scholarly journals Cerebellar transcranial direct current stimulation reconfigurates static and dynamic functional connectivity of the resting-state networks

2020 ◽  
Author(s):  
Fatma Grami ◽  
Giovanni de Marco ◽  
Florian Bodranghien ◽  
Mario Manto ◽  
C. Habas
Keyword(s):  
Functional Connectivity ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Resting State ◽  
Cortical Excitability ◽  
Region Of Interest ◽  
Temporal Variations ◽  
Functional Changes ◽  
Direct Current Stimulation ◽  
The Right

Abstract Background Transcranial direct current stimulation (tDCS) of the cerebellum dynamically modulates cerebello-thalamo-cortical excitability in a polarity-specific manner during motor, visuo- motor and cognitive tasks. It remains to be established whether tDCS of the cerebellum impact also on resting-state intrinsically connected networks (ICNs). Such impact would open novel research and therapeutical doors for the neuromodulation of ICNs in human. Method: We combined tDCS applied over the right cerebellum and fMRI to investigate tDCS- induced resting-state intrinsic functional reconfiguration, using a randomized, sham-controlled design. fMRI data were recorded both before and after real anodal stimulation (2 mA, 20 min) or sham tDCS in 12 right-handed healthy volunteers. We resorted to a region-of-interest static correlational analysis and to a sliding window analysis to assess temporal variations in resting state FC between the cerebellar lobule VII and nodes of the main ICNs. Results After real tDCS and compared with sham tDCS, functional changes were observed between the cerebellum and ICNs. Static FC showed enhanced or decreased correlation between cerebellum and brain areas belonging to visual, default-mode (DMN), sensorimotor and salience networks (SN) (p-corrected < 0.05). The temporal variability (TV) of BOLD signal was significantly modified after tDCS displaying in particular a lesser TV between the whole lobule VII and DMN and central executive network and a greater TV between crus 2 and SN. Static and dynamic FC was also modified between cerebellar lobuli. Conclusion These results demonstrate short- and long-range static and majorly dynamic effects of tDCS stimulation of the cerebellum affecting distinct resting-state ICNs, as well as intracerebellar functional connectivity, so that tDCS of the cerebellum appears as a non-invasive tool reconfigurating the dynamics of ICNs.

scholarly journals Cerebellar transcranial direct current stimulation reconfigurates static and dynamic functional connectivity of the resting-state networks

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
F. Grami ◽  
G. de Marco ◽  
F. Bodranghien ◽  
M. Manto ◽  
C. Habas
Keyword(s):  
Functional Connectivity ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Resting State ◽  
Cortical Excitability ◽  
Region Of Interest ◽  
Temporal Variations ◽  
Functional Changes ◽  
Direct Current Stimulation ◽  
The Right

Abstract Background Transcranial direct current stimulation (tDCS) of the cerebellum dynamically modulates cerebello-thalamo-cortical excitability in a polarity-specific manner during motor, visuo- motor and cognitive tasks. It remains to be established whether tDCS of the cerebellum impact also on resting-state intrinsically connected networks (ICNs). Such impact would open novel research and therapeutical doors for the neuromodulation of ICNs in human. Method We combined tDCS applied over the right cerebellum and fMRI to investigate tDCS- induced resting-state intrinsic functional reconfiguration, using a randomized, sham-controlled design. fMRI data were recorded both before and after real anodal stimulation (2 mA, 20 min) or sham tDCS in 12 right-handed healthy volunteers. We resorted to a region-of-interest static correlational analysis and to a sliding window analysis to assess temporal variations in resting state FC between the cerebellar lobule VII and nodes of the main ICNs. Results After real tDCS and compared with sham tDCS, functional changes were observed between the cerebellum and ICNs. Static FC showed enhanced or decreased correlation between cerebellum and brain areas belonging to visual, default-mode (DMN), sensorimotor and salience networks (SN) (p-corrected < 0.05). The temporal variability (TV) of BOLD signal was significantly modified after tDCS displaying in particular a lesser TV between the whole lobule VII and DMN and central executive network and a greater TV between crus 2 and SN. Static and dynamic FC was also modified between cerebellar lobuli. Conclusion These results demonstrate short- and long-range static and majorly dynamic effects of tDCS stimulation of the cerebellum affecting distinct resting-state ICNs, as well as intracerebellar functional connectivity, so that tDCS of the cerebellum appears as a non-invasive tool reconfigurating the dynamics of ICNs.

Enhancing Working Memory Training with Transcranial Direct Current Stimulation

2016 ◽  
Vol 28 (9) ◽  
pp. 1419-1432 ◽  
Author(s):  
Jacky Au ◽  
Benjamin Katz ◽  
Martin Buschkuehl ◽  
Kimberly Bunarjo ◽  
Thea Senger ◽  
...  
Keyword(s):  
Working Memory ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Cortical Excitability ◽  
Brain Plasticity ◽  
Memory Training ◽  
Direct Current Stimulation ◽  
Training Interventions ◽  
Learning Tasks ◽  
The Right

Working memory (WM) is a fundamental cognitive ability that supports complex thought but is limited in capacity. Thus, WM training interventions have become very popular as a means of potentially improving WM-related skills. Another promising intervention that has gained increasing traction in recent years is transcranial direct current stimulation (tDCS), a noninvasive form of brain stimulation that can modulate cortical excitability and temporarily increase brain plasticity. As such, it has the potential to boost learning and enhance performance on cognitive tasks. This study assessed the efficacy of tDCS to supplement WM training. Sixty-two participants were randomized to receive either right prefrontal, left prefrontal, or sham stimulation with concurrent visuospatial WM training over the course of seven training sessions. Results showed that tDCS enhanced training performance, which was strikingly preserved several months after training completion. Furthermore, we observed stronger effects when tDCS was spaced over a weekend break relative to consecutive daily training, and we also demonstrated selective transfer in the right prefrontal group to nontrained tasks of visual and spatial WM. These findings shed light on how tDCS may be leveraged as a tool to enhance performance on WM-intensive learning tasks.

Dynamic modulation of intrinsic functional connectivity by transcranial direct current stimulation

2012 ◽  
Vol 108 (12) ◽  
pp. 3253-3263 ◽  
Author(s):  
Bernhard Sehm ◽  
Alexander Schäfer ◽  
Judy Kipping ◽  
Daniel Margulies ◽  
Virginia Conde ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Healthy Subjects ◽  
Time Course ◽  
Cortical Excitability ◽  
Eigenvector Centrality ◽  
Resting State Functional Connectivity ◽  
Brain Areas ◽  
Direct Current Stimulation

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique capable of modulating cortical excitability and thereby influencing behavior and learning. Recent evidence suggests that bilateral tDCS over both primary sensorimotor cortices (SM1) yields more prominent effects on motor performance in both healthy subjects and chronic stroke patients than unilateral tDCS over SM1. To better characterize the underlying neural mechanisms of this effect, we aimed to explore changes in resting-state functional connectivity during both stimulation types. In a randomized single-blind crossover design, 12 healthy subjects underwent functional magnetic resonance imaging at rest before, during, and after 20 min of unilateral, bilateral, and sham tDCS stimulation over SM1. Eigenvector centrality mapping (ECM) was used to investigate tDCS-induced changes in functional connectivity patterns across the whole brain. Uni- and bilateral tDCS over SM1 resulted in functional connectivity changes in widespread brain areas compared with sham stimulation both during and after stimulation. Whereas bilateral tDCS predominantly modulated changes in primary and secondary motor as well as prefrontal regions, unilateral tDCS affected prefrontal, parietal, and cerebellar areas. No direct effect was seen under the stimulating electrode in the unilateral condition. The time course of changes in functional connectivity in the respective brain areas was nonlinear and temporally dispersed. These findings provide evidence toward a network-based understanding regarding the underpinnings of specific tDCS interventions.

scholarly journals Modulation of GABA and resting state functional connectivity by transcranial direct current stimulation

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Velicia Bachtiar ◽  
Jamie Near ◽  
Heidi Johansen-Berg ◽  
Charlotte J Stagg
Keyword(s):  
Functional Connectivity ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Resting State ◽  
Resonance Spectroscopy ◽  
Resting State Functional Connectivity ◽  
Direct Current Stimulation ◽  
Motor Network ◽  
Before And After ◽  
Underlying Mechanisms

We previously demonstrated that network level functional connectivity in the human brain could be related to levels of inhibition in a major network node at baseline (<xref ref-type="bibr" rid="bib24">Stagg et al., 2014</xref>). In this study, we build upon this finding to directly investigate the effects of perturbing M1 GABA and resting state functional connectivity using transcranial direct current stimulation (tDCS), a neuromodulatory approach that has previously been demonstrated to modulate both metrics. FMRI data and GABA levels, as assessed by Magnetic Resonance Spectroscopy, were measured before and after 20 min of 1 mA anodal or sham tDCS. In line with previous studies, baseline GABA levels were negatively correlated with the strength of functional connectivity within the resting motor network. However, although we confirm the previously reported findings that anodal tDCS reduces GABA concentration and increases functional connectivity in the stimulated motor cortex; these changes are not correlated, suggesting they may be driven by distinct underlying mechanisms.

Transcranial Direct Current Stimulation Modulates Connectivity of Left Dorsolateral Prefrontal Cortex with Distributed Cortical Networks

2021 ◽  
pp. 1-15
Author(s):  
Kamin Kim ◽  
Matthew S. Sherwood ◽  
Lindsey K. McIntire ◽  
Andy R. McKinley ◽  
Charan Ranganath
Keyword(s):  
Prefrontal Cortex ◽  
Functional Connectivity ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Resting State ◽  
Dorsolateral Prefrontal Cortex ◽  
Resting State Fmri ◽  
Term Memory ◽  
Direct Current Stimulation ◽  
Dorsolateral Prefrontal

Abstract Studies have shown that transcranial direct current stimulation increases neuronal excitability of the targeted region and general connectivity of relevant functional networks. However, relatively little is understood on how the stimulation affects the connectivity relationship of the target with regions across the network structure of the brain. Here, we investigated the effects of transcranial direct current stimulation on the functional connectivity of the targeted region using resting-state fMRI scans of the human brain. Anodal direct current stimulation was applied to the left dorsolateral prefrontal cortex (lDLPFC; cathode on the right bicep), which belongs to the frontoparietal control network (FPCN) and is commonly targeted for neuromodulation of various cognitive functions including short-term memory, long-term memory, and cognitive control. lDLPFC's connectivity characteristics were quantified as graph theory measures, from the resting-state fMRI scans obtained prior to and following the stimulation. Critically, we tested pre- to poststimulation changes of the lDLPFC connectivity metrics following an active versus sham stimulation. We found that the stimulation had two distinct effects on the connectivity of lDLPFC: for Brodmann's area (BA) 9, it increased the functional connectivity between BA 9 and other nodes within the FPCN; for BA 46, net connectivity strength was not altered within FPCN, but connectivity distribution across networks (participation coefficient) was decreased. These findings provide insights that the behavioral changes as the functional consequences of stimulation may come about because of the increased role of lDLPFC in the FPCN.

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