The vagus nerve
The connection between the brain and the body
The vagus nerve, also known as cranial nerve X, is one of the most important parts of the autonomic nervous system. It connects the brainstem with many organs, including the heart, lungs, and digestive tract. It takes part in regulating processes that occur in our body without the need for conscious control.
Its activity helps the body adapt to changing needs — from activity and responding to challenges to rest, digestion, and maintaining internal balance.
The vagus nerve does not work in isolation. It is part of an extensive network of connections between the brain and the body that works together with other parts of the nervous system.
How does the vagus nerve work?
It carries information in both directions
Vagus nerve fibres carry signals both from the organs to the brain and from the brain to the organs. This allows the central nervous system to receive information about the state of the body and take part in adjusting how it functions.
It helps regulate the heart and breathing
The vagus nerve influences, among other things, heart rate and takes part in regulating respiratory functions. Its activity is one element of the body's physiological response to changing conditions.
It supports the digestive system
It plays an important role in regulating digestive processes and gut motility, working together with other nervous and hormonal mechanisms.
It takes part in communication between the body and the brain
Signals from the organs contribute to the information on which the brain bases its interpretation of the body's current state. This is one element of the complex relationship between physiology, sensations, and behaviour.
The vagus nerve and Polyvagal Theory
Stephen Porges, the creator of Polyvagal Theory, drew attention to the importance of different circuits of the autonomic nervous system in responses to challenges, stress, and signals of safety.
In his view, a special role is played by two functionally distinct parasympathetic pathways associated with the vagus nerve: the ventral and the dorsal. The theory describes their part in different patterns of physiological response and behaviour.
This approach helps us consider human reactions not only at the level of thoughts and emotions, but also in the context of physiology. It is worth remembering, however, that the detailed assumptions of Polyvagal Theory are the subject of scientific debate, and its model does not cover all knowledge about the autonomic nervous system.
Why is it worth learning about the vagus nerve?
Understanding its functions helps us learn how the brain and body work together to regulate basic physiological processes. It is an important perspective for anyone interested in stress, emotions, wellbeing, and relationships.
This does not mean, however, that the vagus nerve is a single “calm switch”, or that every emotional reaction can be explained by its activity. The body's regulation is the result of many systems and mechanisms working together.
By getting to know the connections between the brain and the body, we gain a broader perspective on our reactions — and can look more mindfully at how we function day to day.