Abstract
Previous language production studies targeting the inferior frontal and superior temporal gyrus using anodal tDCS have provided mixed results. Part of this heterogeneity may be explained by limited target region focality of conventionally used electrode montages. In this simulation study, the focality of conventionally used and alternative bipolar electrode montages was examined. Specifically, electric field distributions of anodal tDCS targeting IFG and STG in conventional setups (anodal electrode over IFG/STG, reference electrode over right supraorbital region) were compared to a number of alternative electrode montages. Conventional montages showed maximum field strengths that next to the target region included additional neighbouring regions. By contrast, adjustments in electrode size and placement improved focality of anodal tDCS. Thus, the heterogeneity of findings of language production studies deploying conventional tDCS montages may in part be explained by diffuse electric field distributions. Alternative montages improve focality and may yield more unequivocal results.