Modulating lexical and semantic processing by transcranial direct current stimulation

Here we aim to evaluate the ability of transcranial direct current stimulation (tDCS), which is applied over Wernicke's area and its right homologue, to influence lexical decisions and semantic priming and establish an involvement for temporo-parietal areas in lexical and semantic processing. Thirty-two subjects (17 women) completed a lexical decision task and a semantic priming task while receiving 20 min of bilateral tDCS stimulation (right anodal/left cathodal or left anodal/right cathodal stimulation) or sham stimulation. We hypothesized that right anodal/left cathodal stimulation over temporo-parietal areas would selectively interrupt the typical lexical processing dominance of the left hemisphere and facilitate mediated priming, while left anodal/right cathodal stimulation would selectively facilitate lexical processing and direct priming. Results showed impaired lexical processing under right anodal/left cathodal stimulation in comparison with sham and left anodal/right cathodal stimulation. Results are discussed in light of previous findings and hemispheric lateralization models.