How does post traumatic stress disorder effect the brain?

i want to know what causes the brain to give you flashbacks, emotional numbness, sleep disturbances, anxiety, intense guilt, depression, irritability, or outbursts of anger. The amygdala is known for its role in emotion, learning, and memory. What are the signals that the amygdala is sending out and to where? I'm sure there is a lot of different parts of the brain that are effected by ptsd