Effect of transcranial DC sensorimotor cortex stimulation on somatosensory evoked potentials in humans

Although it is well-admitted that transcranial Direct Current Stimulation (tDCS) allows for interacting with brain endogenous rhythms, the exact mechanisms by which externally-applied fields modulate the activity of neurons remain elusive. In this study a novel computational model (a neural mass model including subpopulations of pyramidal cells and inhibitory interneurons mediating synaptic currents with either slow or fast kinetics) of the cerebral cortex was elaborated to investigate the local effects of tDCS on neuronal populations based on an in-vivo experimental study. Model parameters were adjusted to reproduce evoked potentials (EPs) recorded from the somatosensory cortex of the rabbit in response to air-puffs applied on the whiskers. EPs were simulated under control condition (no tDCS) as well as under anodal and cathodal tDCS fields. Results first revealed that a feed-forward inhibition mechanism must be included in the model for accurate simulation of actual EPs (peaks and latencies).Interestingly, results revealed that externally-applied fields are also likely to affect interneurons.Indeed, when interneurons get polarized then the characteristics of simulated EPs become closer to those of real EPs. In particular, under anodal tDCS condition, more realistic EPs could be obtained when pyramidal cells were depolarized and, simultaneously, slow (resp. fast) interneurons became de-(resp. hyper-) polarized. Geometrical characteristics of interneurons might provide some explanations for this effect.

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“…enlargement) of sensory evoked potential components have been previously described after cathodal (resp. anodal) tDCS [37,38].…”

Section: Discussionmentioning

confidence: 99%

Effects of transcranial Direct Current Stimulation (tDCS) on cortical activity: A computational modeling study

et al. 2013

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“…The excitability changes produced by this technique were shown to be functionally relevant because they modify perception as well as cognition in healthy subjects (Antal et al 2001(Antal et al , 2004aMatsunaga et al 2004;Nitsche et al 2003) and were shown to improve clinical symptoms in patients with neuropsychiatric diseases (Fregni et al 2005b(Fregni et al , 2006aHummel et al 2005). …”

Section: General Remarksmentioning

confidence: 99%

“…With appropriate pharmacological interventions, the duration of the aftereffects can be further extended (Nitsche et al ,b, 2006. Using adequate electrode positions, tDCS is also able to modify the excitability and functional properties of visual, somatosensory, and prefrontal cortices (Antal et al 2003(Antal et al , 2004aFregni et al 2005a;Kincses et al 2004;Matsunaga et al 2004). Applied to the motor and visual cortices, tDCS was recently shown to improve learning processes (Antal et al 2004b;Nitsche et al 2003b).…”

Section: Introductionmentioning

confidence: 99%

Shaping the Effects of Transcranial Direct Current Stimulation of the Human Motor Cortex

Nitsche

Doemkes²,

Karaköse³

et al. 2007

Journal of Neurophysiology

660

508

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Transcranial DC stimulation (tDCS) induces stimulation polarity-dependent neuroplastic excitability shifts in the human brain. Because it accomplishes long-lasting effects and its application is simple, it is used increasingly. However, one drawback is its low focality, caused by 1) the large stimulation electrode and 2) the functionally effective reference electrode, which is also situated on the scalp. We aimed to increase the focality of tDCS, which might improve the interpretation of the functional effects of stimulation because it will restrict its effects to more clearly defined cortical areas. Moreover, it will avoid unwanted reversed effects of tDCS under the reference electrode, which is of special importance in clinical settings, when a homogeneous shift of cortical excitability is needed. Because current density (current strength/electrode size) determines the efficacy of tDCS, increased focality should be accomplished by 1) reducing stimulation electrode size, but keeping current density constant; or 2) increasing reference electrode size under constant current strength. We tested these hypotheses for motor cortex tDCS. The results show that reducing the size of the motor cortex DC-stimulation electrode focalized the respective tDCS-induced excitability changes. Increasing the size of the frontopolar reference electrode rendered stimulation over this cortex functionally inefficient, but did not compromise the tDCS-generated motor cortical excitability shifts. Thus tDCS-generated modulations of cortical excitability can be focused by reducing the size of the stimulation electrode and by increasing the size of the reference electrode. For future applications of tDCS, such paradigms may help to achieve more selective tDCS effects.

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“…Neuroimaging studies have shown that modulatory actions of tDCS on cortical activity correlate with both localized and more widespread changes in brain activity underlying behaviour (Baudewig, Nitsche, Paulus & Frahm, 2001;Shafi, Westover, Fox & Pascual-Leone, 2012). Anodal tDCS centred over somatosensory (S1) cortex modulates somatosensory evoked potentials to median nerve stimulation (Dieckhofer et al, 2006;Matsunaga, Nitsche, Tsuji & Rothwell, 2004) and when centred over M1, increased pain perception thresholds of electrical stimulation (Boggio, Zaghi, Lopes & Fregni, 2008). These tDCS effect on Perception of Effort Lampropoulou 2013 [5] studies suggest that acute anodal tDCS application over sensorimotor cortex elicits subjective perceptual changes.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Transcranial Direct Current Stimulation on Perception of Effort in an Isolated Isometric Elbow Flexion Task

Nowicky¹

2013

Motor Control

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The purported ergogenic actions of transcranial direct current stimulation (tDCS) applied to motor cortex (M1) on force production and perception of effort were investigated using a 10-item numerical rating scale (0–10 NRS) in nonfatiguing bouts of a force-matching task utilizing isometric elbow flexion. Using a crossover design, 12 healthy volunteers received sham, anodal, and cathodal tDCS randomly for 10 min (1.5 mA, 62 μA/cm2) to the left M1 in a double-blind manner. Corticospinal excitability changes were also monitored using transcranial magnetic stimulation (TMS) with surface electromyography (sEMG) to monitor both motor evoked potentials (MEPs) and force-EMG from right m. biceps brachii and m. brachioradialis brachii. No significant differences between the verum and sham stimulation were obtained for elbow flexion maximum voluntary force, perception of effort, or sEMG. There were also no significant differences in MEP changes for the types of tDCS, which is consistent with reports that tDCS excitability effects are diminished during ongoing cognitive and motor activities.

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Effect of transcranial DC sensorimotor cortex stimulation on somatosensory evoked potentials in humans

Cited by 172 publications

References 23 publications

Effects of transcranial Direct Current Stimulation (tDCS) on cortical activity: A computational modeling study

Effects of transcranial Direct Current Stimulation (tDCS) on cortical activity: A computational modeling study

Shaping the Effects of Transcranial Direct Current Stimulation of the Human Motor Cortex

The Effect of Transcranial Direct Current Stimulation on Perception of Effort in an Isolated Isometric Elbow Flexion Task

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