Experimental Brain Research

, Volume 216, Issue 1, pp 1–10

tDCS polarity effects in motor and cognitive domains: a meta-analytical review

Mini-Review

DOI: 10.1007/s00221-011-2891-9

Cite this article as:
Jacobson, L., Koslowsky, M. & Lavidor, M. Exp Brain Res (2012) 216: 1. doi:10.1007/s00221-011-2891-9

Abstract

In vivo effects of transcranial direct current stimulation (tDCS) have attracted much attention nowadays as this area of research spreads to both the motor and cognitive domains. The common assumption is that the anode electrode causes an enhancement of cortical excitability during stimulation, which then lasts for a few minutes thereafter, while the cathode electrode generates the opposite effect, i.e., anodal-excitation and cathodal-inhibition effects (AeCi). Yet, this dual-polarity effect has not been observed in all tDCS studies. Here, we conducted a meta-analytical review aimed to investigate the homogeneity/heterogeneity of the effect sizes of the AeCi dichotomy in both motor and cognitive functions. The AeCi effect was found to occur quite commonly with motor investigations and rarely in cognitive studies. When the anode electrode is applied over a non-motor area, in most cases, it will cause an excitation as measured by a relevant cognitive or perceptual task; however, the cathode electrode rarely causes an inhibition. We found homogeneity in motor studies and heterogeneity in cognitive studies with the electrode’s polarity serving as a moderator that can explain the source of heterogeneity in cognitive studies. The lack of inhibitory cathodal effects might reflect compensation processes as cognitive functions are typically supported by rich brain networks. Further insights as to the polarity and domain interaction are offered, including subdivision to different classes of cognitive functions according to their likelihood of being affected by stimulation.

Keywords

Cognitive Meta-analysis Motor Transcranial direct current stimulation (tDCS) 

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Liron Jacobson
    • 1
  • Meni Koslowsky
    • 2
  • Michal Lavidor
    • 1
    • 2
    • 3
  1. 1.The Gonda Multidisciplinary Brain Research CenterBar-Ilan UniversityRamat GanIsrael
  2. 2.Department of PsychologyBar Ilan UniversityRamat GanIsrael
  3. 3.Department of PsychologyUniversity of HullHullUK

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