Answer:
Norepinephrine
Step-by-step explanation:
The neurotransmitter norepinephrine, also known as noradrenaline, is a highly important chemical that is part of the catecholamine family. It plays a role in the fight-or-flight response, enabling the body to react or retreat from a threatening situation.
However, in PTSD, there is an abnormal regulation of catecholamine neurotransmitters, especially norepinephrine, along with serotonin as well. According to research, in PTSD patients, there is an increased signaling that results from an increased release of norepinephrine.
Therefore, the neurotransmitter that brings about enhanced memory of traumatic moments which used to help us remember how to survive and escape (fight or flight), but now are painful to the survivor (a.k.a flashback) is norepinephrine.