A Review of Parameter Settings for Invasive and Non-invasive Vagus Nerve Stimulation (VNS) Applied in Neurological and Psychiatric Disorders Author: Sean L Thompson1, Georgia H O&#39;Leary1, Christopher W Austelle1, Elise Gruber1, Alex T Kahn1, Andrew J Manett1, Baron Short1, Bashar W Badran1 Affiliation: <sup>1</sup> Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States. Conference/Journal: Front Neurosci Date published: 2021 Jul 13 Other: Volume ID: 15 , Pages: 709436 , Special Notes: doi: 10.3389/fnins.2021.709436. , Word Count: 166 Vagus nerve stimulation (VNS) is an established form of neuromodulation with a long history of promising applications. Earliest reports of VNS in the literature date to the late 1800's in experiments conducted by Dr. James Corning. Over the past century, both invasive and non-invasive VNS have demonstrated promise in treating a variety of disorders, including epilepsy, depression, and post-stroke motor rehabilitation. As VNS continues to rapidly grow in popularity and application, the field generally lacks a consensus on optimum stimulation parameters. Stimulation parameters have a significant impact on the efficacy of neuromodulation, and here we will describe the longitudinal evolution of VNS parameters in the following categorical progression: (1) animal models, (2) epilepsy, (3) treatment resistant depression, (4) neuroplasticity and rehabilitation, and (5) transcutaneous auricular VNS (taVNS). We additionally offer a historical perspective of the various applications and summarize the range and most commonly used parameters in over 130 implanted and non-invasive VNS studies over five applications. Keywords: VNS; depression; epilepsy; neuroplasticity; parameter optimization; rehabilitation; tVNS; taVNS. PMID: 34326720 PMCID: PMC8313807 DOI: 10.3389/fnins.2021.709436