Abstract:
Anxiety disorders are amongst the most common psychiatric disorders affecting
approximately 25% of all adults. Fear and anxiety have many shared neuroanatomical and neurochemical
characteristics. In this paper we refer to a) fear conditioning, (i.e. after a harmless and an
aversive stimulus have coincided, the harmless stimulus encountered on its own will cause fear), b)
the fear response, including the effects on the hypothalamo-pituitary-adrenal (HPA) axis, c)
sensitization, which refers to a general hyperresponsivity of the fear circuits, d) fear memory, and
e) extinction, the new learning that the harmless stimulus no longer forecasts a threat. The role
of the amygdala and long-term potentiation (LTP) are discussed. Possible anatomical correlates of
anxiety disorders and different therapeutic modalities, including the novel drug D-cycloserine, are
briefly discussed.
