Fear extinction circuits. (A) Basic extinction circuit centered on the BLA. The contributions of a few key regions are labeled with their putative functional contributions. (B) Extended circuit, with a larger set of brain regions believedtobeinvolved(notintended to becomprehensive). The blue arrows indicate indirect anatomical connectivity. The red arrows indicate the extensive norepinephric projections of the locus coeruleus. HIPP, hippocampus; LC, locus coeruleus; MPFC, medial pFC; THAL, thalamus; VTA, ventral tegmental area.