Visual evoked potentials modulation during direct current cortical polarization

Neri Accornero, Pietro Li Voti, Maurizio La Riccia, Bruno Gregori

Research output: Contribution to journalArticlepeer-review


Transcranial direct current stimulation (tDCS) at low intensity induces changes in cortical excitability that persist after polarization ends. The effects of anodal and cathodal polarization remain controversial. We studied changes in visual evoked potentials (VEPs) during and after anodal and cathodal tDCS by applying, in healthy volunteers, 1 mA polarization through surface electrodes placed over the occipital scalp (polarizing) and over the anterior or posterior neck-base (reference). We compared tDCS applied at two durations, 3 and 10 min and both polarities. We assessed VEP-P100 latencies and amplitudes in response to pattern-reversal checkerboard stimuli before, during, and after polarization. Anodal polarization reduced VEP-P100 amplitude whereas cathodal polarization significantly increased amplitude but both polarities left latency statistically unchanged. These changes persisted for some minutes after polarization ended depending on the duration of tDCS and on the contrast level of visual stimuli. tDCS-induced changes in VEPs seem to depend on the duration of polarization and type of visual stimuli used. The effects induced on visual cortical neurones during polarization are more consistent than the aftereffects. Studying these changes during polarization may therefore improve our understanding of these phenomena.

Original languageEnglish
Pages (from-to)261-266
Number of pages6
JournalExperimental Brain Research
Issue number2
Publication statusPublished - Apr 2007


  • Cortical polarization
  • Modulation
  • TDCS
  • VEP

ASJC Scopus subject areas

  • Neuroscience(all)


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