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 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.

Optimized auditory transcranial alternating current stimulation improves individual auditory temporal resolution

2018 ◽  
Vol 11 (1) ◽  
pp. 118-124 ◽  
Author(s):  
Alina Baltus ◽  
Sven Wagner ◽  
Carsten Hermann Wolters ◽  
Christoph Siegfried Herrmann
Keyword(s):  
Temporal Resolution ◽  
Alternating Current ◽  
Transcranial Alternating Current Stimulation ◽  
Auditory Temporal Resolution

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.

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 Synaptic Recruitment Enhances Gap Termination Responses in Auditory Cortex

2020 ◽  
Vol 30 (8) ◽  
pp. 4465-4480 ◽  
Author(s):  
Bshara Awwad ◽  
Maciej M Jankowski ◽  
Israel Nelken
Keyword(s):  
Auditory Cortex ◽  
Temporal Resolution ◽  
Perceptual Task ◽  
Gap Detection ◽  
Intracellular Recordings ◽  
Short Term ◽  
Mere Existence ◽  
Onset Response ◽  
Synaptic Mechanisms

Abstract The ability to detect short gaps in noise is an important tool for assessing the temporal resolution in the auditory cortex. However, the mere existence of responses to temporal gaps bounded by two short broadband markers is surprising, because of the expected short-term suppression that is prevalent in auditory cortex. Here, we used in-vivo intracellular recordings in anesthetized rats to dissect the synaptic mechanisms that underlie gap-related responses. When a gap is bounded by two short markers, a gap termination response was evoked by the onset of the second marker with minimal contribution from the offset of the first marker. Importantly, we show that the gap termination response was driven by a different (potentially partially overlapping) synaptic population than that underlying the onset response to the first marker. This recruitment of additional synaptic resources is a novel mechanism contributing to the important perceptual task of gap detection.

scholarly journals Investigating the effects of transcranial alternating current stimulation on primary somatosensory cortex

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nicoletta Manzo ◽  
Andrea Guerra ◽  
Margherita Giangrosso ◽  
Daniele Belvisi ◽  
Giorgio Leodori ◽  
...  
Keyword(s):  
Somatosensory Cortex ◽  
Alternating Current ◽  
Primary Somatosensory Cortex ◽  
Alpha Frequency ◽  
Tactile Stimuli ◽  
Frequency Peak ◽  
Transcranial Alternating Current Stimulation ◽  
Gamma Frequencies ◽  
Alpha Beta ◽  
Near Threshold

Abstract Near-threshold tactile stimuli perception and somatosensory temporal discrimination threshold (STDT) are encoded in the primary somatosensory cortex (S1) and largely depend on alpha and beta S1 rhythm. Transcranial alternating current stimulation (tACS) is a non-invasive neurophysiological technique that allows cortical rhythm modulation. We investigated the effects of tACS delivered over S1 at alpha, beta, and gamma frequencies on near-threshold tactile stimuli perception and STDT, as well as phase-dependent tACS effects on near-threshold tactile stimuli perception in healthy subjects. In separate sessions, we tested the effects of different tACS montages, and tACS at the individualised S1 μ-alpha frequency peak, on STDT and near-threshold tactile stimuli perception. We found that tACS applied over S1 at alpha, beta, and gamma frequencies did not modify STDT or near-threshold tactile stimuli perception. Moreover, we did not detect effects of tACS phase or montage. Finally, tACS did not modify near-threshold tactile stimuli perception and STDT even when delivered at the individualised μ-alpha frequency peak. Our study showed that tACS does not alter near-threshold tactile stimuli or STDT, possibly due to the inability of tACS to activate deep S1 layers. Future investigations may clarify tACS effects over S1 in patients with focal dystonia, whose pathophysiology implicates increased STDT.

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.

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