Kumagai Shinichi, Shiramatsu Tomoyo Isoguchi, Matsumura Akane, Ishishita Yohei, Ibayashi Kenji, Onuki Yoshiyuki, Kawai Kensuke, Takahashi Hirokazu
Department of Neurosurgery, Jichi Medical University, Tochigi, Japan; Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan.
Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan.
Brain Stimul. 2023 Sep-Oct;16(5):1476-1485. doi: 10.1016/j.brs.2023.09.019. Epub 2023 Sep 29.
We previously found that vagus nerve stimulation (VNS) strengthened stimulus-evoked activity in the superficial layer of the sensory cortex but not in the deep layer, suggesting that VNS altered the balance between the feedforward (FF) and feedback (FB) pathways. Band-specific oscillatory activities in the cortex could serve as an index of the FF-FB balance, but whether VNS affects cortical oscillations along sensory pathways through neuromodulators remains unclear.
VNS modulates the FF-FB balance through the cholinergic and noradrenergic systems, which modulate stimulus gain in the cortex.
We investigated the effects of VNS using electrocorticography in the auditory cortex of 34 Wistar rats under general anesthesia while presenting click stimuli. In the time-frequency analyses, the putative modulation of the FF and FB pathways was estimated using high- and low-frequency power. We assessed, using analysis of variance, how VNS modulates auditory-evoked activities and how the modulation changes with cholinergic and noradrenergic antagonists.
VNS increased auditory cortical evoked potentials, consistent with results of our previous work. Furthermore, VNS increased auditory-evoked gamma and beta powers and decreased theta power. Local administration of cholinergic antagonists in the auditory cortex selectively disrupted the VNS-induced increase in gamma and beta power, while noradrenergic antagonists disrupted the decrease in theta power.
VNS might strengthen the FF pathway through the cholinergic system and attenuate the FB pathway through the noradrenergic system in the auditory cortex. Cortical gain modulation through the VNS-induced neuromodulatory system provides new mechanistic insights into the effect of VNS on auditory processing.
我们之前发现，迷走神经刺激（VNS）增强了感觉皮层浅层的刺激诱发活动，但深层未增强，这表明VNS改变了前馈（FF）和反馈（FB）通路之间的平衡。皮层中特定频段的振荡活动可作为FF-FB平衡的指标，但VNS是否通过神经调节剂影响感觉通路中的皮层振荡仍不清楚。
VNS通过胆碱能和去甲肾上腺素能系统调节FF-FB平衡，这两种系统调节皮层中的刺激增益。
我们在34只Wistar大鼠全身麻醉下，通过皮层脑电图研究了VNS在听觉皮层中的作用，同时呈现点击刺激。在时频分析中，使用高频和低频功率估计FF和FB通路的假定调制。我们使用方差分析评估VNS如何调节听觉诱发活动，以及这种调制如何随胆碱能和去甲肾上腺素能拮抗剂而变化。
VNS增加了听觉皮层诱发电位，与我们之前的工作结果一致。此外，VNS增加了听觉诱发的γ和β功率，并降低了θ功率。在听觉皮层局部给予胆碱能拮抗剂选择性地破坏了VNS诱导的γ和β功率增加，而去甲肾上腺素能拮抗剂则破坏了θ功率的降低。
VNS可能通过胆碱能系统增强听觉皮层中的FF通路，并通过去甲肾上腺素能系统减弱FB通路。通过VNS诱导的神经调节系统进行的皮层增益调制为VNS对听觉处理的影响提供了新的机制见解。
