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 Transcranial alternating current stimulation modulates auditory temporal resolution in elderly people

2017 ◽  
Author(s):  
Alina Baltus ◽  
Christoph Siegfried Herrmann
Keyword(s):  
Auditory Cortex ◽  
Elderly People ◽  
Temporal Resolution ◽  
Alternating Current ◽  
Detection Performance ◽  
Gap Detection ◽  
Gamma Frequency ◽  
Transcranial Alternating Current Stimulation ◽  
Gamma Frequencies ◽  
Auditory Temporal Resolution

AbstractRecent research provides evidence for a functional role of brain oscillations for perception. For example, auditory temporal resolution seems to be linked to individual gamma frequency of auditory cortex. Individual gamma frequency not only correlates with performance in between-channel gap detection tasks but can be modulated via auditory transcranial alternating current stimulation. Modulation of individual gamma frequency is accompanied by an improvement in gap detection performance. Aging changes electrophysiological frequency components and sensory processing mechanisms. Therefore, we conducted a study to investigate the link between individual gamma frequency and gap detection performance in elderly people using auditory transcranial alternating current stimulation. In a within-subject design, nine participants were electrically stimulated with two individualized transcranial alternating current stimulation frequencies: 3 Hz above their individual gamma frequency (experimental condition) and 4 Hz below their individual gamma frequency (control condition) while they were performing a between-channel gap detection task. As expected, individual gamma frequencies correlated significantly with gap detection performance at baseline and in the experimental condition, transcranial alternating current stimulation modulated gap detection performance. In the control condition, stimulation did not modulate gap detection performance. In addition, in elderly, the effect of transcranial alternating current stimulation on auditory temporal resolution seems to be dependent on endogenous frequencies in auditory cortex: elderlies with slower individual gamma frequencies and lower auditory temporal resolution profit from auditory transcranial alternating current stimulation and show increased gap detection performance during stimulation. Our results strongly suggest individualized transcranial alternating current stimulation protocols for successful modulation of performance.

scholarly journals Theta-gamma cross-frequency transcranial alternating current stimulation over the trough impairs cognitive control

2020 ◽  
Author(s):  
Zsolt Turi ◽  
Matthias Mittner ◽  
Albert Lehr ◽  
Hannah Bürger ◽  
Andrea Antal ◽  
...  
Keyword(s):  
Cognitive Control ◽  
Repeated Measures ◽  
Instrumental Learning ◽  
Learning Task ◽  
Alternating Current ◽  
Double Blind ◽  
Bayesian Hierarchical ◽  
Theta Wave ◽  
Gamma Frequency ◽  
Transcranial Alternating Current Stimulation

Cognitive control is a hypothetical mental process, which underlies adaptive goal-directed decisions. Previous studies have linked cognitive control to electrophysiological fluctuations in the theta band and theta-gamma cross-frequency coupling (CFC) arising from the cingulate and frontal cortices. Yet, to date the behavioral consequences of different forms of theta-gamma CFC remain elusive. Here, we studied the behavioral effects of the theta-gamma CFC via transcranial alternating current stimulation (tACS) designed to stimulate the frontal and cingulate cortices. Using a double-blind, randomized, repeated measures study design, 24 healthy participants were subjected to three main, active CFC-tACS protocols: Short gamma frequency bursts (80 Hz) were coupled to an ongoing theta cycle (4 Hz) to coincide with either the peaks or the troughs of the theta wave. In a third condition, the amplitude of the gamma oscillation was modulated by the phase of a theta cycle. In the fourth, control protocol, gamma was continuously superimposed over the theta cycle, therefore lacking any phase-specificity in the CFC. During the 20-minute stimulations, the participants performed a Go/NoGo monetary reward- and punishment-based instrumental learning task. A Bayesian hierarchical logistic regression analysis revealed that CFC-tACS over peak had no effects on the behavioral performance, whereas CFC-tACS over trough and, to a lesser extent, amplitude-modulated tACS reduced performance in conflicting trials. Our results suggest that cognitive control depends on the phase-specificity of the theta-gamma CFC.

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.

Modulation of auditory gamma-band responses using transcranial electrical stimulation

2020 ◽  
Vol 123 (6) ◽  
pp. 2504-2514
Author(s):  
Kevin T. Jones ◽  
Elizabeth L. Johnson ◽  
Zoe S. Tauxe ◽  
Donald C. Rojas
Keyword(s):  
Electrical Stimulation ◽  
Psychiatric Disorders ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Alternating Current ◽  
Transcranial Electrical Stimulation ◽  
Gamma Phase ◽  
Sham Stimulation ◽  
Gamma Frequency ◽  
Transcranial Alternating Current Stimulation

Gamma frequency-tuned transcranial alternating current stimulation (tACS) adjusts the magnitude and timing of auditory gamma responses, as compared with both sham stimulation and transcranial direct current stimulation (tDCS). However, both tACS and tDCS strengthen the gamma phase connectome, which is disrupted in numerous neurological and psychiatric disorders. These findings reveal dissociable neurophysiological changes following two noninvasive neurostimulation techniques commonly applied in clinical and research settings.

scholarly journals Disruption and rescue of interareal theta phase coupling and adaptive behavior

2017 ◽  
Vol 114 (43) ◽  
pp. 11542-11547 ◽  
Author(s):  
Robert M. G. Reinhart
Keyword(s):  
Executive Functions ◽  
Adaptive Behavior ◽  
Computer Training ◽  
Executive Dysfunction ◽  
Alternating Current ◽  
High Definition ◽  
Phase Coupling ◽  
Positive Effects ◽  
Transcranial Alternating Current Stimulation ◽  
Theta Phase

Rescuing executive functions in people with neurological and neuropsychiatric disorders has been a major goal of psychology and neuroscience for decades. Innovative computer-training regimes for executive functions have made tremendous inroads, yet the positive effects of training have not always translated into improved cognitive functioning and often take many days to emerge. In the present study, we asked whether it was possible to immediately change components of executive function by directly manipulating neural activity using a stimulation technology called high-definition transcranial alternating current stimulation (HD-tACS). Twenty minutes of inphase stimulation over medial frontal cortex (MFC) and right lateral prefrontal cortex (lPFC) synchronized theta (∼6 Hz) rhythms between these regions in a frequency and spatially specific manner and rapidly improved adaptive behavior with effects lasting longer than 40 min. In contrast, antiphase stimulation in the same individuals desynchronized MFC-lPFC theta phase coupling and impaired adaptive behavior. Surprisingly, the exogenously driven impairments in performance could be instantly rescued by reversing the phase angle of alternating current. The results suggest executive functions can be rapidly up- or down-regulated by modulating theta phase coupling of distant frontal cortical areas and can contribute to the development of tools for potentially normalizing executive dysfunction in patient populations.

PHASE SYNCHRONIZATION OF NEURONAL NOISE IN MOUSE HIPPOCAMPAL EPILEPTIFORM DYNAMICS

2012 ◽  
Vol 23 (01) ◽  
pp. 1250033 ◽  
Author(s):  
DEMITRE SERLETIS ◽  
PETER L. CARLEN ◽  
TAUFIK A. VALIANTE ◽  
BERJ L. BARDAKJIAN
Keyword(s):  
Phase Synchronization ◽  
Brain Activity ◽  
Phase Coupling ◽  
Intact Mouse ◽  
Frequency Bands ◽  
Gamma Frequency ◽  
Nonlinear Phase ◽  
Mouse Hippocampus ◽  
Show Evidence ◽  
Interictal State

Organized brain activity is the result of dynamical, segregated neuronal signals that may be used to investigate synchronization effects using sophisticated neuroengineering techniques. Phase synchrony analysis, in particular, has emerged as a promising methodology to study transient and frequency-specific coupling effects across multi-site signals. In this study, we investigated phase synchronization in intracellular recordings of interictal and ictal epileptiform events recorded from pairs of cells in the whole (intact) mouse hippocampus. In particular, we focused our analysis on the background noise-like activity (NLA), previously reported to exhibit complex neurodynamical properties. Our results show evidence for increased linear and nonlinear phase coupling in NLA across three frequency bands [theta (4–10 Hz), beta (12–30 Hz) and gamma (30–80 Hz)] in the ictal compared to interictal state dynamics. We also present qualitative and statistical evidence for increased phase synchronization in the theta, beta and gamma frequency bands from paired recordings of ictal NLA. Overall, our results validate the use of background NLA in the neurodynamical study of epileptiform transitions and suggest that what is considered "neuronal noise" is amenable to synchronization effects in the spatiotemporal domain.

scholarly journals Modulation of Long-Term Potentiation by Gamma Frequency Transcranial Alternating Current Stimulation in Transgenic Mouse Models of Alzheimer’s Disease

2021 ◽  
Vol 11 (11) ◽  
pp. 1532
Author(s):  
Won-Hyeong Jeong ◽  
Wang-In Kim ◽  
Jin-Won Lee ◽  
Hyeng-Kyu Park ◽  
Min-Keun Song ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Western Blot ◽  
Mouse Models ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Alternating Current ◽  
Wild Type ◽  
Gamma Frequency ◽  
Transcranial Alternating Current Stimulation ◽  
5Xfad Mice

Transcranial alternating current stimulation (tACS) is a neuromodulation procedure that is currently studied for the purpose of improving cognitive function in various diseases. A few studies have shown positive effects of tACS in Alzheimer’s disease (AD). However, the mechanism underlying tACS has not been established. The purpose of this study was to investigate the mechanism of tACS in five familial AD mutation (5xFAD) mouse models. We prepared twenty 4-month-old mice and divided them into four groups: wild-type mice without stimulation (WT-NT group), wild-type mice with tACS (WT-T group), 5xFAD mice without stimulation (AD-NT group), and 5xFAD mice with tACS (AD-T group). The protocol implemented was as follows: gamma frequency 200 μA over the bilateral frontal lobe for 20 min over 2 weeks. The following tests were conducted: excitatory postsynaptic potential (EPSP) recording, Western blot analysis (cyclic AMP response element-binding (CREB) proteins, phosphorylated CREB proteins, brain-derived neurotrophic factor, and parvalbumin) to examine the synaptic plasticity. The EPSP was remarkably increased in the AD-T group compared with in the AD-NT group. In the Western blot analysis, the differences among the groups were not significant. Hence, tACS can affect the long-lasting enhancement of synaptic transmission in mice models of AD.

scholarly journals Speaker-normalized vowel representations in the human auditory cortex

2018 ◽  
Author(s):  
Matthias J. Sjerps ◽  
Neal P. Fox ◽  
Keith Johnson ◽  
Edward F. Chang
Keyword(s):  
Auditory Cortex ◽  
Vocal Tract ◽  
Contextual Information ◽  
Critical Role ◽  
Speech Sound ◽  
Building Blocks ◽  
Speech Sounds ◽  
Preceding Context ◽  
Speech Cues ◽  
Linguistic Units

AbstractHumans identify speech sounds, the fundamental building blocks of spoken language, using the same cues, or acoustic dimensions, as those that differentiate the voices of different speakers. The correct interpretation of speech cues is hence uncertain, and requires normalizing to the specific speaker. Here we assess how the human brain uses speaker-related contextual information to constrain the processing of speech cues. Using high-density electrocorticography, we recorded local neural activity from the cortical surface of participants who were engaged in a speech sound identification task. The speech sounds were preceded by speech from different speakers whose voices differed along the same acoustic dimension that differentiated the target speech sounds (the first formant; the lowest resonance frequency of the vocal tract). We found that the same acoustic speech sound tokens were perceived differently, and evoked different neural responses in auditory cortex, when they were heard in the context of different speakers. Such normalization involved the rescaling of acoustic-phonetic representations of speech, demonstrating a form of recoding before the signal is mapped onto phonemes or higher level linguistic units. This process is the result of auditory cortex’ sensitivity to the contrast between the dominant frequencies in speech sounds and those in their just preceding context. These findings provide important insights into the mechanistic implementation of normalization in human listeners. Moreover, they provide the first direct evidence of speaker-normalized speech sound representations in human parabelt auditory cortex, highlighting its critical role in resolving variability in sensory signals.

scholarly journals Hearing through Your Eyes: Neural Basis of Audiovisual Cross-activation, Revealed by Transcranial Alternating Current Stimulation

2019 ◽  
Vol 31 (6) ◽  
pp. 922-935 ◽  
Author(s):  
Christopher Fassnidge ◽  
Danny Ball ◽  
Zainab Kazaz ◽  
Synøve Knudsen ◽  
Andrew Spicer ◽  
...  
Keyword(s):  
Visual Stimulation ◽  
Alternating Current ◽  
Auditory Modality ◽  
Neural Basis ◽  
Band Frequency ◽  
Gamma Frequency ◽  
Transcranial Alternating Current Stimulation ◽  
Sensory Cortices ◽  
40 Hz ◽  
A Performance

Some people experience auditory sensations when seeing visual flashes or movements. This prevalent synaesthesia-like visually evoked auditory response (vEAR) could result either from overexuberant cross-activation between brain areas and/or reduced inhibition of normally occurring cross-activation. We have used transcranial alternating current stimulation (tACS) to test these theories. We applied tACS at 10 Hz (alpha band frequency) or 40 Hz (gamma band), bilaterally either to temporal or occipital sites, while measuring same/different discrimination of paired auditory (A) versus visual (V) Morse code sequences. At debriefing, participants were classified as vEAR or non-vEAR, depending on whether they reported “hearing” the silent flashes. In non-vEAR participants, temporal 10-Hz tACS caused impairment of A performance, which correlated with improved V; conversely under occipital tACS, poorer V performance correlated with improved A. This reciprocal pattern suggests that sensory cortices are normally mutually inhibitory and that alpha-frequency tACS may bias the balance of competition between them. vEAR participants showed no tACS effects, consistent with reduced inhibition, or enhanced cooperation between modalities. In addition, temporal 40-Hz tACS impaired V performance, specifically in individuals who showed a performance advantage for V (relative to A). Gamma-frequency tACS may therefore modulate the ability of these individuals to benefit from recoding flashes into the auditory modality, possibly by disrupting cross-activation of auditory areas by visual stimulation. Our results support both theories, suggesting that vEAR may depend on disinhibition of normally occurring sensory cross-activation, which may be expressed more strongly in some individuals. Furthermore, endogenous alpha- and gamma-frequency oscillations may function respectively to inhibit or promote this cross-activation.

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