Both the cutaneous sensation and phosphene perception are modulated in a frequency-specific manner during transcranial alternating current stimulation

Turi, Zsolt; Ambrus, Géza Gergely; Janacsek, Karolina; Emmert, Kirsten; Hahn, Larissa; Paulus, Walter; Antal, Andrea

doi:10.3233/rnn-120297

Cited by 74 publications

(87 citation statements)

References 27 publications

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“…The phosphene and cutaneous perception threshold was lowest for beta tACS, in agreement with previous studies (Kanai et al, 2008; Chaieb et al, 2011; Turi et al, 2013), which resulted in the use of different stimulation intensities for different frequencies of tACS. We have further reported that, to the best of our knowledge, the observed effects were not related to the intensity, but rather to the frequency of stimulation, which, when at sufficient intensity, was capable of inducing the reported effects.…”

Section: Discussionsupporting

confidence: 91%

Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABA_AInhibition: A tACS-TMS Study

et al. 2017

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Beta and gamma oscillations are the dominant oscillatory activity in the human motor cortex (M1). However, their physiological basis and precise functional significance remain poorly understood. Here, we used transcranial magnetic stimulation (TMS) to examine the physiological basis and behavioral relevance of driving beta and gamma oscillatory activity in the human M1 using transcranial alternating current stimulation (tACS). tACS was applied using a sham-controlled crossover design at individualized intensity for 20 min and TMS was performed at rest (before, during, and after tACS) and during movement preparation (before and after tACS). We demonstrated that driving gamma frequency oscillations using tACS led to a significant, duration-dependent decrease in local resting-state GABAA inhibition, as quantified by short interval intracortical inhibition. The magnitude of this effect was positively correlated with the magnitude of GABAA decrease during movement preparation, when gamma activity in motor circuitry is known to increase. In addition, gamma tACS-induced change in GABAA inhibition was closely related to performance in a motor learning task such that subjects who demonstrated a greater increase in GABAA inhibition also showed faster short-term learning. The findings presented here contribute to our understanding of the neurophysiological basis of motor rhythms and suggest that tACS may have similar physiological effects to endogenously driven local oscillatory activity. Moreover, the ability to modulate local interneuronal circuits by tACS in a behaviorally relevant manner provides a basis for tACS as a putative therapeutic intervention.SIGNIFICANCE STATEMENT Gamma oscillations have a vital role in motor control. Using a combined tACS-TMS approach, we demonstrate that driving gamma frequency oscillations modulates GABAA inhibition in the human motor cortex. Moreover, there is a clear relationship between the change in magnitude of GABAA inhibition induced by tACS and the magnitude of GABAA inhibition observed during task-related synchronization of oscillations in inhibitory interneuronal circuits, supporting the hypothesis that tACS engages endogenous oscillatory circuits. We also show that an individual's physiological response to tACS is closely related to their ability to learn a motor task. These findings contribute to our understanding of the neurophysiological basis of motor rhythms and their behavioral relevance and offer the possibility of developing tACS as a therapeutic tool.

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Section: Discussionsupporting

confidence: 91%

Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABA_AInhibition: A tACS-TMS Study

et al. 2017

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“…To confirm the task performance was not affected by potential visual phosphenes (i.e. flickering perception of the light) induced by tACS [18, 41], we explicitly asked participants if they saw slight “flickering” during the stimulation runs and none of the participants reported a phosphene effect. Given that phosphenes are most likely when stimulation is at higher frequencies than theta band [42] and none of the participants experienced phosphenes, it seems unlikely that the current results would be confounded by visual phosphenes.…”

Section: Resultsmentioning

confidence: 99%

Enhancement of multitasking performance and neural oscillations by transcranial alternating current stimulation

et al. 2017

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Multitasking is associated with the generation of stimulus-locked theta (4–7 Hz) oscillations arising from prefrontal cortex (PFC). Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique that influences endogenous brain oscillations. Here, we investigate whether applying alternating current stimulation within the theta frequency band would affect multitasking performance, and explore tACS effects on neurophysiological measures. Brief runs of bilateral PFC theta-tACS were applied while participants were engaged in a multitasking paradigm accompanied by electroencephalography (EEG) data collection. Unlike an active control group, a tACS stimulation group showed enhancement of multitasking performance after a 90-minute session (F1,35 = 6.63, p = 0.01, ηp2 = 0.16; effect size = 0.96), coupled with significant modulation of posterior beta (13–30 Hz) activities (F1,32 = 7.66, p = 0.009, ηp2 = 0.19; effect size = 0.96). Across participant regression analyses indicated that those participants with greater increases in frontal theta, alpha and beta oscillations exhibited greater multitasking performance improvements. These results indicate frontal theta-tACS generates benefits on multitasking performance accompanied by widespread neuronal oscillatory changes, and suggests that future tACS studies with extended treatments are worth exploring as promising tools for cognitive enhancement.

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“…Another possible control that can be used for tACS is to stimulate using a non-effective frequency, or, in other words, a different frequency from the one of interest. The exception here would be that somatosensation and phosphene perception vary according to stimulation frequency31. Finally, regarding subjective experiences of stimulation, tACS-induced phosphenes vary across individuals, so in order to best capture subject variability, consider using a detailed rating system for phosphene perception, and spend some time with the subject describing the various features of phosphenes ( e.g.…”

Section: Discussionmentioning

confidence: 99%

Simultaneous Transcranial Alternating Current Stimulation and Functional Magnetic Resonance Imaging

Williams¹,

Cabral‐Calderín

Schmidt‐Samoa³

et al. 2017

JoVE

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Transcranial alternating current stimulation (tACS) is a promising tool for noninvasive investigation of brain oscillations. TACS employs frequency-specific stimulation of the human brain through current applied to the scalp with surface electrodes. Most current knowledge of the technique is based on behavioral studies; thus, combining the method with brain imaging holds potential to better understand the mechanisms of tACS. Because of electrical and susceptibility artifacts, combining tACS with brain imaging can be challenging, however, one brain imaging technique that is well suited to be applied simultaneously with tACS is functional magnetic resonance imaging (fMRI). In our lab, we have successfully combined tACS with simultaneous fMRI measurements to show that tACS effects are state, current, and frequency dependent, and that modulation of brain activity is not limited to the area directly below the electrodes. This article describes a safe and reliable setup for applying tACS simultaneously with visual task fMRI studies, which can lend to understanding oscillatory brain function as well as the effects of tACS on the brain.

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Both the cutaneous sensation and phosphene perception are modulated in a frequency-specific manner during transcranial alternating current stimulation

Cited by 74 publications

References 27 publications

Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABA_AInhibition: A tACS-TMS Study

Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABA_AInhibition: A tACS-TMS Study

Enhancement of multitasking performance and neural oscillations by transcranial alternating current stimulation

Simultaneous Transcranial Alternating Current Stimulation and Functional Magnetic Resonance Imaging

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Both the cutaneous sensation and phosphene perception are modulated in a frequency-specific manner during transcranial alternating current stimulation

Cited by 74 publications

References 27 publications

Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABAAInhibition: A tACS-TMS Study

Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABAAInhibition: A tACS-TMS Study

Enhancement of multitasking performance and neural oscillations by transcranial alternating current stimulation

Simultaneous Transcranial Alternating Current Stimulation and Functional Magnetic Resonance Imaging

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Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABA_AInhibition: A tACS-TMS Study

Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABA_AInhibition: A tACS-TMS Study