Development of a Vagus Nerve Stimulation and Recording Setup for Ultrasound Characterization

Abstract

The objective for my MS Thesis was to develop a stable electrical stimulation and recording preparation for the vagus nerve in guinea pigs so that ultrasound stimulation on this pathway can be studied robustly. In particular, the plan was to electrically stimulate the vagus nerve and characterize the response patterns (i.e., different components and peaks of the evoked compound action potential corresponding to different subpopulation of fibers) using electrodes wrapped around the nerve. Ultrasound stimulation of the vagus nerve can then be performed and the corresponding response patterns can be compared with those caused by electrical stimulation to assess how ultrasound is activating the vagus nerve. Ultrasound stimulation will also be performed while electrically stimulating the vagus nerve to assess suppressive or modulatory effects of ultrasound. To further demonstrate proof-of-concept of US neuromodulation in a simplified preparation, I assessed how ultrasound stimulation with electrical stimulation of the vagus nerve modulates the heart rate in guinea pigs. The long term goal is to develop a non-invasive method for modulating vagus nerve activity that can have clinical applications for treating inflammatory disorders, seizures, depression, tinnitus, and other conditions that may be modulated by the vagus nerve.