Peng Xiaolong, Baker-Vogel Brenna, Sarhan Mutaz, Short Edward B, Zhu Wenzhen, Liu Hesheng, Kautz Steven, Badran Bashar W
Department of Psychiatry and Behavioral Sciences, Neuro-X Lab, Medical University of South Carolina, Charleston, SC, USA; Deparment of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Brain Stimul. 2023 Jul-Aug;16(4):1144-1153. doi: 10.1016/j.brs.2023.07.050. Epub 2023 Jul 28.
Implanted vagus nerve stimulation (VNS) and transcutaneous auricular VNS (taVNS) have been primarily administered clinically to the unilateral-left vagus nerve. This left-only convention has proved clinically beneficial in brain disorders. However, in stroke survivors, the presence of a lesion in the brain may complicate VNS-mediated signaling, and it is important to understand the laterality effects of VNS in stroke survivors to optimize the intervention.
To understand whether taVNS delivered to different ear targets relative to the lesion (ipsilesional vs contralesional vs bilateral vs sham) impacts blood oxygenation level dependent (BOLD) signal propagation in stroke survivors.
We enrolled 20 adults with a prior history of stroke. Each participant underwent a single visit, during which taVNS was delivered concurrently during functional magnetic resonance imaging (fMRI) acquisition. Each participant received three discrete active stimulation conditions (ipsilesional, contralesional, bilateral) and one sham condition in a randomized order. Stimulation-related BOLD signal changes in the active conditions were compared to sham conditions to understand the interaction taVNS and laterality effects.
All active taVNS conditions deactivated the contralesional default mode network related regions compared to sham, however only ipsilesional taVNS enhanced the activations in the ipsilesional visuomotor and secondary visual cortex. Furthermore, we reveal an interaction in task activations between taVNS and cortical visuomotor areas, where ipsilesional taVNS significantly increased ipsilesional visuomotor activity and decreased contralesional visuomotor activity compared to sham.
Laterality of taVNS relative to the lesion is a critical factor in optimizing taVNS in a stroke population, with ipsilesional stimulation providing largest direct brain activation and should be explored further when designing taVNS studies in neurorehabilitation.
植入式迷走神经刺激（VNS）和经皮耳迷走神经刺激（taVNS）在临床上主要作用于单侧左侧迷走神经。这种仅针对左侧的惯例已在脑部疾病的临床治疗中证明是有益的。然而，在中风幸存者中，脑部病变的存在可能会使VNS介导的信号传导变得复杂，了解VNS在中风幸存者中的侧别效应对于优化干预措施很重要。
了解相对于病变部位（患侧、对侧、双侧与假刺激），将taVNS施加于不同耳部靶点是否会影响中风幸存者的血氧水平依赖（BOLD）信号传播。
我们招募了20名有中风病史的成年人。每位参与者接受一次就诊，在此期间，在功能磁共振成像（fMRI）采集过程中同时进行taVNS。每位参与者以随机顺序接受三种不同的主动刺激条件（患侧、对侧、双侧）和一种假刺激条件。将主动刺激条件下与刺激相关的BOLD信号变化与假刺激条件进行比较，以了解taVNS与侧别效应之间的相互作用。
与假刺激相比，所有主动taVNS条件均使对侧默认模式网络相关区域失活，然而只有患侧taVNS增强了患侧视觉运动和二级视觉皮层的激活。此外，我们揭示了taVNS与皮质视觉运动区域在任务激活方面的相互作用，与假刺激相比，患侧taVNS显著增加了患侧视觉运动活动并降低了对侧视觉运动活动。
taVNS相对于病变的侧别是在中风人群中优化taVNS的关键因素，患侧刺激可提供最大程度的直接脑激活，在设计神经康复中的taVNS研究时应进一步探索。
