The reptilian brain (brain stem) is the innermost part of the brain and is responsible for survival instincts and autonomic body processes. During a traumatic experience, the reptilian brain takes control, shifting the body into reactive mode. During this time the sympathetic nervous system increases stress hormones and prepares the body to fight, flee or freeze.
For some people who have experienced trauma the shift from reactive too responsive mode never occurs. Instead, the reptilian brain, primed to threat and supported by dysregulated activity in significant brain structures, holds the survivor in a constant reactive state.
This gecko is a reminder: