The interaction with task-induced activity is more important than polarization: A tDCS study

Marta Bortoletto, Maria Concetta Pellicciari, Claudia Rodella, Carlo Miniussi

Research output: Contribution to journalArticle

Abstract

Background: Anodal transcranial direct current stimulation (A-tDCS) is a non-invasive technique in which cortical polarization can be used to increase excitability and facilitate learning through the modulation of neuroplasticity. Although the facilitatory effects of A-tDCS are well documented, there is evidence that they are not always present and may even be reversed during task execution. Objective: In this study, we explored the interaction between A-tDCS and task execution. We aimed to test how the excitability induced by the task interacts with the excitability induced by A-tDCS and determines the behavioral outcome. Methods: We performed an experiment in which A-tDCS or a control stimulation (Ctrl) were combined with one of two motor practices (MP), one inducing learning and increasing cortical excitability (F-MP) and the other neither inducing learning nor changing cortical excitability (S-MP). Six blocks of MP were performed while the primary motor cortex was stimulated. Moreover, one block of F-MP was performed before the stimulation (baseline) and one after. In an additional experiment, motor evoked potentials (MEPs) were recorded before the baseline block (TMS-pre) and after the MP (TMS-post). Results: We observed that A-tDCS reduced learning when participants performed the F-MP and facilitated learning for the S-MP. MEPs data paralleled behavioral results, confirming that the effects generated by A-tDCS depend on the excitability changes induced by the task. Conclusions: Our results demonstrate that tDCS-induced plasticity is task-dependent, and the concurrent combination of A-tDCS with another excitability-increasing event, e.g., motor practice, may trigger non-additive mechanisms, hindering neuroplasticity.

Original languageEnglish
Pages (from-to)269-276
Number of pages8
JournalBrain Stimulation
Volume8
Issue number2
DOIs
Publication statusPublished - Mar 1 2015

Keywords

  • Cortical plasticity
  • Motor learning
  • Noise
  • Non-invasive brain stimulation (NIBS)
  • State-dependent
  • Transcranial direct current stimulation

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)
  • Biophysics
  • Medicine(all)

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