Local Network-Level Integration Mediates Effects of Transcranial Alternating Current Stimulation

Fuscà, Marco; Ruhnau, Philipp; Neuling, Toralf; Weisz, Nathan

doi:10.1089/brain.2017.0564

Cited by 9 publications

(7 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our results are in line with several other studies that did not find stimulation effects on motor cortex excitability [45,46], while Cappon et al (2016) demonstrated inhibitory effects following 20 Hz stimulation [47]. Unlike Cappon (2016), we did not use a task during stimulation; this activation during stimulation might influence the effects of tACS, since previous studies showed state-dependent effects of tACS [48,49]. Importantly, no difference between children/adolescents and adults was observed in our study.…”

Section: Neural Plasticitysupporting

confidence: 92%

The Effects of 1 mA tACS and tRNS on Children/Adolescents and Adults: Investigating Age and Sensitivity to Sham Stimulation

et al. 2020

View full text Add to dashboard Cite

The aim of this study was to investigate the effect of transcranial random noise (tRNS) and transcranial alternating current (tACS) stimulation on motor cortex excitability in healthy children and adolescents. Additionally, based on our recent results on the individual response to sham in adults, we explored this effect in the pediatric population. We included 15 children and adolescents (10–16 years) and 28 adults (20–30 years). Participants were stimulated four times with 20 Hz and 140 Hz tACS, tRNS, and sham stimulation (1 mA) for 10 minutes over the left M1HAND. Single-pulse MEPs (motor evoked potential), short-interval intracortical inhibition, and facilitation were measured by TMS before and after stimulation (baseline, 0, 30, 60 minutes). We also investigated aspects of tolerability. According to the individual MEPs response immediately after sham stimulation compared to baseline (Wilcoxon signed-rank test), subjects were regarded as responders or nonresponders to sham. We did not find a significant age effect. Regardless of age, 140 Hz tACS led to increased excitability. Incidence and intensity of side effects did not differ between age groups or type of stimulation. Analyses on responders and nonresponders to sham stimulation showed effects of 140 Hz, 20 Hz tACS, and tRNS on single-pulse MEPs only for nonresponders. In this study, children and adolescents responded to 1 mA tRNS and tACS comparably to adults regarding the modulation of motor cortex excitability. This study contributes to the findings that noninvasive brain stimulation is well tolerated in children and adolescents including tACS, which has not been studied before. Finally, our study supports a modulating role of sensitivity to sham stimulation on responsiveness to a broader stimulation and age range.

show abstract

Section: Neural Plasticitysupporting

confidence: 92%

The Effects of 1 mA tACS and tRNS on Children/Adolescents and Adults: Investigating Age and Sensitivity to Sham Stimulation

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The interaction between stimulation and recurrent network frequency, and thus the specific peak oscillating frequency, emphasizes that the effects of tACS are brain state-dependent [27,58]. "None reported" was used if skin sensations or phosphene perception was not explicitly reported by the authors.…”

Section: Discussionmentioning

confidence: 99%

“…The variability can be traced back to individual differences, such as scalp-cortex distance, gyrification, intrinsic peak neural oscillation frequency, gender, age, genetics, current state of brain physiology, and attention. Furthermore, differences in tACS parameters, such as the montage, intensity, and whether MEPs were investigated during or after tACS contribute to the heterogeneity [27,28].…”

Section: Introductionmentioning

confidence: 99%

Effects of beta-tACS on corticospinal excitability: A meta-analysis

2019

View full text Add to dashboard Cite

Over the past decade several studies have shown that transcranial alternating current stimulation (tACS) delivered at the beta (15e25 Hz) frequency range can increase corticospinal excitability of the primary motor cortex (M1). The aim of this study was to systematically quantify the effect size of beta-tACS on corticospinal excitability in healthy volunteers, as well as to identify significant outcome predictors. A meta-analysis was performed on the results of 47 experiments reported in 21 studies. Random effects modelling of the effect sizes showed that beta-tACS significantly increases M1 excitability (E ¼ 0.287, 95% CI ¼ 0.133e0.440). Further analysis showed that tACS intensities above 1 mA peak-to-peak yield a robust increase in M1 excitability, whereas intensities of 1 mA peak-to-peak and below do not induce a reliable change. Additionally, results showed an impact of tACS montages on these effects. No difference in effect size for online compared to offline application of tACS was found. In conclusion, these findings indicate that beta-tACS can increase cortical excitability if stimulation intensity is above 1 mA, yet more research is needed to titrate the stimulation parameters that yield optimal results.

show abstract

“…These results support the known extensive, interrelated connectivity between posterior and anterior neural networks, especially those originating from the visual system, which is by far the dominant human sense ( Thomas Yeo et al , 2011 ; Parks and Madden, 2013 ; Vossel et al , 2014 ). In sharp contrast to anterior tACS stimulation, the latter finding suggests that positioning the IAF tACS montage over posterior brain regions could reveal to be efficient in modifying alpha activity involved in occipito-parietal brain functions such as visual-spatial attention ( Zaehle et al , 2010 , Neuling et al , 2013a ; Strüber et al , 2015 ; Vossen et al , 2015 ; Dowsett and Herrmann, 2016 ; Kasten et al , 2016 ; Stecher et al , 2017 ; Fuscà et al , 2018 ; Stecher and Herrmann, 2018 ; Schwab et al , 2019 ). Moreover, this significant modulation of alpha power induced by the posterior IAF tACS montage also suggests a modulation of spectral power occurring distally to the stimulation site.…”

Section: Discussionmentioning

confidence: 95%

Parametric study of transcranial alternating current stimulation for brain alpha power modulation

Koninck

Guay

Blais

2021

Brain Communications

View full text Add to dashboard Cite

Transcranial alternating current stimulation, a non-invasive brain stimulation technique, has been used to increase alpha (8–12 Hz) power, the latter being associated with various brain functions and states. Heterogeneity among stimulation parameters across studies makes it difficult to implement reliable transcranial alternating current stimulation protocols, explaining the absence of consensus on optimal stimulation parameters to modulate the alpha rhythm. This project documents the differential impact of controlling for key transcranial alternating current stimulation parameters, namely the intensity, the frequency and the stimulation site (anterior versus posterior). Phase 1:20 healthy participants underwent 4 different stimulation conditions. In each experimental condition, stimulation via 2 electrodes was delivered for 20 min. Stimulation conditions were administered at PO7-PO8 or F3-F4 at individual’s alpha frequency, or at individual’s theta frequency or sham. Stimulation intensity was set according to each participant’s comfort following a standardized unpleasantness scale (≤ 40 out of 100) and could not exceed 6 mA. All conditions were counterbalanced. Phase 2: participants who tolerated higher intensity of stimulation (4–6 mA) underwent alpha-frequency stimulation applied over PO7–PO8 at 1 mA to investigate within-subject modulation of stimulation response according to stimulation intensity. Whether set over posterior or anterior cortical sites, alpha-frequency stimulation showed greater increase in alpha power relative to stimulation at theta frequency and sham stimulation. Posterior alpha-frequency stimulation showed a greater increase in alpha power relative to the adjacent frequency bands over frontal and occipito-parietal brain areas. Low intensity (1 mA) posterior alpha stimulation showed a similar increase in alpha power than at high (4–6 mA) intensity when measured immediately after stimulation. However, when tested at 60 min or 120 min, low intensity stimulation was associated with significantly superior alpha power increase relative to high intensity stimulation. This study shows that posterior individual’s alpha frequency stimulation at higher intensities is well tolerated but fails to increase stimulation aftereffects recorded within 2 h of stimulation on brain oscillations of the corresponding frequency band. In sharp contrast, stimulating at 1 mA (regardless of phosphene generation or sensory perception) effectively and selectively modulates alpha power within that 2-h time window, thus validating that it as a reliable stimulus intensity for future studies. This study also shows that posterior alpha-frequency stimulation preferentially modulates endogenous brain oscillations of the corresponding frequency band. Moreover, our data suggest that posterior alpha-frequency transcranial alternating current stimulation is a reliable and precise non-invasive brain stimulation technique for persistent modulation of both frontal and occipito-parietal alpha power.

show abstract

Local Network-Level Integration Mediates Effects of Transcranial Alternating Current Stimulation

Cited by 9 publications

References 39 publications

The Effects of 1 mA tACS and tRNS on Children/Adolescents and Adults: Investigating Age and Sensitivity to Sham Stimulation

The Effects of 1 mA tACS and tRNS on Children/Adolescents and Adults: Investigating Age and Sensitivity to Sham Stimulation

Effects of beta-tACS on corticospinal excitability: A meta-analysis

Parametric study of transcranial alternating current stimulation for brain alpha power modulation

Contact Info

Product

Resources

About