Psychopath, sociopath, borderline personality disorder, choose your phrase as these are often used interchangeably but in the end they are terms used to describe certain criminal offenders. In many cases, the worst of the worst. These individuals are often impulsive, lack self-control, and have little, if any, empathy with others, particularly their victims. The annals of serial predators are filled with such persons.
Forensic science has for many years searched for a true lie detector and a reliable method of determining someone's criminal tendencies. Most have not panned out. One recent investigative arena is the use of functional MRIs to determine segmental brain activity in both "normal" and "psychopathic" individuals. The hope is to discover reliable and repeatable differences that might prove useful in criminal investigations.
One current study at Radboud University in the Netherlands has revealed some interesting results. It appears that persons with sociopathic tendencies possess an overly active "reward" area of their brains while at the same time showing some loss of communication between this area and one that is used for "self-control." Obviously this leads to a dangerous combination of psychiatric defects. If someone is reward driven, impulsive, and narcissistic, while at the same time lacking any sort of consistent control of these impulses, it is easy to see that criminal behavior could follow.
Though this study and none of the others that have looked into this area of psychopathology have delivered the "smoking gun" of psychopathic behavior, they are intriguing investigations.