Articles de revues : « Cathodal tDCS »

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Lang, Nicolas, Michael A. Nitsche, Michele Dileone, Paolo Mazzone, Javier De Andrés-Arés, Luis Diaz-Jara, Walter Paulus, Vincenzo Di Lazzaro et Antonio Oliviero. « Transcranial direct current stimulation effects on I-wave activity in humans ». Journal of Neurophysiology 105, n^o 6 (juin 2011) : 2802–10. http://dx.doi.org/10.1152/jn.00617.2010.

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Transcranial direct current stimulation (tDCS) of the human cerebral cortex modulates cortical excitability noninvasively in a polarity-specific manner: anodal tDCS leads to lasting facilitation and cathodal tDCS to inhibition of motor cortex excitability. To further elucidate the underlying physiological mechanisms, we recorded corticospinal volleys evoked by single-pulse transcranial magnetic stimulation of the primary motor cortex before and after a 5-min period of anodal or cathodal tDCS in eight conscious patients who had electrodes implanted in the cervical epidural space for the control of pain. The effects of anodal tDCS were evaluated in six subjects and the effects of cathodal tDCS in five subjects. Three subjects were studied with both polarities. Anodal tDCS increased the excitability of cortical circuits generating I waves in the corticospinal system, including the earliest wave (I1 wave), whereas cathodal tDCS suppressed later I waves. The motor evoked potential (MEP) amplitude changes immediately following tDCS periods were in agreement with the effects produced on intracortical circuitry. The results deliver additional evidence that tDCS changes the excitability of cortical neurons.

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Nejati, Vahid, Mohammad Ali Salehinejad, Michael A. Nitsche, Asal Najian et Amir-Homayoun Javadi. « Transcranial Direct Current Stimulation Improves Executive Dysfunctions in ADHD : Implications for Inhibitory Control, Interference Control, Working Memory, and Cognitive Flexibility ». Journal of Attention Disorders 24, n^o 13 (22 septembre 2017) : 1928–43. http://dx.doi.org/10.1177/1087054717730611.

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Objective: This study examined effects of transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) and orbitofrontal cortex (OFC) on major executive functions (EFs), including response inhibition, executive control, working memory (WM), and cognitive flexibility/task switching in ADHD. Method: ADHD children received (a) left anodal/right cathodal DLPFC tDCS and (b) sham stimulation in Experiment 1 and (a) left anodal DLPFC/right cathodal OFC tDCS, (b) left cathodal DLPFC/right anodal OFC tDCS, and (c) sham stimulation in Experiment 2. The current intensity was 1 mA for 15 min with a 72-hr interval between sessions. Participants underwent Go/No-Go task, N-back test, Wisconsin Card Sorting Test (WCST), and Stroop task after each tDCS condition. Results: Anodal left DLPFC tDCS most clearly affected executive control functions (e.g., WM, interference inhibition), while cathodal left DLPFC tDCS improved inhibitory control. Cognitive flexibility/task switching benefited from combined DLPFC-OFC, but not DLPFC stimulation alone. Conclusion: Task-specific stimulation protocols can improve EFs in ADHD.

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Dai, Wenjun, Yao Geng, Hao Liu, Chuan Guo, Wenxiang Chen, Jinhui Ma, Jinjin Chen, Yanbing Jia, Ying Shen et Tong Wang. « Preconditioning with Cathodal High-Definition Transcranial Direct Current Stimulation Sensitizes the Primary Motor Cortex to Subsequent Intermittent Theta Burst Stimulation ». Neural Plasticity 2021 (21 octobre 2021) : 1–8. http://dx.doi.org/10.1155/2021/8966584.

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Noninvasive brain stimulation techniques such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) can induce long-term potentiation-like facilitation, but whether the combination of TMS and tDCS has additive effects is unclear. To address this issue, in this randomized crossover study, we investigated the effect of preconditioning with cathodal high-definition (HD) tDCS on intermittent theta burst stimulation- (iTBS-) induced plasticity in the left motor cortex. A total of 24 healthy volunteers received preconditioning with cathodal HD-tDCS or sham intervention prior to iTBS in a random order with a washout period of 1 week. The amplitude of motor evoked potentials (MEPs) was measured at baseline and at several time points (5, 10, 15, and 30 min) after iTBS to determine the effects of the intervention on cortical plasticity. Preconditioning with cathodal HD-tDCS followed by iTBS showed a greater increase in MEP amplitude than sham cathodal HD-tDCS preconditioning and iTBS at each time postintervention point, with longer-lasting after-effects on cortical excitability. These results demonstrate that preintervention with cathodal HD-tDCS primes the motor cortex for long-term potentiation induced by iTBS and is a potential strategy for improving the clinical outcome to guide therapeutic decisions.

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Spielmann, K., R. van der Vliet, W. M. E. van de Sandt-Koenderman, M. A. Frens, G. M. Ribbers, R. W. Selles, S. van Vugt, J. N. van der Geest et P. Holland. « Cerebellar Cathodal Transcranial Direct Stimulation and Performance on a Verb Generation Task : A Replication Study ». Neural Plasticity 2017 (2017) : 1–12. http://dx.doi.org/10.1155/2017/1254615.

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The role of the cerebellum in cognitive processing is increasingly recognized but still poorly understood. A recent study in this field applied cerebellar Transcranial Direct Current Stimulation (c-tDCS) to the right cerebellum to investigate the role of prefrontal-cerebellar loops in language aspects of cognition. Results showed that the improvement in participants’ verbal response times on a verb generation task was facilitated immediately after cathodal c-tDCS, compared to anodal or sham c-tDCS. The primary aim of the present study is to replicate these findings and additionally to investigate possible longer term effects. A crossover within-subject design was used, comparing cathodal and sham c-tDCS. The experiment consisted of two visits with an interval of one week. Our results show no direct contribution of cathodal c-tDCS over the cerebellum to language task performance. However, one week later, the group receiving cathodal c-tDCS in the first visit show less improvement and increased variability in their verbal response times during the second visit, compared to the group receiving sham c-tDCS in the first visit. These findings suggest a potential negative effect of c-tDCS and warrant further investigation into long term effects of c-tDCS before undertaking clinical studies with poststroke patients with aphasia.

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Wang, Jiarui, Jinhua Tian, Renning Hao, Lili Tian et Qiang Liu. « Transcranial direct current stimulation over the right DLPFC selectively modulates subprocesses in working memory ». PeerJ 6 (28 mai 2018) : e4906. http://dx.doi.org/10.7717/peerj.4906.

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Background Working memory, as a complex system, consists of two independent components: manipulation and maintenance process, which are defined as executive control and storage process. Previous studies mainly focused on the overall effect of transcranial direct current stimulation (tDCS) on working memory. However, little has been known about the segregative effects of tDCS on the sub-processes within working memory. Method Transcranial direct current stimulation, as one of the non-invasive brain stimulation techniques, is being widely used to modulate the cortical activation of local brain areas. This study modified a spatial n-back experiment with anodal and cathodal tDCS exertion on the right dorsolateral prefrontal cortex (DLPFC), aiming to investigate the effects of tDCS on the two sub-processes of working memory: manipulation (updating) and maintenance. Meanwhile, considering the separability of tDCS effects, we further reconfirmed the causal relationship between the right DLPFC and the sub-processes of working memory with different tDCS conditions. Results The present study showed that cathodal tDCS on the right DLPFC selectively improved the performance of the modified 2-back task in the difficult condition, whereas anodal tDCS significantly reduced the performance of subjects and showed an speeding-up tendency of response time. More precisely, the results of discriminability index and criterion showed that only cathodal tDCS enhanced the performance of maintenance in the difficult condition. Neither of the two tDCS conditions affected the performance of manipulation (updating). Conclusion These findings provide evidence that cathodal tDCS of the right DLPFC selectively affects maintenance capacity. Besides, cathodal tDCS also serves as an interference suppressor to reduce the irrelevant interference, thereby indirectly improving the working memory capacity. Moreover, the right DLPFC is not the unique brain regions for working memory manipulation (updating).

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Paquette, Caroline, Michael Sidel, Basia A. Radinska, Jean-Paul Soucy et Alexander Thiel. « Bilateral Transcranial Direct Current Stimulation Modulates Activation-Induced Regional Blood Flow Changes during Voluntary Movement ». Journal of Cerebral Blood Flow & ; Metabolism 31, n^o 10 (11 mai 2011) : 2086–95. http://dx.doi.org/10.1038/jcbfm.2011.72.

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Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that induces changes in cortical excitability: anodal stimulation increases while cathodal stimulation reduces excitability. Imaging studies performed after unilateral stimulation have shown conflicting results regarding the effects of tDCS on surrogate markers of neuronal activity. The aim of this study was to directly measure these effects on activation-induced changes in regional cerebral blood flow (⊿rBF) using positron emission tomography (PET) during bilateral tDCS. Nine healthy subjects underwent repeated rCBF measurements with 15O-water and PET during a simple motor task while receiving tDCS or sham stimulation over the primary motor cortex (M1). Motor evoked potentials (MEPs) were also assessed before and after real and sham stimulation. During tDCS with active movement, ⊿rBF in M1 was significantly lower on the cathodal than the anodal side when compared with sham stimulation. This decrease in ⊿rBF was accompanied by a decrease in MEP amplitude on the cathodal side. No effect was observed on resting or activated rCBF relative to sham stimulation. We thus conclude that it is the interaction of cathodal tDCS with activation-induced ⊿rBF rather than the effect on resting or activated rCBF itself which constitutes the physiological imaging correlate of tDCS.

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Valero-Cabré, Antoni, Clara Sanches, Juliette Godard, Oriane Fracchia, Bruno Dubois, Richard Levy, Dennis Q. Truong, Marom Bikson et Marc Teichmann. « Language boosting by transcranial stimulation in progressive supranuclear palsy ». Neurology 93, n^o 6 (3 juillet 2019) : e537-e547. http://dx.doi.org/10.1212/wnl.0000000000007893.

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ObjectiveTo explore whether transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) can improve language capacities in patients with progressive supranuclear palsy (PSP).MethodsWe used a sham-controlled double-blind crossover design to assess the efficiency of tDCS over the DLPFC in a cohort of 12 patients with PSP. In 3 separate sessions, we evaluated the ability to boost the left DLPFC via left-anodal (excitatory) and right-cathodal (inhibitory) tDCS, while comparing them to sham tDCS. Tasks assessing lexical access (letter fluency task) and semantic access (category judgment task) were applied immediately before and after the tDCS sessions to provide a marker of potential language modulation.ResultsThe comparison with healthy controls showed that patients with PSP were impaired on both tasks at baseline. Contrasting poststimulation vs prestimulation performance across tDCS conditions revealed language improvement in the category judgment task following right-cathodal tDCS, and in the letter fluency task following left-anodal tDCS. A computational finite element model of current distribution corroborated the intended effect of left-anodal and right-cathodal tDCS on the targeted DLPFC.ConclusionsOur results demonstrate tDCS-driven language improvement in PSP. They provide proof-of-concept for the use of tDCS in PSP and set the stage for future multiday stimulation regimens, which might lead to longer-lasting therapeutic effects promoted by neuroplasticity.Classification of evidenceThis study provides Class III evidence that for patients with PSP, tDCS over the DLPFC improves performance in some language tasks.

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de Venecia, Angelito Braulio F., et Shane M. Fresnoza. « Visual Cortex Transcranial Direct Current Stimulation for Proliferative Diabetic Retinopathy Patients : A Double-Blinded Randomized Exploratory Trial ». Brain Sciences 11, n^o 2 (21 février 2021) : 270. http://dx.doi.org/10.3390/brainsci11020270.

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Proliferative diabetic retinopathy (PDR) is a severe complication of diabetes. PDR-related retinal hemorrhages often lead to severe vision loss. The main goals of management are to prevent visual impairment progression and improve residual vision. We explored the potential of transcranial direct current stimulation (tDCS) to enhance residual vision. tDCS applied to the primary visual cortex (V1) may improve visual input processing from PDR patients’ retinas. Eleven PDR patients received cathodal tDCS stimulation of V1 (1 mA for 10 min), and another eleven patients received sham stimulation (1 mA for 30 s). Visual acuity (logarithm of the minimum angle of resolution (LogMAR) scores) and number acuity (reaction times (RTs) and accuracy rates (ARs)) were measured before and immediately after stimulation. The LogMAR scores and the RTs of patients who received cathodal tDCS decreased significantly after stimulation. Cathodal tDCS has no significant effect on ARs. There were no significant changes in the LogMAR scores, RTs, and ARs of PDR patients who received sham stimulation. The results are compatible with our proposal that neuronal noise aggravates impaired visual function in PDR. The therapeutic effect indicates the potential of tDCS as a safe and effective vision rehabilitation tool for PDR patients.

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Jahshan, Carol, Jonathan K. Wynn, Brian J. Roach, Daniel H. Mathalon et Michael F. Green. « Effects of Transcranial Direct Current Stimulation on Visual Neuroplasticity in Schizophrenia ». Clinical EEG and Neuroscience 51, n^o 6 (28 mai 2020) : 382–89. http://dx.doi.org/10.1177/1550059420925697.

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People with schizophrenia (SZ) exhibit visual processing abnormalities that affect their daily functioning and remediating these deficits might help to improve functioning. Transcranial direct current stimulation (tDCS) is a potential tool for perceptual enhancement for this purpose, though there are no reports of tDCS applied to visual cortex in SZ. In a within-subject, crossover design, we evaluated the effects of tDCS on visual processing in 27 SZ. All patients received anodal, cathodal, or sham stimulation over the central occipital region in 3 visits separated by 1 week. In each visit, a backward masking task and an electroencephalography measure of visual neuroplasticity were administered after tDCS. Neuroplasticity was assessed with visual evoked potentials before and after tetanizing visual high-frequency stimulation. Masking performance was significantly poorer in the anodal and cathodal conditions compared with sham. Both anodal and cathodal stimulation increased the amplitude of P1 but did not change the plasticity index. We found significant plasticity effects of tDCS for only one waveform for one stimulation condition (P2 for anodal tDCS) which did not survive correction for multiple comparisons. The reason for the lack of tDCS stimulation effects on plasticity may be because tDCS was not delivered simultaneously with the tetanizing visual stimulus. The present findings emphasize the need for more research on the relevant parameters for stimulation of visual processing regions in clinical populations.

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Liu, Hui-Hua, Xiao-Kuo He, Hsin-Yung Chen, Chih-Wei Peng, Alexander Rotenberg, Chi-Hung Juan, Yu-Cheng Pei et al. « Neuromodulatory Effects of Transcranial Direct Current Stimulation on Motor Excitability in Rats ». Neural Plasticity 2019 (17 décembre 2019) : 1–9. http://dx.doi.org/10.1155/2019/4252943.

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Transcranial direct current stimulation (tDCS) is a noninvasive technique for modulating neural plasticity and is considered to have therapeutic potential in neurological disorders. For the purpose of translational neuroscience research, a suitable animal model can be ideal for providing a stable condition for identifying mechanisms that can help to explore therapeutic strategies. Here, we developed a tDCS protocol for modulating motor excitability in anesthetized rats. To examine the responses of tDCS-elicited plasticity, the motor evoked potential (MEP) and MEP input-output (IO) curve elicited by epidural motor cortical electrical stimulus were evaluated at baseline and after 30 min of anodal tDCS or cathodal tDCS. Furthermore, a paired-pulse cortical electrical stimulus was applied to assess changes in the inhibitory network by measuring long-interval intracortical inhibition (LICI) before and after tDCS. In the results, analogous to those observed in humans, the present study demonstrates long-term potentiation- (LTP-) and long-term depression- (LTD-) like plasticity can be induced by tDCS protocol in anesthetized rats. We found that the MEPs were significantly enhanced immediately after anodal tDCS at 0.1 mA and 0.8 mA and remained enhanced for 30 min. Similarly, MEPs were suppressed immediately after cathodal tDCS at 0.8 mA and lasted for 30 min. No effect was noted on the MEP magnitude under sham tDCS stimulation. Furthermore, the IO curve slope was elevated following anodal tDCS and presented a trend toward diminished slope after cathodal tDCS. No significant differences in the LICI ratio of pre- to post-tDCS were observed. These results indicated that developed tDCS schemes can produce consistent, rapid, and controllable electrophysiological changes in corticomotor excitability in rats. This newly developed tDCS animal model could be useful to further explore mechanical insights and may serve as a translational platform bridging human and animal studies, establishing new therapeutic strategies for neurological disorders.

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Monte-Silva, Katia, Min-Fang Kuo, David Liebetanz, Walter Paulus et Michael A. Nitsche. « Shaping the Optimal Repetition Interval for Cathodal Transcranial Direct Current Stimulation (tDCS) ». Journal of Neurophysiology 103, n^o 4 (avril 2010) : 1735–40. http://dx.doi.org/10.1152/jn.00924.2009.

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Transcranial DC stimulation (tDCS) is a plasticity-inducing noninvasive brain stimulation tool with various potential therapeutic applications in neurological and psychiatric diseases. Currently, the duration of the aftereffects of stimulation is restricted. For future clinical applications, stimulation protocols are required that produce aftereffects lasting for days or weeks. Options to prolong the effects of tDCS are further prolongation or repetition of tDCS. Nothing is known thus far about optimal protocols in this behalf, although repetitive stimulation is already performed in clinical applications. Thus we explored the effects of different break durations on cathodal tDCS-induced cortical excitability alterations. In 12 subjects, two identical periods of cathodal tDCS (9-min duration; 1 mA) with an interstimulation interval of 0 (no break), 3, or 20 min or 3 or 24 h were performed. The results indicate that doubling stimulation duration without a break prolongs the aftereffects from 60 to 90 min after tDCS. When the second stimulation was performed during the aftereffects of the first, a prolongation and enhancement of tDCS-induced effects for ≤120 min after stimulation was observed. In contrast, when the second stimulation followed the first one after 3 or 24 h, the aftereffects were initially attenuated, or abolished, but afterwards re-established for up to 120 min after tDCS in the 24-h condition. These results suggest that, for prolonging the aftereffects of cathodal tDCS, stimulation interval might be important.

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Hansen, Niels, Mark Obermann, Franziska Poitz, Dagny Holle, Hans-Christoph Diener, Andrea Antal, Walter Paulus et Zaza Katsarava. « Modulation of human trigeminal and extracranial nociceptive processing by transcranial direct current stimulation of the motor cortex ». Cephalalgia 31, n^o 6 (13 janvier 2011) : 661–70. http://dx.doi.org/10.1177/0333102410390394.

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Objective: The study was conducted to investigate the after-effect of transcranial direct current stimulation (tDCS) applied over the human primary motor cortex (M1) on trigeminal and extracranial nociceptive processing. Basic procedures: Nineteen healthy volunteers were stimulated using cathodal, anodal (both 1 mA) or sham tDCS for 20 minutes. Pain processing was assessed by recording trigeminal and extracranial pain-related evoked potentials (PREPs) following electrical stimulation of the contralateral forehead and hand at baseline, 0, 20 and 50 minutes post-tDCS. Main findings: Cathodal tDCS resulted in decreased peak-to-peak amplitudes (PPAs) by 18% while anodal tDCS lead to increased PPAs of PREPs by 35% ( p < .05). Principal conclusions: The decreased PPAs suggest an inhibition and the increased PPAs of PREPs suggest an excitation of trigeminal and extracranial pain processing induced by tDCS of the M1. These results may provide evidence for the effectiveness of tDCS as a therapeutic instrument in treating headache disorders.

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Li, Lucia, Robert Leech, Barry Seemungal, Paresh Malhotra et David Sharp. « A SENSE OF DIRECTION : BRAIN STIMULATION IN LATERALISED BRAIN FUNCTION ». Journal of Neurology, Neurosurgery & ; Psychiatry 86, n^o 11 (14 octobre 2015) : e4.109-e4. http://dx.doi.org/10.1136/jnnp-2015-312379.21.

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Many cognitive functions demonstrate varying degrees of hemispheric lateralisation. Lateralised pathology can lead to striking deficits, such as the dyscalculia produced by dominant parietal lesions.Transcranial direct current stimulation (tDCS) non-invasively delivers weak electrical currents to the brain, resulting in transient changes in neuronal excitability: anodal tDCS is thought to be facilitatory, whilst cathodal is inhibitory.We investigated the effect of bi-parietal tDCS on numeracy, spatial attention and, sustained attention. We hypothesised that tDCS has distinct effects because of varying lateralisation (numeracy left, spatial attention right and sustained attention uncertain). We performed a single-blinded, cross-over, sham-controlled study. Eighteen healthy right-handed subjects performed cognitive tasks during 3 sessions of bi-parietal tDCS stimulation: sham, right cathodal plus left anodal (RC/LA) and left cathodal plus right anodal (LC/RA).Inhibition of the left parietal lobe by LC/RA stimulation impaired numeracy performance, compared to sham or RA/LC stimulation (F(2,16)=3.684, p=0.048). LC/RA stimulation also resulted in significantly impaired sustained attention performance, as compared to sham or RA/LC stimulation (F(2,34)=5.3, p=0.01).We demonstrate that bilateral tDCS modulates numeracy and sustained attention in an electrode polarity-dependent manner. This method can be used to interrogate lateralised cognitive functions in future studies of healthy and diseased populations.

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Bolognini, Nadia, Luca Zigiotto, Maíra Izzadora Souza Carneiro et Giuseppe Vallar. « “How Did I Make It?” : Uncertainty about Own Motor Performance after Inhibition of the Premotor Cortex ». Journal of Cognitive Neuroscience 28, n^o 7 (juillet 2016) : 1052–61. http://dx.doi.org/10.1162/jocn_a_00950.

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Optimal motor performance requires the monitoring of sensorimotor input to ensure that the motor output matches current intentions. The brain is thought to be equipped with a “comparator” system, which monitors and detects the congruence between intended and actual movement; results of such a comparison can reach awareness. This study explored in healthy participants whether the cathodal transcranial direct current stimulation (tDCS) of the right premotor cortex (PM) and right posterior parietal cortex (PPC) can disrupt performance monitoring in a skilled motor task. Before and after tDCS, participants underwent a two-digit sequence motor task; in post-tDCS session, single-pulse TMS (sTMS) was applied to the right motor cortex, contralateral to the performing hand, with the aim of interfering with motor execution. Then, participants rated on a five-item questionnaire their performance at the motor task. Cathodal tDCS of PM (but not sham or PPC tDCS) impaired the participants' ability to evaluate their motor performance reliably, making them unconfident about their judgments. Congruently with the worsened motor performance induced by sTMS, participants reported to have committed more errors after sham and PPC tDCS; such a correlation was not significant after PM tDCS. In line with current computational and neuropsychological models of motor control and awareness, the present results show that a mechanism in the PM monitors and compares intended versus actual movements, evaluating their congruence. Cathodal tDCS of the PM impairs the activity of such a “comparator,” disrupting self-confidence about own motor performance.

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Mannarelli, Daniela, Caterina Pauletti, Alessia Petritis, Roberto Delle Chiaie, Antonio Currà, Carlo Trompetto et Francesco Fattapposta. « Effects of Cerebellar tDCS on Inhibitory Control : Evidence from a Go/NoGo Task ». Cerebellum 19, n^o 6 (14 juillet 2020) : 788–98. http://dx.doi.org/10.1007/s12311-020-01165-z.

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Abstract Response inhibition as an executive function refers to the ability to suppress inappropriate but prepotent responses. Several brain regions have been implicated in the process underlying inhibitory control, including the cerebellum. The aim of the present study was to explore the role of the cerebellum in executive functioning, particularly in response inhibition. For this purpose, we transitorily inhibited cerebellar activity by means of cathodal tDCS and studied the effects of this inhibition on ERP components elicited during a Go/NoGo task in healthy subjects. Sixteen healthy subjects underwent a Go/NoGo task prior to and after cathodal and sham cerebellar tDCS in separate sessions. A reduction in N2-NoGo amplitude and a prolongation in N2-NoGo latency emerged after cathodal tDCS whereas no differences were detected after sham stimulation. Moreover, commission errors in NoGo trials were significantly higher after cathodal tDCS than at the basal evaluation. No differences emerged between performances in Go trials and those after sham stimulation. These data indicate that cerebellar inhibition following cathodal stimulation alters the ability to allocate attentional resources to stimuli containing conflict information and the inhibitory control. The cerebellum may regulate the attentional mechanisms of stimulus orientation and inhibitory control both directly, by making predictions of errors or behaviors related to errors, and indirectly, by controlling the functioning of the cerebral cortical areas involved in the perception of conflict signals and of the basal ganglia involved in the inhibitory control of movement.

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Fusco, Augusto, Federica Assenza, Marco Iosa, Simona Izzo, Riccardo Altavilla, Stefano Paolucci et Fabrizio Vernieri. « The Ineffective Role of Cathodal tDCS in Enhancing the Functional Motor Outcomes in Early Phase of Stroke Rehabilitation : An Experimental Trial ». BioMed Research International 2014 (2014) : 1–9. http://dx.doi.org/10.1155/2014/547290.

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Transcranial direct current stimulation (tDCS) is a noninvasive technique that could improve the rehabilitation outcomes in stroke, eliciting neuroplastic mechanisms. At the same time conflicting results have been reported in subacute phase of stroke, when neuroplasticity is crucial. The aim of this double-blind, randomized, and sham-controlled study was to determine whether a treatment with cathodal tDCS before the rehabilitative training might augment the final outcomes (upper limb function, hand dexterity and manual force, locomotion, and activities of daily living) in respect of a traditional rehabilitation for a sample of patients affected by ischemic stroke in the subacute phase. An experimental group (cathodal tDCS plus rehabilitation) and a control group (sham tDCS plus rehabilitation) were assessed at the beginning of the protocol, after 10 days of stimulation, after 30 days from ending of stimulation, and at the end of inpatient rehabilitation. Both groups showed significant improvements for all the assessed domains during the rehabilitation, except for the manual force, while no significant differences were demonstrated between groups. These results seem to indicate that the cathodal tDCS, provided in an early phase of stroke, does not lead to a functional improvement. To depict a more comprehensive scenario, further studies are needed.

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Jefferson, Samantha, Satish Mistry, Salil Singh, John Rothwell et Shaheen Hamdy. « Characterizing the application of transcranial direct current stimulation in human pharyngeal motor cortex ». American Journal of Physiology-Gastrointestinal and Liver Physiology 297, n^o 6 (décembre 2009) : G1035—G1040. http://dx.doi.org/10.1152/ajpgi.00294.2009.

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Transcranial direct current stimulation (tDCS) is a novel intervention that can modulate brain excitability in health and disease; however, little is known about its effects on bilaterally innervated systems such as pharyngeal motor cortex. Here, we assess the effects of differing doses of tDCS on the physiology of healthy human pharyngeal motor cortex as a prelude to designing a therapeutic intervention in dysphagic patients. Healthy subjects ( n = 17) underwent seven regimens of tDCS (anodal 10 min 1 mA, cathodal 10 min 1 mA, anodal 10 min 1.5 mA, cathodal 10 min 1.5 mA, anodal 20 min 1 mA, cathodal 20 min 1 mA, Sham) on separate days, in a double blind randomized order. Bihemispheric motor evoked potential (MEP) responses to single-pulse transcranial magnetic stimulation (TMS) as well as intracortical facilitation (ICF) and inhibition (ICI) were recorded using a swallowed pharyngeal catheter before and up to 60 min following the tDCS. Compared with sham, both 10 min 1.5 mA and 20 min 1 mA anodal stimulation induced increases in cortical excitability in the stimulated hemisphere (+44 ± 17% and +59 ± 16%, respectively; P < 0.005) whereas only 10 min 1.5 mA cathodal stimulation induced inhibition (−26 ± 4%, P = 0.02). There were neither contralateral hemisphere changes nor any evidence for ICI or ICF in driving the ipsilateral effects. In conclusion, anodal tDCS can alter pharyngeal motor cortex excitability in an intensity-dependent manner, with little evidence for transcallosal spread. Anodal stimulation may therefore provide a useful means of stimulating pharyngeal cortex and promoting recovery in dysphagic patients.

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Pikhovych, Anton, Nina Paloma Stolberg, Lea Jessica Flitsch, Helene Luise Walter, Rudolf Graf, Gereon Rudolf Fink, Michael Schroeter et Maria Adele Rueger. « Transcranial Direct Current Stimulation Modulates Neurogenesis and Microglia Activation in the Mouse Brain ». Stem Cells International 2016 (2016) : 1–9. http://dx.doi.org/10.1155/2016/2715196.

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Transcranial direct current stimulation (tDCS) has been suggested as an adjuvant tool to promote recovery of function after stroke, but the mechanisms of its action to date remain poorly understood. Moreover, studies aimed at unraveling those mechanisms have essentially been limited to the rat, where tDCS activates resident microglia as well as endogenous neural stem cells. Here we studied the effects of tDCS on microglia activation and neurogenesis in the mouse brain. Male wild-type mice were subjected to multisession tDCS of either anodal or cathodal polarity; sham-stimulated mice served as control. Activated microglia in the cerebral cortex and neuroblasts generated in the subventricular zone as the major neural stem cell niche were assessed immunohistochemically. Multisession tDCS at a sublesional charge density led to a polarity-dependent downregulation of the constitutive expression of Iba1 by microglia in the mouse cortex. In contrast, both anodal and, to an even greater extent, cathodal tDCS induced neurogenesis from the subventricular zone. Data suggest that tDCS elicits its action through multifacetted mechanisms, including immunomodulation and neurogenesis, and thus support the idea of using tDCS to induce regeneration and to promote recovery of function. Furthermore, data suggest that the effects of tDCS may be animal- and polarity-specific.

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Ganho-Ávila, Ana, Óscar F Gonçalves, Raquel Guiomar, Paulo Sérgio Boggio, Manish Kumar Asthana, Angelos-Miltiadis Krypotos et Jorge Almeida. « Cathodal tDCS enhances extinction-based procedures ». L'Encéphale 45 (juin 2019) : S66. http://dx.doi.org/10.1016/j.encep.2019.04.009.

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Cabibel, Vincent, Makii Muthalib, Wei-Peng Teo et Stephane Perrey. « High-definition transcranial direct-current stimulation of the right M1 further facilitates left M1 excitability during crossed facilitation ». Journal of Neurophysiology 119, n^o 4 (1 avril 2018) : 1266–72. http://dx.doi.org/10.1152/jn.00861.2017.

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The crossed-facilitation (CF) effect refers to when motor-evoked potentials (MEPs) evoked in the relaxed muscles of one arm are facilitated by contraction of the opposite arm. The aim of this study was to determine whether high-definition transcranial direct-current stimulation (HD-tDCS) applied to the right primary motor cortex (M1) controlling the left contracting arm [50% maximum voluntary isometric contraction (MVIC)] would further facilitate CF toward the relaxed right arm. Seventeen healthy right-handed subjects participated in an anodal and cathodal or sham HD-tDCS session of the right M1 (2 mA for 20 min) separated by at least 48 h. Single-pulse transcranial magnetic stimulation (TMS) was used to elicit MEPs and cortical silent periods (CSPs) from the left M1 at baseline and 10 min into and after right M1 HD-tDCS. At baseline, compared with resting, CF (i.e., right arm resting, left arm 50% MVIC) increased left M1 MEP amplitudes (+97%) and decreased CSPs (−11%). The main novel finding was that right M1 HD-tDCS further increased left M1 excitability (+28.3%) and inhibition (+21%) from baseline levels during CF of the left M1, with no difference between anodal and cathodal HD-tDCS sessions. No modulation of CSP or MEP was observed during sham HD-tDCS sessions. Our findings suggest that CF of the left M1 combined with right M1 anodal or cathodal HD-tDCS further facilitated interhemispheric interactions during CF from the right M1 (contracting left arm) toward the left M1 (relaxed right arm), with effects on both excitatory and inhibitory processing. NEW & NOTEWORTHY This study shows modulation of the nonstimulated left M1 by right M1 HD-tDCS combined with crossed facilitation, which was probably achieved through modulation of interhemispheric interactions.

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Mansour, Anthony G., Rechdi Ahdab, Georges Khazen, Christelle El-Khoury, Toni M. Sabbouh, Maher Salem, Wissam Yamak, Moussa A. Chalah, Samar S. Ayache et Naji Riachi. « Transcranial Direct Current Stimulation of the Occipital Cortex in Medication Overuse Headache : A Pilot Randomized Controlled Cross-Over Study ». Journal of Clinical Medicine 9, n^o 4 (10 avril 2020) : 1075. http://dx.doi.org/10.3390/jcm9041075.

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Background: Medication overuse headache (MOH) is a chronic pain syndrome that arises from the frequent use of acute antimigraine drugs. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique with a possible therapeutic effect in this particular context. Methods: This was a randomized, sham-controlled, cross-over study. Eighteen patients with MOH (17 women, age range: 20–38 years) received three sets of three consecutive daily sessions of tDCS: anodal tDCS over the prefrontal cortex, cathodal tDCS over the occipital cortex ipsilateral to the dominant side of migraine pain, and sham. The order in which the tDCS blocks were delivered was randomly defined based on a 1:1:1 ratio. Patients filled in a migraine diary that allowed recording of the pain intensity (visual analogue scale) and the daily consumption of analgesic pills from one week before to two weeks after each condition. Results: Both prefrontal and occipital tDCS lowered the total number of migraine days and the number of severe migraine days per week at week 1, but only the effects of occipital tDCS on these two outcomes lasted until week 2. Only occipital tDCS decreased the daily analgesic pills consumption, at weeks 1 and 2. Conclusion: Three consecutive days of cathodal occipital tDCS appear to improve the clinical outcomes in patients with MOH.

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Bellaïche, Lisa, Manish Asthana, Ann-Christine Ehlis, Thomas Polak et Martin J. Herrmann. « The Modulation of Error Processing in the Medial Frontal Cortex by Transcranial Direct Current Stimulation ». Neuroscience Journal 2013 (17 avril 2013) : 1–10. http://dx.doi.org/10.1155/2013/187692.

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Background. In order to prevent future errors, we constantly control our behavior for discrepancies between the expected (i.e., intended) and the real action outcome and continuously adjust our behavior accordingly. Neurophysiological correlates of this action-monitoring process can be studied with event-related potentials (error-related negativity (ERN) and error positivity (Pe)) originating from the medial prefrontal cortex (mPFC). Patients with neuropsychiatric diseases often show performance monitoring dysfunctions potentially caused by pathological changes of cortical excitability; therefore, a modulation of the underlying neuronal activity might be a valuable therapeutic tool. One technique which allows us to explore cortical modulation of neural networks is transcranial direct current stimulation (tDCS). Therefore, we tested the effect of medial-prefrontal tDCS on error-monitoring potentials in 48 healthy subjects randomly assigned to anodal, cathodal, or sham stimulation. Results. We found that cathodal stimulation attenuated Pe amplitudes compared to both anodal and sham stimulation, but no effect for the ERN. Conclusions. Our results indicate that cathodal tDCS over the mPFC results in an attenuated cortical excitability leading to decreased Pe amplitudes. We therefore conclude that tDCS has a neuromodulatory effect on error-monitoring systems suggesting a future approach to modify the sensitivity of corresponding neural networks in patients with action-monitoring deficits.

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Emadi Andani, Mehran, Bernardo Villa-Sánchez, Federico Raneri, Silvia Dametto, Michele Tinazzi et Mirta Fiorio. « Cathodal Cerebellar tDCS Combined with Visual Feedback Improves Balance Control ». Cerebellum 19, n^o 6 (30 juillet 2020) : 812–23. http://dx.doi.org/10.1007/s12311-020-01172-0.

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Abstract Balance control is essential to maintain a stable body position and to prevent falls. The aim of this study was to determine whether balance control could be improved by using cerebellar transcranial direct current stimulation (tDCS) and visual feedback in a combined approach. A total of 90 healthy volunteers were randomly assigned to six groups defined by the delivery of tDCS (cathodal or anodal or sham) and the provision or not of visual feedback on balance during the acquisition phase. tDCS was delivered over the cerebellar hemisphere ipsilateral to the dominant leg for 20 min at 2 mA during a unipedal stance task. Body sway (i.e., ankle angle and hip position) was measured as an overall maximal unit in anteroposterior and mediolateral direction, together with participant rating of perception of stability, before (baseline), during (acquisition), and after (final) the intervention. We found a reduction in body sway during the acquisition session when visual feedback alone was provided. When the visual feedback was removed (final session), however, body sway increased above baseline. Differently, the reduction in overall maximal body sway was maintained during the final session when the delivery of cathodal tDCS and visual feedback was combined. These findings suggest that cathodal tDCS may support the short-term maintenance of the positive effects of visual feedback on balance and provide the basis for a new approach to optimize balance control, with potential translational implications for the elderly and patients with impaired posture control.

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Lazzaro, Giulia, Sara Bertoni, Deny Menghini, Floriana Costanzo, Sandro Franceschini, Cristiana Varuzza, Luca Ronconi et al. « Beyond Reading Modulation : Temporo-Parietal tDCS Alters Visuo-Spatial Attention and Motion Perception in Dyslexia ». Brain Sciences 11, n^o 2 (19 février 2021) : 263. http://dx.doi.org/10.3390/brainsci11020263.

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Dyslexia is a neurodevelopmental disorder with an atypical activation of posterior left-hemisphere brain reading networks (i.e., temporo-occipital and temporo-parietal regions) and multiple neuropsychological deficits. Transcranial direct current stimulation (tDCS) is a tool for manipulating neural activity and, in turn, neurocognitive processes. While studies have demonstrated the significant effects of tDCS on reading, neurocognitive changes beyond reading modulation have been poorly investigated. The present study aimed at examining whether tDCS on temporo-parietal regions affected not only reading, but also phonological skills, visuo-spatial working memory, visuo-spatial attention, and motion perception in a polarity-dependent way. In a within-subjects design, ten children and adolescents with dyslexia performed reading and neuropsychological tasks after 20 min of exposure to Left Anodal/Right Cathodal (LA/RC) and Right Anodal/Left Cathodal (RA/LC) tDCS. LA/RC tDCS compared to RA/LC tDCS improved text accuracy, word recognition speed, motion perception, and modified attentional focusing in our group of children and adolescents with dyslexia. Changes in text reading accuracy and word recognition speed—after LA/RC tDCS compared to RA/LC—were related to changes in motion perception and in visuo-spatial working memory, respectively. Our findings demonstrated that reading and domain-general neurocognitive functions in a group of children and adolescents with dyslexia change following tDCS and that they are polarity-dependent.

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Almeida, Camila Carolinne Silva de, Marcelo Moraes Valença, Emanuela Paz Rosas, Eduardo José Nepomuceno Montenegro, Laura Izabel do Nascimento Alves, Débora Wanderley, Angélica da Silva Tenório et Daniella Araújo de Oliveira. « Electrical parameters of transcranial direct current stimulation that effectively alter cerebral blood flow in experimental animals : a systematic review ». Research, Society and Development 11, n^o 8 (17 juin 2022) : e22811830794. http://dx.doi.org/10.33448/rsd-v11i8.30794.

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Objective: To identify the electrical parameters of transcranial direct current stimulation (tDCS) that effectively alter cerebral blood flow in rats. Methodology: Six eletronic databases were searched with no time or language restrictions to identify experimental studies with rats using tDCS with anodal and/or cathodal stimulation with or without a comparison group. Internal validity was assessed via the following criteria: housing, lighting, temperature, water/food, groups randomization and ethical aspects. The ‘Laboratory Systematic Review Center for Laboratory animal Experimentation’ (SYRCLE) tool was used to assess risk of bias. The tDCS electrical parameters and cerebral blood flow were considered as primary outcomes and cerebral histological alterations as the secondary outcome. Results: Four articles were included. All four studies were considered to present a high level of scientific bias. The electrical tDCS parameters implemented were heterogeneous but overall, tDCS with anodal stimulation promoted an increase in cerebral blood flow while the cathodal stimulation decreased it. Cerebral histological alterations were assessed in two studies and tissue necrosis was reported in only one animal per study. Conclusion: The identification of tDCS electrical parameters that effectively alter cerebral blood flow in rats was not possible due to the heterogeneity of tDCS protocols being implemented in the literature. Considering the high risk of scientific bias in the included studies, the current available evidence regarding tDCS efficacy is insufficient and inconclusive.

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Biabani, Mana, Maryam Aminitehrani, Maryam Zoghi, Michael Farrell, Gary Egan et Shapour Jaberzadeh. « The effects of transcranial direct current stimulation on short-interval intracortical inhibition and intracortical facilitation : a systematic review and meta-analysis ». Reviews in the Neurosciences 29, n^o 1 (20 décembre 2017) : 99–114. http://dx.doi.org/10.1515/revneuro-2017-0023.

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Abstract Transcranial direct current stimulation (tDCS) is increasingly being used to affect the neurological conditions with deficient intracortical synaptic activities (i.e. Parkinson’s disease and epilepsy). In addition, it is suggested that the lasting effects of tDCS on corticospinal excitability (CSE) have intracortical origin. This systematic review and meta-analysis aimed to examine whether tDCS has any effect on intracortical circuits. Eleven electronic databases were searched for the studies investigating intracortical changes induced by anodal (a) and cathodal (c) tDCS, in healthy individuals, using two paired-pulse transcranial magnetic stimulation (TMS) paradigms: short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF). Additionally, motor-evoked potential (MEP) size alterations, assessed by single-pulse TMS, were extracted from these studies to investigate the probable intracortical origin of tDCS effects on CSE. The methodological quality of included studies was examined using Physiotherapy Evidence Database (PEDro) and Downs and Black’s (D&B) assessment tools. Thirteen research papers, including 24 experiments, were included in this study scoring good and medium quality in PEDro and D&B scales, respectively. Immediately following anodal tDCS (a-tDCS) applications, we found significant decreases in SICI, but increases in ICF and MEP size. However, ICF and MEP size significantly decreased, and SICI increased immediately following cathodal tDCS (c-tDCS). The results of this systematic review and meta-analysis reveal that a-tDCS changes intracortical activities (SICI and ICF) toward facilitation, whereas c-tDCS alters them toward inhibition. It can also be concluded that increases and decreases in CSE after tDCS application are associated with corresponding changes in intracortical activities. The results suggest that tDCS can be clinically useful to modulate intracortical circuits.

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Caleb A, Adeagbo, Gbiri Caleb AO et Olawale Olajide A. « Efficacy of transcranial direct current stimulation and over-ground walking task on functional mobility and quality of life of stroke survivors ». Journal of Novel Physiotherapy and Rehabilitation 4, n^o 2 (3 décembre 2020) : 049–56. http://dx.doi.org/10.29328/journal.jnpr.1001037.

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Introduction: High proportion of stroke survivors have impaired functional mobility and decrease in overall quality of life (QoL). Transcranial direct current stimulation (tDCS) (non-invasive brain stimulation) and over-ground walking task (OGWT) (functional task-oriented training) have been suggested to improve functional mobility and QoL of stroke survivors. Hence, this study determined the efficacy of tDCS (anodal and cathodal) with OGWT on functional mobility and QoL of stroke survivors. Materials and methods: Seventy eight (78) stroke survivors were randomised into three groups: anodal group (anodal tDCS with OGWT); cathodal group (cathodal tDCS with OGWT) and control group (OGWT only). Participants had two sessions of intervention per week for six weeks. Functional mobility was assessed using 10 meter walk test (10MWT) measuring steps, time and velocity while QoL was measured using Stroke Specific QoL (SSQoL) scale. Significance level was set at p < 0.05. Results: Participants (46 males) were aged 56.78 ± 10.24 years. The groups were matched for functional mobility and QoL at baseline and only work/productivity domain of SSQoL showed statistically significant difference (p = 0.028). Each group showed statistically significant improvement between baseline and post-intervention scores of items in functional mobility (p ≤ 0.001) and total SSQoL (p ≤ 0.001). Anodal group showed better statistically significant improvement in step (p = 0.008), time (p = 0.024), velocity (p = 0.001) and total SSQoL (p = 0.016) among the groups when the mean differences were compared. Conclusion: tDCS with OGWT is efficacious in improving functional mobility and QoL of stroke survivors. Specifically anodal tDCS with OGWT showed better clinical improvement in step, time, velocity and QoL in stroke survivors.

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McCambridge, Alana B., James W. Stinear et Winston D. Byblow. « A dissociation between propriospinal facilitation and inhibition after bilateral transcranial direct current stimulation ». Journal of Neurophysiology 111, n^o 11 (1 juin 2014) : 2187–95. http://dx.doi.org/10.1152/jn.00879.2013.

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Propriospinal premotoneurons (PN) are essential for accurate control of the upper limb. They receive bilateral input from premotor (PM) and primary motor (M1) cortices. In humans, excitability of PNs can be estimated from motor-evoked potentials (MEPs) by pairing a descending volley using transcranial magnetic stimulation (TMS) to summate with an ascending volley from peripheral nerve stimulation at the C3–C4 level of the spinal cord. Transcranial direct current stimulation (tDCS) alters excitability of cortical and subcortical areas. A recent study demonstrated that cathodal tDCS can suppress facilitatory (FAC) and inhibitory (INH) components of PN excitability, presumably via effects on corticoreticulospinal neurons (Bradnam LV, Stinear CM, Lewis GN, Byblow WD. J Neurophysiol 103: 2382–2389, 2010). The present study investigated the effects of bilateral tDCS with healthy subjects. The cathode was placed over left dorsal PM or M1 and the anode over right M1 in separate sessions (PM-M1, M1-M1, or Sham). TMS of right M1 elicited MEPs in left biceps brachii across a range of TMS intensities chosen to examine PN-mediated FAC and INH. Conditioning was applied using median nerve stimulation with an interstimulus interval that coincided with TMS and peripheral volleys summating at the C3–C4 level. All participants showed FAC at TMS intensities near active motor threshold and INH at slightly higher intensities. After tDCS, FAC was reduced for M1-M1 compared with Sham but not after PM-M1 stimulation. Contrary to an earlier study with cathodal tDCS, INH was unchanged across all sessions. The difference between these and earlier findings may relate to dual- vs. single-hemisphere M1 stimulation. M1-M1 tDCS may be a useful adjuvant to techniques that aim to reduce upper limb impairment after stroke.

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Keerthy, B. N., Sai Sreevalli Sarma Sreepada, Shalini S. Naik, Anushree Bose, Raju Hanumegowda, Urvakhsh Meherwan Mehta, Ganesan Venkatasubramanian, Jagadisha Thirthalli, Talakad N. Sathyaprabha et Kaviraja Udupa. « Effects of a single session of cathodal transcranial direct current stimulation primed intermittent theta-burst stimulation on heart rate variability and cortical excitability measures ». Indian Journal of Physiology and Pharmacology 65 (8 décembre 2021) : 162–66. http://dx.doi.org/10.25259/ijpp_339_2020.

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Objectives: Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have been used as neuromodulators in neuropsychiatric conditions. This study is aimed to find the effects of a single session of priming cathodal tDCS with intermittent theta-burst stimulation (iTBS) over left dorsolateral prefrontal cortex on heart rate variability (HRV) and cortical excitability parameters before and after perturbation. Materials and Methods: The neuromodulatory techniques used in the study were Cathodal tDCS for 20 min followed by iTBS for 3 min on the left dorsolateral prefrontal cortex (DLPFC). HRV variables and TMS parameters were recorded before and after this intervention of combined neuromodulation in 31 healthy volunteers (20 males and 11 females; age range of 19–35 years with Mean ± SD = 24.2 ± 4.7 years). Results: The results showed an overall increase in cortical excitability and parasympathetic dominance in healthy volunteers. Other measures of cortical excitability and HRV did not change significantly following single session of combined neuromodulation. Conclusion: This study showed that there is an overall increase in cortical excitability and parasympathetic dominance in the cohort of healthy volunteers following a combination of neuromodulation involving cathodal tDCS followed by iTBS over left DLPFC. Future studies exploring the effects of other possible combinations with sham stimulation could be carried out to explore the utility of dual stimulation as add-on therapy in disorders.

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Pingue, Valeria, Alberto Priori, Alberto Malovini et Caterina Pistarini. « Dual Transcranial Direct Current Stimulation for Poststroke Dysphagia : A Randomized Controlled Trial ». Neurorehabilitation and Neural Repair 32, n^o 6-7 (juin 2018) : 635–44. http://dx.doi.org/10.1177/1545968318782743.

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Background. Poststroke dysphagia is associated with considerable morbidity and has high health care cost implications. Objective. To evaluate whether anodal transcranial direct current stimulation (tDCS) over the lesioned hemisphere and cathodal tDCS to the contralateral one during the early stage of rehabilitation can improve poststroke dysphagia. Methods. A total of 40 patients referred to our neurorehabilitation department were randomized to receive anodal tDCS over the damaged hemisphere plus cathodal stimulation over the contralateral one versus sham stimulation during swallowing maneuvers over the course of 10 sessions of treatment. Swallowing function was evaluated before and after stimulation using the Dysphagia Outcome and Severity Scale (DOSS). Results. The percentage of patients who reached various thresholds of improvement was higher in the tDCS group than in the sham group, but the differences were not significant (eg, DOSS score ≥ 20% increase from baseline: 55% in the tDCS group vs 40% in the sham group; P = .53). Among all variables recorded at baseline, only a subgroup of patients without nasogastric tube showed a significantly higher improvement with tDCS treatment versus sham (DOSS score ≥10% and ≥20% from baseline: 64.29% vs 0%, P = .01). Conclusions. In patients with poststroke dysphagia, treatment with dual tDCS in the early phase of rehabilitation does not significantly increase the probability of recovery compared with sham stimulation.

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Fricke, K., A. A. Seeber, N. Thirugnanasambandam, W. Paulus, M. A. Nitsche et J. C. Rothwell. « Time course of the induction of homeostatic plasticity generated by repeated transcranial direct current stimulation of the human motor cortex ». Journal of Neurophysiology 105, n^o 3 (mars 2011) : 1141–49. http://dx.doi.org/10.1152/jn.00608.2009.

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Several mechanisms have been proposed that control the amount of plasticity in neuronal circuits and guarantee dynamic stability of neuronal networks. Homeostatic plasticity suggests that the ease with which a synaptic connection is facilitated/suppressed depends on the previous amount of network activity. We describe how such homeostatic-like interactions depend on the time interval between two conditioning protocols and on the duration of the preconditioning protocol. We used transcranial direct current stimulation (tDCS) to produce short-lasting plasticity in the motor cortex of healthy humans. In the main experiment, we compared the aftereffect of a single 5-min session of anodal or cathodal tDCS with the effect of a 5-min tDCS session preceded by an identical 5-min conditioning session administered 30, 3, or 0 min beforehand. Five-minute anodal tDCS increases excitability for about 5 min. The same duration of cathodal tDCS reduces excitability. Increasing the duration of tDCS to 10 min prolongs the duration of the effects. If two 5-min periods of tDCS are applied with a 30-min break between them, the effect of the second period of tDCS is identical to that of 5-min stimulation alone. If the break is only 3 min, then the second session has the opposite effect to 5-min tDCS given alone. Control experiments show that these shifts in the direction of plasticity evolve during the 10 min after the first tDCS session and depend on the duration of the first tDCS but not on intracortical inhibition and facilitation. The results are compatible with a time-dependent “homeostatic-like” rule governing the response of the human motor cortex to plasticity probing protocols.

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Smirni, Daniela, Massimiliano Oliveri, Eliana Misuraca, Angela Catania, Laura Vernuccio, Valentina Picciolo, Flora Inzerillo, Mario Barbagallo, Lisa Cipolotti et Patrizia Turriziani. « Verbal Fluency in Mild Alzheimer’s Disease : Transcranial Direct Current Stimulation over the Dorsolateral Prefrontal Cortex ». Journal of Alzheimer's Disease 81, n^o 3 (1 juin 2021) : 1273–83. http://dx.doi.org/10.3233/jad-210003.

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Background: Recent studies showed that in healthy controls and in aphasic patients, inhibitory trains of repetitive transcranial magnetic stimulation (rTMS) over the right prefrontal cortex can improve phonemic fluency performance, while anodal transcranial direct current stimulation (tDCS) over the left prefrontal cortex can improve performance in naming and semantic fluency tasks. Objective: This study aimed at investigating the effects of cathodal tDCS over the left or the right dorsolateral prefrontal cortex (DLPFC) on verbal fluency tasks (VFT) in patients with mild Alzheimer’s disease (AD). Methods: Forty mild AD patients participated in the study (mean age 73.17±5.61 years). All participants underwent cognitive baseline tasks and a VFT twice. Twenty patients randomly received cathodal tDCS to the left or the right DLPFC, and twenty patients were assigned to a control group in which only the two measures of VFT were taken, without the administration of the tDCS. Results: A significant improvement of performance on the VFT in AD patients was present after tDCS over the right DLPFC (p = 0.001). Instead, no difference was detected between the two VFTs sessions after tDCS over the left DLPFC (p = 0.42). Furthermore, these results cannot be related to task learning effects, since no significant difference was found between the two VFT sessions in the control group (p = 0.73). Conclusion: These data suggest that tDCS over DLPFC can improve VFT performance in AD patients. A hypothesis is that tDCS enhances adaptive patterns of brain activity between functionally connected areas.

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Carter, Michael J., Dana Maslovat et Anthony N. Carlsen. « Anodal transcranial direct current stimulation applied over the supplementary motor area delays spontaneous antiphase-to-in-phase transitions ». Journal of Neurophysiology 113, n^o 3 (1 février 2015) : 780–85. http://dx.doi.org/10.1152/jn.00662.2014.

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Coordinated bimanual oscillatory movements often involve one of two intrinsically stable phasing relationships characterized as in-phase (symmetrical) or antiphase (asymmetrical). The in-phase mode is typically more stable than antiphase, and if movement frequency is increasing during antiphase movements, a spontaneous transition to the in-phase pattern occurs. There is converging neurophysiological evidence that the supplementary motor area (SMA) plays a critical role in the successful performance of these patterns, especially during antiphase movements. We investigated whether modulating the excitability of the SMA via offline transcranial direct current stimulation (tDCS) would delay the onset of anti-to-in-phase transitions. Participants completed two sessions (separated by ∼48 h), each consisting of a pre- and post-tDCS block in which they performed metronome-paced trials of rhythmic in- and antiphase bimanual supination-pronation movements as target oscillation frequency was systematically increased. Anodal or cathodal tDCS was applied over the SMA between the pre- and post-tDCS blocks in each session. Following anodal tDCS, participants performed the antiphase pattern with increased accuracy and stability and were able to maintain the coordination pattern at a higher oscillation frequency. Antiphase performance was unchanged following cathodal tDCS, and neither tDCS polarity affected the in-phase mode. Our findings suggest increased SMA excitability induced by anodal tDCS can improve antiphase performance and adds to the accumulating evidence of the pivotal role of the SMA in interlimb coordination.

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Ahdab, Rechdi, Anthony G. Mansour, Georges Khazen, Christelle El-Khoury, Toni M. Sabbouh, Maher Salem, Wissam Yamak, Samar S. Ayache et Naji Riachi. « Cathodal Transcranial Direct Current Stimulation of the Occipital cortex in Episodic Migraine : A Randomized Sham-Controlled Crossover Study ». Journal of Clinical Medicine 9, n^o 1 (26 décembre 2019) : 60. http://dx.doi.org/10.3390/jcm9010060.

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Summary: Three consecutive daily sessions of cathodal transcranial direct current stimulation (tDCS) was sufficient to show a significant decrease in headache duration and intensity as well as tablets consumption, in patients suffering from episodic migraine. Background: Migraine prophylaxis is recommended in patients with frequent and/or intense headaches, but poor tolerability and lack of efficacy of preventive drugs are common in clinical practice. Hence, new prophylactic strategies are needed. Objective: The aim of this study was to evaluate the efficacy of tDCS in terms of migraine prophylaxis. Methods: This was a double blind and sham-controlled trial. Forty-two migraine patients were randomly assigned in a crossover design to receive three consecutive daily sessions of both sham and cathodal tDCS stimulation (2.0 mA, 20 min) over the occipital cortex of the dominant side of the migraine pain (O1/O2). Migraine duration and intensity, number of analgesic tablets, and number of headache-free days (where no headache abortive medications are taken) were recorded one week before and two weeks after treatment. A washout period of one week was allowed before crossing to the other treatment arm. Results: Relative to sham, cathodal stimulation was associated with a significant reduction in the number of headache days, tablets consumption, and pain intensity; and a significant increase in the number of headache-free days. These beneficial effects were sustained over two weeks. No serious side effects were observed, and the procedure was well tolerated. Conclusion: Based on these findings, cathodal tDCS applied to the occipital cortex seems to be an effective and well tolerated alternative to pharmacotherapy in patients with episodic migraine.

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Swanson, Clayton W., et Felix Proessl. « High-definition transcranial direct-current stimulation of the right M1 further facilitates left M1 excitability during crossed facilitation ». Journal of Neurophysiology 120, n^o 1 (1 juillet 2018) : 4–6. http://dx.doi.org/10.1152/jn.00177.2018.

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Cabibel et al. (J Neurophysiol 119: 1266–1272, 2018) report non-polarity-specific effects of high-definition direct current stimulation (HD-tDCS) on crossed facilitation (CF), demonstrated by complex excitatory and inhibitory interhemispheric interactions coupled with HD-tDCS. Choosing a variety of stimulation and muscle contraction parameters and having all participants undergo anodal, cathodal, and sham stimulation may increase the current understanding of HD-tDCS on CF. Furthermore, complementary metrics like the ipsilateral silent period may provide more clarity regarding the polarity-specific enhancement of HD-tDCS on CF.

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Shimizu, Renee E., Allan D. Wu, Jasmine K. Samra et Barbara J. Knowlton. « The impact of cerebellar transcranial direct current stimulation (tDCS) on learning fine-motor sequences ». Philosophical Transactions of the Royal Society B : Biological Sciences 372, n^o 1711 (5 janvier 2017) : 20160050. http://dx.doi.org/10.1098/rstb.2016.0050.

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The cerebellum has been shown to be important for skill learning, including the learning of motor sequences. We investigated whether cerebellar transcranial direct current stimulation (tDCS) would enhance learning of fine motor sequences. Because the ability to generalize or transfer to novel task variations or circumstances is a crucial goal of real world training, we also examined the effect of tDCS on performance of novel sequences after training. In Study 1, participants received either anodal, cathodal or sham stimulation while simultaneously practising three eight-element key press sequences in a non-repeating, interleaved order. Immediately after sequence practice with concurrent tDCS, a transfer session was given in which participants practised three interleaved novel sequences. No stimulation was given during transfer. An inhibitory effect of cathodal tDCS was found during practice, such that the rate of learning was slowed in comparison to the anodal and sham groups. In Study 2, participants received anodal or sham stimulation and a 24 h delay was added between the practice and transfer sessions to reduce mental fatigue. Although this consolidation period benefitted subsequent transfer for both tDCS groups, anodal tDCS enhanced transfer performance. Together, these studies demonstrate polarity-specific effects on fine motor sequence learning and generalization. This article is part of the themed issue ‘New frontiers for statistical learning in the cognitive sciences’.

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Marangolo, Paola, Valentina Fiori, Carlo Caltagirone, Francesca Pisano et Alberto Priori. « Transcranial Cerebellar Direct Current Stimulation Enhances Verb Generation but Not Verb Naming in Poststroke Aphasia ». Journal of Cognitive Neuroscience 30, n^o 2 (février 2018) : 188–99. http://dx.doi.org/10.1162/jocn_a_01201.

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Although the role of the cerebellum in motor function is well recognized, its involvement in the lexical domain remains to be further elucidated. Indeed, it has not yet been clarified whether the cerebellum is a language structure per se or whether it contributes to language processing when other cognitive components (e.g., cognitive effort, working memory) are required by the language task. Neuromodulation studies on healthy participants have suggested that cerebellar transcranial direct current stimulation (tDCS) is a valuable tool to modulate cognitive functions. However, so far, only a single case study has investigated whether cerebellar stimulation enhances language recovery in aphasic individuals. In a randomized, crossover, double-blind design, we explored the effect of cerebellar tDCS coupled with language treatment for verb improvement in 12 aphasic individuals. Each participant received cerebellar tDCS (20 min, 2 mA) in four experimental conditions: (1) right cathodal and (2) sham stimulation during a verb generation task and (3) right cathodal and (4) sham stimulation during a verb naming task. Each experimental condition was run in five consecutive daily sessions over 4 weeks. At the end of treatment, a significant improvement was found after cathodal stimulation only in the verb generation task. No significant differences were present for verb naming among the two conditions. We hypothesize that cerebellar tDCS is a viable tool for recovery from aphasia but only when the language task, such as verb generation, also demands the activation of nonlinguistic strategies.

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Antal, Andrea, Michael A. Nitsche, Wolfgang Kruse, Tamás Z. Kincses, Klaus-Peter Hoffmann et Walter Paulus. « Direct Current Stimulation over V5 Enhances Visuomotor Coordination by Improving Motion Perception in Humans ». Journal of Cognitive Neuroscience 16, n^o 4 (mai 2004) : 521–27. http://dx.doi.org/10.1162/089892904323057263.

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The primary aim of this study was to determine the extent to which human MT+/V5, an extrastriate visual area known to mediate motion processing, is involved in visuomotor coordination. To pursue this we increased or decreased the excitability of MT+/V5, primary motor, and primary visual cortex by the application of 7 min of anodal and cathodal transcranial direct current stimulation (tDCS) in healthy human subjects while they were performing a visuomotor tracking task involving hand movements. The percentage of correct tracking movements increased specifically during and immediately after cathodal stimulation, which decreases cortical excitability, only when V5 was stimulated. None of the other stimulation conditions affected visuomotor performance. We propose that the improvement in performance caused by cathodal tDCS of V5 is due to a focusing effect on to the complex motion perception conditions involved in this task. This hypothesis was proven by additional experiments: Testing simple and complex motion perception in dot kinetograms, we found that a diminution in excitability induced by cathodal stimulation improved the subject's perception of the direction of the coherent motion only if this was presented among random dots (complex motion perception), and worsened it if only one motion direction was presented (simple movement perception). Our data suggest that area V5 is critically involved in complex motion perception and identification processes important for visuomotor coordination. The results also raise the possibility of the usefulness of tDCS in rehabilitation strategies for neurological patients with visuomotor disorders.

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Friehs, Maximilian A., et Christian Frings. « Cathodal tDCS increases stop-signal reaction time ». Cognitive, Affective, & ; Behavioral Neuroscience 19, n^o 5 (16 juillet 2019) : 1129–42. http://dx.doi.org/10.3758/s13415-019-00740-0.

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Hinson, E., S. Thein et C. Stagg. « P260 Modulating motor learning using cathodal tDCS ». Clinical Neurophysiology 128, n^o 3 (mars 2017) : e140. http://dx.doi.org/10.1016/j.clinph.2016.10.373.

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Cherney, Leora R., Edna M. Babbitt, Xue Wang et Laura L. Pitts. « Extended fMRI-Guided Anodal and Cathodal Transcranial Direct Current Stimulation Targeting Perilesional Areas in Post-Stroke Aphasia : A Pilot Randomized Clinical Trial ». Brain Sciences 11, n^o 3 (28 février 2021) : 306. http://dx.doi.org/10.3390/brainsci11030306.

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Transcranial direct current stimulation (tDCS) may enhance speech and language treatment (SLT) for stroke survivors with aphasia; however, to date, there is no standard protocol for the application of tDCS in post-stroke aphasia. We explored the safety and efficacy of fMRI-guided tDCS on functional language and cortical activity when delivered to the lesioned left hemisphere concurrently with SLT across an extended, six-week treatment period. Twelve persons with chronic, nonfluent aphasia following a single left-hemisphere stroke participated in the three-arm (anodal vs. cathodal vs. sham) single-blind, parallel, pilot trial. No serious adverse events occurred during 30 treatment sessions or in the following six weeks. All groups demonstrated functional language gains following intensive treatment; however, active tDCS resulted in greater gains in standardized, probe, and caregiver-reported measures of functional language than sham. Evidence declaring one polarity as superior for inducing language recovery was mixed. However, cathodal stimulation to the lesioned left hemisphere, expected to have a down-regulating effect, resulted in increased areas of cortical activation across both hemispheres, and specifically perilesionally. Generalization of these preliminary findings is limited; however, results are nevertheless compelling that tDCS combined with SLT can be safely applied across extended durations, with the potential to enhance functional language and cortical activation for persons with aphasia.

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Weiss, Michal, et Michal Lavidor. « When Less Is More : Evidence for a Facilitative Cathodal tDCS Effect in Attentional Abilities ». Journal of Cognitive Neuroscience 24, n^o 9 (septembre 2012) : 1826–33. http://dx.doi.org/10.1162/jocn_a_00248.

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Many previous studies reported that the hyperpolarization of cortical neurons following cathodal stimulation (in transcranial direct current stimulation) has resulted in cognitive performance degradation. Here, we challenge this assumption by showing that cathodal stimulation will not always degrade cognitive performance. We used an attentional load paradigm in which irrelevant stimuli are processed only under low but not under high attentional load. Thirty healthy participants were randomly allocated into three interventional groups with different brain stimulation parameters (active anodal posterior parietal cortex [PPC], active cathodal PPC, and sham). Cathodal but not anodal stimulation enabled flanker processing even in high-loaded scenes. A second experiment was carried out to assert whether the improved flanker processing under cathodal stimulation is because of altered attention allocation between center and surround or, alternatively, enhanced attentional resources. In this experiment, the flanker was presented centrally. The results of Experiment 2 replicated Experiment 1's finding of improved flanker processing. We interpret the results from these two experiments as evidence for the ability of cathodal stimulation to enhance attentional resources rather than simply change attention allocation between center and periphery. Cathodal stimulation in high-loaded scenes can act like a noise filter and may in fact enhance cognitive performance. This study contributes to understanding the way the PPC is engaged with attentional functions and explains the cathodal effects, which thus might lead to more efficient brain stimulation protocols.

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Benussi, Alberto, Valentina Cantoni, Marta Manes, Ilenia Libri, Valentina Dell’Era, Abhishek Datta, Chris Thomas et al. « Motor and cognitive outcomes of cerebello-spinal stimulation in neurodegenerative ataxia ». Brain 144, n^o 8 (5 mai 2021) : 2310–21. http://dx.doi.org/10.1093/brain/awab157.

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Abstract Cerebellar ataxias represent a heterogeneous group of disabling disorders characterized by motor and cognitive disturbances, for which no effective treatment is currently available. In this randomized, double-blind, sham-controlled trial, followed by an open-label phase, we investigated whether treatment with cerebello-spinal transcranial direct current stimulation (tDCS) could improve both motor and cognitive symptoms in patients with neurodegenerative ataxia at short and long-term. Sixty-one patients were randomized in two groups for the first controlled phase. At baseline (T0), Group 1 received placebo stimulation (sham tDCS) while Group 2 received anodal cerebellar tDCS and cathodal spinal tDCS (real tDCS) for 5 days/week for 2 weeks (T1), with a 12-week (T2) follow-up (randomized, double-blind, sham controlled phase). At the 12-week follow-up (T2), all patients (Group 1 and Group 2) received a second treatment of anodal cerebellar tDCS and cathodal spinal tDCS (real tDCS) for 5 days/week for 2 weeks, with a 14-week (T3), 24-week (T4), 36-week (T5) and 52-week follow-up (T6) (open-label phase). At each time point, a clinical, neuropsychological and neurophysiological evaluation was performed. Cerebellar-motor cortex connectivity was evaluated using transcranial magnetic stimulation. We observed a significant improvement in all motor scores (scale for the assessment and rating of ataxia, international cooperative ataxia rating scale), in cognition (evaluated with the cerebellar cognitive affective syndrome scale), in quality-of-life scores, in motor cortex excitability and in cerebellar inhibition after real tDCS compared to sham stimulation and compared to baseline (T0), both at short and long-term. We observed an addon-effect after two repeated treatments with real tDCS compared to a single treatment with real tDCS. The improvement at motor and cognitive scores correlated with the restoration of cerebellar inhibition evaluated with transcranial magnetic stimulation. Cerebello-spinal tDCS represents a promising therapeutic approach for both motor and cognitive symptoms in patients with neurodegenerative ataxia, a still orphan disorder of any pharmacological intervention.

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London, Raquel E., et Heleen A. Slagter. « Effects of Transcranial Direct Current Stimulation over Left Dorsolateral pFC on the Attentional Blink Depend on Individual Baseline Performance ». Journal of Cognitive Neuroscience 27, n^o 12 (décembre 2015) : 2382–93. http://dx.doi.org/10.1162/jocn_a_00867.

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Selection mechanisms that dynamically gate only relevant perceptual information for further processing and sustained representation in working memory are critical for goal-directed behavior. We examined whether this gating process can be modulated by anodal transcranial direct current stimulation (tDCS) over left dorsolateral pFC (DLPFC)—a region known to play a key role in working memory and conscious access. Specifically, we examined the effects of tDCS on the magnitude of the so-called “attentional blink” (AB), a deficit in identifying the second of two targets presented in rapid succession. Thirty-four participants performed a standard AB task before (baseline), during, and after 20 min of 1-mA anodal and cathodal tDCS in two separate sessions. On the basis of previous reports linking individual differences in AB magnitude to individual differences in DLPFC activity and on suggestions that effects of tDCS depend on baseline brain activity levels, we hypothesized that anodal tDCS over left DLPFC would modulate the magnitude of the AB as a function of individual baseline AB magnitude. Indeed, individual differences analyses revealed that anodal tDCS decreased the AB in participants with a large baseline AB but increased the AB in participants with a small baseline AB. This effect was only observed during (but not after) stimulation, was not found for cathodal tDCS, and could not be explained by regression to the mean. Notably, the effects of tDCS were not apparent at the group level, highlighting the importance of taking individual variability in performance into account when evaluating the effectiveness of tDCS. These findings support the idea that left DLPFC plays a critical role in the AB and in conscious access more generally. They are also in line with the notion that there is an optimal level of prefrontal activity for cognitive function, with both too little and too much activity hurting performance.

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Ferrucci, R., S. Marceglia, M. Vergari, F. Cogiamanian, S. Mrakic-Sposta, F. Mameli, S. Zago, S. Barbieri et A. Priori. « Cerebellar Transcranial Direct Current Stimulation Impairs the Practice-dependent Proficiency Increase in Working Memory ». Journal of Cognitive Neuroscience 20, n^o 9 (septembre 2008) : 1687–97. http://dx.doi.org/10.1162/jocn.2008.20112.

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How the cerebellum is involved in the practice and proficiency of non-motor functions is still unclear. We tested whether transcranial direct current stimulation (tDCS) over the cerebellum (cerebellar tDCS) induces after-effects on the practice-dependent increase in the proficiency of a working memory (WM) task (Sternberg test) in 13 healthy subjects. We also assessed the effects of cerebellar tDCS on visual evoked potentials (VEPs) in four subjects and compared the effects of cerebellar tDCS on the Sternberg test with those elicited by tDCS delivered over the prefrontal cortex in five subjects. Our experiments showed that anodal or cathodal tDCS over the cerebellum impaired the practice-dependent improvement in the reaction times in a WM task. Because tDCS delivered over the prefrontal cortex induced an immediate change in the WM task but left the practice-dependent proficiency unchanged, the effects of cerebellar tDCS are structure-specific. Cerebellar tDCS left VEPs unaffected, its effect on the Sternberg task therefore seems unlikely to arise from visual system involvement. In conclusion, tDCS over the cerebellum specifically impairs the practice-dependent proficiency increase in verbal WM.

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Senftleben, Ulrike, Johanna Kruse, Franziska M. Korb, Stefan Goetz et Stefan Scherbaum. « Is value-based choice repetition susceptible to medial frontal transcranial direct current stimulation (tDCS) ? A preregistered study ». Cognitive, Affective, & ; Behavioral Neuroscience 21, n^o 4 (2 avril 2021) : 747–62. http://dx.doi.org/10.3758/s13415-021-00889-7.

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AbstractIn value-based decision making, people have to weigh different options based on their subjective value. This process, however, also is influenced by choice biases, such as choice repetition: in a series of choices, people are more likely to repeat their decision than to switch to a different choice. Previously, it was shown that transcranial direct current stimulation (tDCS) can affect such choice biases. We applied tDCS over the medial prefrontal cortex to investigate whether tDCS can alter choice repetition in value-based decision making. In a preregistered study, we applied anodal, cathodal, and sham tDCS stimulation to 52 participants. While we found robust choice repetition effects, we did not find support for an effect of tDCS stimulation. We discuss these findings within the larger scope of the tDCS literature and highlight the potential roles of interindividual variability and current density strength.

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Pollok, Bettina, Claire Schmitz-Justen et Vanessa Krause. « Cathodal Transcranial Direct Current Stimulation (tDCS) Applied to the Left Premotor Cortex Interferes with Explicit Reproduction of a Motor Sequence ». Brain Sciences 11, n^o 2 (9 février 2021) : 207. http://dx.doi.org/10.3390/brainsci11020207.

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Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that allows the modulation of cortical excitability. TDCS effects can outlast the stimulation period presumably due to changes of GABA concentration which play a critical role in use-dependent plasticity. Consequently, tDCS and learning-related synaptic plasticity are assumed to share common mechanisms. Motor sequence learning has been related to activation changes within a cortico-subcortical network and findings from a meta-analysis point towards a core network comprising the cerebellum as well as the primary motor (M1) and the dorsolateral premotor cortex (dPMC). The latter has been particularly related to explicit motor learning by means of brain imaging techniques. We here test whether tDCS applied to the left dPMC affects the acquisition and reproduction of an explicitly learned motor sequence. To this end, 18 healthy volunteers received anodal, cathodal and sham tDCS to the left dPMC and were then trained on a serial reaction time task (SRTT) with their right hand. Immediately after the training and after overnight sleep, reproduction of the learned sequence was tested by means of reaction times as well as explicit recall. Regression analyses suggest that following cathodal tDCS reaction times at the end of the SRTT training-block explained a significant proportion of the number of correctly reported sequence items after overnight sleep. The present data suggest the left premotor cortex as one possible target for the application of non-invasive brain stimulation techniques in explicit motor sequence learning with the right hand.

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Westphal, Andrew J., Tiffany E. Chow, Corey Ngoy, Xiaoye Zuo, Vivian Liao, Laryssa A. Storozuk, Megan A. K. Peters, Allan D. Wu et Jesse Rissman. « Anodal Transcranial Direct Current Stimulation to the Left Rostrolateral Prefrontal Cortex Selectively Improves Source Memory Retrieval ». Journal of Cognitive Neuroscience 31, n^o 9 (septembre 2019) : 1380–91. http://dx.doi.org/10.1162/jocn_a_01421.

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Functional neuroimaging studies have consistently implicated the left rostrolateral prefrontal cortex (RLPFC) as playing a crucial role in the cognitive operations supporting episodic memory and analogical reasoning. However, the degree to which the left RLPFC causally contributes to these processes remains underspecified. We aimed to assess whether targeted anodal stimulation—thought to boost cortical excitability—of the left RLPFC with transcranial direct current stimulation (tDCS) would lead to augmentation of episodic memory retrieval and analogical reasoning task performance in comparison to cathodal stimulation or sham stimulation. Seventy-two healthy adult participants were evenly divided into three experimental groups. All participants performed a memory encoding task on Day 1, and then on Day 2, they performed continuously alternating tasks of episodic memory retrieval, analogical reasoning, and visuospatial perception across two consecutive 30-min experimental sessions. All groups received sham stimulation for the first experimental session, but the groups differed in the stimulation delivered to the left RLPFC during the second session (either sham, 1.5 mA anodal tDCS, or 1.5 mA cathodal tDCS). The experimental group that received anodal tDCS to the left RLPFC during the second session demonstrated significantly improved episodic memory source retrieval performance, relative to both their first session performance and relative to performance changes observed in the other two experimental groups. Performance on the analogical reasoning and visuospatial perception tasks did not exhibit reliable changes as a result of tDCS. As such, our results demonstrate that anodal tDCS to the left RLPFC leads to a selective and robust improvement in episodic source memory retrieval.

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Donaldson, Peter H., Melissa Kirkovski, Joel S. Yang, Soukayna Bekkali et Peter G. Enticott. « High-definition tDCS to the right temporoparietal junction modulates slow-wave resting state power and coherence in healthy adults ». Journal of Neurophysiology 122, n^o 4 (1 octobre 2019) : 1735–44. http://dx.doi.org/10.1152/jn.00338.2019.

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The right temporoparietal junction (rTPJ) is a multisensory integration hub that is increasingly utilized as a target of stimulation studies exploring its rich functional network roles and potential clinical applications. While transcranial direct current stimulation (tDCS) is frequently employed in such studies, there is still relatively little known regarding its local and network neurophysiological effects, particularly at important nonmotor sites such as the rTPJ. The current study applied either anodal, cathodal, or sham high-definition tDCS to the rTPJ of 53 healthy participants and used offline EEG to assess the impacts of stimulation on resting state (eyes open and eyes closed) band power and coherence. Temporoparietal and central region delta power was increased after anodal stimulation (the latter trend only), whereas cathodal stimulation increased frontal region delta and theta power. Increased coherence between right and left temporoparietal regions was also observed after anodal stimulation. All significant effects occurred in the eyes open condition. These findings are discussed with reference to domain general and mechanistic theories of rTPJ function. Low-frequency oscillatory activity may exert long-range inhibitory network influences that enable switching between and integration of endogenous/exogenous processing streams. NEW & NOTEWORTHY Through the novel use of high-definition transcranial direct current stimulation (tDCS) and EEG, we provide evidence that both anodal and cathodal stimulation of the right temporoparietal junction selectively modulate slow-wave power and coherence in distributed network regions of known relevance to proposed temporoparietal junction functionality. These results also provide direct evidence of the ability of tDCS to modulate oscillatory activity at a long-range network level, which may have explanatory power in terms of both neurophysiological and behavioral effects.

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Luca, Francesca De, Manuel Petrucci, Bianca Monachesi, Michal Lavidor et Anna Pecchinenda. « Asymmetric Contributions of the Fronto-Parietal Network to Emotional Conflict in the Word–Face Interference Task ». Symmetry 12, n^o 10 (16 octobre 2020) : 1701. http://dx.doi.org/10.3390/sym12101701.

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The fronto-parietal network is involved in top-down and bottom-up processes necessary to achieve cognitive control. We investigated the role of asymmetric enhancement of the left dorsolateral prefrontal cortex (lDLPFC) and right posterior parietal cortex (rPPC) in cognitive control under conditions of emotional conflict arising from emotional distractors. The effects of anodal tDCS over the lDLPFC/cathodal over the rPPC and the effects of anodal tDCS over the rPPC/cathodal over the lDLPFC were compared to sham tDCS in a double-blind design. The findings showed that anodal stimulation over the lDLPFC reduced interference from emotional distractors, but only when participants had already gained experience with the task. In contrast, having already performed the task only eliminated facilitation effects for positive stimuli. Importantly, anodal stimulation of the rPPC did not affect distractors’ interference. Therefore, the present findings indicate that the lDLPFC plays a crucial role in implementing top-down control to resolve emotional conflict, but that experience with the task is necessary to reveal this role.

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