Bedrock Layer 5: Empathy & the CNS

Today we’re getting into the hardcore neuroscience behind why SPAN’s work is important. I’m going to tell you a story, teach you about your autonomic nervous system (ANS), and translate all the ideas into one concrete principle we at SPAN believe you should keep in mind—and in your voice—when working with people in transition.

As we proceed, I’d like you to keep a paradox in mind. I’d call this the central paradox of SPAN’s work: people perform better when they feel safe. But true safety comes from mastering challenge. How do you support safety and challenge simultaneously?

Let me challenge you with a funny question: raise your hand if you knew you had three bones in your middle ear? Keep your hand raised if you knew these bones used to be attached to the jawbone in our reptilian ancestors? Keep your hand raised if you know why this knowledge is essential for managing late-night arguments with your family? Or for helping people in transition?

Raise your hand if you’re curious? Great!

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First, the story. I’m working on a book about natural metaphors, and how it’s always seemed to me that nature is teaching us about life. Water. Trees. Roots. Today I have a story about topsoil, because SPAN—metaphorically speaking—is all about healthy topsoil.

Hopefully you know what happened across the Great Plains of the U.S. in the 1930’s. For years, farmers cleared prairie grasses in pursuit of ever larger crops. But the roots of those prairie grasses had gone down three meters, holding the soil together. When a severe drought began in 1931, the earth dried and crumbled. There was no vegetation to protect it from the wind. A hundred million acres turned into billowing clouds of dust, and blew away.

Let’s extend the metaphor.

Topsoil is our prefrontal cortex: that part of the brain that allows us to reflect and be most human. But stress, like wind or rain, can erode the topsoil, compromising prefrontal functioning and predisposing people to act in habitual, fear-driven ways. That’s where vegetation comes in. Social connection provides the roots and stability our prefrontal areas need to stay regulated in the face of stress. The more social support people have, the thicker the foliage, and the thicker foliage, the more the roots can absorb heavy rain and protect the soil from washing or blowing away.

That’s the story.

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Now a five-minute masterclass on the neuroscience guiding SPAN’s approach to mobility.

In the world of clinical practice, Stephen Porges’ “Polyvagal Theory” fundamentally reshaped our understanding of the autonomic nervous system (ANS). We used to believe there were two antagonistic branches of the ANS, the parasympathetic and the sympathetic branch, and that they worked in opposition. Either the sympathetic branch readied us to fight or flee, or the parasympathetic branch allowed us to rest and digest. Increasing the activity of one suppressed the activity of the other, like a see-saw.

It may, however, be more accurate to believe the ANS evolved three branches over time.

First there was the dorsal motor nucleus. It sends signals down the dorsal branch of the vagus nerve—a branch we share with reptiles. Like a crocodile in water, this layer of the ANS shuts us down to save energy and oxygen. It’s the system we experience when we collapse under overwhelming stress—the very same system that makes animals play dead.

Since predators avoid dead animals, some speculate that our bodies are using an old trick.

Today we call it dissociation.

This first dorsal layer of the vagus can get suppressed by the layer that evolved next, the sympathetic branch. This “fight-flight” system activates the release of catecholamines in the brain and adrenaline in the body, raising heart rate and priming large muscles for action. Sympathetic activation is metabolically expensive. But it’s worth spending a lot of energy to avoid getting eaten by a crocodile. (You may say that schools don’t have crocodiles. Consider, though, that our bodies don’t distinguish between outside safety and inside safety. A lunch room full of strangers can feel for your body like it’s entering a pool full of crocodiles. The physiological reaction is identical—and not good for learning.)

One way to quiet this second sympathetic branch occurs via the last, most evolved layer of the ANS, mediated by the ventral branch of the vagus nerve. The evolutionary story of our ventral vagus is fascinating. Mammals evolved in a world full of large predators. Strength for mammals came through teamwork. But you could only cluster together in teams if you could calm your sympathetic nervous system—the very branch that would have you fight or flee if people got close. A new nucleus formed, the nucleus ambiguous. It became the hub for a second branch of the vagus nerve, known as the ventral vagus. The nucleus ambiguous became integrated in the brainstem with all kinds of cranial nerves, including those enervating the face, larynx, and middle ear. This ventral vagus became able to slow the heart, allowing us to stay calm in the presence of others. Because it was interconnected with all those cranial nerves, this ventral vagus also allowed us to modulate how we speak. We could speak gently to our partner and children. We could have a social life.

During this process, the bones of our middle ear separated from our jaw, allowing mammals to develop species-specific frequencies for communication. Cranial nerve VII made it possible to tighten the stapedius muscle on our middle ear—much like a violin string. We could speak, and hear each other, with higher, gentler voices. Under stress, however, ventral vagal regulation of the stapedius gets removed. The brain becomes biased towards lower frequencies. In other words, under stress, our ears and brains are listening for threats. They’re less good at hearing normal human speech. This is why I explain to couples that they can’t even hear each other accurately in the middle of a fight. Students overwhelmed by transition cannot either. We all need to feel safe to truly hear each other.

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Let’s connect this neuroscience to our topsoil metaphor.

The goal is thick topsoil. Remember our paradox: kids do better when they’re safe. But they need to be comfortable with stress to feel authentically safe. Total sheltering from rain isn’t the answer. But overwhelming rains and winds aren’t either, since they strip the soil that makes us human.

The “inverted U” graphic from Yerkes and Dodson in 1908 described changes in performance across increasing levels of stress. Too little and we’re bored; too much and we’re overwhelmed. The sweet spot is in the middle.

You now know enough about the architecture of the ANS to understand why. Moderate stress creates sympathetic activation, readying us for performance. Rain is falling on the topsoil, causing the locus coeruleus to release catecholamines. Dopamine and noradrenaline are like fast-acting fertilizer for our prefrontal cortex: they sharpen thinking. But like most things, more is not always better. Too much stress—too much fertilizer in the form of dopamine and noradrenaline—can lead to prefrontal networks getting overwhelmed.

Thank goodness for the ventral vagus nerve. How many of you have heard of heart rate variability (HRV)? Most modern smart watches measure it. HRV is a good thing because a changing heart rate is a sign of a ventral vagus functioning well. The more ventral vagal regulation you have, the better your prefrontal areas can cope with stress. You can handle more fertilizer before getting overwhelmed. The roots in our metaphor symbolize vagal regulation. The thicker and deeper the roots, the better the topsoil (or prefrontal cortex) can handle the strain.

Social support is the foliage above the surface. The more foliage, the more roots! People with thicker social networks experience higher vagal tone, which helps them cope with arousal better and longer, leading to better performance in all walks of life. Like in the rainforest, the optimal situation is a deep layer of foliage (or social support), because it supports deep roots (or good ventral vagal tone), allowing the soil to handle even heavy rains and support fertile growth.

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So what does this have to do with those middle ear bones I asked about?

When I speak to you like this, I’m stimulating your middle ear. I’m encouraging it to tune into friendly, modulated, higher frequencies. Even if you’re stressed, your seventh cranial nerve has to activate the tiny stapedius muscle to tighten middle ear, so you can hear me. This increases tone in the ventral vagus, since it was highly interconnected with these cranial nerves. By stimulating these nerves, my voice is sending a message to your neuroceptive faculties that the world is safe. It is okay. Somebody is with you.

This is why I encourage people at the Nest to wear headphones. A big part of what we’re doing is happening right through your ears. Sure, we can teach you rhythmic breathing, at the rate of six breaths per minute, with longer exhalations. We can teach you to splash cold water on your face, to activate the mammalian dive reflex. We can teach you the importance of cognitive reframing, of seeing threats as opportunities, thereby shifting your neurochemistry and bringing your prefrontal cortex back on line. All of them are valuable because they increase vagal tone and support the topsoil. But they require time and overt action. With my voice, I can communicate information while also massaging your autonomic nervous system, all under the radar.

If I hadn’t explained any of this, you might have still felt better after your visit to our Nest today. We certainly hope so! But now you know why.

And the point is that you can do this with your students. You can teach this to your colleagues. You can teach this to parents. Your voice is the instrument by which you communicate not only the information in the words you’re using, but also something about the state of the world. If you’re regulated, you can help others be, and stay, regulated, too. And then they can go off and be the people that they’re meant to be in the world.

This is why SPAN exists: to provide the social support for you, so that you can bring high vagal tone into what you do, including now with your voice. What we do is challenging. Emotional. Full of change and loss and transition. We are out there in the rain. We are exposed to the winds. SPAN is here to help you from getting washed away, because you see other like-minded, like-hearted people standing right beside you, with their roots digging deep, into the worlds where they work, into the hearts with which they do this work.

You don’t have to do it alone. You have us. You have SPAN.

Thanks for being here.