Abstract
Transcranial direct-current stimulation (tDCS) is a form of neurostimulation in which a constant, low current is delivered directly to the brain area of interest by small electrodes. The overall aim of this study was to examine and monitor the modulation of brain activity by electroencephalogram (EEG) in the frequency domain during tDCS in the resting state. To this end, we considered the modulation of spontaneous EEG to be a marker of the perturbation that was induced through the direct current (1.5 mA for 15 min). In all conditions (anodal, cathodal, and sham), an active electrode was placed over the right posterior parietal cortex, and a reference electrode was placed on the ipsilateral deltoid muscle. The EEG was recorded using a 64-channel system. The effect of tDCS was limited to the alpha rhythm, and the anodal stimulation significantly affected the alpha rhythm, whereas the cathodal stimulation did not elicit any modifications. Further, we observed modulation of alpha activity in areas that were stimulated directly through tDCS and in anterior noncontiguous areas. Finally, the anodal effect peaked 7.5 min after stimulation and decreased gradually over time. Our study demonstrates that in the resting brain, monocephalic anodal tDCS over posterior parietal areas alters ongoing brain activity, specifically in the alpha band rhythm. Our data can be used to fine-tune tDCS protocols in neurorehabilitation settings.
Highlights
Transcranial direct-current stimulation is a noninvasive technique that modulates the neuronal excitability of targeted cerebral areas through constant stimulation with low direct current (DC) from the scalp using a pair of electrodes
We examined the effects of Transcranial direct-current stimulation (tDCS) on spontaneous cortical activity to determine the modulation of spontaneous oscillatory brain activity in a resting brain that has been perturbed electrically through anodal and cathodal stimulation
Four main findings emerged: (1) the tDCS effect was limited to the alpha rhythm band; (2) anodal tDCS affected the alpha rhythm, but cathodal tDCS did not; (3) the alpha activity was modulated in noncontiguous frontal areas, but stronger modulation was observed in the parietal areas under the active stimulating electrode; and (4)
Summary
Transcranial direct-current stimulation (tDCS) is a noninvasive technique that modulates the neuronal excitability of targeted cerebral areas through constant stimulation with low direct current (DC) from the scalp using a pair of electrodes. Depending on the orientation of the cells with respect to the current, the membrane potentials can be hyperpolarized (anodal stimulation) or depolarized (cathodal stimulation) by several mV (Paulus, 2004). This change in neuronal excitability effects several alterations in brain function (Nitsche et al, 2008), including motor, sensory, and high-level cognitive function (Calvo-Merino and Haggard, 2004; Nitsche et al, 2005). Since the publication of seminal studies on motor tasks (Rosenkranz et al, 2000; Lang et al, 2004), this discipline has focused increasingly on the effects of tDCS on various cognitive domains, such as language (Floel et al, 2008; Fertonani et al, 2010; Fiori et al, 2011), spatial attention (Bolognini et al, 2010), executive functions (Dockery et al, 2009; Hecht et al, 2010), visual processing (Antal and Paulus, 2008), body representation (Spitoni et al, 2013), and emotions (Boggio et al, 2008), and on its implications for neuropsychological rehabilitation (Vallar and Bolognini, 2011)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
