scholarly journals How to target inter-regional phase synchronization with dual-site Transcranial Alternating Current Stimulation

NeuroImage ◽  
2017 ◽  
Vol 163 ◽  
pp. 68-80 ◽  
Author(s):  
Guilherme Bicalho Saturnino ◽  
Kristoffer Hougaard Madsen ◽  
Hartwig Roman Siebner ◽  
Axel Thielscher
Keyword(s):  
Phase Synchronization ◽  
Alternating Current ◽  
Transcranial Alternating Current Stimulation ◽  
Dual Site

scholarly journals Transcranial Alternating Current Stimulation (tACS) Entrains Alpha Oscillations by Preferential Phase Synchronization of Fast-Spiking Cortical Neurons to Stimulation Waveform

2019 ◽  
Author(s):  
Ehsan Negahbani ◽  
Iain M. Stitt ◽  
Marshall Davey ◽  
Thien T. Doan ◽  
Moritz Dannhauer ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Cortical Neurons ◽  
Posterior Parietal Cortex ◽  
Phase Synchronization ◽  
Alternating Current ◽  
Arnold Tongue ◽  
Transcranial Alternating Current Stimulation ◽  
Neuronal Oscillators

SummaryModeling studies predict that transcranial alternating current stimulation (tACS) entrains brain oscillations, yet direct examination has been lacking or potentially contaminated by stimulation artefact. Here we first demonstrate how the posterior parietal cortex drives primary visual cortex and thalamic LP in the alpha-band in head-fixed awake ferrets. The spike-field synchrony is maximum within alpha frequency, and more prominent for narrow-spiking neurons than broad-spiking ones. Guided by a validated model of electric field distribution, we produced electric fields comparable to those in humans and primates (< 0.5 mV/mm). We found evidence to support the model-driven predictions of how tACS entrains neural oscillations as explained by the triangular Arnold tongue pattern. In agreement with the stronger spike-field coupling of narrow-spiking cells, tACS more strongly entrained this cell population. Our findings provide the firstin vivoevidence of how tACS with electric field amplitudes used in human studies entrains neuronal oscillators.

scholarly journals Bilateral Gamma/Delta Transcranial Alternating Current Stimulation Affects Interhemispheric Speech Sound Integration

2020 ◽  
Vol 32 (7) ◽  
pp. 1242-1250 ◽  
Author(s):  
Basil C. Preisig ◽  
Matthias J. Sjerps ◽  
Alexis Hervais-Adelman ◽  
Anne Kösem ◽  
Peter Hagoort ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Phase Synchronization ◽  
Speech Sound ◽  
Alternating Current ◽  
Phase Lag ◽  
Disruptive Effect ◽  
Phase Coupling ◽  
Gamma Frequency ◽  
Transcranial Alternating Current Stimulation ◽  
Speech Cues

Perceiving speech requires the integration of different speech cues, that is, formants. When the speech signal is split so that different cues are presented to the right and left ear (dichotic listening), comprehension requires the integration of binaural information. Based on prior electrophysiological evidence, we hypothesized that the integration of dichotically presented speech cues is enabled by interhemispheric phase synchronization between primary and secondary auditory cortex in the gamma frequency band. We tested this hypothesis by applying transcranial alternating current stimulation (TACS) bilaterally above the superior temporal lobe to induce or disrupt interhemispheric gamma-phase coupling. In contrast to initial predictions, we found that gamma TACS applied in-phase above the two hemispheres (interhemispheric lag 0°) perturbs interhemispheric integration of speech cues, possibly because the applied stimulation perturbs an inherent phase lag between the left and right auditory cortex. We also observed this disruptive effect when applying antiphasic delta TACS (interhemispheric lag 180°). We conclude that interhemispheric phase coupling plays a functional role in interhemispheric speech integration. The direction of this effect may depend on the stimulation frequency.

scholarly journals Spike-timing-dependent plasticity can account for aftereffects of dual-site transcranial alternating current stimulation

2020 ◽  
Author(s):  
Bettina C. Schwab ◽  
Peter König ◽  
Andreas K. Engel
Keyword(s):  
Computational Models ◽  
Alternating Current ◽  
Spike Timing ◽  
Spike Timing Dependent Plasticity ◽  
Dependent Plasticity ◽  
Eeg Data ◽  
Transcranial Alternating Current Stimulation ◽  
Eeg Connectivity ◽  
Phase Lags ◽  
Dual Site

AbstractBackgroundTranscranial alternating current stimulation (tACS), applied to two brain sites with different phase lags, has been shown to modulate stimulation-outlasting functional connectivity between the targeted regions.ObjectiveHere, we test if spike-timing-dependent plasticity (STDP) can explain stimulation-outlasting connectivity modulation by dual-site tACS and explore the effects of tACS parameter choices.MethodsNetworks with two populations of spiking neurons were simulated. Synapses between the populations were subject to STDP. We re-analyzed resting-state EEG data to validate the model.ResultsSimulations showed stimulation-outlasting connectivity changes between in- and anti-phase tACS, dependent on both tACS frequency and conduction delays. Importantly, the model predicted that the largest effects would occur for short conduction delays between the stimulated regions, which agreed with experimental EEG connectivity modulation by 10 Hz tACS.ConclusionSTDP can explain connectivity aftereffects of dual-site tACS. However, not all combinations of tACS frequency and application sites are expected to effectively modulate connectivity via STDP. We therefore suggest using appropriate computational models and/or EEG analysis for planning and interpretation of dualsite tACS studies relying on aftereffects.

scholarly journals Transcranial alternating current stimulation entrains alpha oscillations by preferential phase synchronization of fast-spiking cortical neurons to stimulation waveform

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wei A. Huang ◽  
Iain M. Stitt ◽  
Ehsan Negahbani ◽  
D. J. Passey ◽  
Sangtae Ahn ◽  
...  
Keyword(s):  
Computational Model ◽  
Cortical Neurons ◽  
Phase Synchronization ◽  
Alternating Current ◽  
Inhibitory Interneurons ◽  
Alpha Oscillations ◽  
Alpha Oscillation ◽  
Transcranial Alternating Current Stimulation ◽  
Fast Spiking ◽  
Cortical System

AbstractComputational modeling and human studies suggest that transcranial alternating current stimulation (tACS) modulates alpha oscillations by entrainment. Yet, a direct examination of how tACS interacts with neuronal spiking activity that gives rise to the alpha oscillation in the thalamo-cortical system has been lacking. Here, we demonstrate how tACS entrains endogenous alpha oscillations in head-fixed awake ferrets. We first show that endogenous alpha oscillations in the posterior parietal cortex drive the primary visual cortex and the higher-order visual thalamus. Spike-field coherence is largest for the alpha frequency band, and presumed fast-spiking inhibitory interneurons exhibit strongest coupling to this oscillation. We then apply alpha-tACS that results in a field strength comparable to what is commonly used in humans (<0.5 mV/mm). Both in these ferret experiments and in a computational model of the thalamo-cortical system, tACS entrains alpha oscillations by following the theoretically predicted Arnold tongue. Intriguingly, the fast-spiking inhibitory interneurons exhibit a stronger entrainment response to tACS in both the ferret experiments and the computational model, likely due to their stronger endogenous coupling to the alpha oscillation. Our findings demonstrate the in vivo mechanism of action for the modulation of the alpha oscillation by tACS.

scholarly journals Dual-site high-density 4Hz transcranial alternating current stimulation applied over auditory and motor cortical speech areas does not influence auditory-motor mapping

2019 ◽  
Author(s):  
Basil Preisig ◽  
Matthias J. Sjerps ◽  
Anne Kösem ◽  
Lars Riecke
Keyword(s):  
Low Frequency ◽  
Alternating Current ◽  
High Density ◽  
Phase Coupling ◽  
Motor Mapping ◽  
Oscillatory Phase ◽  
Transcranial Alternating Current Stimulation ◽  
Theta Phase ◽  
Verbal Repetition ◽  
Dual Site

AbstractBackgroundVerbal repetition of auditory speech requires the mapping of a sensory acoustic input onto articulatory motor plans (auditory-motor mapping). Recent evidence indicates that auditory-motor mapping could rely on low frequency neural synchronization (i.e., theta oscillatory phase coupling) between sensory and motor speech areas.ObjectiveIn the present study, we apply dual-site high-density (HD) Transcranial Alternating Current Stimulation (TACS) above the auditory and motor cortex to induce, or disrupt, theta phase coupling between the two areas. We predicted that functionally coupling the two areas would strengthen auditory-motor mapping, compared with functionally decoupling them. We assessed the strength of auditory-motor mapping using a verbal repetition task.ResultsWe found no significant effect of TACS-induced theta phase coupling on auditory-motor mapping as indexed by verbal repetition performance.ConclusionAuditory-motor mapping may rely on a different mechanism than we hypothesized, for example, oscillatory phase-coupling outside the theta range. Alternatively, modulation of interregional theta-phase coupling may require more effective stimulation protocols, for example, TACS at higher intensities.

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