Abstract：
One mechanism by which transcranial direct current stimulation (tDCS) has been proposed to improve attention is by transcutaneous stimulation of cranial nerves, thereby activating the locus coeruleus (LC). Specifically, placement of the electrodes over the frontal bone and mastoid is thought to facilitate current flow across the face as a path of least resistance. The face is innervated by the trigeminal nerve, and the trigeminal nerve is interconnected with the LC. In this study, we tested whether stimulating the trigeminal nerve impacts indices of LC activity and performance on a sustained attention task. We replicated previous research that shows deterioration in task performance, increases in the rate of task-unrelated thoughts, and reduced pupil responses due to time on task irrespective of tDCS condition (sham, anodal, and cathodal stimulation). Importantly, tDCS did not influence pupil dynamics (pretrial or stimulus-evoked), self-reported attention state, nor task performance in active versus sham stimulation conditions. The findings reported here are consistent with theories about arousal centered on a hypothesized link between LC activity indexed by pupil size, task performance, and self-reported attention state but fail to support hypotheses that tDCS over the trigeminal nerve influences indices of LC function.
摘要：
已经提出了经颅直流电刺激（tDCS）以提高注意力的一种机制是通过经皮刺激颅神经。从而激活蓝斑(LC)。具体来说,将电极放置在额骨和乳突上被认为有助于电流流过面部作为最小电阻的路径。面部受三叉神经支配,三叉神经与LC相连.在这项研究中,我们测试了刺激三叉神经是否会影响持续注意力任务的LC活动和表现指数。我们复制了以前的研究，这些研究表明任务绩效下降，与任务无关的想法的比率增加，以及由于任务时间而降低的瞳孔反应，而与tDCS条件无关(假，阳极，和阴极刺激)。重要的是,tDCS不影响瞳孔动力学(试验前或刺激诱发),自我报告的注意力状态，在主动刺激和假刺激条件下也没有任务表现。这里报道的发现与关于唤醒的理论一致，该理论集中在以瞳孔大小为索引的LC活动之间的假设联系上，任务性能，和自我报告的注意力状态，但未能支持三叉神经上的tDCS影响LC功能指数的假设。
