A comprehensive explanation is lacking for the broad array of cognitive effects modulated by transcranial direct current stimulation (tDCS). We advanced the testable hypothesis that tDCS to the default mode network (DMN) increases processing of goals and stored information at the expense of external events. We further hypothesized that tDCS to the dorsal attention network (DAN) increases processing of external events at the expense of goals and stored information. A literature search (PsychINFO) identified 42 empirical studies and 3 meta-analyses examining effects of prefrontal and/or parietal tDCS on tasks that selectively required external and/or internal processing. Most, though not all, of the studies that met our search criteria supported our hypothesis. Three meta-analyses supported our hypothesis. The hypothesis we advanced provides a framework for the design and interpretation of results in light of the role of large-scale intrinsic networks that govern attention.

对于经颅直流电刺激（tDCS）调节的广泛认知作用尚缺乏全面的解释。我们提出了可验证的假设，即tDCS到默认模式网络（DMN）会以牺牲外部事件为代价来增加目标和存储信息的处理量。我们进一步假设，背注意力网络（DAN）的tDCS会以牺牲目标和存储信息为代价来增加对外部事件的处理。文献检索（PsychINFO）确定了42项实证研究和3项荟萃分析，检查前额叶和/或顶壁tDCS对选择性地需要外部和/或内部处理的任务的影响。满足我们搜索标准的大多数（尽管不是全部）研究都支持我们的假设。三个荟萃分析支持了我们的假设。