Introduction to the special issue on the Neurobiology of Human Fear and Anxiety.

Pathological fear and anxiety are a leading cause of human misery and morbidity, afflicting millions of individuals worldwide. Yet existing treatments are inconsistently effective or associated with significant adverse effects, underscoring the urgency of developing a more complete understanding of the neural systems governing fear and anxiety in humans. This emphasis reflects the fact that fear and anxiety disorders are defined and diagnosed based on subjective symptoms, and human studies are essential for understanding the neural mechanisms that underlie the experience of fear and anxiety. Human studies are also crucial for identifying the features of animal models that are conserved and, hence, most relevant to human disease and treatment development ('forward translation'). Finally, human studies afford opportunities for developing objective biomarkers of disease or disease risk, accelerating the development of new diagnostic and treatment strategies, and generating novel hypotheses that can be mechanistically assessed in animal models ('reverse translation'). The present Special Issue-The Neurobiology of Human Fear and Anxiety-provides a concise survey of recent progress in this burgeoning area of research. Here we provide an Introduction to the Special Issue, highlighting some of the most significant and exciting advances.