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Tracking the Effect of Cathodal Transcranial Direct Current Stimulation on Cortical Excitability and Connectivity by Means of TMS-EEG.
Front Neurosci 2018; 12:319FN

Abstract

Transcranial direct current stimulation (tDCS) is increasingly used in both research and therapeutic settings, but its precise mechanisms remain largely unknown. At a neuronal level, tDCS modulates cortical excitability by shifting the resting membrane potential in a polarity-dependent way: anodal stimulation increases the spontaneous firing rate, while cathodal decreases it. However, the neurophysiological underpinnings of anodal/cathodal tDCS seem to be different, as well as their behavioral effect, in particular when high order areas are involved, compared to when motor or sensory brain areas are targeted. Previously, we investigated the effect of anodal tDCS on cortical excitability, by means of a combination of Transcranial Magnetic Stimulation (TMS) and Electroencephalography (EEG). Results showed a diffuse rise of cortical excitability in a bilateral fronto-parietal network. In the present study, we tested, with the same paradigm, the effect of cathodal tDCS. Single pulse TMS was delivered over the left posterior parietal cortex (PPC), before, during, and after 10 min of cathodal or sham tDCS over the right PPC, while recording HD-EEG. Indexes of global and local cortical excitability were obtained both at sensors and cortical sources level. At sensors, global and local mean field power (GMFP and LMFP) were computed for three temporal windows (0-50, 50-100, and 100-150 ms), on all channels (GMFP), and in four different clusters of electrodes (LMFP, left and right, in frontal and parietal regions). After source reconstruction, Significant Current Density was computed at the global level, and for four Broadmann's areas (left/right BA 6 and 7). Both sensors and cortical sources results converge in showing no differences during and after cathodal tDCS compared to pre-stimulation sessions, both at global and local level. The same holds for sham tDCS. These data highlight an asymmetric impact of anodal and cathodal stimulation on cortical excitability, with a diffuse effect of anodal and no effect of cathodal tDCS over the parietal cortex. These results are consistent with the current literature: while anodal-excitatory and cathodal-inhibitory effects are well-established in the sensory and motor domains, both at physiological and behavioral levels, results for cathodal stimulation are more controversial for modulation of exitability of higher order areas.

Authors+Show Affiliations

Ph.D. Program in Neuroscience, Department of Medicine and Surgery, University Milano-Bicocca, Monza, Italy. NeuroMi - Milan Center of Neuroscience, Milan, Italy.NeuroMi - Milan Center of Neuroscience, Milan, Italy. Department of Psychology, University of Milano-Bicocca, Milan, Italy.NeuroMi - Milan Center of Neuroscience, Milan, Italy. Department of Psychology, University of Milano-Bicocca, Milan, Italy.NeuroMi - Milan Center of Neuroscience, Milan, Italy. Department of Psychology, University of Milano-Bicocca, Milan, Italy.Department of Psychology, University of Milano-Bicocca, Milan, Italy.Department of Psychology, University of Milano-Bicocca, Milan, Italy.Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, Italy. Fondazione Europea per la Ricerca Biomedica Onlus, Milan, Italy.NeuroMi - Milan Center of Neuroscience, Milan, Italy. Department of Psychology, University of Milano-Bicocca, Milan, Italy. Laboratory of Neuropsychology, IRCCS Istituto Auxologico, Milan, Italy.NeuroMi - Milan Center of Neuroscience, Milan, Italy. Department of Psychology, University of Milano-Bicocca, Milan, Italy. Laboratory of Neuropsychology, IRCCS Istituto Auxologico, Milan, Italy.NeuroMi - Milan Center of Neuroscience, Milan, Italy. Department of Psychology, University of Milano-Bicocca, Milan, Italy.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

29867330

Citation

Varoli, Erica, et al. "Tracking the Effect of Cathodal Transcranial Direct Current Stimulation On Cortical Excitability and Connectivity By Means of TMS-EEG." Frontiers in Neuroscience, vol. 12, 2018, p. 319.
Varoli E, Pisoni A, Mattavelli GC, et al. Tracking the Effect of Cathodal Transcranial Direct Current Stimulation on Cortical Excitability and Connectivity by Means of TMS-EEG. Front Neurosci. 2018;12:319.
Varoli, E., Pisoni, A., Mattavelli, G. C., Vergallito, A., Gallucci, A., Mauro, L. D., ... Romero Lauro, L. J. (2018). Tracking the Effect of Cathodal Transcranial Direct Current Stimulation on Cortical Excitability and Connectivity by Means of TMS-EEG. Frontiers in Neuroscience, 12, p. 319. doi:10.3389/fnins.2018.00319.
Varoli E, et al. Tracking the Effect of Cathodal Transcranial Direct Current Stimulation On Cortical Excitability and Connectivity By Means of TMS-EEG. Front Neurosci. 2018;12:319. PubMed PMID: 29867330.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Tracking the Effect of Cathodal Transcranial Direct Current Stimulation on Cortical Excitability and Connectivity by Means of TMS-EEG. AU - Varoli,Erica, AU - Pisoni,Alberto, AU - Mattavelli,Giulia C, AU - Vergallito,Alessandra, AU - Gallucci,Alessia, AU - Mauro,Lilia D, AU - Rosanova,Mario, AU - Bolognini,Nadia, AU - Vallar,Giuseppe, AU - Romero Lauro,Leonor J, Y1 - 2018/05/15/ PY - 2018/02/13/received PY - 2018/04/24/accepted PY - 2018/6/6/entrez PY - 2018/6/6/pubmed PY - 2018/6/6/medline KW - TMS-EEG KW - cathodal tDCS KW - cortical excitability KW - neuromodulation KW - posterior parietal cortex SP - 319 EP - 319 JF - Frontiers in neuroscience JO - Front Neurosci VL - 12 N2 - Transcranial direct current stimulation (tDCS) is increasingly used in both research and therapeutic settings, but its precise mechanisms remain largely unknown. At a neuronal level, tDCS modulates cortical excitability by shifting the resting membrane potential in a polarity-dependent way: anodal stimulation increases the spontaneous firing rate, while cathodal decreases it. However, the neurophysiological underpinnings of anodal/cathodal tDCS seem to be different, as well as their behavioral effect, in particular when high order areas are involved, compared to when motor or sensory brain areas are targeted. Previously, we investigated the effect of anodal tDCS on cortical excitability, by means of a combination of Transcranial Magnetic Stimulation (TMS) and Electroencephalography (EEG). Results showed a diffuse rise of cortical excitability in a bilateral fronto-parietal network. In the present study, we tested, with the same paradigm, the effect of cathodal tDCS. Single pulse TMS was delivered over the left posterior parietal cortex (PPC), before, during, and after 10 min of cathodal or sham tDCS over the right PPC, while recording HD-EEG. Indexes of global and local cortical excitability were obtained both at sensors and cortical sources level. At sensors, global and local mean field power (GMFP and LMFP) were computed for three temporal windows (0-50, 50-100, and 100-150 ms), on all channels (GMFP), and in four different clusters of electrodes (LMFP, left and right, in frontal and parietal regions). After source reconstruction, Significant Current Density was computed at the global level, and for four Broadmann's areas (left/right BA 6 and 7). Both sensors and cortical sources results converge in showing no differences during and after cathodal tDCS compared to pre-stimulation sessions, both at global and local level. The same holds for sham tDCS. These data highlight an asymmetric impact of anodal and cathodal stimulation on cortical excitability, with a diffuse effect of anodal and no effect of cathodal tDCS over the parietal cortex. These results are consistent with the current literature: while anodal-excitatory and cathodal-inhibitory effects are well-established in the sensory and motor domains, both at physiological and behavioral levels, results for cathodal stimulation are more controversial for modulation of exitability of higher order areas. SN - 1662-4548 UR - https://www.unboundmedicine.com/medline/citation/29867330/Tracking_the_Effect_of_Cathodal_Transcranial_Direct_Current_Stimulation_on_Cortical_Excitability_and_Connectivity_by_Means_of_TMS_EEG_ L2 - https://dx.doi.org/10.3389/fnins.2018.00319 DB - PRIME DP - Unbound Medicine ER -