There are three main parts of the brain which are greatly affected by experiences severe or chronic traumatic events.
The hippocampus processes trauma memories, by recycling the memory, mostly at night via dreams, which takes place over weeks or months. It then transfers the integrated stored memory to another part of the brain. High levels of stress hormones causes the hippocampus to shrink or under-develop, resulting in impaired function. Childhood traumas exaggerates this effect. The trauma memory therefore remains unprocessed in the hippocampus, disintegrated, fragmented, and feels “current” rather than in the past. Some people can be born with a smaller hippocampus making them more vulnerable to develop PTSD.
The brains “fear center.” The amygdala helps to store memories, paticularly emotions and physical sensations. It also controls activation of stress hormones … the body’s flight or fight response. In PTSD, the amygdala becomes over-reactive causing frequent or near constant high levels of stress hormones.
The pre-frontal cortex helps us to asses threats, manage emotion, plan reaponses, and control impulses. It is the centre of rational thinking. Childhood trauma causes under-development of the pre-frontal cortex, which results in impaired ability to assess theeat through thinking, manage emotions and control impulses.