Pharmacology of Fear Extinction

Excessive fear and anxiety are hallmarks of a variety of disabling anxiety disorders that affect millions of people throughout the world. Hence, it is critical for the field of neuroscience to have a greater understanding of the brain mechanisms involved in the inhibition of fear. Experimentally, fear inhibition typically is analyzed with a procedure called extinction, in which a fearful stimulus is presented repeatedly in the absence of any aversive event. This leads to a decrease in the fear response that is generally mediated by active inhibition of fear rather than an erasure of acquired fear. This article reviews what is currently known about how neurotransmitters and intracellular effectors mediate and modulate extinction of conditioned fear.