An “incorrect” assumption that fear and anxiety are mediated in the brain by a single “fear circuit” has stalled progress in developing better treatments for anxiety disorders, argue two leading experts. Designing future research based on a “two-system” framework holds promise for improving treatment outcomes, say Daniel Pine, M.D., a clinical researcher in the NIMH Emotion and Development Branch, and Joseph LeDoux, Ph.D. , a basic scientist and NIMH grantee at New York University