So they're saying. . .the brain pays extra attention to things that frighten us

http://www.newscientist.com/article/mg20627541.200-picking-our-brains-what-are-memories-made-of.html

So, short-term memories are stored in the hippocampi and frightening memories are stored in the amygdala. Makes perfect sense to me. These two sections of the brain are the oldest and direct our most primitive drives. Primitive man only would've needed short-term memory and memories of what frightens him in order to survive.

But what's most interesting to me about this article is its talk about the finding made by a research team in Canada that was printed in the Science journal (volume 323, p. 1492), where they were able to, "erase a frightening memory of a noise in a mouse by killing amygdala neurons whose synapses had recently been strengthened after exposure to the noise".

This immediately made me think about humans who incur trauma (specifically, emotional, physical, and/or sexual abuse). If the trauma is a "frightening" experience, why do some of us who incur this trauma remember every detail (i.e. the colors, emotions, physical sensations, scents, and sounds of the scene), while some of us draw a blank? Is there something else going on that directly inhibits the strengthening of these amygdala neural synapses in those of us who can't remember our traumas? Are those of us who dissociate during the traumatic experience more susceptible to these interruptions in the strengthening of the associated amygdala neural synapses? In keeping with this same population of "persons who dissociate", might this pattern then be repeated in other sections of our brain and result in other memory or associated brain malfunctions?