Electrical brain stimulation (tES) improves learning more than performance: A meta-analysis

Simonsmeier, Bianca A.; Grabner, Roland H.; Hein, Julia; Krenz, Ugne; Schneider, Michael

doi:10.1016/j.neubiorev.2017.11.001

“…As in our previous work [14,61] and in many tDCS studies [28,62,63], we observe asymmetric results with respect to DCS polarity. Anodal DCS enhanced LTP, while cathodal DCS had no discernible effect with the current sample sizes.…”

Section: Asymmetrysupporting

confidence: 83%

Direct current stimulation boosts hebbian plasticity in vitro

Kronberg

¹

,

Rahman

²

,

Sharma

³

et al. 2020

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Background: There is evidence that transcranial direct current stimulation (tDCS) can improve learning performance. Arguably, this effect is related to long term potentiation (LTP), but the precise biophysical mechanisms remain unknown. Hypothesis: We propose that direct current stimulation (DCS) causes small changes in postsynaptic membrane potential during ongoing endogenous synaptic activity. The altered voltage dynamics in the postsynaptic neuron then modify synaptic strength via the machinery of endogenous voltage-dependent Hebbian plasticity. This hypothesis predicts that DCS should exhibit Hebbian properties, namely pathway specificity and associativity. Methods: We studied the effects of DCS applied during the induction of LTP in the CA1 region of rat hippocampal slices and using a biophysical computational model. Results: DCS enhanced LTP, but only at synapses that were undergoing plasticity, confirming that DCS respects Hebbian pathway specificity. When different synaptic pathways cooperated to produce LTP, DCS enhanced this cooperation, boosting Hebbian associativity. Further slice experiments and computer simulations support a model where polarization of postsynaptic pyramidal neurons drives these plasticity effects through endogenous Hebbian mechanisms. The model is able to reconcile several experimental results by capturing the complex interaction between the induced electric field, neuron morphology, and endogenous neural activity. Conclusions: These results suggest that tDCS can enhance associative learning. We propose that clinical tDCS should be applied during tasks that induce Hebbian plasticity to harness this phenomenon, and that the effects should be task specific through their interaction with endogenous plasticity mechanisms. Models that incorporate brain state and plasticity mechanisms may help to improve prediction of tDCS outcomes.

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“…Their findings suggested that tDCS was more effective for carriers of the Val66-Met allele, whereas tRNS produced similar effects on both Val/Val and Val/Met carriers. A recent meta-analysis 32 indicated that the overall effect of tRNS on language and mathematics was stronger than that of tDCS. However, as the study claimed 32 , the low number of investigations using tRNS prevented the authors from drawing firm conclusions.…”

mentioning

confidence: 99%

“…A recent meta-analysis 32 indicated that the overall effect of tRNS on language and mathematics was stronger than that of tDCS. However, as the study claimed 32 , the low number of investigations using tRNS prevented the authors from drawing firm conclusions. Altogether, evidence has suggested that tRNS is more effective than tDCS regarding some cognitive skills (such as learning, and language or numerical cognition), and that it can be extrapolated to participants regardless of at least some genetics (BDNF).…”

mentioning

confidence: 99%

Improvement in creativity after transcranial random noise stimulation (tRNS) over the left dorsolateral prefrontal cortex

Peña

¹

,

Sampedro

²

,

Ibarretxe‐Bilbao

³

et al. 2019

Sci Rep

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Improvement in creativity after transcranial random noise stimulation (tRNs) over the left dorsolateral prefrontal cortexJavier peña , Agurne sampedro, Naroa Ibarretxe-Bilbao, Leire Zubiaurre-elorza & Natalia ojeda Creativity has previously been shown to improve after the application of direct and alternating current transcranial stimulation over the dorsolateral prefrontal cortex (DLpFC). However, previous studies have not tested whether transcranial random noise stimulation (tRNS) was efficient for this purpose. The aim of this randomized, double-blind, placebo-controlled study was to investigate the effect of tRNs on both verbal convergent and (verbal and visual) divergent thinking during left DLpFC tRNs stimulation. thirty healthy participants were randomly allocated to either a tRNs active group or a sham group. Each session lasted 20 min and the current was set to 1.5 mA (100-500 Hz). Participants' verbal convergent thinking was assessed with the Remote Associates test (RAt). Verbal and visual divergent thinking were respectively measured by using the Unusual Uses and picture Completion subtests from the torrance tests of Creative thinking. Bootstrapped analysis of variance showed significant differences in the mean change scores between the active tRNS group and the sham group in RAt scores (d = 1.68); unusual uses: fluency (d = 2.29) and originality (d = 1.43); and general creativity (d = 1.45). Visual divergent thinking, in contrast, did not show any significant improvement. Our results suggested that tRNS over the left DLPFC is effective for increasing verbal divergent and convergent thinking.Creativity plays a key role in many areas of human life, as has been previously suggested 1 . An increasing number of studies have attempted to investigate the neurological basis for creativity using either MRI 2,3 or EEG techniques 4 . Additional evidence of brain areas and networks related to creativity performance has come from studies that included noninvasive transcranial stimulation A review recently carried out by Weinberger et al. 5 indicated that creative cognition may involve two main processes: idea generation (which depends on the availability of unfiltered information), and idea selection (which includes task-directed thoughts and integration of semantically distant concepts). Each of these processes has been suggested to rely primarily on different neural mechanisms 6 .More specifically, idea generation has been mostly related to cathodal Transcranial Direct Current Stimulation (tDCS) of the left inferior frontotemporal cortex, including the anterior temporal lobe 7,8 , inferior frontal gyrus 9 and prefrontal cortex 10 . This improvement in idea generation generally refers to divergent thinking. Divergent thinking has been defined as the ability to simultaneously establish remote associations between unrelated concepts from distant categories, as well as to generate multiple alternative and novel answers to a single problem 11 . For example, Chrysikou et al. 10 reported a higher number of uncommon use...

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“…These results suggest that the effects of DCS depend on the interaction between the induced electric field, neuron morphology, and the endogenous brain dynamics. Given this complexity, it is perhaps no surprise that results from human clinical trials with tDCS have remained inconclusive (28)(29)(30)(31), or that optimization of tDCS protocols has been slow. For example, there is an ongoing debate as to whether tDCS should be applied before, during, or after a behavioral or cognitive task (32)(33)(34).…”

Section: Introductionmentioning

confidence: 99%

Direct current stimulation boosts associative Hebbian synaptic plasticity and maintains its pathway specificity

Kronberg

¹

,

Rahman

²

,

Lafon³

et al. 2019

Preprint

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Background: There is evidence that transcranial direct current stimulation (tDCS) can improve learning performance. Arguably, this effect is related to long term potentiation (LTP), but the precise biophysical mechanisms remain unknown. Hypothesis: We propose that direct current stimulation (DCS) causes small changes in postsynaptic membrane potential during ongoing endogenous synaptic activity. The altered voltage dynamics in the postsynaptic neuron then modify synaptic strength via the machinery of endogenous voltage-dependent Hebbian plasticity. This hypothesis predicts that DCS should exhibit Hebbian properties, namely pathway specificity and associativity. Methods: We studied the effects of DCS applied during the induction of LTP in the CA1 region of rat hippocampal slices and using a biophysical computational model. Results: DCS enhanced LTP, but only at synapses that were undergoing plasticity, confirming that DCS respects Hebbian pathway specificity. When different synaptic pathways cooperated to produce LTP, DCS enhanced this cooperation, boosting Hebbian associativity. Further slice experiments and computer simulations support a model where polarization of postsynaptic pyramidal neurons drives these plasticity effects through endogenous Hebbian mechanisms. The model is able to reconcile several experimental results by capturing the complex interaction between the induced electric field, neuron morphology, and endogenous neural activity. Conclusions: These results suggest that tDCS can enhance associative learning. We propose that clinical tDCS should be applied during tasks that induce Hebbian plasticity to harness this phenomenon, and that the effects should be task specific through their interaction with endogenous plasticity mechanisms. Models that incorporate brain state and plasticity mechanisms may help to improve prediction of tDCS outcomes.Abbreviations: tDCS (transcranial direct current stimulation); DCS (direct current stimulation); LTP (long term potentiation); TBS (theta burst stimulation); STDP (spike-timing dependent plasticity) Effect of DCS on LTP is pathway specificHebbian synaptic plasticity is classically characterized as a pathway specific process, i.e. only pathways that are coactive with the postsynaptic neuron are strengthened (35). Our proposal that DCS enhances LTP through membrane potential implies that the effects of DCS should follow this pathway specificity. We tested this by monitoring two independent synaptic pathways in CA1 (Figure 2A). During induction, the strong pathway received TBS while the other inactive pathway was not stimulated. As expected, LTP was observed in the strong pathway ( Figure 2B black; 1.377+-0.052, N=16, p=2.8E-6), but not the inactive pathway ( Figure 2B gray; 0.986+-0.031, N=14, p=0.657), demonstrating the wellestablished pathway specificity of LTP (35). When this induction protocol was paired with anodal DCS, LTP was enhanced only in the strong pathway ( Figure 2B red; 1.613+-0.071, N=14, p=0.011 vs. control), while the inactive pathway was unaff...

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Electrical brain stimulation (tES) improves learning more than performance: A meta-analysis

Cited by 99 publications

References 39 publications

Direct current stimulation boosts hebbian plasticity in vitro

Direct current stimulation boosts hebbian plasticity in vitro

Improvement in creativity after transcranial random noise stimulation (tRNS) over the left dorsolateral prefrontal cortex

Direct current stimulation boosts associative Hebbian synaptic plasticity and maintains its pathway specificity

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