By means of transcranial direct current stimulation applied to the left dorsolateral prefrontal cortex, we investigated the causal role of increased or decreased excitability of this brain region for two facets of executive functions: working memory and Stroop interference control. We tested 1) whether anodal tDCS of the left DLPFC enhances working memory 15 minutes after termination of stimulation and in the absence of direct task practice under stimulation; 2) whether anodal tDCS of the left DLPFC enhances interference control, as evidenced by Stroop performance and Stroop sequence effects; and 3) whether cathodal tDCS leads to compromised executive functioning compared to anodal stimulation. In a between-subject design with 88 healthy psychology students, we compared the impact of anodal and cathodal stimulation against a sham condition, on performance on a Stroop task (during active stimulation) and on an n-back task (completed 15 minutes after active stimulation ended). We found significantly enhanced accuracy in the n-back task after anodal stimulation compared with sham, as well as speeded reactions in the Stroop tasks independent of trial type. By contrast, we found no modulation of Stroop interference effects or Stroop sequence effects. No inhibitory effects of cathodal stimulation were observed. These results support the causal role of the left DLPFC in working memory but lend no support to its involvement in Stroop interference control.

中文翻译：

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工作记忆和 Stroop 干扰控制的因果基础：测试阳极和阴极 tDCS 对左侧 DLPFC 的影响。

通过对左背外侧前额叶皮层施加经颅直流电刺激，我们研究了该大脑区域的兴奋性增加或减少对于执行功能的两个方面：工作记忆和斯特鲁普干扰控制的因果作用。我们测试了 1) 左侧 DLPFC 的阳极 tDCS 是否在刺激终止后 15 分钟且在刺激下没有直接任务练习的情况下增强工作记忆；2）左侧DLPFC的阳极tDCS是否增强了干扰控制，如Stroop性能和Stroop序列效应所证明的；3) 与阳极刺激相比，阴极 tDCS 是否会导致执行功能受损。在一项针对 88 名健康心理学学生的受试者间设计中，我们比较了阳极和阴极刺激与假条件下的影响，以及对 Stroop 任务（主动刺激期间）和 n-back 任务（主动刺激后 15 分钟完成）表现的影响。刺激结束）。我们发现，与假手术相比，阳极刺激后 n-back 任务的准确性显着提高，并且 Stroop 任务的反应速度加快，与试验类型无关。相比之下，我们没有发现斯特鲁普干扰效应或斯特鲁普序列效应的调制。没有观察到阴极刺激的抑制作用。这些结果支持左 DLPFC 在工作记忆中的因果作用，但不支持其参与 Stroop 干扰控制。