While all nerves in our body are incredibly important, there are very few that have the notoriety of the vagus nerve. The vagus nerve is one of the largest, most far-reaching nerves in your body! In fact, the word “Vagus” is latin for “wandering.” It originates in the brain and travels out to almost every major organ in the body (heart, lungs, stomach, intestines, etc…) (Kenny & Bordoni, 2021). It is responsible for communicating parasympathetic (rest and digest, to counteract the sympathetic fight or flight response) messages throughout your peripheral nervous system. In recent years, our understanding of the functions this nerve serves has grown significantly. As we learn more and more about the ins and outs of the vagus nerve, the potential clinical applications become increasingly numerous. Today let’s break down the vagus nerve.
An important thing to understand about the vagus nerve is that it is bidirectional. We often think of nerves as analogous to wires, sending signals in a single direction, but, in reality, many of our nerves can send and receive signals in both directions (Anderson, 1985; Howland, 2014)! In this manner, the vagus nerve acts as the main branch of communication between the brain and many of our vital organs!
Today focus on how the Vagus nerve interacts with our gut. The vagus is responsible for releasing signals to your gut to stimulate digestion and if need be, vomiting. Additionally, the vagus nerve receives signals from the gut (often in the form of inflammation) to regulate the HPA-axis, which mediates the body’s stress response (Howland, 2014). Through the interplay between the vagus nerve and the HPA-axis, the brain is able to exert a high level of control over various cellular processes that occur within the stomach, resulting in a variety of effects on the gut microbiome (Breit et al., 2018).
Considering the role that inflammation and the gut microbiome plays in the function of our nervous system, the vagus nerve is highly interconnected with our mental health (Howland, 2014). In recent years, stimulation of the vagus nerve stimulation (VNS) by an electrical device has shown statistically significant antidepressant effects for individuals with treatment resistant depression (Breit et al., 2018; Mayo Clinic, 2020).
Research on the vagus nerve has provided the scientific community with insight on how our brain and body interact with each other. Through further study of this interaction, we can better understand how our brains work in both health and disease!
