When I speak of the nervous system I am primarily referring to the mechanisms of our stress response. This is a primitive protective system that we share with all other animals to keep us safe. Human’s more complex brain systems (cortex and limbic system) can complicate this process.
When we are in danger or think that we are in danger, our stress response becomes activated. When our sympathetic nervous system is activated in this way, we respond with fight or flight. This is helpful when we need to fight off an attack or run from a predator, but less helpful or harmful when we fight our partner when it feels like they are attacking us or when we leave a good job after a conflict with a co-worker
Our freeze, or immobilization response is activated when we cannot or perceive that we cannot fight or escape. This response is helpful when further harm would come to us by fighting, and fleeing is not an option, but can translate to major depression, dissociation, or learning difficulties.
The “fawn” response is a newer concept than the fight, flight, and freeze, coined by Pete Walker (http://www.pete-walker.com/fourFs_TraumaTypologyComplexPTSD.htm). Fawn refers to the impulsive reaction to please and appease in order to avoid or diffuse conflicts with others which are or are perceived to be dangerous or threatening. This can lead to difficulties setting healthy boundaries and being authentic in relationships. Like the other fear responses, this perception of threat occurs in the body prior to being recognized by the conscious mind, causing us to react before we have any understanding of what’s happening. In many cases, there is no conscious understanding.
When we experience stressful/traumatic events, especially when we have a sensitive predisposition, these experiences become deeply imprinted in our explicit and/or implicit memory and shape our neural pathways and bodily functions. This impacts our behaviors, reactions, and emotions without our conscious control. Fortunately, we have the ability to reshape and alter these neural pathways and bodily functions. Therapy can play a big role in facilitating this change.