The Nervous System, Metaphor, and the Polyvagal Debate

Over the years, I've watched clients have profound moments of relief simply from hearing that their nervous system was trying to protect them, not punish them. So when a group of 39 neuroscientists recently published a formal critique of Polyvagal Theory, calling aspects of it "scientifically untenable," I understood why many therapists and clients felt unsettled.

So what is actually being debated? And does it change the way we work?

What Is Polyvagal Theory?

Developed by neuroscientist Stephen Porges in the 1990s, Polyvagal Theory proposed a hierarchical way of understanding how the autonomic nervous system responds to safety and threat.

In simplified terms, it described three broad states:

• Ventral vagal, calm, connected, socially engaged
• Sympathetic activation, mobilisation, fight or flight
• Dorsal vagal, shutdown, collapse, dissociation

For trauma-informed therapists, this was transformative. It provided a coherent story for why the body reacts before the mind understands. It helped clients see panic, shutdown, or rage not as moral failings, but as protective adaptations.

And that reframing alone reduced enormous amounts of shame.

What Are the Critics Actually Saying?

The scientific critique, led by researcher Paul Grossman and supported by other neurophysiologists, focuses on anatomy and evolutionary claims. The argument is that the neat three-tier hierarchy does not map cleanly onto the known structure and function of the vagus nerve. The ventral/dorsal distinction may be more complex than originally described.

This is not a trivial objection.

Therapy should not be built on inaccurate biology. Scientific models should evolve as evidence evolves.

But here is the nuance: questioning the precision of a neural pathway is not the same as dismissing the observable patterns of human stress responses.

The debate is about mechanism, not about whether people experience mobilisation, shutdown, or relational safety.

Those patterns are real.

The Map Is Not the Territory

All therapeutic models are maps. They simplify complex systems to make them workable.

The question is not whether the map is perfect. The question is: does it help people navigate their experience?

Polyvagal language gave millions of people a way to understand their internal states. It shifted the narrative from "What's wrong with me?" to "What is my nervous system trying to protect me from?"

That move, from self-blame to adaptive understanding, is clinically powerful.

But it's also important not to confuse metaphor with mechanism. The body does not operate in tidy tiers. The autonomic nervous system is dynamic, overlapping, and deeply complex.

Good therapy acknowledges that complexity.

What This Means in Practice

When I draw on polyvagal-informed ideas, I'm not presenting them as settled neurobiology.

I'm using them as a shared language.

We might notice when you move into activation, when you shut down, when connection feels possible. We might explore what helps you return to regulation.

None of that work depends on the vagus nerve being anatomically divided exactly as first proposed. It depends on attunement, safety, and relational experience.

The clinical reality remains:

The body responds before the mind narrates. Safety is felt, not reasoned into existence. And regulation is relational before it becomes individual.

A Useful Conversation

The most valuable outcome of the polyvagal debate, much like the discussion around IFS, is that it has brought the nervous system into the centre of psychotherapy.

It has encouraged us to treat stress responses as adaptive biology rather than character flaws.

That conversation is worth continuing, even as the science refines itself.

Good therapy holds frameworks lightly. It stays open to correction. It values evidence. And it keeps the person, not the model, at the centre.

If you're curious about body-aware, relationally grounded therapy, I'd be glad to explore that with you.