scholarly journals Bilateral Transcranial Direct Current Stimulation Reshapes Resting-State Brain Networks: A Magnetoencephalography Assessment

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Giovanni Pellegrino ◽  
Matteo Maran ◽  
Cristina Turco ◽  
Luca Weis ◽  
Giovanni Di Pino ◽  
...  
Keyword(s):  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Resting State ◽  
Brain Plasticity ◽  
Brain Networks ◽  
Network Activity ◽  
Double Blind Study ◽  
Double Blind ◽  
Direct Current Stimulation ◽  
Alpha Beta

Transcranial direct current stimulation (tDCS) can noninvasively induce brain plasticity, and it is potentially useful to treat patients affected by neurological conditions. However, little is known about tDCS effects on resting-state brain networks, which are largely involved in brain physiological functions and in diseases. In this randomized, sham-controlled, double-blind study on healthy subjects, we have assessed the effect of bilateral tDCS applied over the sensorimotor cortices on brain and network activity using a whole-head magnetoencephalography system. Bilateral tDCS, with the cathode (−) centered over C4 and the anode (+) centered over C3, reshapes brain networks in a nonfocal fashion. Compared to sham stimulation, tDCS reduces left frontal alpha, beta, and gamma power and increases global connectivity, especially in delta, alpha, beta, and gamma frequencies. The increase of connectivity is consistent across bands and widespread. These results shed new light on the effects of tDCS and may be of help in personalizing treatments in neurological disorders.

scholarly journals Brain state and polarity dependent modulation of brain networks by transcranial direct current stimulation

2017 ◽  
Author(s):  
Lucia M. Li ◽  
Ines R. Violante ◽  
Rob Leech ◽  
Ewan Ross ◽  
Adam Hampshire ◽  
...  
Keyword(s):  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Large Scale ◽  
Inferior Frontal Gyrus ◽  
Brain Networks ◽  
Cognitive Networks ◽  
Network Activity ◽  
Brain State ◽  
Direct Current Stimulation ◽  
Network Activation

AbstractTranscranial direct current stimulation (TDCS) has been widely used to improve cognitive function. However, current deficiencies in mechanistic understanding hinders wider applicability. To clarify its physiological effects, we acquired fMRI whilst simultaneously acquiring TDCS to the right inferior frontal gyrus (rIFG) of healthy human participants, a region involved in coordinating activity within brain networks. TDCS caused widespread modulation of network activity depending on brain state (‘rest’ or choice reaction time task) and polarity (anodal or cathodal). During task, TDCS increased salience network activation and default mode network deactivation, but had the opposite effect during ‘rest’. Furthermore, there was an interaction between brain state and TDCS polarity, with cathodal effects more pronounced during task performance and anodal effects more pronounced during ‘rest’. Overall, we show that rIFG TDCS produces brain state and polarity dependent effects within large-scale cognitive networks, in a manner that goes beyond predictions from the current literature.

scholarly journals Transcranial direct current stimulation above the medial prefrontal cortex counteracts the effects of diminished outcome controllability during reinforcement learning

2020 ◽  
Author(s):  
Gábor Csifcsák ◽  
Jorunn Bjørkøy ◽  
Sarjo Kuyateh ◽  
Haakon Reithe ◽  
Matthias Mittner
Keyword(s):  
Prefrontal Cortex ◽  
Medial Prefrontal Cortex ◽  
Direct Current ◽  
Learned Helplessness ◽  
Transcranial Direct Current Stimulation ◽  
Parameter Estimates ◽  
Double Blind Study ◽  
High Definition ◽  
Double Blind ◽  
Direct Current Stimulation

Background: The arbitration between decision-making strategies is shaped by the degree of controllability over environmental events. Under low control, individuals might rely more heavily on Pavlovian bias (PB), which facilitates and inhibits actions when facing appetitive and aversive cues, respectively. More recently, extreme PB was implicated in learned helplessness (LH), which is typically induced by uncontrollable punishment. On the neural level, the medial prefrontal cortex (mPFC) was pinpointed as a region underlying both cognitive control over PB, and the pathogenesis of LH.Objective/Hypothesis: To test if high-definition transcranial direct current stimulation (HD-tDCS) targeting the mPFC counteracts with the deleterious behavioral effects of low controllability over rewards/losses (“yoking”) during reinforcement learning.Methods: In a pre-registered, between-group, double-blind study (N = 103, healthy adults), we tested the interaction of low controllability and HD-tDCS on performance in a Go/NoGo task. Yoking was implemented by presenting random outcomes following responses, while matching reward/loss frequencies between control and yoked groups. HD-tDCS was delivered for 15 minutes at 2 mA using a 4x1 montage centered at position Fz.Results: HD-tDCS improved response accuracy by the end of the task only when applied simultaneously with yoking. The beneficial consequences of active stimulation in yoked participants were more pronounced in reward-predictive trials. Finally, computational modeling revealed that parameter estimates of learning rate and choice randomness were modulated by yoking and HD-tDCS in an interactive manner.Conclusions: These results highlight the potential of our HD-tDCS protocol for interfering with choice arbitration in volatile environments, resulting in more adaptive behavior.

Cerebellar, but not Motor or Parietal, High-Density Anodal Transcranial Direct Current Stimulation Facilitates Motor Adaptation

2016 ◽  
Vol 22 (9) ◽  
pp. 928-936 ◽  
Author(s):  
Michael Doppelmayr ◽  
Nils Henrik Pixa ◽  
Fabian Steinberg
Keyword(s):  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Motor Adaptation ◽  
Double Blind Study ◽  
Single Session ◽  
High Definition ◽  
Double Blind ◽  
Direct Current Stimulation ◽  
Anodal Stimulation ◽  
The Right

AbstractObjectives: Although motor adaptation is a highly relevant process for both everyday life as well as rehabilitation many details of this process are still unresolved. To evaluate the contribution of primary motor (M1), parietal and cerebellar areas to motor adaptation processes transcranial direct current stimulation (tDCS) has been applied. We hypothesized that anodal stimulation of the cerebellum and the M1 improves the learning process in mirror drawing, a task involving fine grained and spatially well-organized hand movements. Methods: High definition tDCS (HD-tDCS) allows a focal stimulation to modulate brain processes. In a single-session double-blind study, we compared the effects of different anodal stimulation procedures. The groups received stimulation either at the cerebellum (CER), at right parietal (PAR), or at left M1, and a SHAM group was included. Participants (n=83) had to complete several mirror drawing tasks before, during, and after stimulation. They were instructed to re-trace a line in the shape of a pentagonal star as fast and accurate as possible. Tracing time (seconds) and accuracy (deviation in mm) have been evaluated. Results: The results indicated that cerebellar HD-tDCS can facilitate motor adaptation in a single session. The stimulation at M1 showed only a tendency to increase motor adaptation and these effects were visible only during the first part of the stimulation. Stimulating the right parietal area, relevant for visuospatial processing did not lead to increased performance. Conclusions: Our results suggest that motor adaptation relies to a great extent on cerebellar functions and HD-tDCS can speed up this process. (JINS, 2016, 22, 928–936)

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