Duration but not intensity influences transcranial direct current stimulation (tDCS) after-effects on cortical excitability

Vignaud, Philippe; Mondino, Marine; Poulet, Emmanuel; Palm, Ulrich; Brunelin, Jérôme

doi:10.1016/j.neucli.2018.02.001

Cited by 43 publications

(19 citation statements)

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“…We hypothesized that the facilitatory effect of a-tDCS on CSE would decrease and even reverse into LTD-like plasticity when stimulation intensities of ≥ 1 mA are used. Our results support this hypothesis, and are in line with previous studies showing non-linear effects of a-tDCS 8,14,[17][18][19] . On the other hand, these findings are not in line with other studies showing a CSE increase following higher intensities of stimulation of 1.2, 1.5, and 2 mA probably due to shorter stimulation duration (10 min) compared to the current study 20,21,38 .…”

Section: Burning Sensationsupporting

confidence: 93%

“…Although the current findings support the assumption of a-tDCS intensity and duration windows for linear effects, they also reveal that exceeding stimulation parameters beyond specific limits results in non-linear effects. Increasing stimulation intensity/duration therefore does not necessarily improve the efficacy of a-tDSC, in principle accordance with previous studies 9,14,18,20,38 .…”

Section: Burning Sensationsupporting

confidence: 90%

“…The assumption of a generally linear association between stimulation intensity/duration and LTP-like plasticity was however challenged by other studies, which showed a reduction or even reversal of tDCS-induced excitability alterations with specific current intensities and/or stimulation durations 9,[14][15][16][17][18][19] . Other a-tDCS studies have shown no significant CSE-difference following different stimulation intensities for stimulation durations of 10 min 20,21 , 15 min 8 , 20 min 9,15 , and 30 min 9 .…”

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confidence: 99%

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Determination of anodal tDCS intensity threshold for reversal of corticospinal excitability: an investigation for induction of counter-regulatory mechanisms

Hassanzahraee

Nitsche

Zoghi

et al. 2020

Sci Rep

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Transcranial direct current stimulation is applied to modulate activity, and excitability of the brain. Basically, LTP-like plasticity is induced when anodal tDCS (a-tDCS) is applied over the primary motor cortex. However, it has been shown that specific parameters of a-tDCS can induce a plasticity reversal. We aimed to systematically assess the intensity threshold for reversal of the direction of plasticity induced by a-tDCS, monitored by corticospinal excitability (CSE), and explored mechanisms regulating this reversal. Fifteen healthy participants received a-tDCS in pseudo-random order for 26 min with four intensities of 0.3, 0.7, 1, and 1.5 mA. To measure CSE changes, single-pulse TMS was applied over the left M1, and motor evoked potentials of a contralateral hand muscle were recorded prior to a-tDCS, immediately and 30-min post-intervention. Paired-pulse TMS was used to evaluate intracortical excitation and inhibition. CSE increased significantly following a-tDCS with an intensity of 0.7 mA; however, the expected effect decreased and even reversed at intensities of 1 and 1.5 mA. ICF was significantly increased while SICI and LICI decreased at 0.7 mA. On the other hand, a significant decrease of ICF, but SICI and LICI enhancement was observed at intensities of 1, and 1.5 mA. The present findings show an intensity threshold of ≥ 1 mA for 26 min a-tDCS to reverse LTP- into LTD-like plasticity. It is suggested that increasing stimulation intensity, with constant stimulation duration, activates counter-regulatory mechanisms to prevent excessive brain excitation. Therefore, stimulation intensity and plasticity induced by a-tDCS might non-linearly correlate in scenarios with prolonged stimulation duration.

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Section: Burning Sensationsupporting

confidence: 93%

Section: Burning Sensationsupporting

confidence: 90%

mentioning

confidence: 99%

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Determination of anodal tDCS intensity threshold for reversal of corticospinal excitability: an investigation for induction of counter-regulatory mechanisms

Hassanzahraee

Nitsche

Zoghi

et al. 2020

Sci Rep

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“…Also, longer lasting effects have been associated with greater current intensities [15]. However, other studies have found no differences in cortical excitability when comparing 2 mA and 1 mA [52][53][54]. Further research is required to understand if current intensity is a moderator factor when tDCS is applied in combination with other complementary interventions.…”

Section: Methodological Aspectsmentioning

confidence: 99%

Transcranial direct current stimulation combined with physical or cognitive training in people with Parkinson’s disease: a systematic review

Beretta

Conceição

Nóbrega‐Sousa

et al. 2020

J NeuroEngineering Rehabil

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Background: Pharmacologic therapy is the primary treatment used to manage Parkinson's disease (PD) symptoms. However, it becomes less effective with time and some symptoms do not respond to medication. Complementary interventions are therefore required for PD. Recent studies have implemented transcranial direct current stimulation (tDCS) in combination with other modalities of interventions, such as physical and cognitive training. Although the combination of tDCS with physical and cognitive training seems promising, the existing studies present mixed results. Therefore, a systematic review of the literature is necessary. Aims: This systematic review aims to (i) assess the clinical effects of tDCS when applied in combination with physical or cognitive therapies in people with PD and; (ii) analyze how specific details of the intervention protocols may relate to findings. Methods: The search strategy detailed the technique of stimulation, population and combined interventions (i.e. cognitive and/or physical training). Only controlled studies were included. Results: Seventeen of an initial yield of 408 studies satisfied the criteria. Studies involved small sample sizes. tDCS protocols and characteristics of combined interventions varied. The reviewed studies suggest that synergistic effects may be obtained for cognition, upper limb function, gait/mobility and posture when tDCS is combined with cognitive and/or motor interventions in PD. Conclusion: The reported results encourage further research to better understand the therapeutic utility of tDCS and to inform optimal clinical use in PD. Future studies in this field should focus on determining optimal stimulation parameters and intervention characteristics for maximal benefits in people with PD.

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“…Firstly, the protocol was shown to be effective on behavior and DLPFC excitability (Chua & Ahmed, 2016;Nikolin et al, 2015). Secondly, the protocol had a duration of 20 minutes, which previous findings suggested to be more effective on cortical excitability than longer stimulation durations (Vignaud, Mondino, Poulet, Palm, & Brunelin, 2018). Last but not least, as empirical results of DLPFC tDCS effects showed that different intensities seem not decisive to influence reaction times and accuracy (Dedoncker, Brunoni, Baeken, & Vanderhasselt, 2016;Nikolin, Martin, Loo, & Boonstra, 2018), stimulation intensity was not a crucial criteria for the selection of the protocol.…”

Section: Accepted Manuscriptmentioning

confidence: 95%

High Definition Transcranial Direct Current Stimulation Does Not Modulate Implicit Task Sequence Learning and Consolidation

2019

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The incidental acquisition of a succession of tasks is termed implicit task sequence learning. Patients with dorsolateral prefrontal cortex (DLPFC) lesions are strongly impaired in this ability. However, recent results of conventional transcranial direct current stimulation (tDCS) above the prefrontal cortex showed no modulation of implicit task sequence learning and consolidation. One explanation for these null findings is that conventional tDCS has non-focal effects on the cortex. Thus, the aim of the present study was to use a focal type of tDCS, namely high definition tDCS (HD-tDCS), to influence implicit task sequence learning and consolidation. Participants received stimulation during implicit task sequence learning and, 24 hours later, consolidation was measured. The results showed that sequence learning was present in all conditions and sessions. Furthermore, consolidation was robust. However, both sequence learning and consolidation were not modulated by stimulation. Thus, this study corroborates previous findings by showing that even focal HD-tDCS is not sufficient to modulate implicit task sequence learning and consolidation.

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Duration but not intensity influences transcranial direct current stimulation (tDCS) after-effects on cortical excitability

Cited by 43 publications

References 20 publications

Determination of anodal tDCS intensity threshold for reversal of corticospinal excitability: an investigation for induction of counter-regulatory mechanisms

Determination of anodal tDCS intensity threshold for reversal of corticospinal excitability: an investigation for induction of counter-regulatory mechanisms

Transcranial direct current stimulation combined with physical or cognitive training in people with Parkinson’s disease: a systematic review

High Definition Transcranial Direct Current Stimulation Does Not Modulate Implicit Task Sequence Learning and Consolidation

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