Single session tDCS over the left DLPFC disrupts interference processing

Whether single session tDCS can impact upon cognition in healthy subjects is currently a heated debate against the background of inconsistent results. In view of the current methodological discussion concerning tDCS we developed an alternative approach to measure effects of single session tDCS on the Stroop task. The left DLPFC was stimulated in a pre-post design using a new electrode set-up (a 9 cm2 electrode was placed over the left DLPFC while a 35 cm2 was placed over the parieto-occipital cortex) contrasting anodal versus cathodal stimulation. The Stroop task was optimized concerning confounding variables that were not controlled in previous attempts to measure the effects of single-session tDCS on the Stroop task. In our sample of N = 32 healthy students we observed a significant single session tDCS effect on the Stroop effect in the error data as in our study cathodal stimulation as compared to anodal stimulation of the left DLPFC disrupted interference processing. This result confirms previous studies suggesting that neuromodulation of the left DLPFC impacts interference processing. Single-session tDCS can impact upon cognitive processes. A rigorous methodical approach is emphasized as the effects seem to be only of small to medium size.