Background Individuals are able to perform goal-directed behaviors thanks to executive functions. According to the neurovisceral integration model, executive functions are upregulated by brain areas such as the prefrontal and cingulate cortices, which are also crucially involved in controlling cardiac vagal activity. An array of neuroimaging studies already showed that these same brain areas are activated by transcutaneous vagus nerve stimulation (tVNS). Despite evidence toward effects of tVNS on specific executive functions such as inhibitory control, there have been no studies investigating what type of inhibition is improved by tVNS by systematically addressing them within the same experiment. Furthermore, the effect of tVNS on another core executive function, cognitive flexibility, has not yet been investigated. Objective We investigated the effects of tVNS on core executive functions such as inhibitory control and cognitive flexibility. Methods Thirty-two participants (nine women, Mage = 23.17) took part in this study. Vagally mediated heart rate variability parameters (root mean square of successive differences, RMSSD, and high frequency, HF) were measured while participants performed four different cognitive tasks that mainly rely on different aspects of both the aforementioned executive functions. Results Despite clear conflict effects in the four tasks, only performance on the task used to measure set-shifting paradigm was improved by tVNS, with switch costs being lower during tVNS than during sham stimulation. Furthermore, HF increased during each of the cognitive flexibility tasks, although HF during tVNS did not differ from HF during sham stimulation. Conclusion The results indicate for the first time (a) that tVNS can increase cognitive flexibility in a set-shifting paradigm, and (b) that tVNS may exert a stronger effect on cognitive flexibility than inhibition. The present study provides only partial evidence for the neurovisceral integration model. Future studies should address further paradigms that demand cognitive flexibility, thus investigating this new hypothesis on the specificity of the tVNS effects on cognitive flexibility.

中文翻译：

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经皮迷走神经刺激可能仅增强核心执行功能的特定方面。随机交叉试验

背景 由于执行功能，个人能够执行目标导向的行为。根据神经内脏整合模型，执行功能由前额叶和扣带皮层等大脑区域上调，这些区域在控制心脏迷走神经活动方面也至关重要。一系列神经影像学研究已经表明，这些相同的大脑区域被经皮迷走神经刺激 (tVNS) 激活。尽管有证据表明 tVNS 对特定执行功能（例如抑制性控制）的影响，但没有研究通过在同一实验中系统地解决它们来调查 tVNS 改善了哪种类型的抑制。此外，尚未研究 tVNS 对另一个核心执行功能——认知灵活性的影响。目的我们研究了 tVNS 对抑制控制和认知灵活性等核心执行功能的影响。方法 32 名参与者（9 名女性，Mage = 23.17）参加了这项研究。测量迷走神经介导的心率变异性参数（连续差异的均方根，RMSSD 和高频，HF），同时参与者执行四种不同的认知任务，这些任务主要依赖于上述两种执行功能的不同方面。结果 尽管四项任务中存在明显的冲突效应，但 tVNS 仅提高了用于测量组转换范式的任务的性能，tVNS 期间的转换成本低于假刺激期间。此外，在每个认知灵活性任务中，HF 都会增加，尽管 tVNS 期间的 HF 与假刺激期间的 HF 没有区别。结论结果首次表明 (a) tVNS 可以增加集合转换范式中的认知灵活性，以及​​ (b) tVNS 对认知灵活性的影响可能比抑制作用更强。本研究仅提供神经内脏整合模型的部分证据。未来的研究应该解决需要认知灵活性的进一步范式，从而研究这个关于 tVNS 对认知灵活性影响的特异性的新假设。本研究仅提供神经内脏整合模型的部分证据。未来的研究应该解决需要认知灵活性的进一步范式，从而研究这个关于 tVNS 对认知灵活性影响的特异性的新假设。本研究仅提供神经内脏整合模型的部分证据。未来的研究应该解决需要认知灵活性的进一步范式，从而研究这个关于 tVNS 对认知灵活性影响的特异性的新假设。