Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, And Tuebingen NeuroCampus, University of Tuebingen, Tuebingen, Germany.
Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, And Tuebingen NeuroCampus, University of Tuebingen, Tuebingen, Germany.
Brain Stimul. 2021 Mar-Apr;14(2):209-216. doi: 10.1016/j.brs.2021.01.001. Epub 2021 Jan 7.
Transcutaneous auricular Vagus Nerve Stimulation (taVNS) is a non-invasive neuromodulation technique that may constitute an effective treatment for a wide range of neurological, psychiatric, and medical conditions. One key challenge in taVNS research is the high interindividual response variability. To gain an understanding of this variability, reliable biomarkers for taVNS responsiveness would be highly desirable. In this study, we investigated physiological candidate biomarkers while systematically varying stimulation conditions and observing physiological state characteristics.
Forty-four healthy young adults received taVNS and sham-stimulation. Subjects were pseudo-randomly assigned to stimulation of the left or right ear. Each subject underwent six blocks of stimulation. Across blocks, respiration-locking (inhalation-locked taVNS vs. exhalation-locked taVNS vs. sham) and the electrode location (tragus vs. cymba conchae) were varied. We analyzed heart rate (HR), various heart rate variability (HRV) scores, and neuro-cardiac coupling (NCC), indexed by the relationship between electroencephalographic delta power and heartbeat length.
We observed an effect of taVNS on HR and HRV scores during, but not after stimulation. The direction of the effects was consistent with parasympathetic activation. We did not observe any systematic influence of the stimulation conditions that we varied. However, we found baseline NCC scores to be significant predictors for the individual effect of taVNS on HRV scores.
Cardiac effects of taVNS indicate parasympathetic activation. These effects were short lived, which might explain that some previous studies were unable to detect them. We propose NCC as a novel candidate biomarker for responsiveness to taVNS.
经皮耳迷走神经刺激（taVNS）是一种非侵入性神经调节技术，可能对广泛的神经、精神和医疗状况构成有效治疗。taVNS 研究中的一个关键挑战是个体间反应的高度可变性。为了了解这种可变性，我们非常希望获得 taVNS 反应的可靠生物标志物。在这项研究中，我们在系统改变刺激条件并观察生理状态特征的同时，研究了生理候选生物标志物。
44 名健康的年轻成年人接受了 taVNS 和假刺激。受试者被随机分配到左耳或右耳刺激。每位受试者接受了六轮刺激。在各轮中，改变了呼吸锁定（吸气锁定 taVNS 与呼气锁定 taVNS 与假刺激）和电极位置（耳屏与耳甲腔）。我们分析了心率（HR）、各种心率变异性（HRV）评分和神经心脏耦合（NCC），通过脑电图 delta 功率与心跳长度之间的关系来表示。
我们观察到 taVNS 在刺激期间而非刺激后对 HR 和 HRV 评分产生影响。这些影响的方向与副交感神经激活一致。我们没有观察到我们所改变的刺激条件有任何系统的影响。然而，我们发现基线 NCC 评分是 taVNS 对 HRV 评分个体影响的重要预测指标。
taVNS 的心脏效应表明副交感神经激活。这些影响是短暂的，这可能解释了为什么以前的一些研究无法检测到它们。我们提出 NCC 作为 taVNS 反应性的一种新的候选生物标志物。
