Investigation of the Effects of Transcutaneous Vagus Nerve Stimulation (tVNS) using Magnetoencephalography (MEG)

Transcutaneous vagus nerve stimulation (tVNS) is a type of non-invasive brain stimulation that uses low-level electrical current to stimulate the auricular branch of the vagus nerve on the ear. It has been utilised as a treatment option for a number of different medical conditions, although the parameters of stimulation have not been investigated or optimised fully. I used a neuro-imaging technique called magnetoencephalography (MEG) to measure how the brain responds to tVNS and investigated whether varying the frequency or site of stimulation led to a difference in brain response. This was a novel approach, as simultaneous MEG and tVNS had not been performed before due to large stimulation artifacts from the electrical stimulation. I developed a successful methodology that reduced and removed stimulation artifact in the data and allowed for the recovery of underlying brain dynamics that could then be analysed further. The results from this thesis suggest that different stimulation frequencies and sites elicit different brain response and illustrate the potential for customised stimulation parameters to be developed for the personalised treatment of different individuals or medical conditions.