One of the many biological systems that have been identified as being affected by traumatic experiences is the part of the limbic system that is centrally involved in interpreting the emotional significance of experience: the amygdala. The amygdala detects whether incoming sensory information is a threat and forms emotional memories in response to particular sensations such as sounds and images that have become associated with physical threats. These emotional interpretations are thought to be extraordinarily hard to extinguish. Therefore the challenge of psychotherapy is to de-condition the amygdala from interpreting innocuous reminders as a return of the trauma. In other words, certain smells, objects, or relational dynamics have become, for the individual, associated with the actual experience of the trauma, even if the object, smell, or whatever is actually itself benign. Part of what psychotherapy offers as a means of de-conditioning the amygdala is various forms of what psychotherapists call “Exposure Therapy.” Most psychologists can explain what forms “Exposure Therapy” can take.