Lab of Action and Body, Department of Psychology, Royal Holloway University of London, Egham Hill, Egham TW20 0EX, United Kingdom.
Lab of Action and Body, Department of Psychology, Royal Holloway University of London, Egham Hill, Egham TW20 0EX, United Kingdom; Humane Technology Lab, Università Cattolica del Sacro Cuore, Milano 20100, Italy.
Psychoneuroendocrinology. 2022 Jun;140:105719. doi: 10.1016/j.psyneuen.2022.105719. Epub 2022 Mar 10.
Transcutaneous auricular vagus nerve stimulation (taVNS) is a neuromodulatory technique that is thought to activate the Locus Coeruleus-Noradrenaline (LC-NA) system. Standard taVNS protocols consist of the administration of intermittent or continuous stimulation over long periods. However, there is currently a limited understanding of the temporal dynamics of taVNS modulation of cognitive processes, as well as its mechanisms of action. We argue that novel stimulation approaches, informed by established theories of the LC-NA system, are needed to further our understanding of the neurocognitive underpinnings of taVNS. In this pre-registered study, we tested whether an "event-related" taVNS protocol can modulate the LC-NA system. In a within-subject design (single session) we delivered brief trains of taVNS (3 s) during an auditory oddball paradigm. The taVNS was time-locked to the target stimuli presentation and randomly interleaved with sham stimulation. Response times (RT) and stimuli-driven pupillary diameter (PD) were used as indices of LC-NA activity. Results revealed that active taVNS increased RT to targets, as compared to sham trials. Notably, in line with current theories of LC-NA functioning, taVNS modulation of target-related pupil dilation depended on pre-stimulation PD, an index of baseline LC-NA activity. In particular, active (vs. sham) taVNS was associated with smaller pupil dilation in trials where the baseline PD was small. These results demonstrate, for the first time, the effectiveness of brief event-related taVNS in the modulation of cognitive processes and highlight the importance of using pupil size as an index of tonic and phasic LC-NA activity.
经皮耳迷走神经刺激（taVNS）是一种神经调节技术，被认为可以激活蓝斑-去甲肾上腺素（LC-NA）系统。标准的 taVNS 方案包括长时间的间歇性或连续性刺激。然而，目前对于 taVNS 调节认知过程的时间动态及其作用机制的理解还很有限。我们认为，需要新的刺激方法，以既定的 LC-NA 系统理论为依据，进一步了解 taVNS 的神经认知基础。在这项预先注册的研究中，我们测试了一种“事件相关”的 taVNS 方案是否可以调节 LC-NA 系统。在一项基于个体的设计（单次会议）中，我们在听觉Oddball 范式期间给予短暂的 taVNS 刺激（3 秒）。taVNS 与目标刺激呈现时间锁定，并与假刺激随机交替。反应时间（RT）和刺激驱动的瞳孔直径（PD）被用作 LC-NA 活性的指标。结果表明，与假刺激相比，主动 taVNS 增加了对目标的 RT。值得注意的是，与当前的 LC-NA 功能理论一致，taVNS 对目标相关的瞳孔扩张的调制取决于预刺激 PD，这是 LC-NA 活动的基线指标。具体来说，在 PD 较小的情况下，与假刺激相比，主动（而非假刺激）taVNS 与瞳孔扩张较小有关。这些结果首次证明了短暂的事件相关 taVNS 在调节认知过程中的有效性，并强调了使用瞳孔大小作为 tonic 和 phasic LC-NA 活动的指标的重要性。
