It is thought that in individuals with APD there is a chemical imbalance in areas of the brain involved in judgment, decision-making, planning, and impulsive and aggressive behavior. Areas of the brain involved with these functions are the prefrontal cortex and frontal lobe. The doctor in this video who has studied many brain scans of psychopaths and non-psychopaths observed that, "One of the key differences that we find in the brains of psychopaths is that there's a structural impairment to part of the brain called the amygdala. This is a part of the brain very much involved in the generation of emotion. It was structurally deformed in the psychopaths…They just don’t have those normal feelings of revulsion and disgust.” (2:40)