Bifocal tACS over the primary sensorimotor cortices increases interhemispheric inhibition and improves bimanual dexterity

Cerebral Cortex, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 3, 2025

Abstract Concurrent application of transcranial alternating current stimulation over distant cortical regions has been shown to modulate functional connectivity between stimulated regions; however, the precise mechanisms remain unclear. Here, we investigated how bifocal applied bilateral primary sensorimotor cortices modulates left and right motor (M1). Using a cross-over sham-controlled triple-blind design, 37 (27 female, age: 18 yrs) healthy participants received (1.0 mA, 20 Hz, min) cortices. Before after stimulation, M1s was assessed using imaginary coherence measured via resting-state electroencephalography interhemispheric inhibition dual-site magnetic protocol. Additionally, manual dexterity Purdue pegboard task. While remained unchanged beta (20 Hz) power decreased during session. Bifocal but not sham strengthened improved bimanual assembly performance. These results suggest that improvement in performance may be explained by modulation inhibition, rather than coupling oscillatory activity. As underlies many clinical symptoms neurological psychiatric disorders, these findings are invaluable developing noninvasive therapeutic interventions target neural networks alleviate symptoms.

Language: Английский

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Modulating Cortico-Cortical Networks with Transcranial Alternating Current Stimulation: A Minireview

Physical Therapy Research, Journal Year: 2025, Volume and Issue: 28(1), P. 1 - 8

Published: Jan. 1, 2025

Advancements in brain imaging and analytical methods have demonstrated that behavior arises from the coordinated activity of multiple regions within cortico-cortical networks. Transcranial alternating current stimulation (tACS), a noninvasive (NIBS) technique, applies weak sinusoidal currents to specific using scalp-mounted electrodes. Traditionally, tACS has been used target single enhance functions such as motor, sensory, cognitive abilities. However, recent findings indicate its potential for simultaneously stimulating 2 regions, thereby modulating network strength through neural entrainment-where oscillations synchronize with external rhythmic stimuli. Despite this potential, applications remain primarily focused on individual regions. Given stems dynamic interactions networks rather than isolated minireview explores role these shaping functional connectivity identified by neuroimaging. It also provides an in-depth analysis tool modifying via entrainment, offering promising neurorehabilitation disorders linked dysfunction. This highlights novel approach targeted modulation networks, distinguishing it traditional NIBS techniques.

Language: Английский

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Predictive role of endogenous phase lags between target brain regions in dual-site transcranial alternating current stimulation

Brain stimulation, Journal Year: 2025, Volume and Issue: 18(3), P. 780 - 793

Published: April 11, 2025

Dual-site transcranial alternating current stimulation (tACS) provides a promising tool for modulating interregional brain connectivity by entraining neural oscillations. However, prior studies have reported inconsistent effects on and behavioral outcomes. They often focused individualized stimulation-frequency as key entrainment factor, while typically not focusing the role of endogenous phase lags. To address this gap, we explored predictive value lags in dual-site tACS to modulate interhemispheric during dichotic listening. Thirty healthy participants (16 females) completed listening task undergoing simultaneous electroencephalography tACS, including four bitemporal verum conditions with varying (0°, 45°, 90°, 180°), sham condition across five sessions. Each session involved 20 min 40-Hz at 0.5 mA peak-to-baseline amplitude applied temporal regions, differing Endogenous between auditory cortices were calculated explain changes laterality index (LI) defining optimal disruptive each participant. Consistent our hypothesis, personalized analysis based showed significantly lower LI closest (optimal) compared both farthest (disruptive) conditions. Conversely, did statistically increase sham. These findings highlight importance incorporating dynamics into protocols, paving way more consistent neuromodulatory interventions.

Language: Английский

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Dual‐Site Beta tACS Over the rIFG and preSMA‐Induced Phase‐Specific Changes in Functional Connectivity but not Response Inhibition Performance in Older Adults

Psychophysiology, Journal Year: 2025, Volume and Issue: 62(5)

Published: May 1, 2025

ABSTRACT Research suggests that changes in functional connectivity contribute to age‐related declines response inhibition. Through a double‐blind crossover study, we investigated the effects of dual‐site beta transcranial alternating current stimulation (tACS) over right inferior frontal gyrus (rIFG) and pre‐supplementary motor area (preSMA) on measured with electroencephalography inhibition (stop‐signal task performance) 15 older (aged 61–79 years) 18 young 18–34 adults. Two tACS conditions were administered separate sessions: in‐phase tACS, where electrical currents delivered rIFG preSMA had 0° phase difference, anti‐phase 180° difference. Resting‐state band rIFG‐preSMA significantly increased after for adults decreased Response improved both in‐ These findings suggest can potentially modulate phase‐specific manner aging brain, inhibitory performance might not be directly regulated by resting‐state connectivity. Due lack sham control, placebo cannot ruled out. However, differing neurophysiological from is unlikely underpin performance. Future studies incorporating control are required verify these findings.

Language: Английский

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Repeated application of bifocal transcranial alternating current stimulation improves network connectivity but not response inhibition: a double-blind sham control study.

Cerebral Cortex, Journal Year: 2025, Volume and Issue: 35(5)

Published: May 1, 2025

Mounting evidence suggests that transcranial alternating current stimulation can enhance response inhibition, a cognitive process crucial for sustained effort and decision-making. However, most studies have focused on within-session effects, with limited investigation into the effects of repeated applications, which are clinical applications. We examined bifocal targeting right inferior frontal gyrus pre-supplementary motor area functional connectivity, simulated driving performance. Thirty young adults (18-35 yr) received either sham or (20 Hz, 20 min) across 5 sessions over 2 wk. Resting-state electroencephalography assessed connectivity between at baseline, final session, 7-d follow-up. Response inhibition was measured using stop-signal task, performance before after intervention. The results showed significant improvements in group sessions, though braking remained unchanged. while not targeted behavior, general potentially improved following stimulation, participants maintaining stable behavior alongside increased spare attentional capacity. These findings suggest may cortical related cognitive-motor processes, supporting its potential

Language: Английский

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A bibliometric analysis of transcranial alternating current stimulation

Frontiers in Neuroscience, Journal Year: 2024, Volume and Issue: 18

Published: Aug. 2, 2024

Transcranial alternating current stimulation (tACS) can apply currents of varying intensity to the scalp, modulating cortical excitability and brain activity. tACS is a relatively new neuromodulation intervention that now widely used in clinical practice. Many papers related have been published various journals. However, there are no articles objectively directly introduce development trend research hotspots tACS. Therefore, aim this study use CiteSpace visually analyze recent tACS-related publications, systematically detail summarize trends field, provide valuable information for future research.

Language: Английский

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Immediate Modulation of the Blood Oxygenation Level-Dependent Signals by Dual-Site Transcranial Alternating Current Stimulation Propagates Across the Whole Brain

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 5, 2024

Abstract Transcranial alternating current stimulation (tACS) is assumed to target specific brain regions and modulate their activity. Recent discussions of tACS propose that, entraining the phase activity current, effects extend globally across whole based on differences. However, immediate online spatiotemporal propagation resting-state blood oxygenation level-dependent (BOLD) signals within due multi-region remains unclear. The objectives present study were three-fold: 1) elucidate effect BOLD signal, 2) examine extent influence when applying tACS, 3) explore whether variations in difference between two result differential stimulated areas brain. Through experiments involving high-definition with simultaneous measurements using a functional magnetic resonance imaging (fMRI), we revealed that not only altered but also propagated patterns (functional networks). Stimulation observed specifically rich neural fibres, including grey white matter, no containing cerebrospinal fluid. timing signal value peaks depended region networks, notable trend observed. Thus, anatomically connected can immediately dynamics at both local global scales. Graphical abstract

Language: Английский

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Beta tACS of varying intensities differentially affect resting-state and movement-related M1-M1 connectivity

Frontiers in Neuroscience, Journal Year: 2024, Volume and Issue: 18

Published: Sept. 20, 2024

Due to the interconnected nature of brain, changes in one region are likely affect other structurally and functionally connected regions. Emerging evidence indicates that single-site transcranial alternating current stimulation (tACS) can modulate functional connectivity between stimulated unstimulated brain However, our understanding network response tACS is incomplete. Here, we investigated effect beta different intensities on phase-based left right primary motor cortices 21 healthy young adults (13 female; mean age 24.30 ± 4.84 years). Participants underwent four sessions 20 min Hz varying (sham, 0.5 mA, 1.0 or 1.5 mA) applied cortex at rest. We recorded resting-state event-related electroencephalography (EEG) before after tACS, analyzing sensorimotor (13–30 Hz) imaginary coherence (ImCoh), an index connectivity. Event-related EEG captured movement-related activity as participants performed self-paced button presses using their finger. For connectivity, observed intensity-dependent ImCoh: sham mA resulted increase ImCoh, while decreased ImCoh. broadband ImCoh (4–90 during movement execution. None significantly modulated preparation, execution, termination. Interestingly, preparation following were associated with participants’ pre-tACS peak frequency, suggesting alignment frequency affected extent neuromodulation. Collectively, these results suggest a single site influences within manner depends intensity stimulation. These findings have significant implications for both research clinical applications.

Language: Английский

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Dual-site transcranial alternating current stimulation over the primary motor cortices increases interhemispheric inhibition and improves bimanual dexterity: A triple-blind, randomised, sham-controlled study

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: Oct. 30, 2024

Abstract Concurrent application of transcranial alternating current stimulation (tACS) over distant cortical regions has been shown to modulate functional connectivity between stimulated regions; however, the precise mechanisms remain unclear. Here, we investigated how dual-site tACS (ds-tACS) applied bilateral primary motor cortices (M1s) modulates M1s. Using a cross-over sham-controlled triple-blind within- subject design, 37 (27 female, age 18-37yrs) healthy participants received (1.0mA, 20Hz) M1s for 20 min. Before and after tACS, was assessed using imaginary coherence (ImCoh) measured via resting-state electroencephalography (EEG) interhemispheric inhibition (IHI) magnetic (TMS) protocol. Additionally, manual dexterity Purdue pegboard task. While ImCoh remained unchanged simulation, spectral power analysis showed significant decrease in beta (20 Hz) during session. ds-tACS but not sham strengthened IHI improved bimanual assembly performance. These results suggest that improvement performance may be explained by modulation M1-M1 IHI, rather than coupling oscillatory activity. As underlies many clinical symptoms neurological psychiatric disorders, these findings are invaluable developing non-invasive therapeutic interventions target neural networks alleviate symptoms.

Language: Английский

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Effects of repetitive transcranial magnetic stimulation combined with cognitive training for improving response inhibition: A proof-of-concept, single-blind randomised controlled study

Behavioural Brain Research, Journal Year: 2024, Volume and Issue: 480, P. 115372 - 115372

Published: Dec. 4, 2024

Language: Английский

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