The polyvagal theory
The autonomic nervous system has two branches: the sympathetic branch (the throttle) and the parasympathetic branch (the brake). In 1994, scientist Stephen Porges presented what he came to call the polyvagal theory, in which he describes how the parasympathetic nervous system can in turn be divided into two so-called vagus systems: the anterior parasympathetic system (the mylienated ventral vagus system) and the posterior parasympathetic system (the unmylienated dorsal vagus system). Porges thus concluded that we have two braking systems: the anterior one leading to calm and the posterior one leading to stiffening or paralysis.
When we experience an event that overwhelms us, that fills us with fear and powerlessness, and that makes us feel alone and abandoned, the body’s stress and danger response is activated. The danger response wants us to seek safety. If there is no safety, the body starts a series of processes to make us flee or defend ourselves. If we cannot escape or defend ourselves, the body goes into a freeze response. The freezing reaction is actually two different reactions: one that leads to stiffening (the body becomes tense) and one that leads to paralysis (the body collapses). In the stiffening and paralysis state, the energy – the trauma energy – that the flight and defence reaction triggered remains in the body. This is what traumatization is.
Based on the polyvagal theory, the stress and danger response can be explained with a picture of a ladder, where we can see how we move daily between the different states of the autonomic nervous system.
The anterior parasympathetic system, which I choose to call the calm-and-quiet brake, slows us down in a good way and makes us feel calm, safe, content, playful and socially engaged. The system is also called the social engagement system. It is activated when we feel safe and also makes us seek safety from others. The posterior parasympathetic system panics us when we cannot escape or defend ourselves and causes us to freeze in fear or become paralyzed in resignation. I call this system the panic brake.
The sympathetic nervous system is not divided into two branches in the same way, but we can see that when we are active and in contact with the anterior parasympathetic system, we enter a creative activity where we are curious and playful, while when we are active and the posterior parasympathetic system is about to strike, we enter an anxious activity where we enter a state of flight and defense where anxiety, restlessness and sometimes anxiety and aggressiveness take over.