Current intensity‐ and polarity‐specific online and aftereffects of transcranial direct current stimulation: An fMRI study

Jamil, Asif; Batsikadze, Giorgi; Kuo, Hsiao-I; Meesen, Raf; Dechent, Peter; Paulus, Walter; Nitsche, Michael A.

doi:10.1002/hbm.24901

Cited by 76 publications

(91 citation statements)

References 104 publications

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“…Several factors may contribute to such. First, different tDCS protocol parameters, such as stimulation duration, intensity and inter-tDCS interval, may exert varied effects on neuronal activity and neurotransmitter production (Monte-Silva et al 2010;Mosayebi Samani et al 2019;Jamil et al 2020;Stagg, 2020;Teti Mayer et al 2020). Second, the variability of the tDCS effects measured using MRS may result from the limitations of the MRS technique itself.…”

Section: Effects Of A-and C-tdcs On Gaba and Glu Synthesesmentioning

confidence: 99%

Anodal and cathodal tDCS modulate neural activity and selectively affect GABA and glutamate syntheses in the visual cortex of cats

Zhao

Ding

Pan

et al. 2020

The Journal of Physiology

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Key points The present study showed that anodal and cathodal transcranial direct current stimulation (tDCS) can respectively increase and decrease the amplitude of visually evoked field potentials in the stimulated visual cortex of cats, with the effect lasting for ∼60–70 min. We directly measured tDCS‐induced changes in the concentration of inhibitory and excitatory neurotransmitters in the visual cortex using the enzyme‐linked immunosorbent assay method and showed that anodal and cathodal tDCS can selectively decrease the concentration of GABA and glutamate in the stimulated cortical area. Anodal and cathodal tDCS can selectively inhibit the synthesis of GABA and glutamate by suppressing the expression of GABA‐ and glutamate‐synthesizing enzymes, respectively. Abstract Transcranial direct current stimulation (tDCS) evokes long‐lasting neuronal excitability in the target brain region. The underlying neural mechanisms remain poorly understood. The present study examined tDCS‐induced alterations in neuronal activities, as well as the concentration and synthesis of GABA and glutamate (GLU), in area 21a (A21a) of cat visual cortex. Our analysis showed that anodal and cathodal tDCS respectively enhanced and suppressed neuronal activities in A21a, as indicated by a significantly increased and decreased amplitude of visually evoked field potentials (VEPs). The tDCS‐induced effect lasted for ∼60–70 min. By contrast, sham tDCS had no significant impact on the VEPs in A21a. On the other hand, the concentration of GABA, but not that of GLU, in A21a significantly decreased after anodal tDCS relative to sham tDCS, whereas the concentration of GLU, but not that of GABA, in A21a significantly decreased after cathodal tDCS relative to sham tDCS. Furthermore, the expression of GABA‐synthesizing enzymes GAD65 and GAD67 in A21a significantly decreased in terms of both mRNA and protein concentrations after anodal tDCS relative to sham tDCS, whereas that of GLU‐synthesizing enzyme glutaminase (GLS) did not change significantly after anodal tDCS. By contrast, both mRNA and protein concentrations of GLS in A21a significantly decreased after cathodal tDCS relative to sham tDCS, whereas those of GAD65/GAD67 showed no significant change after cathodal tDCS. Taken together, these results indicate that anodal and cathodal tDCS may selectively reduce GABA and GLU syntheses and thus respectively enhance and suppress neuronal excitability in the stimulated brain area.

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Section: Effects Of A-and C-tdcs On Gaba and Glu Synthesesmentioning

confidence: 99%

Anodal and cathodal tDCS modulate neural activity and selectively affect GABA and glutamate syntheses in the visual cortex of cats

Zhao

Ding

Pan

et al. 2020

The Journal of Physiology

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“…But these dose-response relationships have been less frequently studied for other brain areas (Antal et al, 2004;Matsunaga et al, 2004) and have yielded somewhat divergent results. This also applies to the concurrent tES-fMRI approach (Jamil et al, 2020). We recommend that the timeline of experimentation is reported in detail together with other design related information, such as counterbalancing of scans for within-subject studies, and whether subjects are repositioned in between scan runs should also be reported.…”

Section: Methodological Factorsmentioning

confidence: 99%

A Checklist for Assessing the Methodological Quality of Concurrent tES-fMRI Studies (ContES Checklist): A Consensus Study and Statement

Ekhtiari

Ghobadi‐Azbari

Thielscher

et al. 2020

Preprint

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BackgroundLow intensity transcranial electrical stimulation (tES), including alternating or direct current stimulation (tACS or tDCS), applies weak electrical stimulation to modulate brain circuits. Integration of tES with concurrent functional magnetic resonance imaging (fMRI) allows neuromodulation of brain regions while mapping network functions, therefore supporting causal studies of both brain function and tES effects. The methodology of tES-fMRI studies, including hardware and protocols, underpin any outcomes - so reporting methods in appropriate detail is required for reproducible experimental protocols. Despite the growing number of published reports, consensus-based checklists for disclosing standards of methodological details for concurrent tES-fMRI studies were not previously established.ObjectiveTo develop a consensus-based checklist of reporting standards for concurrent tES-fMRI studies to support methodological rigor, transparency, and reproducibility (ContES Checklist).MethodsA two-phase Delphi consensus process was conducted by a steering committee (SC) of 13 members and 49 expert panelists (EP) through the International Network of the tES-fMRI (INTF) Consortium. The process began with a preliminary checklist including essential items and additional recommendations developed by the SC based on a systematic review of 57 concurrent tES-fMRI studies published before January 1, 2020. In the revision phase, contributors were invited to comment, revise, or add items/recommendations to the initial checklist. Then, in the rating phase, contributors were asked to evaluate the importance of the 17 essential items and 42 additional recommendations in the final checklist. Furthermore, the state of methodological transparency and reproducibility within the 57 collected concurrent tES-fMRI studies was assessed with the proposed checklist.ResultsDuring the revision and rating phases, the EP and SC refined the checklist based on a pre-registered consensus framework and agreed upon essential items and additional recommendations, which involved three categories: (1) technological factors, (2) safety and noise tests, and (3) methodological factors. The level of adherence to the checklist varied among the 57 published concurrent tES-fMRI articles, ranging from 24% to 76%. On average, 53% of the checklist items were reported in a given article.ConclusionsIt is expected that the use of the ContES checklist will enhance the methodological reporting quality of future concurrent tES-fMRI studies and thus increase methodological transparency and reproducibility.

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“…However, the physiological mechanisms of tDCS evoked CBF response is unknown 6,7 . A recent study 8 showed that the spatial distribution of CBF changes correlated with the tDCS-induced electric field distribution (< 1 V/m) computed using finite element modeling. CBF changes can also be evoked rapidly (<100 ms) with transcranial alternating current stimulation at 10-20 Hz; however, at higher electric field strengths (5-20 V/m) 9 .…”

Section: Introductionmentioning

confidence: 99%

Grey-box modeling and hypothesis testing of functional near-infrared spectroscopy-based cerebrovascular reactivity to anodal high-definition tDCS in healthy humans

Arora

Walia

Hayashibe

et al. 2021

Preprint

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Transcranial direct current stimulation (tDCS) has been shown to evoke hemodynamics response; however, the mechanisms have not been investigated systematically using systems biology approaches. We postulate that such a mechanistic understanding of the hemodynamics response, called cerebrovascular reactivity (CVR) to tDCS, can facilitate adequate delivery of the tDCS current density to the neurovascular tissue in cerebrovascular diseases. Our study presents a systems biology approach to evaluate CVR during high-definition (HD) tDCS using a physiologically constrained grey-box linear model. Our grey-box linear model was developed for the multi-compartmental neurovascular unit consisting of the vascular smooth muscle, perivascular space, synaptic space, and astrocyte glial cell. The physiologically detailed model generated vessel oscillations in the frequency range of 0.05 – 0.2 Hz driven mainly by non-linear calcium dynamics. Then, model linearization was performed to develop a grey-box linear model for evaluating the acute effects during the first 150 seconds of anodal HD-tDCS in eleven healthy humans using functional near-infrared spectroscopy (fNIRS) based measure of blood volume. The grey-box linear model was fitted to the total hemoglobin concentration (tHb) changes with optodes in the vicinity of 4x1 HD-tDCS electrodes. We found that the grey-box model pathway from perivascular potassium to the vessel circumference (Pathway 3) presented the best fit to fNIRS tHb time series with the least mean square error (MSE, median < 2.5%). Then, minimal realization transfer function with reduced-order approximations of the grey-box model pathways was fitted to the average tHb time series. Pathway 3, with nine poles and two zeros (all free parameters), provided the best Chi-Square Goodness of Fit of 0.0078. Therefore, our study provided a sound systems biology approach to investigate the hemodynamic response to tDCS that needs further investigation in health, aging, and disease. Future studies can leverage transcranial alternating current stimulation for frequency-dependent physiological entrainment of relevant pathways, e.g., oscillations driven by nonlinear calcium dynamics, that can provide additional insights based on our grey-box modeling approach.

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Current intensity‐ and polarity‐specific online and aftereffects of transcranial direct current stimulation: An fMRI study

Cited by 76 publications

References 104 publications

Anodal and cathodal tDCS modulate neural activity and selectively affect GABA and glutamate syntheses in the visual cortex of cats

Anodal and cathodal tDCS modulate neural activity and selectively affect GABA and glutamate syntheses in the visual cortex of cats

A Checklist for Assessing the Methodological Quality of Concurrent tES-fMRI Studies (ContES Checklist): A Consensus Study and Statement

Grey-box modeling and hypothesis testing of functional near-infrared spectroscopy-based cerebrovascular reactivity to anodal high-definition tDCS in healthy humans

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