Evidence that transcranial direct current stimulation (tDCS) generates little-to-no reliable neurophysiologic effect beyond MEP amplitude modulation in healthy human subjects: A systematic review

Horvath, Jared Cooney; Forte, Jason D.; Carter, Olivia

doi:10.1016/j.neuropsychologia.2014.11.021

Cited by 466 publications

(371 citation statements)

References 138 publications

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“…Indeed, the size of the effect of tDCS on neuronal excitability is reportedly relatively small compared with other neuro-modulatory techniques such as transcranial magnetic stimulation [TMS,33]. Meta-analyses data support the idea that there is large inter-participant variability in the neuronal response to tDCS stimulation and the neurophysiological effect of tDCS may be restricted to modulation of motor evoked potential (MEP) as estimated by TMS [36]. In the present study, since both HR and RPE are associated with the IC, a lack of change in both variables implies that neuronal excitability in the IC was not sufficiently altered following stimulation to result in a meaningful effect.…”

Section: Rpe Ts and Tc Responsesmentioning

confidence: 93%

The Effects of Direct Current Stimulation on Exercise Performance, Pacing and Perception in Temperate and Hot Environments

et al. 2016

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Section: Rpe Ts and Tc Responsesmentioning

confidence: 93%

The Effects of Direct Current Stimulation on Exercise Performance, Pacing and Perception in Temperate and Hot Environments

et al. 2016

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“…Of note, the relatively small number of studies fitting the inclusion criteria is a primary example of the challenges faced when attempting to perform quantitative reviews of tDCS effects on motor learning (Antal, Keeser, Priori, Padberg, & Nitsche, 2015;Nitsche, Bikson, & Bestmann, 2015). Other meta-analyses focusing on effects of a single tDCS session have reported few significant physiological (Horvath, Forte, & Carter, 2015a) and no significant cognitive effects (Horvath, Forte, & Carter, 2015b), although questions regarding methodology used in these analyses have been raised (Antal et al, 2015). Additionally, it should be kept in mind that in the absence of systematic critical assessment of the quality of individual studies, and understanding of the biases that they may be prone to, interpretation of meta-analysis findings remains uncertain (Bastian, 2016).…”

Section: Meta-analyses and Systematic Reviews Of The Literaturementioning

confidence: 99%

Effects of tDCS on motor learning and memory formation: A consensus and critical position paper

Buch

Santarnecchi

Antal

et al. 2017

Clinical Neurophysiology

297

267

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Motor skills are required for activities of daily living. Transcranial direct current stimulation (tDCS) applied in association with motor skill learning has been investigated as a tool for enhancing training effects in health and disease. Here, we review the published literature investigating whether tDCS can facilitate the acquisition and retention of motor skills and adaptation. A majority of reports focused on the application of anodal tDCS over the primary motor cortex (M1) during motor skill acquisition, while some evaluated tDCS applied over the cerebellum during adaptation of existing motor skills. Work in multiple laboratories is under way to develop a mechanistic understanding of tDCS effects on different forms of learning, and to optimize stimulation protocols.Efforts are required to improve reproducibility and standardization. Overall, reproducibility remains to be fully tested, effect sizes with present techniques are moderate (up to d= 0.5) (Hashemirad, Zoghi, Fitzgerald, & Jaberzadeh, 2016) and the basis of inter-individual variability in tDCS effects is incompletely understood. It is recommended that future studies explicitly state in the Methods the exploratory (hypothesisgenerating) or hypothesis-driven (confirmatory) nature of the experimental designs. General research practices could be improved with prospective pre-registration of hypothesis-based investigations, more emphasis on detailed description of methods and use of post-publication open data repositories. A checklist is proposed for reporting tDCS investigations in a way that can improve efforts to assess reproducibility.

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“…tDCS is thought to alter the resting membrane potential of target neurons in a polarity-dependent manner such that the anode increases while the cathode decreases cortical excitability (e.g., Nitsche et al 2003). Behaviorally, this has been shown to manifest in increased motor-evoked potentials (MEP; Horvath et al 2015a), improved motor functioning (Hashemirad et al 2016), enhanced working memory (WM) performance (Mancuso et al 2016), as well as a plethora of other cognitive, physical, and emotional changes (e.g., Utz et al 2010). …”

Section: Introductionmentioning

confidence: 99%

Optimizing Transcranial Direct Current Stimulation Protocols to Promote Long-Term Learning

Karsten

Buschkuehl

et al. 2017

J Cogn Enhanc

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Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that has the potential to induce polarity-specific changes in neural activity within targeted brain regions. There is growing interest in the use of this technology for the enhancement of higher cognitive functions, and application of tDCS directly before or concomitant with task performance has shown promise in modulating a range of behavioral outcomes, including motor skill acquisition, working memory performance, and implicit and explicit learning. The proposed mechanism for the observed enhancements is a temporary and targeted shift in the excitability of the cortical regions that subserve the relevant tasks, lasting from minutes up to about an hour after cessation of stimulation. Although empirical work does support at least a partial role for this mechanism, an arguably more potent but relatively underexplored phenomenon is thought to occur in the hours or days after stimulation-that is, a facilitation of consolidative processes. Here, we review the literature describing the nature of tDCS-enhanced consolidation and argue that some of the mixed results among the single-session studies that currently dominate the extant literature may be explained by a failure to take advantage of these potentially powerful offline effects. Accordingly, we further contend that the full potential of tDCS cannot be truly realized without a longitudinal design which allows for tDCS to act directly upon learning by promoting consolidation between sessions. Finally, we review preliminary evidence that these consolidation effects can be even further enhanced via strategically spaced out stimulation sessions, which take advantage of a long-held tenet in the literature that distributed learning produces better outcomes than massed learning. We conclude by proposing potential study designs to encourage the use of tDCS as more than merely a method to promote temporary enhancement, but also a technique to enhance long-term learning.

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Evidence that transcranial direct current stimulation (tDCS) generates little-to-no reliable neurophysiologic effect beyond MEP amplitude modulation in healthy human subjects: A systematic review

Cited by 466 publications

References 138 publications

The Effects of Direct Current Stimulation on Exercise Performance, Pacing and Perception in Temperate and Hot Environments

The Effects of Direct Current Stimulation on Exercise Performance, Pacing and Perception in Temperate and Hot Environments

Effects of tDCS on motor learning and memory formation: A consensus and critical position paper

Optimizing Transcranial Direct Current Stimulation Protocols to Promote Long-Term Learning

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