The Effect of Transcranial Direct Current Stimulation (tDCS) Electrode Size and Current Intensity on Motor Cortical Excitability: Evidence From Single and Repeated Sessions

Ho, Kerrie-Anne; Taylor, Janet L.; Chew, Taariq; Gálvez, Verònica; Alonzo, Angelo; Bai, Siwei; Dokos, Socrates; Loo, Colleen

doi:10.1016/j.brs.2015.08.003

Cited by 124 publications

(81 citation statements)

References 36 publications

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“…For instance, maximal atDCS polarization is at the tips of basal and apical dendrites of CA1 neurons (Bikson et al, 2004) which may reflect the effect of passive cable properties on the effects of tDCS. Human studies also confirm that atDCS effects on cortical excitability depend on position, size and orientation of the electrodes (Opitz et al, 2015; Ho et al, 2016). However, standardization of the stimulation amplitude requires serious attention (Rampersad et al, 2014).…”

Section: Effects Of Electrode Polarity and Placement On Neuronal Respmentioning

confidence: 80%

Impact of Transcranial Direct Current Stimulation (tDCS) on Neuronal Functions

et al. 2016

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Transcranial direct current stimulation (tDCS), a non-invasive brain stimulation technique, modulates neuronal excitability by the application of a small electrical current. The low cost and ease of the technique has driven interest in potential clinical applications. However, outcomes are highly sensitive to stimulation parameters, leading to difficulty maximizing the technique's effectiveness. Although reversing the polarity of stimulation often causes opposite effects, this is not always the case. Effective clinical application will require an understanding of how tDCS works; how it modulates a neuron; how it affects the local network; and how it alters inter-network signaling. We have summarized what is known regarding the mechanisms of tDCS from sub-cellular processing to circuit level communication with a particular focus on what can be learned from the polarity specificity of the effects.

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Section: Effects Of Electrode Polarity and Placement On Neuronal Respmentioning

confidence: 80%

Impact of Transcranial Direct Current Stimulation (tDCS) on Neuronal Functions

et al. 2016

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“…Because our outcomes were not assessed after Session 1, we cannot be certain that treatment effect on false positive errors was a cumulative effect of three stimulation sessions, rather than an acute effect of stimulation at Session 3. However, multiple tDCS sessions have been shown to produce a cumulative increase in cortical excitability, and combining tDCS with a training task over time may result in greater gain on a non-trained test than tDCS alone [46, 92]. Sham stimulation may not be the optimal method for blinding participants during tDCS treatment [93, 94].…”

Section: Discussionmentioning

confidence: 99%

“…The fractal N-back is a working memory task which has been shown to robustly activate the DLPFC, and co-administration of this task with tDCS results in greater DLPFC activation than when the task is performed alone [11, 29, 30, 44, 45]. Finally, multiple tDCS sessions with concurrent cognitive training may provide greater benefits than a single session [26, 46]. …”

Section: Introductionmentioning

confidence: 99%

Transcranial direct current brain stimulation decreases impulsivity in ADHD

et al. 2018

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Background Impulsivity is a core deficit in attention deficit hyperactivity disorder (ADHD). Transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) has been shown to modulate cognitive control circuits and could enhance DLPFC activity, leading to improved impulse control in ADHD. Objective/Hypothesis We predicted 2.0 mA anodal stimulation (tDCS) versus sham stimulation applied over the left DLPFC would improve Conners Continuous Performance Task (CPT) scores. Our secondary hypothesis predicted that stop signal task (SST) reaction time would decrease with tDCS (versus sham). Methods Thirty-seven participants completed two periods of three tDCS (or sham) sessions two weeks apart in a within-subject, double-blind, counterbalanced order. Participants performed a fractal N-back training task concurrent with tDCS (or sham) stimulation. Participants completed the CPT and SST at the beginning of treatment (baseline), at the end of the treatment, and at a 3-day post-stimulation follow-up. Results There was a significant stimulation condition by session interaction for CPT false positive scores (χ2 =15.44, p<0.001) driven by a decrease in false positive errors from baseline to end of treatment in the tDCS group (β=−0.36, 95% Confidence Interval (CI) −0.54 to −0.18, p<0.001). This effect did not persist at follow-up (β=−0.13, p>0.05). There was no significant stimulation condition by session interaction effect on CPT true positive errors or response time (ps>0.05). No significant change in SSRT performance was observed (p>0.05). Conclusion These findings suggest that stimulation of the left DLPFC with tDCS can improve impulsivity symptoms in ADHD, supporting the therapeutic potential for tDCS in adult ADHD patients.

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“…Large variability in tES-outcome has been shown within and across studies. This variability is likely to be explained by the large number of factors influencing outcome (Fertonani and Miniussi, 2016), including current strength/density (Teo et al, 2011; Moos et al, 2012; Bastani and Jaberzadeh, 2013; Batsikadze et al, 2013; Hoy et al, 2013; Benwell et al, 2015; Ho et al, 2016), electrode montage (Moliadze et al, 2010; Sehm et al, 2013; Scheldrup et al, 2014; Mehta et al, 2015), stimulation duration (Nitsche and Paulus, 2000; Stagg and Nitsche, 2011), stimulation frequency (Kanai et al, 2010; Feurra et al, 2011; Brignani et al, 2013; Wach et al, 2013; Cabral-Calderin et al, 2016), timing of stimulation relative to task engagement (Pirulli et al, 2013; Scheldrup et al, 2014; Bortoletto et al, 2015; Cabral-Calderin et al, 2016), baseline trait/task performance levels of participants (Dockery et al, 2009; Tseng et al, 2012; Hsu et al, 2014; Sarkar et al, 2014; Benwell et al, 2015; Learmonth et al, 2015; Li et al, 2015b; London and Slagter, 2015), task demands (Li et al, 2015a; Roe et al, 2016) and the initial excitatory/oscillatory state of the stimulated region (Feurra et al, 2013). In addition to the difficulty of understanding all of the potential contributors to tES outcome, its effects tend to be relatively small and difficult to replicate (Walsh, 2013).…”

Section: Introductionmentioning

confidence: 99%

Inconsistent Effects of Parietal α-tACS on Pseudoneglect across Two Experiments: A Failed Internal Replication

et al. 2017

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Transcranial electrical stimulation (tES) is being investigated as an experimental and clinical interventional technique in human participants. While promising, important limitations have been identified, including weak effect sizes and high inter- and intra-individual variability of outcomes. Here, we compared two “inhibitory” tES-techniques with supposedly different mechanisms of action as to their effects on performance in a visuospatial attention task, and report on a direct replication attempt. In two experiments, 2 × 20 healthy participants underwent tES in three separate sessions testing different protocols (10 min stimulation each) with a montage targeting right parietal cortex (right parietal–left frontal, electrode-sizes: 3cm × 3cm–7 cm × 5 cm), while performing a perceptual line bisection (landmark) task. The tES-protocols were compared as to their ability to modulate pseudoneglect (thought to be under right hemispheric control). In experiment 1, sham-tES was compared to transcranial alternating current stimulation at alpha frequency (10 Hz; α-tACS) (expected to entrain “inhibitory” alpha oscillations) and to cathodal transcranial direct current stimulation (c-tDCS) (shown to suppress neuronal spiking activity). In experiment 2, we attempted to replicate the findings of experiment 1, and establish frequency-specificity by adding a 45 Hz-tACS condition to α-tACS and sham. In experiment 1, right parietal α-tACS led to the expected changes in spatial attention bias, namely a rightward shift in subjective midpoint estimation (relative to sham). However, this was not confirmed in experiment 2 and in the complete sample. Right parietal c-tDCS and 45 Hz-tACS had no effect. These results highlight the importance of replication studies, adequate statistical power and optimizing tES-interventions for establishing the robustness and reliability of electrical stimulation effects, and best practice.

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The Effect of Transcranial Direct Current Stimulation (tDCS) Electrode Size and Current Intensity on Motor Cortical Excitability: Evidence From Single and Repeated Sessions

Cited by 124 publications

References 36 publications

Impact of Transcranial Direct Current Stimulation (tDCS) on Neuronal Functions

Impact of Transcranial Direct Current Stimulation (tDCS) on Neuronal Functions

Transcranial direct current brain stimulation decreases impulsivity in ADHD

Inconsistent Effects of Parietal α-tACS on Pseudoneglect across Two Experiments: A Failed Internal Replication

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