Experimental Brain Research

, Volume 166, Issue 1, pp 23–30

Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory

  • Felipe Fregni
  • Paulo S. Boggio
  • Michael Nitsche
  • Felix Bermpohl
  • Andrea Antal
  • Eva Feredoes
  • Marco A. Marcolin
  • Sergio P. Rigonatti
  • Maria T.A. Silva
  • Walter Paulus
  • Alvaro Pascual-Leone
Research Article

Abstract

Previous studies have claimed that weak transcranial direct current stimulation (tDCS) induces persisting excitability changes in the human motor cortex that can be more pronounced than cortical modulation induced by transcranial magnetic stimulation, but there are no studies that have evaluated the effects of tDCS on working memory. Our aim was to determine whether anodal transcranial direct current stimulation, which enhances brain cortical excitability and activity, would modify performance in a sequential-letter working memory task when administered to the dorsolateral prefrontal cortex (DLPFC). Fifteen subjects underwent a three-back working memory task based on letters. This task was performed during sham and anodal stimulation applied over the left DLPFC. Moreover seven of these subjects performed the same task, but with inverse polarity (cathodal stimulation of the left DLPFC) and anodal stimulation of the primary motor cortex (M1). Our results indicate that only anodal stimulation of the left prefrontal cortex, but not cathodal stimulation of left DLPFC or anodal stimulation of M1, increases the accuracy of the task performance when compared to sham stimulation of the same area. This accuracy enhancement during active stimulation cannot be accounted for by slowed responses, as response times were not changed by stimulation. Our results indicate that left prefrontal anodal stimulation leads to an enhancement of working memory performance. Furthermore, this effect depends on the stimulation polarity and is specific to the site of stimulation. This result may be helpful to develop future interventions aiming at clinical benefits.

Keywords

Electrical stimulation Prefrontal cortex Transcranial magnetic stimulation Working memory 

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Felipe Fregni
    • 1
  • Paulo S. Boggio
    • 2
  • Michael Nitsche
    • 3
  • Felix Bermpohl
    • 1
  • Andrea Antal
    • 3
  • Eva Feredoes
    • 3
  • Marco A. Marcolin
    • 4
  • Sergio P. Rigonatti
    • 4
  • Maria T.A. Silva
    • 2
  • Walter Paulus
    • 3
  • Alvaro Pascual-Leone
    • 1
  1. 1.Harvard Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical CenterHarvard Medical SchoolBostonUSA
  2. 2.Department of Experimental Psychology, Institute of PsychologyUniversity of Sao PauloSao PauloBrazil
  3. 3.Department of Clinical NeurophysiologyGeorg-August-UniversityGoettingenGermany
  4. 4.Department of PsychiatryUniversity of Sao PauloSao PauloBrazil

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