Brain stimulation in posttraumatic stress disorder: animal studies

Posttraumatic stress disorder (PTSD) is a severe, complex, heterogeneous disorder usually precipitated by psychological trauma, typically affecting vulnerable individuals, with many perceptual, cognitive, affective, physiological and psychological features [1,2]. According to the most recent edition of the Diagnostic and Statistical Manual of Psychiatric Disorders (DSM-IV-TR) [1], the essential feature of PTSD is the development of characteristic symptoms following exposure to an extreme traumatic stressor characterized by: direct personal experience of an event that involves actual or threatened death or serious injury, or other threat to one’s physical integrity; or witnessing an event that involves death, injury, or a threat to the physical integrity of another person; or learning about unexpected or violent death, serious harm, or threat of death or injury experienced by a family member or other close associate. The person reacts to this event with fear and helplessness, and tries to avoid being reminded of it. The characteristic symptoms resulting from the exposure to a traumatic event include persistent reexperiencing of the traumatic event, persistent avoidance of stimuli associated with the trauma and numbing of general responsiveness, and persistent symptoms of increased arousal. Re-experiencing symptoms consist of intrusions of the traumatic memory in the form of distressing images, nightmares, or dissociative experiences, such as flashbacks. Avoidance symptoms include actively avoiding reminders of the traumatic event, including persons, places, or things associated with the trauma, and more passive behaviors reflecting emotional numbing and constriction. Hyperarousal symptoms include insomnia, irritability, impaired concentration, hypervigilance, and increased startle responses.