Institute of Psychology, Leiden University, Leiden, the Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, the Netherlands.
Institute of Psychology, Leiden University, Leiden, the Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, the Netherlands.
Brain Stimul. 2023 Jul-Aug;16(4):1001-1008. doi: 10.1016/j.brs.2023.06.010. Epub 2023 Jun 20.
Transcutaneous auricular vagus nerve stimulation (taVNS) has been tested as a potential treatment for pharmaco-resistant epilepsy and depression. Its clinical efficacy is thought to depend on taVNS-induced activation of the locus coeruleus and other neuromodulator systems. However, unlike for invasive VNS in rodents, there is little evidence for an effect of taVNS on noradrenergic activity.
We attempted to replicate recently published findings by Sharon et al. (2021), showing that short bursts of taVNS transiently increased pupil size and decreased EEG alpha power, two correlates of central noradrenergic activity.
Following the original study, we used a single-blind, sham-controlled, randomized cross-over design. Human volunteers (n = 29) received short-term (3.4 s) taVNS at the maximum level below the pain threshold, while we collected resting-state pupil-size and EEG data. To analyze the data, we used scripts provided by Sharon and colleagues.
Consistent with Sharon et al. (2021), pupil dilation was significantly larger during taVNS than during sham stimulation (p = .009; Bayes factor supporting the difference = 7.45). However, we failed to replicate the effect of taVNS on EEG alpha power (p = .37); the data were four times more likely under the null hypothesis (BF = 0.28).
Our findings support the effectiveness of short-term taVNS in inducing transient pupil dilation, a correlate of phasic noradrenergic activity. However, we failed to replicate the recent finding by Sharon et al. (2021) that taVNS attenuates EEG alpha activity. Overall, this study highlights the need for continued research on the neural mechanisms underlying taVNS efficacy and its potential as a treatment option for pharmaco-resistant conditions. It also highlights the need for direct replications of influential taVNS studies.
经皮耳迷走神经刺激（taVNS）已被测试作为一种治疗药物难治性癫痫和抑郁症的潜在方法。其临床疗效被认为取决于 taVNS 诱导的蓝斑和其他神经调质系统的激活。然而，与啮齿动物的侵入性 VNS 不同，很少有证据表明 taVNS 对去甲肾上腺素能活性有影响。
我们试图复制 Sharon 等人最近发表的研究结果（2021 年），该研究表明，短时间的 taVNS 会短暂地增加瞳孔大小并降低 EEGα 功率，这两个指标都是中枢去甲肾上腺素能活性的相关指标。
按照原始研究，我们使用了单盲、假刺激对照、随机交叉设计。人类志愿者（n=29）在低于疼痛阈值的最大水平下接受短期（3.4s）taVNS，同时我们收集静息状态下的瞳孔大小和 EEG 数据。为了分析数据，我们使用了 Sharon 及其同事提供的脚本。
与 Sharon 等人（2021 年）的研究一致，在 taVNS 期间，瞳孔扩张明显大于假刺激期间（p=0.009；支持差异的贝叶斯因子为 7.45）。然而，我们未能复制 taVNS 对 EEGα 功率的影响（p=0.37）；数据更倾向于零假设（BF=0.28）。
我们的研究结果支持短期 taVNS 诱导短暂瞳孔扩张的有效性，瞳孔扩张是相位性去甲肾上腺素能活动的一个相关指标。然而，我们未能复制 Sharon 等人（2021 年）的最近发现，即 taVNS 减弱 EEGα 活动。总的来说，这项研究强调了需要继续研究 taVNS 疗效的神经机制及其作为治疗药物难治性疾病的潜在选择。它还强调了需要对有影响力的 taVNS 研究进行直接复制。
