Switching between two or more tasks is a key component in our modern world. Task switching, however, requires time-consuming executive control processes and thus produces performance costs when compared to task repetitions. While executive control during task switching has been associated with activation in the lateral prefrontal cortex (lPFC), only few studies so far have investigated the causal relation between lPFC activation and task-switching performance by modulating lPFC activation. In these studies, the results of lPFC modulation were not conclusive or limited to the left lPFC. In the present study, we aimed to investigate the effect of non-invasive transcranial direct current stimulation [tDCS; anodal tDCS (1 mA, 20 min) vs. cathodal tDCS (1 mA, 20 min) vs. sham tDCS (1 mA, 30 s)] over the right inferior frontal junction on task-switching performance in a well-established task-switching paradigm. In response times, we found a significant effect of tDCS Condition (atDCS, ctDCS vs. sham) on task-switching costs, indicating the modulation of task-switching performance by tDCS. In addition, we found a task-unspecific tDCS Condition effect in the first experimental session, in which participants were least familiar with the task, indicating a general enhancement of task performance in both task repetitions and task-switching trials. Taken together, our study provides evidence that the right lPFC is involved in task switching as well as in general task processing. Further studies are needed to investigate whether these findings can be translated into clinically relevant improvement in older subjects or populations with executive function impairment.

在两个或多个任务之间切换是我们现代世界的一个关键组成部分。然而，任务切换需要耗时的执行控制过程，因此与任务重复相比会产生性能成本。虽然任务切换期间的执行控制与外侧前额叶皮层 (lPFC) 的激活有关，但迄今为止只有少数研究通过调节 lPFC 激活来研究 lPFC 激活与任务切换性能之间的因果关系。在这些研究中，lPFC 调制的结果不是结论性的或仅限于左侧 lPFC。在本研究中，我们旨在研究无创经颅直流电刺激的效果 [tDCS; 阳极 tDCS（1 mA，20 分钟）与阴极 tDCS（1 mA，20 分钟）与假 tDCS（1 mA，30 s)] 在一个成熟的任务切换范式中，在右下额叶交界处对任务切换性能的影响。在响应时间中，我们发现 tDCS 条件（atDCS、ctDCS 与 sham）对任务切换成本的显着影响，表明 tDCS 对任务切换性能的调节。此外，我们在第一个实验会话中发现了任务非特异性 tDCS 条件效应，其中参与者最不熟悉任务，表明在任务重复和任务切换试验中任务性能普遍增强。总之，我们的研究提供了正确的 lPFC 参与任务切换以及一般任务处理的证据。