#28 - Wandering Around Vagus (WAV) - May 2025

The Vagus & the Brain

Welcome to Month 28 of Wandering Around Vagus, a paid monthly subscription series exploring the Vagus Nerve + Polyvagal Theory.

I’m Tina Foster of Foster & Flourish, the creator and guide of Wandering Around Vagus.

First, a few quick notes to help you orient within our pages:

• If you’re new, or need a review, here’s the link to the START page.

• You can find last month’s post (our 27th) on the vagus nerve and the heart here.

• Monthly & Supplementary Posts + Recordings can be accessed by topic from the navigation bar atop the Wandering Around Vagus Homepage.

• All past posts are listed in reverse chronological order on the archive page.​

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THIS MONTH’S WORK

This edition of WAV explores the intimate relationship between the vagus nerve and the brain, and how that connection shapes everything from physical health to emotional well-being.

The vagus nerve is many things, including a bridge between body and brain, connecting physiology and psychology. It helps explain why we feel calm or on edge, connected or shut down, depending on our internal state. It also explains why our emotions and body act in sync—why, when we’re nervous, our heart speeds up and our gut gets butterflies or when we’re calm, our heart slows down and our eyes soften.

At the site of brainstem, the vagus sends signals to specific parts of the brain, depending on the situation, how we feel and what actions are called for in said situation.

We’ll begin with a quick review of some vagal anatomy important to brain functioning, then move on to how the vagus and the brain dialogue with one another to create an effective and meaningful body-brain bridge.

By the end of this post, you’ll have a better sense of:

• the overall role of the vagus nerve in brain health and function

• how vagal tone contributes to emotional and cognitive health

• the body-brain-bridge in your own nervous system and how it might relate to how you’re feeling in a particular moment as well as to any pre-existing issues you might have

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The Vagus Nerve: A Quick Review

The vagus nerve originates in the medulla oblongata, a brainstem structure that governs automatic, involuntary functions—like breathing and heart rate—that don’t require conscious control.

As a mixed nerve, the vagus contains both:

• Afferent fibers (about 80%) that carry sensory information from the body to the brain

• Efferent fibers that carry signals from the brain to the body

This means the vagus nerve acts less like a one-way command line and more like a feedback loop: constantly informing the brain about the state of the body.

The Brain–Vagus Dialogue & the Body-Brain Bridge

The vagus nerve enables a steady back-and-forth between body and brain, shaping not only physical states but also emotional tone and cognitive clarity.

Below are three brain regions that work closely with the vagus nerve: