Psychological trauma is the mind's perception of an unpleasant event, stored as a memory. Each person perceives their experiences in their own way which means the limiting factor with traumatic severity is a personal recall of experience. No two experiences are the same and previous factors may add or detract from traumatic exposure. For example, someone who is in the Military may have a relatively high tolerance for seeing violence and may even witness an opponent be killed, however this will impact him differently over time, due to desensitization. At first he may have a feeling of guilt or sadness to see an opponent be killed but after prolonged exposure these feelings may shift entirely to a sense of accomplishment or even gratification. Our mind has a remarkable ability for developing resilience yet also we tend to cling to traumatic memories much differently. A very small region in the center of our brain, known as the amygdala, is largely responsible for these heightened or vivid memories. Typically when memories are attached to an unpleasant emotional charge they become stored in the amygdala, as opposed to other regions where memory can be held. The amygdala serves as a primitive function in our brain and was initially used to throw us into survival mode, several thousands of years ago. Therefore when activated we feel a surge of adrenaline and cortisol from the activation of our autonomic nervous system, initiating the fight or flight response. Another variable to consider with trauma exposure is that sometimes it may be so damaging to our conscious awareness that our subconscious represses these memories and the residual symptoms or outcome of PTSD takes weeks or months to surface. Others may be presented with symptoms of PTSD immediately after such as trouble sleeping, trouble eating, poor interpersonal relationships, isolation, depression, lack of motivation, inability to conduct daily activities, heightened drug or alcohol consumption, increased aggression, lack of patience, feeling emotional unstable, guilt, grief and possible feelings of suicide. The amount of time it takes for someone to get over their symptoms of PTSD also may vary depending on several factors. How they perceived that event in relation to other events in their life, how much damage they perceived the event to cause them, how much support they have from friends and family and how resilient they are to find positive coping mechanisms, may all effect their outcome.