Introduction and scope of the review -- Anxiety and risk assessment -- Fear/panic and the fight/flight/freeze system -- “Coping” styles, stress reactivity, and the active-passive continuum -- Serotonin in the nervous system of vertebrates -- Synthesis and metabolism of serotonin -- Transport of serotonin: SERT and uptake -- Serotonin receptors -- 5-HT1A receptors -- 5-HT1B receptors -- 5-HT2C receptors -- Nodal structures in anxiety-like and panic-like responses -- Nodal structures regulating anxiety: The behavioral inhibition system -- “Limbic” portions of the medial prefrontal cortex -- The extended amygdala -- The ventral hippocampus -- The lateral habenula -- Nodal structures regulating panic: The cerebral aversive system -- The central amygdala -- The medial hypothalamic defense system -- The mesopontine rostromedial tegmental nucleus -- The periaqueductal gray area -- Locus coeruleus -- The dual role hypothesis -- Destruction or blockade of DRN neurons is anxiolytic and panicogenic -- The defensive context for increased serotonin release -- Topographic organization of DRN. - The dorsal portion of the DRN is part of a mesocorticolimbic system involved in anxiety-like responses -- The caudal portion of the DRN is highly responsive to stress-related peptides -- The lateral wings of the DRN are involved in panic-like responses -- General conclusions.

Anxiety disorders have long been a research subject for scientists in different areas of inquiry, and the particular role of serotonin – the neurotransmitter which has probably most captured the imagination of laymen and academics alike – is as elusive as the clinical aspects of serotonergic medications. Why are drugs acting at certain serotonin receptors efficacious against generalized anxiety disorder, but not panic disorder? Why is the inverse true for monoamine oxidase inhibitors? These clinically relevant issues are clarified by the neurochemical, anatomical and physiological organization of the serotonergic system. In this book, the author summarizes the latest findings regarding the role of serotonin in modulating the activity of brain regions which organize behavioral patterns associated with fear, anxiety and stress. The emergent picture is one of far greater complexity than previously thought: while the serotonergic innervation of those brain regions arises from the same structure – the dorsal raphe nucleus – that structure is not homogeneous from anatomical, physiological and neurochemical points of view, nor are its projections to the cerebral aversive and behavioral inhibition systems. The diverse findings which compose this picture of complexity – whether they arise from developmental neurobiology, electrophysiology, neurochemistry, neuroendocrinology, neuropsychopharmacology or behavioral neuroscience – are integrated in this book. Advanced undergraduate, graduate students, and researchers will benefit from the information. The result sheds light on many important questions regarding the neuroanatomical, pharmacological and functional aspects of the role of serotonin in anxiety disorders, and points to future avenues of research.