Resting-state fMRI reveals enhanced functional connectivity in spatial navigation networks after transcranial direct current stimulation

Krishnamurthy, Vivek; Gopinath, Kaundinya; Brown, Geoffrey; Hampstead, Benjamin M.

doi:10.1016/j.neulet.2015.07.042

Cited by 33 publications

(27 citation statements)

References 31 publications

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“…Imaging studies confirm this diffusivity (Antal et al 2012;Stagg et al 2013). It has been speculated that the behavioural and clinical outcomes of tDCS reflect changes in connectivity between diffuse brain regions (Polania et al 2011(Polania et al , 2012Dasilva et al 2012;Krishnamurthy et al 2015). We provide data in support of a quantitative theory that diffuse and sustained brain polarization is advantageous in enhancing connectivity across brain regions.…”

Section: Introductionsupporting

confidence: 80%

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Direct current stimulation boosts synaptic gain and cooperativity in vitro

Rahman

Lafon

Parra

et al. 2017

The Journal of Physiology

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Transcranial direct current stimulation (tDCS) produces sustained and diffuse current flow in the brain with effects that are state dependent and outlast stimulation. A mechanistic explanation for tDCS should capture these spatiotemporal features. It remains unclear how sustained DCS affects ongoing synaptic dynamics and how modulation of afferent inputs by diffuse stimulation changes synaptic activity at the target brain region. We tested the effect of acute DCS (10-20 V m for 3-5 s) on synaptic dynamics with constant rate (5-40 Hz) and Poisson-distributed (4 Hz mean) trains of presynaptic inputs. Across tested frequencies, sustained synaptic activity was modulated by DCS with polarity-specific effects. Synaptic depression attenuates the sensitivity to DCS from 1.1% per V m to 0.55%. DCS applied during synaptic activity facilitates cumulative neuromodulation, potentially reversing endogenous synaptic depression. We establish these effects are mediated by both postsynaptic membrane polarization and afferent axon fibre polarization, which boosts cooperativity between synaptic inputs. This potentially extends the locus of neuromodulation from the nominal target to afferent brain regions. Based on these results we hypothesized the polarization of afferent neurons in upstream brain regions may modulate activity in the target brain region during tDCS. A multiscale model of transcranial electrical stimulation including a finite element model of brain current flow, numerical simulations of neuronal activity, and a statistical theory of coincident activity predicts that the diffuse and weak profile of current flow can be advantageous. Thus, we propose that specifically because tDCS is diffuse, weak and sustained it can boost connectivity between co-active brain regions.

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Section: Introductionsupporting

confidence: 80%

“…; Krishnamurthy et al . ). We provide data in support of a quantitative theory that diffuse and sustained brain polarization is advantageous in enhancing connectivity across brain regions.…”

Section: Introductionmentioning

confidence: 97%

Direct current stimulation boosts synaptic gain and cooperativity in vitro

Rahman

Lafon

Parra

et al. 2017

The Journal of Physiology

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“…In fact, neuroimaging studies of tDCS have not yet addressed how many different stimulation parameters affect neurophysiological activity. For example, most functional magnetic resonance imaging (fMRI) studies have focused on offline tDCS and shown that neural activity in regions near the anode are significantly modulated, as well as more distant brain structures that are likely connected to the targeted region (Amadi, Ilie, Johansen‐Berg, & Stagg, ; Baudewig, Nitsche, Paulus, & Frahm, ; Hilgenstock, Weiss, Huonker, & Witte, ; Hunter et al, ; Jang et al, ; Keeser et al, ; Krishnamurthy, Gopinath, Brown, & Hampstead, ; Pena‐Gomez et al, ; Polania, Nitsche, & Paulus, ; Polania, Paulus, Antal, & Nitsche, ; Stagg, O'Shea, et al, ; Stagg et al, ). Thus, much work remains to be completed in regard to illuminating how tDCS affects brain activity.…”

Section: Discussionmentioning

confidence: 99%

tDCS modulates behavioral performance and the neural oscillatory dynamics serving visual selective attention

McDermott

Wiesman

Mills

et al. 2018

Human Brain Mapping

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Transcranial direct‐current stimulation (tDCS) is a noninvasive method for modulating human brain activity. Although there are several hypotheses about the net effects of tDCS on brain function, the field's understanding remains incomplete and this is especially true for neural oscillatory activity during cognitive task performance. In this study, we examined whether different polarities of occipital tDCS differentially alter flanker task performance and the underlying neural dynamics. To this end, 48 healthy adults underwent 20 min of anodal, cathodal, or sham occipital tDCS, and then completed a visual flanker task during high‐density magnetoencephalography (MEG). The resulting oscillatory responses were imaged in the time‐frequency domain using beamforming, and the effects of tDCS on task‐related oscillations and spontaneous neural activity were assessed. The results indicated that anodal tDCS of the occipital cortices inhibited flanker task performance as measured by reaction time, elevated spontaneous activity in the theta (4–7 Hz) and alpha (9–14 Hz) bands in prefrontal and occipital cortices, respectively, and reduced task‐related theta oscillatory activity in prefrontal cortices during task performance. Cathodal tDCS of the occipital cortices did not significantly affect behavior or any of these neuronal parameters in any brain region. Lastly, the power of theta oscillations in the prefrontal cortices was inversely correlated with reaction time. In conclusion, anodal tDCS modulated task‐related oscillations and spontaneous activity across multiple cortical areas, both near the electrode and in distant sites that were putatively connected to the targeted regions.

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“…Such studies are comparatively scarce, with the vast majority of research carried out using resting state fMRI and focussing on established functional networks [28][29][30]. But even when tDCS is applied in the resting state, it has been suggested that it primes networks for their differential recruitment in future tasks [31].…”

Section: Key Pointsmentioning

confidence: 99%

Tuning noninvasive brain stimulation with MRI to cope with intersubject variability

Habich

Canals

Klöppel

2016

Current Opinion in Neurology

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a,c,dPurpose of review The review aims at highlighting the additional benefit that can be gained from combining noninvasive brain stimulation as well as repetitive sensory stimulation protocols with MRI techniques to account for the intersubject variability observed in those treatments. Potentially, this should help to identify predictive patterns in the individual receptiveness to the treatment. Recent findingsKnowledge about the underlying physiological principles of excitability changes as induced by noninvasive brain stimulation or repetitive sensory stimulation is accumulating, revealing strong associations with plasticity processes at the synaptic level. In this context, MRI techniques, such as magnetic resonance spectroscopy and functional MRI, emerged as valuable tools for the qualitative assessment of baseline states and induced changes. Those physiological readouts can help explain the interindividual heterogeneity found in behavioural and/or clinical responses to the specific stimulation protocols. This knowledge will eventually translate, first, into the preliminary classification of study participants into treatment groups according to their neurophysiological baseline state and expected responses to a particular stimulation. Subsequently, this should also aid the optimization of stimulation protocols according to the classification outcome, resulting in retuned protocols for particular groups of study participants. SummaryThe consistent MRI-based monitoring of stimulation effects in the neural network promises a considerable gain for the customization of intervention protocols with improved therapeutic potential and rehabilitative predictions.

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Resting-state fMRI reveals enhanced functional connectivity in spatial navigation networks after transcranial direct current stimulation

Cited by 33 publications

References 31 publications

Direct current stimulation boosts synaptic gain and cooperativity in vitro

Direct current stimulation boosts synaptic gain and cooperativity in vitro

tDCS modulates behavioral performance and the neural oscillatory dynamics serving visual selective attention

Tuning noninvasive brain stimulation with MRI to cope with intersubject variability

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