Connectivity between Right Inferior Frontal Gyrus and Supplementary Motor Area Predicts After-Effects of Right Frontal Cathodal tDCS on Picture Naming Speed

Charlotte Rosso, R. Valabregue, C. Arbizy, S. Ferrieux, P. Vargas, F. Humbert, Y. Attal, A. Messé, C. Zavanone, S. Meunier, L. Cohen, C. Delmaire, Axel Thielscher, D. M. Hertz, H. R. Siebner, Y. Samson, S. Lehericy

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Background: Cathodal transcranial direct current stimulation (tDCS) of the right frontal cortex improves language abilities in post-stroke aphasic patients. Yet little is known about the effects of right frontal cathodal tDCS on normal language function. Objective/hypothesis: To explore the cathodal tDCS effects of the right-hemispheric homologue of Broca’s area on picture naming in healthy individuals. We hypothesized that cathodal tDCS improves Picture naming and that this effect is determined by the anatomical and functional connectivity of the targeted region. Methods: Cathodal and sham tDCS were applied to the right inferior frontal gyrus in 24 healthy subjects before a picture-naming task. All participants were studied with magnetic resonance imaging at pre-interventional baseline. Probabilistic tractography and dynamic causal modeling of functional brain activity during a word repetition task were applied to characterize anatomical and functional connectivity. Results: Subjects named pictures faster after cathodal relative to sham tDCS. The accelerating effect of
tDCS was explained by a reduced frequency of very slow responses. tDCS-induced acceleration of Picture naming correlated with larger volumes of the tract connecting the right Broca’s area and the supplementary motor area (SMA) and greater functional coupling from the right SMA to the right Broca’s area.
Conclusions: The results support the notion that the after-effects of tDCS on brain function are at least in part determined by the anatomical and functional connectivity of the targeted region.
Original languageEnglish
JournalBrain Stimulation
Volume7
Issue number1
Pages (from-to)122–129
Number of pages8
ISSN1935-861X
DOIs
Publication statusPublished - 2014

Keywords

  • Diffusion tensor imaging
  • Functional magnetic resonance imaging
  • Language
  • tDCS

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