You're a Miracle (and a Pain in the Ass): Embracing the Emotions, Habits, and Mystery That Make You You

by Mike McHargue

The polyvagal theory model offers a three-tiered view of our involuntary nervous system. The sympathetic nervous system still handles the “fight or flight” response when in high arousal. But, in this view, the parasympathetic system isn’t just the “chill” network. Because when the parasympathetic system is highly aroused, it can also invoke a trauma response: freeze, or faint. In safe situations, when neither the sympathetic nor parasympathetic systems are highly activated, a third system runs the show: the social engagement system. The social engagement system uses the ventral branch of the vagus nerve, running from your brain stem to your middle ear, to filter out background noise and help you focus on human voices. But the ventral branch also runs to your heart and lungs, which means your brain stem, middle ear, heart, and diaphragm can respond to the tone of someone’s voice several seconds faster than the structures in your neocortex can process the content of their actual words. A sharp word can literally take your breath away. How we say something matters as much as what we say, because our automatic nervous system is listening and responding to tone long before our thinking brains get the message.