Dynamic modulation of intrinsic functional connectivity by transcranial 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.

Download Full-text

High definition-transcranial direct current stimulation changes older adults' subjective sleep and corresponding resting-state functional connectivity

International Journal of Psychophysiology ◽

10.1016/j.ijpsycho.2018.05.002 ◽

2018 ◽

Vol 129 ◽

pp. 1-8 ◽

Cited By ~ 8

Author(s):

Jing Sheng ◽

Chao Xie ◽

Dong-qiong Fan ◽

Xu Lei ◽

Jing Yu

Keyword(s):

Older Adults ◽

Functional Connectivity ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Resting State ◽

Resting State Functional Connectivity ◽

High Definition ◽

Subjective Sleep ◽

Direct Current Stimulation

Download Full-text

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

eLife ◽

10.7554/elife.08789 ◽

2015 ◽

Vol 4 ◽

Cited By ~ 86

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.

Download Full-text

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

10.21203/rs.3.rs-98800/v1 ◽

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.

Download Full-text