Transcranial Alternating Current Stimulation (tACS) Mechanisms and Protocols

Tavakoli, Amir Vala; Yun, Kyongsik

doi:10.3389/fncel.2017.00214

Cited by 149 publications

(108 citation statements)

References 118 publications

(173 reference statements)

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“…There have been initial indications that tES can improve responsiveness of patients in Minimally Conscious States ( Thibaut et al 2014 ). Perhaps the most interesting applications of tES, using either DC or AC current, is the possibility of entraining underlying circuits and thereby altering temporal dynamics of brain activation ( Filmer et al 2014 ; Tavakoli and Yun 2017 ). tES has had problems showing specificity and replicability, but recent techniques using EEG/MEG to guide stimulation timing ( Thut et al 2017 ) may help ameliorate these concerns.…”

Section: Making Progressmentioning

confidence: 99%

How experimental neuroscientists can fix the hard problem of consciousness

Klein

Barron

2020

Neuroscience of Consciousness

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For the materialist, the hard problem is fundamentally an explanatory problem. Solving it requires explaining why the relationship between brain and experience is the way it is and not some other way. We use the tools of the interventionist theory of explanation to show how a systematic experimental project could help move beyond the hard problem. Key to this project is the development of second-order interventions and invariant generalizations. Such interventions played a crucial scientific role in untangling other scientific mysteries, and we suggest that the same will be true of consciousness. We further suggest that the capacity for safe and reliable self-intervention will play a key role in overcoming both the hard and meta-problems of consciousness. Finally, we evaluate current strategies for intervention, with an eye to how they might be improved.

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Section: Making Progressmentioning

confidence: 99%

How experimental neuroscientists can fix the hard problem of consciousness

Klein

Barron

2020

Neuroscience of Consciousness

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“…Transcranial current stimulation (tCS) entails sending weak (≤ 2 mA) currents through the brain via electrodes placed on the scalp (see Reed and Cohen Kadosh, 2018, for a review). Applying direct current (tDCS) has been shown to affect the excitability of stimulated neurons (Nitsche and Paulus, 2000;Dissanayaka et al, 2017), while alternating currents (tACS) can also synchronize neuronal spikes and entrain them to the stimulation frequency (Zaehle et al, 2010;Tavakoli and Yun, 2017). At intensities commonly used for stimulation in humans, tCS does not produce sufficiently high field strengths to directly induce action potentials in neurons (Datta et al, 2009;Rampersad et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Prospects for transcranial temporal interference stimulation in humans: a computational study

Rampersad

Roig-Solvas

Yarossi

et al. 2019

Preprint

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Transcranial alternating current stimulation (tACS) is a noninvasive method used to modulate activity of superficial brain regions. Deeper and more steerable stimulation could potentially be achieved using transcranial temporal interference stimulation (tTIS): two high-frequency alternating fields interact to produce a wave with an envelope frequency in the range thought to modulate neural activity. Promising initial results have been reported for experiments with mice. In this study we aim to better understand the electric fields produced with tTIS and examine its prospects in humans through simulations with murine and human head models. A murine head finite element model was used to simulate previously published experiments of tTIS in mice. With a total current of 0.776 mA, tTIS electric field strengths up to 383 V/m were reached in the modeled mouse brain, affirming experimental results indicating that suprathreshold stimulation is possible in mice. Using a detailed anisotropic human head model, tTIS was simulated with systematically varied electrode configurations and input currents to investigate how these parameters influence the electric fields. An exhaustive search with 88 electrode locations covering the entire head (146M current patterns) was employed to optimize tTIS for target field strength and focality. In all analyses, we investigated maximal effects and effects along the predominant orientation of local neurons. Our results showed that it was possible to steer the peak tTIS field by manipulating the relative strength of the two input fields. Deep brain areas received field strengths similar to conventional tACS, but with less stimulation in superficial areas. Maximum field strengths in the human model were much lower than in the murine model, too low to expect direct stimulation effects. While field strengths from tACS were slightly higher, our results suggest that tTIS is capable of producing more focal fields and allows for better steerability. Finally, we present optimal four-electrode current patterns to maximize tTIS in regions of the pallidum (0.37 V/m), hippocampus (0.24 V/m) and motor cortex (0.57 V/m).

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“…2), the above reported spectral changes are likely to be the result of tACS. Although there are several controversies related to the mechanism of tACS action on brain, the most accepted mechanism is "direct entrainment of endogenous oscillators" by the "external electric field" (15). Therefore, as sleep is supposed to be resilient to external stimulations, spectral perturbations following tACS could imply a poorer sleep.…”

Section: Resultsmentioning

confidence: 99%