Microscopic magnetic stimulation of the cervical vagus nerve

Abstract

Introduction: Electrical vagus nerve stimulation (VNS) is an FDA-approved treatment for drug-resistant epilepsy, depression, and headache. However, oxidation/reduction reactions at the electrode tissue interface can result in damage and reduce the efficacy of stimulation. Micro-magnetic stimulation (μMS) of the vagus nerve has the potential to be an alternative to electrical VNS. μMS is accomplished by running alternating current through a sub-millimeter coil to produce time-varying magnetic fields which can in turn induce electrical fields, leading to neuronal activation. The small size of the coils involved leads to high spatial resolution of μMS. μMS is distinct from electrical stimulation in that it can activate axons based on the particular coil orientation, and in that it does not require charge-balanced stimulation waveform shapes, which are needed in electrical stimulation to avoid electrophoresis. The coils used in μMS do not undergo oxidation/reduction reactions and are compatible with imaging devices such as MRI. Thus, μMS represents a groundbreaking step forward from the traditional electrical stimulation of neurons. Here, we describe the effect of micro-magnetic VNS (μM-VNS) on physiological parameters in rats.