Pimping inhibition: Anodal tDCS enhances stop-signal reaction time

The stop-signal task (SST) is assumed to reliably measure response inhibition; specifically, in this task participants sometimes have to withhold a response according to the onset of a sudden cue. The response-stopping process is estimated by a stochastic model that delivers the stop-signal reaction time (SSRT; Verbruggen & Logan, 2009), that is, the latency to inhibit prepotent responses. The right dorsolateral prefrontal cortex (rDLPFC) plays a key role in goal directed cognitive control in general and particularly an increased activation has been associated with better SST performance (that is with shorter SSRT). We stimulated the rDLPFC in a prepost design via transcranial DC stimulation (tDCS). A 9 cm2 anode was always positioned over the rDLPFC while the 35 cm2 cathode was placed over the left deltoid. We contrasted an anodal stimulation condition (that is assumed to enhance neural processing) with sham stimulation and expected an increase in inhibitory functions after anodal tDCS, as evidenced by a decrease in SSRT. In a sample of N = 56 healthy adults, we found a significant Time × tDCS-Condition interaction in the expected direction. Control analysis confirmed that the statistically significant decrease in SSRT after anodal tDCS was not due to generally faster reaction times. These results confirm the role of the rDLPFC for cognitive inhibition processes and further suggest that inhibition is not a fixed resource but depends on the current state of the PFC. (PsycINFO Database Record (c) 2018 APA, all rights reserved).