New neurological research suggests that each time a memory is recalled, it is subject to slight alternations; the implications could benefit sufferers of PTSD. “Most people have so-called flashbulb memories of where they were and what they were doing when something momentous happened: the assassination of President John F. Kennedy, say, or the explosion of the space shuttle Challenger. But as clear and detailed as these memories feel, psychologists find they are surprisingly inaccurate.”