Roles of the Amygdala and Bed Nucleus of the Stria Terminalis in Fear and Anxiety Measured with the Acoustic Startle Reflex

Over the last several years, our laboratory has been studying how a simple reflex, the acoustic startle reflex, can be modified by prior emotional learning. Thus far, most of our work has concentrated on an experimental paradigm called the fearpotentiated startle effect, in which the amplitude of the startle reflex can be modified by a state of fear. More recently, however, we are trying to develop experimental methods to measure both fear and anxiety using changes in the acoustic startle reflex. Fear is a natural, adaptive change in an organism elicited by a potentially threatening stimulus which prepares the organism to cope with the provocation. Fear generally is elicited by a clearly identifiable stimulus and subsides shortly after its offset. Anxiety also is a change in the state of an organism which has many of the same signs and symptoms of fear. However, it may not be clearly associated with a single eliciting stimulus, may last a long time once activated, and may lack clear adaptive significance.