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This small nucleus contains almost half of all the brain neurons that use norepinephrine as a neurotransmitter. The locus coeruleus also projects its axons to those parts of the brain that may be associated with panic disorders (the amygdala, hippocampus, septum, cortex, brainstem, reticular formation, etc). Stimulating an animal's locus coeruleus, like stimulating its amygdala, produces anxiety behaviours.
The source of many anxiety disorders is a conditioned fear. We speak of a conditioned fear when an object or situation that in itself is neutral becomes associated with something that is threatening , thus triggering a fear reaction. The various anxiety disorders involve many different areas of the brain. These areas reflect both the uniqueness of each of these disorders and the features that they have in common. The amygdala, for example, plays a central role in anxiety disorders. This structure in the warns us when a danger is present in our environment and triggers the fear reaction and then the fight or flight reaction to get us out of it.