The neurobiological basis of anxiety and fear: Circuits, mechanisms, and neurochemical interactions (Part II)

This article is Part II of a review of the neuronal circuits, neural mechanisms, and neuromodulators that seem to be involved in anxiety and fear states. Part I focused on the specific brain structures, including the roles of the amygdala, locus coeruleus, hippocampus, and various cortical regions and the neural mechanisms of fear conditioning, extinction, and behavioral sensitization in mediating the signs and symptoms of anxiety and fear. Part II attempts to develop a better understanding of neurochemical mediation of traumatic remembrance and the neurobiological consequences of stress, particularly when experienced early in life. Finally, the data is synthesized to provide a basis for understanding the pathophysiology of anxiety disorders, such as Panic disorder and Posttraumatic Stress Disorder.