Polarity-Sensitive Modulation of Cortical Neurotransmitters by Transcranial Stimulation

Stagg, Charlotte J.; Best, Jonathan G.; Stephenson, Mary C.; O’Shea, Jacinta; Wylezińska, M; Kincses, Zsigmond Tamás; Morris, Peter G.; Matthews, Paul M.; Johansen‐Berg, Heidi

doi:10.1523/jneurosci.4432-08.2009

Cited by 812 publications

(849 citation statements)

References 31 publications

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“…A tDCS-induced effect on the cortico-subcortical networks is supported also by recent evidence of a functional coupling increase on the thalamo-cortical circuits following anodal stimulation over the motor cortex (Polania et al, 2012). Moreover, we speculate that the not site-limited cortical excitability increase could be determined by a decrease of the contralateral hemisphere inhibition, mediated, at least partially, by the anodal tDCS-induced reduction of GABA concentration (Stagg et al, 2009b). A different pattern of cortical response was observed after the cathodal stimulation.…”

Section: Tdcs-induced Changes In Cortical Excitabilitysupporting

confidence: 85%

Excitability modulation of the motor system induced by transcranial direct current stimulation: A multimodal approach

2013

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Anodal and cathodal transcranial direct current stimulations (tDCS) are both established techniques to induce cortical excitability changes. Typically, in the human motor system, such cortical modulations are inferred through changes in the amplitude of the motor evoked potentials (MEPs). However, it is now possible to directly evaluate tDCS-induced changes at the cortical level by recording the transcranial magnetic stimulation evoked potentials (TEPs) using electroencephalography (EEG). The present study investigated the modulation induced by the tDCS on the motor system. The study evaluates changes in the MEPs, in the amplitude and distribution of the TEPs, in resting state oscillatory brain activity and in behavioral performance in a simple manual response task. Both the short-and long-term tDCS effects were investigated by evaluating their time course at~0 and 30 min after tDCS. Anodal tDCS over the left primary motor cortex (M1) induced an enhancement of corticospinal excitability, whereas cathodal stimulation produced a reduction. These changes in excitability were indexed by changes in MEP amplitude. More interestingly, tDCS modulated the cortical reactivity, which is the neuronal activity evoked by TMS, in a polarity-dependent and site-specific manner. Cortical reactivity increased after anodal stimulation over the left M1, whereas it decreased with cathodal stimulation. These effects were partially present also at long term evaluation. No polarity-specific effect was found either on behavioral measures or on oscillatory brain activity. The latter showed a general increase in the power density of low frequency oscillations (theta and alpha) at both stimulation polarities. Our results suggest that tDCS is able to modulate motor cortical reactivity in a polarity-specific manner, inducing a complex pattern of direct and indirect cortical activations or inhibitions of the motor system-related network, which might be related to changes in synaptic efficacy of the motor cortex.

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Section: Tdcs-induced Changes In Cortical Excitabilitysupporting

confidence: 85%

Excitability modulation of the motor system induced by transcranial direct current stimulation: A multimodal approach

2013

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“…Within the cortex, tDCS modulates synaptic strength and likely stimulates neurons in the cortex, pyramidal neurons, and interneurons (Stagg and Nitsche, 2011). Several neuromodulators such as GABA (Stagg et al, 2009), Na + and Ca 2+ channel blockers (Nitsche et al, 2004), l-DOPA (Kuo et al, 2008), and the D 2 receptor agonists Monte-Silva et al, 2009) also have an effect on increasing and/or decreasing the effects of tDCS stimulation (for more see Stagg and Nitsche, 2011). Some progress in linking DNA genotypes with cognitive performance is underway.…”

Section: Mechanisms Of Tdcsmentioning

confidence: 99%

Parietal Contributions to Visual Working Memory Depend on Task Difficulty

Jones¹,

Crane²,

Feenstra³

et al. 2012

PsycEXTRA Dataset

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The nature of parietal contributions to working memory (WM) remain poorly understood but of considerable interest. We previously reported that posterior parietal damage selectively impaired WM probed by recognition (Berryhill and Olson, 2008a). Recent studies provided support using a neuromodulatory technique, transcranial direct current stimulation (tDCS) applied to the right parietal cortex (P4). These studies confirmed parietal involvement in WM because parietal tDCS altered WM performance: anodal current tDCS improved performance in a change detection task, and cathodal current tDCS impaired performance on a sequential presentation task. Here, we tested whether these complementary results were due to different degrees of parietal involvement as a function of WM task demands, WM task difficulty, and/or participants' WM capacity. In Experiment 1, we applied cathodal and anodal tDCS to the right parietal cortex and tested participants on both previously used WM tasks. We observed an interaction between tDCS (anodal, cathodal), WM task difficulty, and participants' WM capacity. When the WM task was difficult, parietal stimulation (anodal or cathodal) improved WM performance selectively in participants with high WM capacity. In the low WM capacity group, parietal stimulation (anodal or cathodal) impaired WM performance. These nearly equal and opposite effects were only observed when the WM task was challenging, as in the change detection task. Experiment 2 probed the interplay of WM task difficulty and WM capacity in a parametric manner by varying set size in the WM change detection task. Here, the effect of parietal stimulation (anodal or cathodal) on the high WM capacity group followed a linear function as WM task difficulty increased with set size. The low WM capacity participants were largely unaffected by tDCS. These findings provide evidence that parietal involvement in WM performance depends on both WM capacity and WM task demands. We discuss these findings in terms of alternative WM strategies employed by low and high WM capacity individuals. We speculate that low WM capacity individuals do not recruit the posterior parietal lobe for WM tasks as efficiently as high WM capacity individuals. Consequently, tDCS provides greater benefit to individuals with high WM capacity.

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“…These depend on the strength, duration and polarity of the stimulation and can outlast the period of stimulation by up to one hour (Nitsche et al, 2005) Paulus, 2001, Nitsche et al, 2003b). The longer lasting effects have been attributed to synaptic changes which involve modification of the synaptic strength of N-methyl-Daspartate receptors or altering Gamma-Aminobutyric Acid (GABA) activation in the remaining motor areas of the cortex (Liebetanz, Nitsche, Tergau, & Paulus, 2002;Stagg et al, 2009). Because of this, tDCS is sometimes said to promote long term potentiation and neuroplasticity (Fritsch et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

A double-blinded randomised controlled trial exploring the effect of anodal transcranial direct current stimulation and uni-lateral robot therapy for the impaired upper limb in sub-acute and chronic stroke

Triccas

Burridge

Hughes

et al. 2015

NRE

111

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Abstract. BACKGROUND:Neurorehabilitation technologies such as robot therapy (RT) and transcranial Direct Current Stimulation (tDCS) can promote upper limb (UL) motor recovery after stroke. OBJECTIVE: To explore the effect of anodal tDCS with uni-lateral and three-dimensional RT for the impaired UL in people with sub-acute and chronic stroke. METHODS: A pilot randomised controlled trial was conducted. Stroke participants had 18 one-hour sessions of RT (Armeo ® Spring) over eight weeks during which they received 20 minutes of either real tDCS or sham tDCS during each session. The primary outcome measure was the Fugl-Meyer assessment (FMA) for UL impairments and secondary were: UL function, activities and stroke impact collected at baseline, post-intervention and three-month follow-up. RESULTS: 22 participants (12 sub-acute and 10 chronic) completed the trial. No significant difference was found in FMA between the real and sham tDCS groups at post-intervention and follow-up (p = 0.123). A significant 'time' x 'stage of stroke' was found for FMA (p = 0.016). A higher percentage improvement was noted in UL function, activities and stroke impact in people with sub-acute compared to chronic stroke. CONCLUSIONS: Adding tDCS did not result in an additional effect on UL impairment in stroke. RT may be of more benefit in the sub-acute than chronic phase.

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Polarity-Sensitive Modulation of Cortical Neurotransmitters by Transcranial Stimulation

Cited by 812 publications

References 31 publications

Excitability modulation of the motor system induced by transcranial direct current stimulation: A multimodal approach

Excitability modulation of the motor system induced by transcranial direct current stimulation: A multimodal approach

Parietal Contributions to Visual Working Memory Depend on Task Difficulty

A double-blinded randomised controlled trial exploring the effect of anodal transcranial direct current stimulation and uni-lateral robot therapy for the impaired upper limb in sub-acute and chronic stroke

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