P195 Cerebellar alpha transcranial alternating current stimulation (tACS) leads to motor learning deficits and modulation of oscillatory alpha power

Developing effective tools and strategies to promote motor learning is a high-priority scientific and clinical goal. In particular, motor-related areas have been investigated as potential targets to facilitate motor learning by noninvasive brain stimulation (NIBS). In addition to shedding light on the relationship between motor function and oscillatory brain activity, transcranial alternating current stimulation (tACS), which can noninvasively entrain oscillatory brain activity and modulate oscillatory brain communication, has attracted attention as a possible technique to promote motor learning. This review focuses on the use of tACS to enhance motor learning through the manipulation of oscillatory brain activity and its potential clinical applications. We discuss a potential tACS–based approach to ameliorate motor deficits by correcting abnormal oscillatory brain activity and promoting appropriate oscillatory communication in patients after stroke or with Parkinson’s disease. Interpersonal tACS approaches to manipulate intra- and inter-brain communication may result in pro-social effects and could promote the teaching–learning process during rehabilitation sessions with a therapist. The approach of re-establishing oscillatory brain communication through tACS could be effective for motor recovery and might eventually drive the design of new neurorehabilitation approaches based on motor learning.

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Local network-level integration mediates effects of transcranial Alternating Current Stimulation

10.1101/216176 ◽

2017 ◽

Author(s):

Marco Fuscà ◽

Philipp Ruhnau ◽

Toralf Neuling ◽

Nathan Weisz

Keyword(s):

Occipital Cortex ◽

Alternating Current ◽

Functional Network ◽

Local Network ◽

Oscillatory Activity ◽

Alpha Power ◽

State Dependency ◽

External Stimulation ◽

Posterior Cingulate ◽

Transcranial Alternating Current Stimulation

AbstractTranscranial alternating current stimulation (tACS) has been proposed as a tool to draw causal inferences on the role of oscillatory activity in cognitive functioning and has the potential to induce long-term changes in cerebral networks. However, the mechanisms of action of tACS are not yet clear, though previous modeling works have suggested that variability may be mediated by local and network-level brain states. We used magnetoencephalography (MEG) to record brain activity from 17 healthy participants as they kept their eyes open (EO) or closed (EC) while being stimulated either with sham, weak, or strong alpha-tACS using a montage commonly assumed to target occipital areas. We reconstructed the activity of sources in all stimulation conditions by means of beamforming. The analysis of resting-state data revealed an interaction of the external stimulation with the endogenous alpha power difference between EO and EC in the posterior cingulate. This region is remote from occipital cortex, which showed strongest EC vs. EO alpha modulation, thus suggesting state-dependency long-range effects of tACS. In a follow-up analysis of this online-tACS effect, we find evidence that this dependency effect could be mediated by functional network changes: connection strength from the precuneus, a region adjusting for a measure of network integration in the two states (EC vs. EO during no-tACS), was significantly correlated with the state-dependency effect in the posterior cingulate (during tACS). No analogous correlation could be found for alpha power modulations in occipital cortex. Altogether, this is the first strong evidence to illustrate how functional network architectures can shape tACS effects.

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Transcranial Alternating Current Stimulation Has Frequency-Dependent Effects on Motor Learning in Healthy Humans

Neuroscience ◽

10.1016/j.neuroscience.2019.05.041 ◽

2019 ◽

Vol 411 ◽

pp. 130-139 ◽

Cited By ~ 8

Author(s):

Matteo Bologna ◽

Andrea Guerra ◽

Giulia Paparella ◽

Donato Colella ◽

Alessandro Borrelli ◽

...

Keyword(s):

Motor Learning ◽

Alternating Current ◽

Frequency Dependent ◽

Healthy Humans ◽

Transcranial Alternating Current Stimulation

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Effects on motor learning of transcranial alternating current stimulation applied over the primary motor cortex and cerebellar hemisphere

Journal of Clinical Neuroscience ◽

10.1016/j.jocn.2020.05.024 ◽

2020 ◽

Vol 78 ◽

pp. 296-300

Author(s):

Shota Miyaguchi ◽

Yasuto Inukai ◽

Yuya Matsumoto ◽

Mai Miyashita ◽

Ryo Takahashi ◽

...

Keyword(s):

Motor Cortex ◽

Motor Learning ◽

Primary Motor Cortex ◽

Alternating Current ◽

Cerebellar Hemisphere ◽

Transcranial Alternating Current Stimulation

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Ameliorating Emotional Attention through Modulation of Neural Oscillations with Transcranial Alternating Current Stimulation

10.1101/2021.03.08.434260 ◽

2021 ◽

Author(s):

Shuang Liu ◽

Yuchen He ◽

Dongyue Guo ◽

Xiaoya Liu ◽

Xinyu Hao ◽

...

Keyword(s):

Emotional Processing ◽

Emotion Processing ◽

Alternating Current ◽

Event Related Potential ◽

Facial Emotion ◽

Alpha Power ◽

Emotion Identification ◽

Transcranial Alternating Current Stimulation ◽

Emotional Attention ◽

P200 Amplitude

AbstractBackgroundNumerous clinical reports suggest that psychopathy like schizophrenia, anxiety and depressive disorder is accompanied by early attentional abnormalities in emotional information processing. In the past decade, the efficacy of transcranial alternating current stimulation (tACS) in changing emotional functioning has been repeatedly observed and has demonstrated a causal relationship between endogenous oscillations and emotional processing. However, tACS effects on emotional attention have not yet been tested.MethodsA total of 53 healthy participants were randomized to 2 groups, and they were subjected to active or sham tACS at individual alpha frequency (IAF) in the bilaterally dorsolateral prefrontal cortex (dlPFC). Participants and received this treatment for 20 min durations daily for 7 consecutive days. On days 1 and 7, electroencephalogram (EEG) recording of 8 minute resting with eyes open and closed. Responses to a facial emotion identification task were also recorded to measure alpha changes and event-related potential (ERP) alterations.ResultsOn day 7 after tACS, the active group showed a more clear elevation in alpha power at rest, especially in open state around stimulation area, compared to the sham group. ERPs revealed a significant larger P200 amplitude after active stimulation (p < 0.05), indicating attentional improvement in facial emotion processing. Additionally, a notable positive correlation (p < 0.05) between alpha power and P200 amplitude was found, providing an electrophysiological interpretation regarding the role of tACS in emotional attention modulation. In addition, the IAF-tACS showed an obvious advantage in alpha entrainment compared to an additional 10 Hz-tACS.ConclusionsThese results support a seminal outcome for the effect of IAF-tACS on emotional attention modulation, demonstrating a feasible and individual-specific therapy for neuropsychiatric disorders related to emotion processing, especially regarding oscillatory disturbances.

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A Comparison of Closed Loop vs. Fixed Frequency tACS on Modulating Brain Oscillations and Visual Detection

Frontiers in Human Neuroscience ◽

10.3389/fnhum.2021.661432 ◽

2021 ◽

Vol 15 ◽

Author(s):

Heiko I. Stecher ◽

Annika Notbohm ◽

Florian H. Kasten ◽

Christoph S. Herrmann

Keyword(s):

Closed Loop ◽

Alternating Current ◽

Alpha Activity ◽

Stimulation Frequency ◽

Alpha Power ◽

Brain Oscillations ◽

Stimulation Protocol ◽

Fixed Frequency ◽

Transcranial Alternating Current Stimulation ◽

Synaptic Changes

Transcranial alternating current stimulation has emerged as an effective tool for the exploration of brain oscillations. By applying a weak alternating current between electrodes placed on the scalp matched to the endogenous frequency, tACS enables the specific modulation of targeted brain oscillations This results in alterations in cognitive functions or persistent physiological changes. Most studies that utilize tACS determine a fixed stimulation frequency prior to the stimulation that is kept constant throughout the experiment. Yet it is known that brain rhythms can encounter shifts in their endogenous frequency. This could potentially move the ongoing brain oscillations into a frequency region where it is no longer affected by the stimulation, thereby decreasing or negating the effect of tACS. Such an effect of a mismatch between stimulation frequency and endogenous frequency on the outcome of stimulation has been shown before for the parietal alpha-activity. In this study, we employed an intermittent closed loop stimulation protocol, where the stimulation is divided into short epochs, between which an EEG is recorded and rapidly analyzed to determine a new stimulation frequency for the next stimulation epoch. This stimulation protocol was tested in a three-group study against a classical fixed stimulation protocol and a sham-treatment. We targeted the parietal alpha rhythm and hypothesized that this setup will ensure a constant close match between the frequencies of tACS and alpha activity. This closer match should lead to an increased modulation of detection of visual luminance changes depending on the phase of the tACS and an increased rise in alpha peak power post stimulation when compared to a protocol with fixed pre-determined stimulation frequency. Contrary to our hypothesis, our results show that only a fixed stimulation protocol leads to a persistent increase in post-stimulation alpha power as compared to sham. Furthermore, in none of the stimulated groups significant modulation of detection performance occurred. While the lack of behavioral effects is inconclusive due to the short selection of different phase bins and trials, the physiological results suggest that a constant stimulation with a fixed frequency is actually beneficial, when the goal is to produce persistent synaptic changes.

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