the transfer of learning during SVIPT. A total of 48 right-handed healthy participants were randomly assigned to one of the four a-tDCS groups: (1) left primary motor cortex (M1), (2) left dorsolateral prefrontal cortex (DLPFC), (3) left posterior parietal cortex (PPC), and (4) sham. A-tDCS (0.3 mA, 20 min) was applied concurrently with the SVIPT, in which the participants precisely controlled their forces to reach seven different target forces from 10 to 40% of the maximum voluntary contraction (MVC) presented on a computer screen with the right dominant hand. Four test blocks were randomly performed at the baseline and 15 min after the intervention, including sequence and random blocks with either hand. Our results showed significant elongations in the ratio of RTs between the M1 and sham groups in the sequence blocks of both the right-trained and left-untrained hands. No significant differences were found between the DLPFC and sham groups and the PPC and sham groups in RT measurements within the SVIPT. Our findings suggest that RT improvement within implicit learning of an SVIPT is not mediated by single-session a-tDCS over M1, DLPFC, or PPC. Further research is needed to understand the optimal characteristics of tDCS and stimulation sites to modulate reaction time in a precision control task such as an SVIPT.
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Affiliation(s)
- Fahimeh Hashemirad
- Department of Physical Therapy, University of Social Welfare and Rehabilitation Sciences, Tehran 1985713871, Iran
- Monash Neuromodulation Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC 3199, Australia;
| | - Maryam Zoghi
- Discipline of Physiotherapy, Institute of Health and Wellbeing, Federation University, Ballart, VIC 3199, Australia;
| | - Paul B. Fitzgerald
- School of Medicine and Psychology, Australian National University, Canberra, NSW 2601, Australia;
| | | | - Shapour Jaberzadeh
- Monash Neuromodulation Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC 3199, Australia;
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Willmot N, Leow LA, Filmer HL, Dux PE. Exploring the intra-individual reliability of tDCS: A registered report. Cortex 2024; 173:61-79. [PMID: 38382128 DOI: 10.1016/j.cortex.2023.12.015] [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: 10/09/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 02/23/2024]
Abstract
Transcranial direct current stimulation (tDCS), a form of non-invasive brain stimulation, has become an important tool for the study of in-vivo brain function due to its modulatory effects. Over the past two decades, interest in the influence of tDCS on behaviour has increased markedly, resulting in a large body of literature spanning multiple domains. However, the effect of tDCS on human performance often varies, bringing into question the reliability of this approach. While reviews and meta-analyses highlight the contributions of methodological inconsistencies and individual differences, no published studies have directly tested the intra-individual reliability of tDCS effects on behaviour. Here, we conducted a large scale, double-blinded, sham-controlled registered report to assess the reliability of two single-session low-dose tDCS montages, previously found to impact response selection and motor learning operations, across two separate time periods. Our planned analysis found no evidence for either protocol being effective nor reliable. Post-hoc explorative analyses found evidence that tDCS influenced motor learning, but not response selection learning. In addition, the reliability of motor learning performance across trials was shown to be disrupted by tDCS. These findings are amongst the first to shed light specifically on the intra-individual reliability of tDCS effects on behaviour and provide valuable information to the field.
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Affiliation(s)
- Nicholas Willmot
- Department of Defence, Edinburgh, SA, Australia; School of Psychology, The University of Queensland, St Lucia, QLD, Australia.
| | - Li-Ann Leow
- School of Psychology, The University of Queensland, St Lucia, QLD, Australia
| | - Hannah L Filmer
- School of Psychology, The University of Queensland, St Lucia, QLD, Australia
| | - Paul E Dux
- School of Psychology, The University of Queensland, St Lucia, QLD, Australia
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5
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McCane LM, Wolpaw JR, Thompson AK. Effects of active and sham tDCS on the soleus H-reflex during standing. Exp Brain Res 2023; 241:1611-1622. [PMID: 37145136 PMCID: PMC10224818 DOI: 10.1007/s00221-023-06624-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 04/22/2023] [Indexed: 05/06/2023]
Abstract
Weak transcranial direct current stimulation (tDCS) is known to affect corticospinal excitability and enhance motor skill acquisition, whereas its effects on spinal reflexes in actively contracting muscles are yet to be established. Thus, in this study, we examined the acute effects of Active and Sham tDCS on the soleus H-reflex during standing. In fourteen adults without known neurological conditions, the soleus H-reflex was repeatedly elicited at just above M-wave threshold throughout 30 min of Active (N = 7) or Sham (N = 7) 2-mA tDCS over the primary motor cortex in standing. The maximum H-reflex (Hmax) and M-wave (Mmax) were also measured before and immediately after 30 min of tDCS. The soleus H-reflex amplitudes became significantly larger (by 6%) ≈1 min into Active or Sham tDCS and gradually returned toward the pre-tDCS values, on average, within 15 min. With Active tDCS, the amplitude reduction from the initial increase appeared to occur more swiftly than with Sham tDCS. An acute temporary increase in the soleus H-reflex amplitude within the first minute of Active and Sham tDCS found in this study indicates a previously unreported effect of tDCS on the H-reflex excitability. The present study suggests that neurophysiological characterization of Sham tDCS effects is just as important as investigating Active tDCS effects in understanding and defining acute effects of tDCS on the excitability of spinal reflex pathways.
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Affiliation(s)
- Lynn M McCane
- Interdisciplinary Neuroscience Program, University of Rhode Island, Kingston, RI, 02881, USA
- National Center for Adaptive Neurotechnologies, Stratton VAMC, Albany, NY, 12208, USA
| | - Jonathan R Wolpaw
- National Center for Adaptive Neurotechnologies, Stratton VAMC, Albany, NY, 12208, USA
| | - Aiko K Thompson
- Department of Health Sciences and Research, College of Health Professions, Medical University of South Carolina, 77 President Street, MSC 700, Charleston, SC, 29425, USA.
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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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Sevilla-Sanchez M, Hortobágyi T, Carballeira E, Fogelson N, Fernandez-del-Olmo M. A lack of timing-dependent effects of transcranial direct current stimulation (tDCS) on the performance of a choice reaction time task. Neurosci Lett 2022; 782:136691. [DOI: 10.1016/j.neulet.2022.136691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 05/15/2022] [Accepted: 05/17/2022] [Indexed: 10/18/2022]
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High Estrogen Levels Cause Greater Leg Muscle Fatigability in Eumenorrheic Young Women after 4 mA Transcranial Direct Current Stimulation. Brain Sci 2022; 12:brainsci12040506. [PMID: 35448037 PMCID: PMC9032567 DOI: 10.3390/brainsci12040506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 04/07/2022] [Accepted: 04/14/2022] [Indexed: 11/29/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) research has shown great outcome variability in motor performance tasks, with one possible source being sex differences. The goal of this study was to evaluate the effects of estrogen levels on leg muscle fatigability during a fatigue task (FT) after 4 mA tDCS over the left motor cortex (M1). Ten young, healthy eumenorrheic women received 4 mA anodal active or sham stimulation over the left M1 during periods of high and low estrogen levels. A fatigue index (FI) was calculated to quantify fatigability, and the electromyography (EMG) of the knee extensors and flexors was recorded during the FT. The findings showed that tDCS applied during high estrogen levels resulted in greater leg muscle fatigability. Furthermore, a significant increase in EMG activity of the right knee extensors was observed during periods of active stimulation, independent of estrogen level. These results suggest that estrogen levels should be considered in tDCS studies with young healthy women.
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Lee G, Lee J, Kim J, Kim H, Chang WH, Kim YH. Whole Brain Hemodynamic Response Based on Synchrony Analysis of Brain Signals for Effective Application of HD-tDCS in Stroke Patients: An fNIRS Study. J Pers Med 2022; 12:jpm12030432. [PMID: 35330432 PMCID: PMC8949719 DOI: 10.3390/jpm12030432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 02/28/2022] [Accepted: 03/08/2022] [Indexed: 01/27/2023] Open
Abstract
In this study, the effective application of high-definition transcranial direct current stimulation (HD-tDCS) based on the whole brain hemodynamic response in stroke patients was investigated using functional near-infrared spectroscopy (fNIRS). The intrahemispheric and interhemispheric synchronization and cortical activity based on the time during 1 mA HD-tDCS were examined in 26 chronic cerebrovascular disease patients. At the beginning of HD-tDCS, the synchronization and brain activity in the whole brain increased rapidly and decreased after 5 min. In the middle of tDCS, the synchronization began to increase again, and strong synchronic connections were formed around the desired stimulation area. After tDCS, strong cortical activation was observed in the stimulation area, indicating that the baseline of the oxyhemoglobin (HbO) signal increased in the desired stimulation area. Therefore, the results of this study indicate that HD-tDCS can be applied efficiently to enhance the effect of tDCS. This stimulation method with tDCS can be explored clinically for more neurorehabilitation of patients with degenerative brain diseases.
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Affiliation(s)
- Gihyoun Lee
- Department of Health Sciences and Technology, The Samsung Advanced Institute for Health Sciences & Technology (SAIHST), Sungkyunkwan University, Seoul 06351, Korea; (G.L.); (J.K.); (H.K.)
- Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea;
| | - Jungsoo Lee
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39177, Korea;
| | - Jinuk Kim
- Department of Health Sciences and Technology, The Samsung Advanced Institute for Health Sciences & Technology (SAIHST), Sungkyunkwan University, Seoul 06351, Korea; (G.L.); (J.K.); (H.K.)
- Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea;
| | - Heegoo Kim
- Department of Health Sciences and Technology, The Samsung Advanced Institute for Health Sciences & Technology (SAIHST), Sungkyunkwan University, Seoul 06351, Korea; (G.L.); (J.K.); (H.K.)
- Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea;
| | - Won Hyuk Chang
- Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea;
| | - Yun-Hee Kim
- Department of Health Sciences and Technology, The Samsung Advanced Institute for Health Sciences & Technology (SAIHST), Sungkyunkwan University, Seoul 06351, Korea; (G.L.); (J.K.); (H.K.)
- Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea;
- Department of Medical Device Management & Research, Department of Digital Health, The Samsung Advanced Institute for Health Sciences & Technology (SAIHST), Sungkyunkwan University, Seoul 06351, Korea
- Correspondence:
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Neto EDM, da Silva EA, Nunes HRDC, Bazan R, de Souza LAPS, Luvizutto GJ. Effect of transcranial direct current stimulation in addition to visuomotor training on choice reaction time and cognition function in amateur soccer players (FAST trial): A randomized control trial. Neurosci Lett 2022; 766:136346. [PMID: 34785310 DOI: 10.1016/j.neulet.2021.136346] [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: 03/29/2021] [Revised: 10/18/2021] [Accepted: 11/09/2021] [Indexed: 10/19/2022]
Abstract
OBJECTIVES This study aimed to evaluate the effect of anodal transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) in addition to visuomotor training (VMT) on choice reaction time (CRT) and cognitive function in amateur soccer players. DESIGN Single-center, randomized, placebo-controlled, double-blind, parallel-group study. SETTING Neuroscience and Motor Control Laboratory. PARTICIPANTS Thirty Brazilian male amateur soccer players, aged 18-30 years. MAIN OUTCOME MEASURES Participants were allocated to the intervention or control groups. Both groups performed VMT, but the intervention group additionally underwent anodal tDCS over the left dorsolateral prefrontal cortex (DLPFC; F3). The cathodal electrode was positioned in the right supraorbital region (Fp2). The tDCS was applied at 2 mA for 20 min for five consecutive sessions (24 h intervals). The VMT protocol was delivered during the application of tDCS and was composed of kicking a ball for 10 min (between the fifth and fifteenth minutes of the 20 min of tDCS application). The primary outcome was assessed based on changes in CRT during reaching (non-trained limb) and kicking (trained limb) tasks. Secondary outcomes were overall cognitive function measured by the Trail Making Test part A (TMT-A) and part B (TMT-B), and Digit Span Test forward (DSF) and backward (DSB) scores. All outcomes were evaluated before and after the intervention. RESULTS In the primary outcomes, compared with the control group, the anodal tDCS combined with VMT group had greater reduction in CRT for the rectus femoris (p = 0.007) adjusted for age and baseline performance (F (1,26) = 22,23; p < 0,001) and for the triceps (p = 0.039) adjusted for training frequency (days/week) and baseline performance (F (1,26) = 5,70; p = 0,016). No differences were observed in the CRT of other muscles (anterior deltoid [p = 0.181], brachial biceps [p = 0.130], and vastus medialis [p = 0.074]). And, there were no differences between the groups in terms of cognitive function (TMT-A [p = 0.062]; TMT-B [p = 0.320]; DSF [p = 0.102]; DSB [p = 0.345]). CONCLUSION Anodal tDCS over the left DLPFC in addition to visuomotor training of a functional task can be an efficient tool for athletes to decrease the CRT of the rectus femoris (trained limb) and triceps (non-trained limb); however, there were no differences between the groups in the others muscles (anterior deltoid, brachial biceps, and vastus medialis), and in terms of cognitive function.
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Affiliation(s)
- Eduardo de Moura Neto
- Master Student of Physical Education, Federal University of Triângulo Mineiro (UFTM), Uberaba, Minas Gerais, Brazil
| | - Edilaine Aparecida da Silva
- Master Student of Physical Education, Federal University of Triângulo Mineiro (UFTM), Uberaba, Minas Gerais, Brazil
| | | | - Rodrigo Bazan
- Department of Neurology, Psychology and Psychiatry, Botucatu Medical School (UNESP), Botucatu, São Paulo, Brazil
| | | | - Gustavo José Luvizutto
- Department of Applied Physical Therapy, Federal University of Triângulo Mineiro (UFTM), Uberaba, Minas Gerais, Brazil.
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Focality-Oriented Selection of Current Dose for Transcranial Direct Current Stimulation. J Pers Med 2021; 11:jpm11090940. [PMID: 34575717 PMCID: PMC8466113 DOI: 10.3390/jpm11090940] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 09/18/2021] [Accepted: 09/18/2021] [Indexed: 11/30/2022] Open
Abstract
Background: In transcranial direct current stimulation (tDCS), the injected current becomes distributed across the brain areas. The objective is to stimulate the target region of interest (ROI) while minimizing the current in non-target ROIs (the 'focality' of tDCS). For this purpose, determining the appropriate current dose for an individual is difficult. Aim: To introduce a dose-target determination index (DTDI) to quantify the focality of tDCS and examine the dose-focality relationship in three different populations. Method: Here, we extended our previous toolbox i-SATA to the MNI reference space. After a tDCS montage is simulated for a current dose, the i-SATA(MNI) computes the average (over voxels) current density for every region in the brain. DTDI is the ratio of the average current density at the target ROI to the ROI with a maximum value (the peak region). Ideally, target ROI should be the peak region, so DTDI shall range from 0 to 1. The higher the value, the better the dose. We estimated the variation of DTDI within and across individuals using T1-weighted brain images of 45 males and females distributed equally across three age groups: (a) young adults (20 ≤ x ˂ 40 years), (b) mid adults (40 ≤ x ˂ 60 years), and (c) older adults (60 ≤ x ˂ 80 years). DTDI's were evaluated for the frontal montage with electrodes at F3 and the right supraorbital for three current doses of 1 mA, 2 mA, and 3 mA, with the target ROI at the left middle frontal gyrus. Result: As the dose is incremented, DTDI may show (a) increase, (b) decrease, and (c) no change across the individuals depending on the relationship (nonlinear or linear) between the injected tDCS current and the distribution of current density in the target ROI. The nonlinearity is predominant in older adults with a decrease in focality. The decline is stronger in males. Higher current dose at older age can enhance the focality of stimulation. Conclusion: DTDI provides information on which tDCS current dose will optimize the focality of stimulation. The recommended DTDI dose should be prioritized based on the age (>40 years) and sex (especially for males) of an individual. The toolbox i-SATA(MNI) is freely available.
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12
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Fehring DJ, Samandra R, Haque ZZ, Jaberzadeh S, Rosa M, Mansouri FA. Investigating the sex-dependent effects of prefrontal cortex stimulation on response execution and inhibition. Biol Sex Differ 2021; 12:47. [PMID: 34404467 PMCID: PMC8369781 DOI: 10.1186/s13293-021-00390-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 08/08/2021] [Indexed: 12/14/2022] Open
Abstract
Context-dependent execution or inhibition of a response is an important aspect of executive control, which is impaired in neuropsychological and addiction disorders. Transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) has been considered a remedial approach to address deficits in response control; however, considerable variability has been observed in tDCS effects. These variabilities might be related to contextual differences such as background visual-auditory stimuli or subjects' sex. In this study, we examined the interaction of two contextual factors, participants' sex and background acoustic stimuli, in modulating the effects of tDCS on response inhibition and execution. In a sham-controlled and cross-over (repeated-measure) design, 73 participants (37 females) performed a Stop-Signal Task in different background acoustic conditions before and after tDCS (anodal or sham) was applied over the DLPFC. Participants had to execute a speeded response in Go trials but inhibit their response in Stop trials. Participants' sex was fully counterbalanced across all experimental conditions (acoustic and tDCS). We found significant practice-related learning that appeared as changes in indices of response inhibition (stop-signal reaction time and percentage of successful inhibition) and action execution (response time and percentage correct). The tDCS and acoustic stimuli interactively influenced practice-related changes in response inhibition and these effects were uniformly seen in both males and females. However, the effects of tDCS on response execution (percentage of correct responses) were sex-dependent in that practice-related changes diminished in females but heightened in males. Our findings indicate that participants' sex influenced the effects of tDCS on the execution, but not inhibition, of responses.
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Affiliation(s)
- Daniel J Fehring
- Cognitive Neuroscience Laboratory, Monash Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, VIC, 3800, Australia
- ARC Centre of Excellence in Integrative Brain Function, Monash University, Melbourne, VIC, 3800, Australia
| | - Ranshikha Samandra
- Cognitive Neuroscience Laboratory, Monash Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, VIC, 3800, Australia
| | - Zakia Z Haque
- Cognitive Neuroscience Laboratory, Monash Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, VIC, 3800, Australia
| | - Shapour Jaberzadeh
- Department of Physiotherapy, Non-Invasive Brain Stimulation & Neuroplasticity Laboratory, Monash University, Melbourne, VIC, 3199, Australia
| | - Marcello Rosa
- ARC Centre of Excellence in Integrative Brain Function, Monash University, Melbourne, VIC, 3800, Australia
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, 3800, Australia
| | - Farshad A Mansouri
- Cognitive Neuroscience Laboratory, Monash Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, VIC, 3800, Australia.
- ARC Centre of Excellence in Integrative Brain Function, Monash University, Melbourne, VIC, 3800, Australia.
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13
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Lerner O, Friedman J, Frenkel-Toledo S. The effect of high-definition transcranial direct current stimulation intensity on motor performance in healthy adults: a randomized controlled trial. J Neuroeng Rehabil 2021; 18:103. [PMID: 34174914 PMCID: PMC8236155 DOI: 10.1186/s12984-021-00899-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 06/14/2021] [Indexed: 11/22/2022] Open
Abstract
Background The results of transcranial direct current stimulation (tDCS) studies that seek to improve motor performance for people with neurological disorders, by targeting the primary motor cortex, have been inconsistent. One possible reason, among others, for this inconsistency, is that very little is known about the optimal protocols for enhancing motor performance in healthy individuals. The best way to optimize stimulation protocols for enhancing tDCS effects on motor performance by means of current intensity modulation has not yet been determined. We aimed to determine the effect of current intensity on motor performance using–for the first time–a montage optimized for maximal focal stimulation via anodal high-definition tDCS (HD-tDCS) on the right primary motor cortex in healthy subjects. Methods Sixty participants randomly received 20-min HD-tDCS at 1.5, 2 mA, or sham stimulation. Participants’ reaching performance with the left hand on a tablet was tested before, during, and immediately following stimulation, and retested after 24 h. Results In the current montage of HD-tDCS, movement time did not differ between groups in each timepoint. However, only after HD-tDCS at 1.5 mA did movement time improve at posttest as compared to pretest. This reduction in movement time from pretest to posttest was significantly greater compared to HD-tDCS 2 mA. Following HD-tDCS at 1.5 mA and sham HD-tDCS, but not 2 mA, movement time improved at retest compared to pretest, and at posttest and retest compared to the movement time during stimulation. In HD-tDCS at 2 mA, the negligible reduction in movement time from the course of stimulation to posttest was significantly lower compared to sham HD-tDCS. Across all groups, reaction time improved in retest compared to pretest and to the reaction time during stimulation, and did not differ between groups in each timepoint. Conclusions It appears that 2 mA in this particular experimental setup inhibited the learning effects. These results suggest that excitatory effects induced by anodal stimulation do not hold for every stimulation intensity, information that should be taken into consideration when translating tDCS use from the realm of research into more optimal neurorehabilitation. Trial registration: Clinical Trials Gov, NCT04577768. Registered 6 October 2019 -Retrospectively registered, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S000A9B3&selectaction=Edit&uid=U0005AKF&ts=8&cx=buucf0. Supplementary Information The online version contains supplementary material available at 10.1186/s12984-021-00899-z.
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Affiliation(s)
- Ohad Lerner
- Department of Physical Therapy, Faculty of Health Sciences, Ariel University, Ariel, Israel
| | - Jason Friedman
- Department of Physical Therapy, Stanley Steyer School of Health Professions, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Silvi Frenkel-Toledo
- Department of Physical Therapy, Faculty of Health Sciences, Ariel University, Ariel, Israel. .,Department of Neurological Rehabilitation, Loewenstein Hospital, Raanana, Israel.
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14
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Small Enhancement of Bimanual Typing Performance after 20 Sessions of tDCS in Healthy Young Adults. Neuroscience 2021; 466:26-35. [PMID: 33974964 DOI: 10.1016/j.neuroscience.2021.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 03/04/2021] [Accepted: 05/02/2021] [Indexed: 01/10/2023]
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that may improve motor learning. However, the long-term effects of tDCS have not been explored, and the ecological validity of the evaluated tasks was limited. To determine whether 20 sessions of tDCS over the primary motor cortex (M1) would enhance the performance of a complex life motor skill, i.e., typing, in healthy young adults. Healthy young adults (n = 60) were semi-randomly assigned to three groups: the tDCS group (n = 20) received anodal tDCS over M1; the SHAM group (n = 20) received sham tDCS, both while performing a typing task; and the Control group (CON, n = 20) only performed the typing task. Typing speed and errors at maximum (mTT) and submaximal (iTT) speeds were measured before training, and after 10 and 20 sessions of tDCS. Every subject increased maximum typing speed after 10 and 20 tDCS sessions, with no significant differences (p > 0.05) between the groups. The number of errors at submaximal rates decreased significantly (p < 0.05) by 4% after 10 tDCS sessions compared with the 3% increase in the SHAM and the 2% increase in the CON groups. Between the 10th and 20th tDCS sessions, the number of typing errors increased significantly in all groups. While anodal tDCS reduced typing errors marginally, such performance-enhancing effects plateaued after 10 sessions without any further improvements in typing speed. These findings suggest that long-term tDCS may not have functionally relevant effects on healthy young adults' typing performance.
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15
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Brain glucose uptake during transcranial direct current stimulation measured with functional [ 18F]FDG-PET. Brain Imaging Behav 2021; 14:477-484. [PMID: 31598826 PMCID: PMC7160063 DOI: 10.1007/s11682-019-00195-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Previous evidence indicates that transcranial direct stimulation (tDCS) is a neuromodulatory brain stimulation technique. Easy applicability, low side-effects and negligible costs facilitated its wide-spread application in efforts to modulate brain function, however neuronal mechanisms of tDCS are insufficiently understood. Hence, we investigated the immediate impact of tDCS on the brain's glucose consumption in a continuous infusion protocol with the radioligand 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) and positron emission tomography (PET). This novel functional PET (fPET) method is capable to reliably detect area-specific and dynamic absolute glucose demand related to neuronal activity in a single molecular imaging session. Fifteen healthy subjects underwent tDCS at 0.5, 1 and 2 mA (mA) at the bilateral dorsolateral prefrontal cortex (dlPFC, cathodal right) for 10 min during functional [18F]FDG-PET lasting 70 min. Active stimulation compared to sham did not yield significant changes in glucose consumption at any tested stimulation intensity in this paradigm. Exploratory investigation of aftereffects provided hints for increased glucose consumption with a delay of 5 min at 1 mA in the right posterior temporal cortex. This is the first study investigating changes of glucose consumption in the brain during tDCS. The lack of immediately increased glucose consumption indicates that energy demanding processes in the brain such as glutamatergic signaling might not be immediately increased by tDCS. However, our results implicate the need of fPET investigations for medium-term and long-term effects.
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16
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Archer K, Pammer K, Vidyasagar TR. A Temporal Sampling Basis for Visual Processing in Developmental Dyslexia. Front Hum Neurosci 2020; 14:213. [PMID: 32733217 PMCID: PMC7360833 DOI: 10.3389/fnhum.2020.00213] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 05/11/2020] [Indexed: 11/24/2022] Open
Abstract
Knowledge of oscillatory entrainment and its fundamental role in cognitive and behavioral processing has increasingly been applied to research in the field of reading and developmental dyslexia. Growing evidence indicates that oscillatory entrainment to theta frequency spoken language in the auditory domain, along with cross-frequency theta-gamma coupling, support phonological processing (i.e., cognitive encoding of linguistic knowledge gathered from speech) which is required for reading. This theory is called the temporal sampling framework (TSF) and can extend to developmental dyslexia, such that inadequate temporal sampling of speech-sounds in people with dyslexia results in poor theta oscillatory entrainment in the auditory domain, and thus a phonological processing deficit which hinders reading ability. We suggest that inadequate theta oscillations in the visual domain might account for the many magno-dorsal processing, oculomotor control and visual deficits seen in developmental dyslexia. We propose two possible models of a magno-dorsal visual correlate to the auditory TSF: (1) A direct correlate that involves "bottom-up" magnocellular oscillatory entrainment of the visual domain that occurs when magnocellular populations phase lock to theta frequency fixations during reading and (2) an inverse correlate whereby attending to text triggers "top-down" low gamma signals from higher-order visual processing areas, thereby organizing magnocellular populations to synchronize to a theta frequency to drive the temporal control of oculomotor movements and capturing of letter images at a higher frequency.
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Affiliation(s)
- Kim Archer
- Applied Psychology and Human Factors Laboratory, School of Psychology, University of Newcastle, Newcastle, NSW, Australia
| | - Kristen Pammer
- Applied Psychology and Human Factors Laboratory, School of Psychology, University of Newcastle, Newcastle, NSW, Australia
| | - Trichur Raman Vidyasagar
- Visual and Cognitive Neuroscience Laboratory, Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
- The Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
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17
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Zink N, Kang K, Li SC, Beste C. Anodal transcranial direct current stimulation enhances the efficiency of functional brain network communication during auditory attentional control. J Neurophysiol 2020; 124:207-217. [PMID: 32233902 DOI: 10.1152/jn.00074.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Attentional control is crucial for selectively attending to relevant information when our brain is confronted with a multitude of sensory signals. Graph-theoretical measures provide a powerful tool for investigating the efficiency of brain network communication in separating and integrating information. Albeit, it has been demonstrated that anodal transcranial direct current stimulation (atDCS) can boost auditory attention in situations with high control demands, its effect on neurophysiological mechanisms of functional brain network communication in situations when attentional focus conflicts with perceptual saliency remain unclear. This study investigated the effects of atDCS on network connectivity and θ-oscillatory power under different levels of attentional-perceptual conflict. We hypothesized that the benefit of atDCS on network communication efficiency would be particularly apparent in conditions requiring high attentional control. Thirty young adults participated in a dichotic listening task with intensity manipulation, while EEG activity was recorded. In a cross-over design, participants underwent right frontal atDCS and sham stimulations in two separate sessions. Time-frequency decomposition and graph-theoretical analyses of network efficiency (using "small-world" properties) were used to quantify θ-oscillatory power and brain network efficiency, respectively. The atDCS-induced effect on task efficiency in the most demanding condition was mirrored only by an increase in network efficiency during atDCS compared with the sham stimulation. These findings are corroborated by Bayesian analyses. AtDCS-induced performance enhancement under high levels of attentional-perceptual conflicts is accompanied by an increase in network efficiency. Graph-theoretical measures can serve as a metric to quantify the effects of noninvasive brain stimulation on the separation and integration of information in the brain.NEW & NOTEWORTHY As compared with sham stimulation, application of atDCS enhances θ-oscillation-based network efficiency, but it has no impact on θ-oscillation power. Individual differences in θ-oscillation-based network efficiency correlated with performance efficiency under the sham stimulation.
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Affiliation(s)
- Nicolas Zink
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine of the Technische Universität Dresden, Germany
| | - Kathleen Kang
- Lifespan Developmental Neuroscience, Faculty of Psychology, Technische Universität Dresden, Dresden, Germany
| | - Shu-Chen Li
- Lifespan Developmental Neuroscience, Faculty of Psychology, Technische Universität Dresden, Dresden, Germany.,Centre for Tactile Internet with Human-in-the-Loop, Technische Universität Dresden, Dresden, Germany
| | - Christian Beste
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine of the Technische Universität Dresden, Germany
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18
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Transcranial electrical stimulation motor threshold can estimate individualized tDCS dosage from reverse-calculation electric-field modeling. Brain Stimul 2020; 13:961-969. [PMID: 32330607 PMCID: PMC7906246 DOI: 10.1016/j.brs.2020.04.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 04/08/2020] [Accepted: 04/08/2020] [Indexed: 12/15/2022] Open
Abstract
Background: Unique amongst brain stimulation tools, transcranial direct current stimulation (tDCS) currently lacks an easy or widely implemented method for individualizing dosage. Objective: We developed a method of reverse-calculating electric-field (E-field) models based on Magnetic Resonance Imaging (MRI) scans that can estimate individualized tDCS dose. We also evaluated an MRI-free method of individualizing tDCS dose by measuring transcranial magnetic stimulation (TMS) motor threshold (MT) and single pulse, suprathreshold transcranial electrical stimulation (TES) MT and regressing it against E-field modeling. Key assumptions of reverse-calculation E-field modeling, including the size of region of interest (ROI) analysis and the linearity of multiple E-field models were also tested. Methods: In 29 healthy adults, we acquired TMS MT, TES MT, and anatomical T1-weighted MPRAGE MRI scans with a fiducial marking the motor hotspot. We then computed a “reverse-calculated tDCS dose” of tDCS applied at the scalp needed to cause a 1.00 V/m E-field at the cortex. Finally, we examined whether the predicted E-field values correlated with each participant’s measured TMS MT or TES MT. Results: We were able to determine a reverse-calculated tDCS dose for each participant using a 5 × 5 x 5 voxel grid region of interest (ROI) approach (average = 6.03 mA, SD = 1.44 mA, range = 3.75–9.74 mA). The Transcranial Electrical Stimulation MT, but not the Transcranial Magnetic Stimulation MT, significantly correlated with the ROI-based reverse-calculated tDCS dose determined by E-field modeling (R2 = 0.45, p < 0.001). Conclusions: Reverse-calculation E-field modeling, alone or regressed against TES MT, shows promise as a method to individualize tDCS dose. The large range of the reverse-calculated tDCS doses between subjects underscores the likely need to individualize tDCS dose. Future research should further examine the use of TES MT to individually dose tDCS as an MRI-free method of dosing tDCS.
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19
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Patel R, Dawidziuk A, Darzi A, Singh H, Leff DR. Systematic review of combined functional near-infrared spectroscopy and transcranial direct-current stimulation studies. NEUROPHOTONICS 2020; 7:020901. [PMID: 32607389 PMCID: PMC7315225 DOI: 10.1117/1.nph.7.2.020901] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 06/15/2020] [Indexed: 05/05/2023]
Abstract
Significance: Combining transcranial direct-current stimulation (tDCS) with functional near-infrared spectroscopy (fNIRS) is a recent approach to exploring brain activation evoked by neurostimulation. Aim: To critically evaluate studies combining tDCS and fNIRS and provide a consolidated overview of cortical hemodynamic responses to neurostimulation. Approach: Key terms were searched in three databases (MEDLINE, EMBASE, and PsycINFO) with cross-referencing and works from Google Scholar also evaluated. All studies reporting on fNIRS-derived hemoglobin changes evoked by tDCS were included. Results: Literature searches revealed 474 articles, of which 28 were included for final review (22 in healthy individuals: 9 involving rest and 13 with tasks; 6 in the clinical setting). At rest, an overall increase in cortical activation was observed in fNIRS responses at the site of stimulation, with evidence suggesting nonstimulated brain regions are also similarly affected. Conversely, during tasks, reduced cortical activation was observed during online stimulation. Offline and poststimulation effects were less consistent, as is the impact on clinical populations and their symptom correlation. Conclusion: This review explores the methodological frameworks for fNIRS-tDCS evaluations and summarizes hemodynamic responses associated with tDCS in all populations. Our findings provide further evidence of the impact of tDCS on neuronal activation within functionally connected networks.
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Affiliation(s)
- Ronak Patel
- St. Mary’s Hospital Campus, Imperial College London, Department of Surgery and Cancer, London, United Kingdom
- Address all correspondence to Ronak Patel, E-mail:
| | - Aleksander Dawidziuk
- St. Mary’s Hospital Campus, Imperial College London, Department of Surgery and Cancer, London, United Kingdom
| | - Ara Darzi
- St. Mary’s Hospital Campus, Imperial College London, Department of Surgery and Cancer, London, United Kingdom
| | - Harsimrat Singh
- St. Mary’s Hospital Campus, Imperial College London, Department of Surgery and Cancer, London, United Kingdom
| | - Daniel Richard Leff
- St. Mary’s Hospital Campus, Imperial College London, Department of Surgery and Cancer, London, United Kingdom
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20
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Modulating brain activity and behaviour with tDCS: Rumours of its death have been greatly exaggerated. Cortex 2020; 123:141-151. [DOI: 10.1016/j.cortex.2019.10.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 08/07/2019] [Accepted: 10/23/2019] [Indexed: 12/11/2022]
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21
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Boayue NM, Csifcsák G, Aslaksen P, Turi Z, Antal A, Groot J, Hawkins GE, Forstmann B, Opitz A, Thielscher A, Mittner M. Increasing propensity to mind‐wander by transcranial direct current stimulation? A registered report. Eur J Neurosci 2020; 51:755-780. [DOI: 10.1111/ejn.14347] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 11/26/2018] [Accepted: 11/30/2018] [Indexed: 12/20/2022]
Affiliation(s)
| | - Gábor Csifcsák
- Department of PsychologyUniversity of Tromsø Tromsø Norway
| | - Per Aslaksen
- Department of PsychologyUniversity of Tromsø Tromsø Norway
| | - Zsolt Turi
- Department of Clinical NeurophysiologyUniversity Medical Center Göttingen Göttingen Germany
| | - Andrea Antal
- Department of Clinical NeurophysiologyUniversity Medical Center Göttingen Göttingen Germany
| | - Josephine Groot
- Department of PsychologyUniversity of Tromsø Tromsø Norway
- Integrative Model‐based Cognitive Neuroscience Research UnitUniversity of Amsterdam Amsterdam The Netherlands
| | - Guy E. Hawkins
- School of PsychologyUniversity of Newcastle Newcastle New South Wales Australia
| | - Birte Forstmann
- Integrative Model‐based Cognitive Neuroscience Research UnitUniversity of Amsterdam Amsterdam The Netherlands
| | - Alexander Opitz
- Department of Biomedical EngineeringUniversity of Minnesota Minneapolis MN
| | - Axel Thielscher
- Danish Research Centre for Magnetic ResonanceCentre for Functional and Diagnostic Imaging and ResearchCopenhagen University Hospital Hvidovre Denmark
- Department of Electrical EngineeringTechnical University of Denmark Lyngby Denmark
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22
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Rudroff T, Workman CD, Fietsam AC, Kamholz J. Response Variability in Transcranial Direct Current Stimulation: Why Sex Matters. Front Psychiatry 2020; 11:585. [PMID: 32636774 PMCID: PMC7316984 DOI: 10.3389/fpsyt.2020.00585] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/08/2020] [Indexed: 12/16/2022] Open
Affiliation(s)
- Thorsten Rudroff
- Department of Health and Human Physiology, 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
| | - Craig D Workman
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA, United States
| | - Alexandra C Fietsam
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA, United States
| | - John Kamholz
- Department of Neurology, Carver College of Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, United States
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23
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Ruttorf M, Kristensen S, Schad LR, Almeida J. Transcranial Direct Current Stimulation Alters Functional Network Structure in Humans: A Graph Theoretical Analysis. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:2829-2837. [PMID: 31071024 DOI: 10.1109/tmi.2019.2915206] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Transcranial direct current stimulation (tDCS) is routinely used in basic and clinical research, but its efficacy has been challenged on a methodological, statistical and technical basis recently. The arguments against tDCS derive from an insufficient understanding of how this technique interacts with brain processes physiologically. Because of its potential as a central tool in neuroscience, it is important to clarify whether tDCS affects neuronal activity. Here, we investigate influences of offline tDCS on network architecture measured by functional magnetic resonance imaging. Applied to one network node only, offline tDCS affects the architecture of the entire functional network. Furthermore, offline tDCS exerts polarity-specific effects on the topology of the functional network attached. Our results confirm in a functioning brain and in a bias free and independent fashion that offline tDCS influences neuronal activity. Moreover, our results suggest that network-specific connectivity has an important role in improving our understanding of the effects of tDCS.
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24
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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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25
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Debarnot U, Neveu R, Samaha Y, Saruco E, Macintyre T, Guillot A. Acquisition and consolidation of implicit motor learning with physical and mental practice across multiple days of anodal tDCS. Neurobiol Learn Mem 2019; 164:107062. [PMID: 31377178 DOI: 10.1016/j.nlm.2019.107062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 07/16/2019] [Accepted: 07/30/2019] [Indexed: 11/25/2022]
Abstract
BACKGROUND Acquisition and consolidation of a new motor skill occurs gradually over long time span. Motor imagery (MI) and brain stimulation have been showed as beneficial approaches that boost motor learning, but little is known about the extent of their combined effects. OBJECTIVE Here, we aimed to investigate, for the first time, whether delivering multiple sessions of transcranial direct current stimulation (tDCS) over primary motor cortex during physical and MI practice might improve implicit motor sequence learning in a young population. METHODS Participants practiced a serial reaction time task (SRTT) either physically or through MI, and concomitantly received either an anodal (excitatory) or sham stimulation over the primary motor cortex during three successive days. The effect of anodal tDCS on the general motor skill and sequence specific learning were assessed on both acquisition (within-day) and consolidation (between-day) processes. We further compared the magnitude of motor learning reached after a single and three daily sessions of tDCS. RESULTS The main finding showed that anodal tDCS boosted MI practice, but not physical practice, during the first acquisition session. A second major result showed that compared to sham stimulation, multiple daily session of anodal tDCS, for both types of practice, resulted in greater implicit motor sequence learning rather than a single session of stimulation. CONCLUSIONS The present study is of particular importance in the context of rehabilitation, where we postulate that scheduling mental training when patients are not able to perform physical movement might beneficiate from concomitant and consecutive brain stimulation sessions over M1 to promote functional recovery.
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Affiliation(s)
- Ursula Debarnot
- Inter-University Laboratory of Human Movement Biology-EA 7424, University of Lyon, University Claude Bernard Lyon 1, 69 622 Villeurbanne, France.
| | - Rémi Neveu
- Division of Child and Adolescent Psychiatry, University of Geneva, 1200 Geneva, Switzerland
| | - Yvette Samaha
- Inter-University Laboratory of Human Movement Biology-EA 7424, University of Lyon, University Claude Bernard Lyon 1, 69 622 Villeurbanne, France
| | - Elodie Saruco
- Inter-University Laboratory of Human Movement Biology-EA 7424, University of Lyon, University Claude Bernard Lyon 1, 69 622 Villeurbanne, France; Neurologische Universitätsklinik, Bergmannsheil gGmbH, Forschungsgruppe Plastizität, Bürkle-de-la-Camp-Platz 1, 44789 Bochum, Germany
| | - Tadhg Macintyre
- Health Research Institute, University of Limerick, V94 T9PX Limerick, Ireland
| | - Aymeric Guillot
- Inter-University Laboratory of Human Movement Biology-EA 7424, University of Lyon, University Claude Bernard Lyon 1, 69 622 Villeurbanne, France
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Savic B, Müri R, Meier B. High Definition Transcranial Direct Current Stimulation Does Not Modulate Implicit Task Sequence Learning and Consolidation. Neuroscience 2019; 414:77-87. [DOI: 10.1016/j.neuroscience.2019.06.034] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 06/24/2019] [Accepted: 06/25/2019] [Indexed: 12/31/2022]
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27
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Fehring DJ, Illipparampil R, Acevedo N, Jaberzadeh S, Fitzgerald PB, Mansouri FA. Interaction of task-related learning and transcranial direct current stimulation of the prefrontal cortex in modulating executive functions. Neuropsychologia 2019; 131:148-159. [DOI: 10.1016/j.neuropsychologia.2019.05.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 04/08/2019] [Accepted: 05/10/2019] [Indexed: 01/24/2023]
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Ryan K, Schranz AL, Duggal N, Bartha R. Differential effects of transcranial direct current stimulation on antiphase and inphase motor tasks: A pilot study. Behav Brain Res 2019; 366:13-18. [PMID: 30851316 DOI: 10.1016/j.bbr.2019.03.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 02/26/2019] [Accepted: 03/05/2019] [Indexed: 11/15/2022]
Abstract
Ageing is associated with a decline in motor function that critically interferes with activities of daily living involving manual dexterity. Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that has been shown to enhance manual dexterity in healthy aging adults. The supplementary motor area (SMA) is involved in motor preparation and bimanual control; therefore, bihemispheric tDCS incorporating the SMA may preferentially enhance bimanual motor movements in healthy older adults. The aim of the current study was to determine if tDCS incorporating SMA could improve manual dexterity in older adults. Twenty-four adults, aged 67-84 participated in this double-blind, randomized, cross over design, pilot study. One group of participants (n = 17) were randomized to receive stimulation or sham on their first visit and received the contrary on their second visit, seven days later. A second group of participants (n = 10) received three consecutive days of tDCS while performing a motor task. Participants performed unimanual and bimanual hand movements while receiving 2 mA of tDCS. The total time for participants to complete three trials of each task was recorded. No significant differences in performance times were observed between single or tri session tDCS and sham conditions. However, tDCS had opposing effects on the motor consolidation of anti-phase and in-phase bimanual tasks. During the tri session paradigm, older adults improved performance learning of antiphase bimanual movements more quickly than inphase bimanual movements, suggesting a different mechanism of action of these two movements.
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Affiliation(s)
- Kayla Ryan
- Department of Medical Biophysics, The University of Western Ontario, London, Ontario, N6A 3K7, Canada; Centre for Functional and Metabolic Mapping, Robarts Research Institute, The University of Western Ontario, London, Ontario, N6A 5K8, Canada
| | - Amy L Schranz
- Department of Medical Biophysics, The University of Western Ontario, London, Ontario, N6A 3K7, Canada; Centre for Functional and Metabolic Mapping, Robarts Research Institute, The University of Western Ontario, London, Ontario, N6A 5K8, Canada
| | - Neil Duggal
- Department of Medical Biophysics, The University of Western Ontario, London, Ontario, N6A 3K7, Canada; Centre for Functional and Metabolic Mapping, Robarts Research Institute, The University of Western Ontario, London, Ontario, N6A 5K8, Canada; Department of Clinical Neurological Sciences, University Hospital, London Health Sciences Centre, London, Ontario, N6A 5A5, Canada
| | - Robert Bartha
- Department of Medical Biophysics, The University of Western Ontario, London, Ontario, N6A 3K7, Canada; Centre for Functional and Metabolic Mapping, Robarts Research Institute, The University of Western Ontario, London, Ontario, N6A 5K8, Canada.
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29
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No Effect of cathodal tDCS of the posterior parietal cortex on parafoveal preprocessing of words. Neurosci Lett 2019; 705:219-226. [DOI: 10.1016/j.neulet.2019.05.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 04/12/2019] [Accepted: 05/03/2019] [Indexed: 11/19/2022]
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30
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Vidyasagar TR. Visual attention and neural oscillations in reading and dyslexia: Are they possible targets for remediation? Neuropsychologia 2019; 130:59-65. [DOI: 10.1016/j.neuropsychologia.2019.02.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 02/14/2019] [Accepted: 02/15/2019] [Indexed: 01/07/2023]
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31
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Seidel O, Ragert P. Effects of Transcranial Direct Current Stimulation of Primary Motor Cortex on Reaction Time and Tapping Performance: A Comparison Between Athletes and Non-athletes. Front Hum Neurosci 2019; 13:103. [PMID: 31024275 PMCID: PMC6460944 DOI: 10.3389/fnhum.2019.00103] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/07/2019] [Indexed: 12/19/2022] Open
Abstract
Recent studies provided compelling evidence that physical activity leads to specific changes on a functional and structural level of brain organization. The observed neural adaptions are specific to the sport and manifested in those brain regions which are associated with neuronal processing of sport-specific skills. Techniques of non-invasive brain stimulation have been shown to induce neuroplastic changes and thereby also facilitate task performance. In the present study, we investigated the influence of transcranial direct current stimulation (tDCS) over the leg area of the primary motor cortex (M1) on simple reaction time tasks (RTT) and tapping tasks (TT) as a comparison between trained football (FB) and handball players (HB) and non-athletes (NA). We hypothesized that anodal tDCS over M1 (leg area) would lead to specific behavioral gains in RTT and TT performance of the lower extremity as compared to sham condition. On an exploratory level, we aimed at revealing if trained athletes would show stronger tDCS-induced behavioral gains as compared to NA, and, furthermore, if there are any differential effects between FB and HB. A total number of 46 participants were enrolled in a sham-controlled, double-blinded, cross-over study. A test block consisting of RTT and TT was performed before, during, after as well as 30 min after a 20-min tDCS application. Additionally, the specificity of tDCS-induced changes was examined by testing upper extremity using the same experimental design as a control condition. Our data showed no group- or sport-specific tDCS-induced effects (online and offline) on RTT and TT neither for lower nor upper extremities. These findings indicate that neither athletes nor NA seems to benefit from a brief period of tDCS application in speed-related motor tasks. However, more knowledge on neuronal processing of RTT and TT performance in trained athletes, the influence of tDCS parameters including stimulation sites, and the effect of inter-individual differences are required in order to draw a comprehensive picture of whether tDCS can help to enhance motor abilities on a high-performance level.
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Affiliation(s)
- Oliver Seidel
- Institute for General Kinesiology and Exercise Science, Faculty of Sport Science, University of Leipzig, Leipzig, Germany.,Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Patrick Ragert
- Institute for General Kinesiology and Exercise Science, Faculty of Sport Science, University of Leipzig, Leipzig, Germany.,Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
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32
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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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34
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Helfrich RF, Knight RT. Cognitive neurophysiology of the prefrontal cortex. HANDBOOK OF CLINICAL NEUROLOGY 2019; 163:35-59. [DOI: 10.1016/b978-0-12-804281-6.00003-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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35
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Zuk P, Torgerson L, Sierra-Mercado D, Lázaro-Muñoz G. Neuroethics of Neuromodulation: An Update. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2018; 8:45-50. [PMID: 30687802 DOI: 10.1016/j.cobme.2018.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This article reviews neuroethics issues that arise with the development, translation, and use of technologies for neuromodulation. Three electronic databases (PubMed, Embase, and PhilPapers) were searched for relevant articles published between 1/1/16 - 6/26/18. We focus on pressing ethical issues related to the use of deep brain stimulation (DBS), adaptive DBS (aDBS), transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and associated technologies. The neuroethics issues we address include privacy, continued access to devices, device removal, do-it-yourself neurostimulation, neuroenhancement, media coverage, changes in personal identity and agency, informed consent, and neuromodulation in minors. This review should be of assistance to a variety of stakeholders, including neurotechnology developers, as they make important decisions that will drive these neurotechnologies.
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Affiliation(s)
- Peter Zuk
- Center for Medical Ethics and Health Policy, Baylor College of Medicine, Houston, Texas, USA.,Department of Philosophy, Rice University, Houston, Texas, USA
| | - Laura Torgerson
- Center for Medical Ethics and Health Policy, Baylor College of Medicine, Houston, Texas, USA
| | - Demetrio Sierra-Mercado
- Department of Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - Gabriel Lázaro-Muñoz
- Center for Medical Ethics and Health Policy, Baylor College of Medicine, Houston, Texas, USA
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36
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Turkakin E, Akbıyık S, Akyol B, Gürdere C, Çakmak YÖ, Balcı F. Differential Bilateral Primary Motor Cortex tDCS Fails to Modulate Choice Bias and Readiness in Perceptual Decision Making. Front Neurosci 2018; 12:410. [PMID: 29967575 PMCID: PMC6015917 DOI: 10.3389/fnins.2018.00410] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/28/2018] [Indexed: 01/09/2023] Open
Abstract
One of the critical factors that guide choice behavior is the prior bias of the decision-maker with respect to different options, namely, the relative readiness by which the decision-maker opts for a specific choice. Although previous neuroimaging work has shown decision bias related activity in the orbitofrontal cortex, intraparietal sulcus (IPS) and dorsolateral prefrontal cortex, in a recent work by Javadi et al. (2015), primary motor cortex was also implicated. By applying transcranial direct current stimulation (tDCS), they have revealed a causal role of the primary motor cortex excitability in the induction of response time (RT) differences and decision bias in the form of choice probability. The current study aimed to replicate these recent findings with an experimental design that contained a sham group to increase experimental control and an additional testing phase to investigate the possible after-effects of tDCS. The conventional decision outputs such as choice proportion and RT were analyzed along with the theory-driven estimates of choice bias and non-decision related components of RTs (e.g., motor implementation speed of choices made). None of the statistical comparisons favored the alternative hypotheses over the null hypotheses. Consequently, previous findings regarding the effect of primary motor cortex excitability on choice bias and response times could not be replicated with a more controlled experimental design that is recommended for tDCS studies (Horvath et al., 2015). This empirical discrepancy between the two studies adds to the evidence demonstrating inconsistent effects of tDCS in establishing causal relationships between cortical excitability and motor behavior.
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Affiliation(s)
- Esin Turkakin
- Timing and Decision Making Lab, Department of Psychology, Koç University, Istanbul, Turkey
| | - Seda Akbıyık
- Timing and Decision Making Lab, Department of Psychology, Koç University, Istanbul, Turkey
| | - Bihter Akyol
- Timing and Decision Making Lab, Department of Psychology, Koç University, Istanbul, Turkey
| | - Ceren Gürdere
- Timing and Decision Making Lab, Department of Psychology, Koç University, Istanbul, Turkey
| | - Yusuf Ö Çakmak
- Cakmak Lab, Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, Dunedin, New Zealand.,Medical Technologies Centre of Research Excellence, Auckland, New Zealand
| | - Fuat Balcı
- Timing and Decision Making Lab, Department of Psychology, Koç University, Istanbul, Turkey.,Koç University Research Center for Translational Medicine, Koç University, Istanbul, Turkey
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37
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Lopez-Alonso V, Liew SL, Fernández Del Olmo M, Cheeran B, Sandrini M, Abe M, Cohen LG. A Preliminary Comparison of Motor Learning Across Different Non-invasive Brain Stimulation Paradigms Shows No Consistent Modulations. Front Neurosci 2018; 12:253. [PMID: 29740271 PMCID: PMC5924807 DOI: 10.3389/fnins.2018.00253] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 04/03/2018] [Indexed: 12/13/2022] Open
Abstract
Non-invasive brain stimulation (NIBS) has been widely explored as a way to safely modulate brain activity and alter human performance for nearly three decades. Research using NIBS has grown exponentially within the last decade with promising results across a variety of clinical and healthy populations. However, recent work has shown high inter-individual variability and a lack of reproducibility of previous results. Here, we conducted a small preliminary study to explore the effects of three of the most commonly used excitatory NIBS paradigms over the primary motor cortex (M1) on motor learning (Sequential Visuomotor Isometric Pinch Force Tracking Task) and secondarily relate changes in motor learning to changes in cortical excitability (MEP amplitude and SICI). We compared anodal transcranial direct current stimulation (tDCS), paired associative stimulation (PAS25), and intermittent theta burst stimulation (iTBS), along with a sham tDCS control condition. Stimulation was applied prior to motor learning. Participants (n = 28) were randomized into one of the four groups and were trained on a skilled motor task. Motor learning was measured immediately after training (online), 1 day after training (consolidation), and 1 week after training (retention). We did not find consistent differential effects on motor learning or cortical excitability across groups. Within the boundaries of our small sample sizes, we then assessed effect sizes across the NIBS groups that could help power future studies. These results, which require replication with larger samples, are consistent with previous reports of small and variable effect sizes of these interventions on motor learning.
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Affiliation(s)
- Virginia Lopez-Alonso
- Human Cortical Physiology and Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Bethesda, MD, United States.,Department of Physical Activity and Sport Sciences, "Center of Higher Education Alberta Giménez (CESAG)" Comillas Pontifical University, Palma, Spain.,Department of Physical Education, Faculty of Sciences of Sport and Physical Education, University of A Coruña, A Coruña, Spain
| | - Sook-Lei Liew
- Human Cortical Physiology and Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Bethesda, MD, United States.,Departments of Occupational Therapy, Biokinesiology, and Neurology, Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, CA, United States
| | - Miguel Fernández Del Olmo
- Department of Physical Education, Faculty of Sciences of Sport and Physical Education, University of A Coruña, A Coruña, Spain
| | - Binith Cheeran
- Molecular and Clinical Sciences Institute, St. George's, University of London, London, United Kingdom.,The London Clinic, London, United Kingdom
| | - Marco Sandrini
- Department of Psychology, University of Roehampton, London, United Kingdom
| | - Mitsunari Abe
- Faculty of Medicine, Center for Neurological Disorders, Fukushima Medical University, Fukushima, Japan
| | - Leonardo G Cohen
- Human Cortical Physiology and Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Bethesda, MD, United States
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38
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Younger JW, Booth JR. Parietotemporal Stimulation Affects Acquisition of Novel Grapheme-Phoneme Mappings in Adult Readers. Front Hum Neurosci 2018; 12:109. [PMID: 29628882 PMCID: PMC5876236 DOI: 10.3389/fnhum.2018.00109] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 03/06/2018] [Indexed: 11/13/2022] Open
Abstract
Neuroimaging work from developmental and reading intervention research has suggested a cause of reading failure may be lack of engagement of parietotemporal cortex during initial acquisition of grapheme-phoneme (letter-sound) mappings. Parietotemporal activation increases following grapheme-phoneme learning and successful reading intervention. Further, stimulation of parietotemporal cortex improves reading skill in lower ability adults. However, it is unclear whether these improvements following stimulation are due to enhanced grapheme-phoneme mapping abilities. To test this hypothesis, we used transcranial direct current stimulation (tDCS) to manipulate parietotemporal function in adult readers as they learned a novel artificial orthography with new grapheme-phoneme mappings. Participants received real or sham stimulation to the left inferior parietal lobe (L IPL) for 20 min before training. They received explicit training over the course of 3 days on 10 novel words each day. Learning of the artificial orthography was assessed at a pre-training baseline session, the end of each of the three training sessions, an immediate post-training session and a delayed post-training session about 4 weeks after training. Stimulation interacted with baseline reading skill to affect learning of trained words and transfer to untrained words. Lower skill readers showed better acquisition, whereas higher skill readers showed worse acquisition, when training was paired with real stimulation, as compared to readers who received sham stimulation. However, readers of all skill levels showed better maintenance of trained material following parietotemporal stimulation, indicating a differential effect of stimulation on initial learning and consolidation. Overall, these results indicate that parietotemporal stimulation can enhance learning of new grapheme-phoneme relationships in readers with lower reading skill. Yet, while parietotemporal function is critical to new learning, its role in continued reading improvement likely changes as readers progress in skill.
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Affiliation(s)
- Jessica W Younger
- Department of Communication Sciences and Disorders, University of Texas at Austin, Austin, TX, United States
| | - James R Booth
- Department of Communication Sciences and Disorders, University of Texas at Austin, Austin, TX, United States.,Department of Psychology and Human Development, Vanderbilt University, Nashville, TN, United States
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39
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Poststimulation time interval-dependent effects of motor cortex anodal tDCS on reaction-time task performance. COGNITIVE AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2018; 18:167-175. [DOI: 10.3758/s13415-018-0561-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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40
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Beker S, Foxe JJ, Molholm S. Ripe for solution: Delayed development of multisensory processing in autism and its remediation. Neurosci Biobehav Rev 2018; 84:182-192. [PMID: 29162518 PMCID: PMC6389331 DOI: 10.1016/j.neubiorev.2017.11.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 11/09/2017] [Accepted: 11/13/2017] [Indexed: 12/24/2022]
Abstract
Difficulty integrating inputs from different sensory sources is commonly reported in individuals with Autism Spectrum Disorder (ASD). Accumulating evidence consistently points to altered patterns of behavioral reactions and neural activity when individuals with ASD observe or act upon information arriving through multiple sensory systems. For example, impairments in the integration of seen and heard speech appear to be particularly acute, with obvious implications for interpersonal communication. Here, we explore the literature on multisensory processing in autism with a focus on developmental trajectories. While much remains to be understood, some consistent observations emerge. Broadly, sensory integration deficits are found in children with an ASD whereas these appear to be much ameliorated, or even fully recovered, in older teenagers and adults on the spectrum. This protracted delay in the development of multisensory processing raises the possibility of applying early intervention strategies focused on multisensory integration, to accelerate resolution of these functions. We also consider how dysfunctional cross-sensory oscillatory neural communication may be one key pathway to impaired multisensory processing in ASD.
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Affiliation(s)
- Shlomit Beker
- The Sheryl and Daniel R. Tishman Cognitive Neurophysiology Laboratory, Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY, United States; Rose F. Kennedy Intellectual and Developmental Disabilities Research Center (IDDRC), Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, United States
| | - John J Foxe
- The Sheryl and Daniel R. Tishman Cognitive Neurophysiology Laboratory, Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY, United States; Rose F. Kennedy Intellectual and Developmental Disabilities Research Center (IDDRC), Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, United States; The Ernest J. Del Monte Institute for Neuroscience, Department of Neuroscience, University of Rochester Medical Center, Rochester, NY, United States
| | - Sophie Molholm
- The Sheryl and Daniel R. Tishman Cognitive Neurophysiology Laboratory, Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY, United States; Rose F. Kennedy Intellectual and Developmental Disabilities Research Center (IDDRC), Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, United States; The Ernest J. Del Monte Institute for Neuroscience, Department of Neuroscience, University of Rochester Medical Center, Rochester, NY, United States.
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Semantic discrimination impacts tDCS modulation of verb processing. Sci Rep 2017; 7:17162. [PMID: 29215039 PMCID: PMC5719444 DOI: 10.1038/s41598-017-17326-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 11/17/2017] [Indexed: 12/31/2022] Open
Abstract
Motor cortex activation observed during body-related verb processing hints at simulation accompanying linguistic understanding. By exploiting the up- and down-regulation that anodal and cathodal transcranial direct current stimulation (tDCS) exert on motor cortical excitability, we aimed at further characterizing the functional contribution of the motor system to linguistic processing. In a double-blind sham-controlled within-subjects design, online stimulation was applied to the left hemispheric hand-related motor cortex of 20 healthy subjects. A dual, double-dissociation task required participants to semantically discriminate concrete (hand/foot) from abstract verb primes as well as to respond with the hand or with the foot to verb-unrelated geometric targets. Analyses were conducted with linear mixed models. Semantic priming was confirmed by faster and more accurate reactions when the response effector was congruent with the verb's body part. Cathodal stimulation induced faster responses for hand verb primes thus indicating a somatotopical distribution of cortical activation as induced by body-related verbs. Importantly, this effect depended on performance in semantic discrimination. The current results point to verb processing being selectively modifiable by neuromodulation and at the same time to a dependence of tDCS effects on enhanced simulation. We discuss putative mechanisms operating in this reciprocal dependence of neuromodulation and motor resonance.
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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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43
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Russo R, Twyman P, Cooper NR, Fitzgerald PB, Wallace D. When you can, scale up: Large-scale study shows no effect of tDCS in an ambiguous risk-taking task. Neuropsychologia 2017; 104:133-143. [DOI: 10.1016/j.neuropsychologia.2017.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 08/04/2017] [Accepted: 08/05/2017] [Indexed: 11/26/2022]
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44
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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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45
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No effects of transcranial DLPFC stimulation on implicit task sequence learning and consolidation. Sci Rep 2017; 7:9649. [PMID: 28852114 PMCID: PMC5575284 DOI: 10.1038/s41598-017-10128-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 07/27/2017] [Indexed: 12/11/2022] Open
Abstract
Neurostimulation of the dorsolateral prefrontal cortex (DLPFC) can modulate performance in cognitive tasks. In a recent study, however, transcranial direct current stimulation (tDCS) of the DLPFC did not affect implicit task sequence learning and consolidation in a paradigm that involved bimanual responses. Because bimanual performance increases the coupling between homologous cortical areas of the hemispheres and left and right DLPFC were stimulated separately the null findings may have been due to the bimanual setup. The aim of the present study was to test the effect of neuro-stimulation on sequence learning in a uni-manual setup. For this purpose two experiments were conducted. In Experiment 1, the DLPFC was stimulated with tDCS. In Experiment 2 the DLPFC was stimulated with transcranial magnetic stimulation (TMS). In both experiments, consolidation was measured 24 hours later. The results showed that sequence learning was present in all conditions and sessions, but it was not influenced by stimulation. Likewise, consolidation of sequence learning was robust across sessions, but it was not influenced by stimulation. These results replicate and extend previous findings. They indicate that established tDCS and TMS protocols on the DLPFC do not influence implicit task sequence learning and consolidation.
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46
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Eddy CM, Shapiro K, Clouter A, Hansen PC, Rickards HE. Transcranial direct current stimulation can enhance working memory in Huntington's disease. Prog Neuropsychopharmacol Biol Psychiatry 2017; 77:75-82. [PMID: 28390970 DOI: 10.1016/j.pnpbp.2017.04.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 04/03/2017] [Accepted: 04/03/2017] [Indexed: 11/28/2022]
Abstract
UNLABELLED Transcranial direct current stimulation (tDCS) combined with a cognitive task can enhance targeted aspects of cognitive functioning in clinical populations. The movement disorder Huntington's disease (HD) is associated with progressive cognitive impairment. Deficits in working memory (WM) can be apparent early in the disease and impact functional capacity. We investigated whether tDCS combined with cognitive training could improve WM in patients with HD, and if baseline clinical or cognitive measures may predict efficacy. Twenty participants with HD completed this crossover trial, undergoing 1.5mA anodal tDCS over left dorsolateral prefrontal cortex and sham stimulation on separate visits. Participants and assessor were blinded to condition order, which was randomised across participants. All participants completed baseline clinical and cognitive assessments. Pre- and post-stimulation tasks included digit reordering, computerised n-back tests and a Stroop task. During 15min of tDCS/sham stimulation, participants practiced 1- and 2-back WM tasks. Participants exhibited an increase in WM span on the digit re-ordering span task from pre- to post-stimulation after tDCS, but not after sham stimulation. Gains in WM were positively related to motor symptom ratings and negatively associated with verbal fluency scores. Patients with more severe motor symptoms showed greatest improvement, suggesting that motor symptom ratings may help identify patients who are most likely to benefit from tDCS. CONCLUSIONS Dorsolateral prefrontal tDCS appears well tolerated in HD and enhances WM span compared to sham stimulation. Our findings strongly encourage further investigation of the extent to which tDCS combined with cognitive training could enhance everyday function in HD. ClinicalTrials.gov; NCT02216474 Brain stimulation in Movement Disorders; https://clinicaltrials.gov/ct2/show/NCT02216474.
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Affiliation(s)
- Clare M Eddy
- National Centre for Mental Health, BSMHFT, Birmingham and College of Medical and Dental Sciences, University of Birmingham, UK.
| | - Kimron Shapiro
- School of Psychology, College of Life and Environmental Sciences, University of Birmingham, UK
| | - Andrew Clouter
- School of Psychology, College of Life and Environmental Sciences, University of Birmingham, UK
| | - Peter C Hansen
- School of Psychology, College of Life and Environmental Sciences, University of Birmingham, UK
| | - Hugh E Rickards
- National Centre for Mental Health, BSMHFT, Birmingham and College of Medical and Dental Sciences, University of Birmingham, UK
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47
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Norise C, Hamilton RH. Non-invasive Brain Stimulation in the Treatment of Post-stroke and Neurodegenerative Aphasia: Parallels, Differences, and Lessons Learned. Front Hum Neurosci 2017; 10:675. [PMID: 28167904 PMCID: PMC5253356 DOI: 10.3389/fnhum.2016.00675] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 12/19/2016] [Indexed: 11/22/2022] Open
Abstract
Numerous studies over the span of more than a decade have shown that non-invasive brain stimulation (NIBS) techniques, namely transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), can facilitate language recovery for patients who have suffered from aphasia due to stroke. While stroke is the most common etiology of aphasia, neurodegenerative causes of language impairment—collectively termed primary progressive aphasia (PPA)—are increasingly being recognized as important clinical phenotypes in dementia. Very limited data now suggest that (NIBS) may have some benefit in treating PPAs. However, before applying the same approaches to patients with PPA as have previously been pursued in patients with post-stroke aphasia, it will be important for investigators to consider key similarities and differences between these aphasia etiologies that is likely to inform successful approaches to stimulation. While both post-stroke aphasia and the PPAs have clear overlaps in their clinical phenomenology, the mechanisms of injury and theorized neuroplastic changes associated with the two etiologies are notably different. Importantly, theories of plasticity in post-stroke aphasia are largely predicated on the notion that regions of the brain that had previously been uninvolved in language processing may take on new compensatory roles. PPAs, however, are characterized by slow distributed degeneration of cellular units within the language system; compensatory recruitment of brain regions to subserve language is not currently understood to be an important aspect of the condition. This review will survey differences in the mechanisms of language representation between the two etiologies of aphasia and evaluate properties that may define and limit the success of different neuromodulation approaches for these two disorders.
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Affiliation(s)
- Catherine Norise
- Laboratory for Cognition and Neural Stimulation, Department of Neurology, University of Pennsylvania Philadelphia, PA, USA
| | - Roy H Hamilton
- Laboratory for Cognition and Neural Stimulation, Department of Neurology, University of Pennsylvania Philadelphia, PA, USA
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48
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Savic B, Müri R, Meier B. A single session of prefrontal cortex transcranial direct current stimulation does not modulate implicit task sequence learning and consolidation. Brain Stimul 2017; 10:567-575. [PMID: 28089321 DOI: 10.1016/j.brs.2017.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 12/28/2016] [Accepted: 01/03/2017] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Transcranial direct current stimulation (tDCS) is assumed to affect cortical excitability and dependent on the specific stimulation conditions either to increase or decrease learning. OBJECTIVE The purpose of this study was to modulate implicit task sequence learning with tDCS. METHODS As cortico-striatal loops are critically involved in implicit task sequence learning, tDCS was applied above the dorsolateral prefrontal cortex (DLPFC). In Experiment 1, anodal, cathodal, or sham tDCS was applied before the start of the sequence learning task. In Experiment 2, stimulation was applied during the sequence learning task. Consolidation of learning was assessed after 24 h. RESULTS The results of both experiments showed that implicit task sequence learning occurred consistently but it was not modulated by different tDCS conditions. Similarly, consolidation measured after a 24 h-interval including sleep was also not affected by stimulation. CONCLUSIONS These results indicate that a single session of DLPFC tDCS is not sufficient to modulate implicit task sequence learning. This study adds to the accumulating evidence that tDCS may not be as effective as originally thought.
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Affiliation(s)
- Branislav Savic
- Institute of Psychology and Center for Cognition, Learning, and Memory, University of Bern, Switzerland
| | - René Müri
- Department of Neurology, Bern University Hospital Inselspital, and Center for Cognition, Learning, and Memory, University of Bern, Bern, Switzerland
| | - Beat Meier
- Institute of Psychology and Center for Cognition, Learning, and Memory, University of Bern, Switzerland.
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49
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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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50
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Karuza EA, Balewski ZZ, Hamilton RH, Medaglia JD, Tardiff N, Thompson-Schill SL. Mapping the Parameter Space of tDCS and Cognitive Control via Manipulation of Current Polarity and Intensity. Front Hum Neurosci 2016; 10:665. [PMID: 28082886 PMCID: PMC5187365 DOI: 10.3389/fnhum.2016.00665] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 12/14/2016] [Indexed: 11/18/2022] Open
Abstract
In the cognitive domain, enormous variation in methodological approach prompts questions about the generalizability of behavioral findings obtained from studies of transcranial direct current stimulation (tDCS). To determine the impact of common variations in approach, we systematically manipulated two key stimulation parameters—current polarity and intensity—and assessed their impact on a task of inhibitory control (the Eriksen Flanker). Ninety participants were randomly assigned to one of nine experimental groups: three stimulation conditions (anode, sham, cathode) crossed with three intensity levels (1.0, 1.5, 2.0 mA). As participants performed the Flanker task, stimulation was applied over left dorsolateral prefrontal cortex (DLPFC; electrode montage: F3-RSO). The behavioral impact of these manipulations was examined using mixed effects linear regression. Results indicate a significant effect of stimulation condition (current polarity) on the magnitude of the interference effect during the Flanker; however, this effect was specific to the comparison between anodal and sham stimulation. Inhibitory control was therefore improved by anodal stimulation over the DLPFC. In the present experimental context, no reliable effect of stimulation intensity was observed, and we found no evidence that inhibitory control was impeded by cathodal stimulation. Continued exploration of the stimulation parameter space, particularly with more robustly powered sample sizes, is essential to facilitating cross-study comparison and ultimately working toward a reliable model of tDCS effects.
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Affiliation(s)
- Elisabeth A Karuza
- Department of Psychology, University of Pennsylvania, Philadelphia PA, USA
| | - Zuzanna Z Balewski
- Department of Psychology, University of Pennsylvania, Philadelphia PA, USA
| | - Roy H Hamilton
- Department of Neurology, University of Pennsylvania, Philadelphia PA, USA
| | - John D Medaglia
- Department of Psychology, University of Pennsylvania, Philadelphia PA, USA
| | - Nathan Tardiff
- Department of Psychology, University of Pennsylvania, Philadelphia PA, USA
| | - Sharon L Thompson-Schill
- Department of Psychology, University of Pennsylvania, PhiladelphiaPA, USA; Department of Neurology, University of Pennsylvania, PhiladelphiaPA, USA
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