Transcranial direct current stimulation (tDCS) selectively modulates semantic information during reading

The left angular gyrus has long been implicated in semantic processing. Here we tested whether or not transcranial direct current stimulation (tDCS) over the left angular gyrus modulated reading performance. Adult readers (N = 77) (1) read aloud words that varied in degree of imageability, a semantic word property known to activate the angular gyrus, and (2) completed an N-back task (control task). Individuals were randomly assigned to either the anodal, cathodal or sham stimulation conditions. We found that anodal (p = 0.001) and cathodal (p < 0.001) stimulation impacted how imageability facilitates reading times such that readers who showed the largest imageability effects pre-stimulation showed the greatest reduction in these effects post-stimulation. No effects of stimulation were found in the sham group (p > 0.05) or for the control task (i.e., N-back; p > 0.05). These findings indicate that reading pathways can be modulated via brain stimulation (tDCS) to shift individuals' sensitivity to word-level characteristics, namely imageability.