Transcranial direct current stimulation (tDCS) modulation of picture naming and word reading:A meta-analysis of single session tDCS applied to healthy participants


Recent reviews quantifying the effects of single sessions of transcranial direct current stimulation (or tDCS) in healthy volunteers find only minor effects on cognition despite the popularity of this technique. Here, we wanted to quantify the effects of tDCS on language production tasks that measure word reading and picture naming. We reviewed 14 papers measuring tDCS effects across a total of 96 conditions to a) quantify effects of conventional stimulation on language regions (i.e., left hemisphere anodal tDCS administered to temporal/frontal areas) under normal conditions or under conditions of cognitive (semantic) interference; b) identify parameters which may moderate the size of the tDCS effect within conventional stimulation protocols (e.g., online vs offline, high vs. low current densities, and short vs. long durations), as well as within types of stimulation not typically explored by previous reviews (i.e., right hemisphere anodal tDCS or left/right hemisphere cathodal tDCS). In all analyses there was no significant effect of tDCS, but we did find a small but significant effect of time and duration of stimulation with stronger effects for offline stimulation and for shorter durations (< 15 min). We also found some indication of publication bias towards reporting positive effects. We encourage further experimentation in order resolve the disparity between the current popularity of tDCS and its poor efficacy in healthy participants.

Publication DOI:
Divisions: College of Health & Life Sciences > School of Psychology
College of Health & Life Sciences > Clinical and Systems Neuroscience
College of Health & Life Sciences
College of Health & Life Sciences > School of Optometry > Vision, Hearing and Language
Additional Information: © 2017 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license ( Funding: Ministry of Defence, Defence Science and Technology Laboratory.
Uncontrolled Keywords: Meta- analysis,Null effects,Picture naming,Review,tDCS,Word reading,Experimental and Cognitive Psychology,Cognitive Neuroscience,Behavioral Neuroscience
Publication ISSN: 1873-3514
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Review article
Published Date: 2017-09-01
Published Online Date: 2017-07-27
Accepted Date: 2017-07-25
Authors: Westwood, Samuel J.
Romani, Cristina (ORCID Profile 0000-0002-5693-4131)

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