Institute of Neuroscience, Université Catholique de Louvain (UCLouvain), Brussels, Belgium.
Centre for Refractory Epilepsy, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
PLoS One. 2021 Jul 12;16(7):e0254480. doi: 10.1371/journal.pone.0254480. eCollection 2021.
Transcutaneous auricular Vagal Nerve Stimulation (taVNS) is a non-invasive neurostimulation technique with potential analgesic effects. Several studies based on subjective behavioral responses suggest that taVNS modulates nociception differently with either pro-nociceptive or anti-nociceptive effects.
This study aimed to characterize how taVNS alters pain perception, by investigating its effects on event-related potentials (ERPs) elicited by different types of spinothalamic and lemniscal somatosensory stimuli, combined with quantitative sensory testing (detection threshold and intensity ratings).
We performed 3 experiments designed to study the time-dependent effects of taVNS and compare with standard cervical VNS (cVNS). In Experiment 1, we assessed the effects of taVNS after 3 hours of stimulation. In Experiment 2, we focused on the immediate effects of the duty cycle (OFF vs. ON phases). Experiments 1 and 2 included 22 and 15 healthy participants respectively. Both experiments consisted of a 2-day cross-over protocol, in which subjects received taVNS and sham stimulation sequentially. In addition, subjects received a set of nociceptive (thermonociceptive CO2 laser, mechanical pinprick) and non-nociceptive (vibrotactile, cool) stimuli, for which we recorded detection thresholds, intensity of perception and ERPs. Finally, in Experiment 3, we tested 13 epileptic patients with an implanted cVNS by comparing OFF vs. ON cycles, using a similar experimental procedure.
Neither taVNS nor cVNS appeared to modulate the cerebral and behavioral aspects of somatosensory perception.
The potential effect of taVNS on nociception requires a cautious interpretation, as we found no objective change in behavioral and cerebral responses to spinothalamic and lemniscal somatosensory stimulations.
经皮耳迷走神经刺激（taVNS）是一种非侵入性神经刺激技术，具有潜在的镇痛作用。几项基于主观行为反应的研究表明，taVNS 通过产生致痛或抗痛的效果来调节伤害感受。
本研究旨在通过研究 taVNS 对不同类型的脊髓和楔束躯体感觉刺激诱发的事件相关电位（ERPs）的影响，并结合定量感觉测试（检测阈值和强度评分），来描述 taVNS 如何改变疼痛感知。
我们进行了 3 项实验，旨在研究 taVNS 的时变效应，并与标准颈 VNS（cVNS）进行比较。在实验 1 中，我们评估了刺激 3 小时后 taVNS 的影响。在实验 2 中，我们专注于占空比（ON 相与 OFF 相）的即时效应。实验 1 和实验 2 分别纳入了 22 名和 15 名健康参与者。这两项实验均采用 2 天交叉试验方案，其中参与者依次接受 taVNS 和假刺激。此外，参与者还接受了一组伤害性（热 nociceptive CO2 激光、机械刺痛）和非伤害性（振动触觉、冷觉）刺激，我们记录了检测阈值、感知强度和 ERPs。最后，在实验 3 中，我们通过比较 OFF 相与 ON 相，使用类似的实验程序，测试了 13 名植入 cVNS 的癫痫患者。
无论是 taVNS 还是 cVNS，都似乎没有调节躯体感觉感知的大脑和行为方面。
taVNS 对伤害感受的潜在影响需要谨慎解释，因为我们没有发现脊髓和楔束躯体感觉刺激的行为和大脑反应有任何客观变化。
