According to this article, scientists think they discovered why "...fear and other highly emotional experiences lead to incredibly strong memories." As with most technical stuff: "The brain's emotional center, the amygdala, induces the hippocampus, a relay hub for memory, to generate new neurons", sounds like gobbledygook to me. The gist, is that when faced with a fearful situation, the brain creates the new neurons where the memory is stored. I guess for quick later access.
Article also states: "The finding has implications for post traumatic stress disorder (PTSD) and other problems caused by faulty regulation of emotional memory."
Sorry, LOL ~ so I guess knowing this, it is best to stay away from fearful situations, thus one can prevent PTSD or other anxiety disorders from developing? Tell that to citizens in Joplin and Tuscaloosa ~ to name two places where people recently experienced giant size traumas.