In two separate but closely related sham-controlled experiments, two groups of healthy subjects underwent anodal tDCS (2mA) of the left dorsolateral prefrontal cortex (DLPFC) for 20 minutes. In Experiment 1, subjects (n=11) trained on a letter 3Back task during stimulation. In Experiment 2 subjects (n=11) trained on a letter 1Back task, which resembled the 3Back task but featured a lower working memory load. In both experiments, before and after stimulation, subjects completed an adjusting Paced Auditory Serial Addition Task (A-PASAT). Both the experimenter and subjects were blind to stimulation conditions in both experiments.
Subjects were both faster and more accurate on the A-PASAT task after receiving real tDCS paired with 3Back training (Experiment1) compared to sham+3Back, real+1Back, and sham+1Back conditions.
The cognitive demands of a task performed during tDCS can influence the effects of tDCS on post-stimulation performance. This finding has direct relevance to the use of tDCS as an investigative tool in cognitive neuroscience and as a therapy.
via It’s the thought that counts: Examining the task-dependent effects of transcranial direct current stimulation on executive function – Brain Stimulation: Basic, Translational, and Clinical Research in Neuromodulation.