Non-invasive, Spatiotemporal Characterization of Muscle Activation Patterns from Vagus Nerve Stimulation in Human Subjects.

The short latency of the first muscle artifact suggests stimulus signal leakage activating the superior laryngeal nerve. The propagating activity visualized in one subject may show the activity of the external branch of the superior laryngeal nerve, which stimulates the cricothyroid muscle to contract, creating the first muscle artifact. The second artifact with longer latency is likely caused by the recurrent laryngeal nerve, which causes contraction of intrinsic laryngeal muscles such as the posterior cricoarytenoids. Previous analyses may have mischaracterized the first muscle artifact as nerve activity [Usami, K., Kawai, K., Sonoo, M., and Saito, N. (2013). Brain Stimul. 6(4), 615-623]. The use of MEA-based recordings clarifies our understanding of the VN's response to VNS, which may lead to better treatment efficacy and the eventual development of personalized VNS therapies for epilepsy and a range of inflammatory disorders.