Upon increasing levels of threat, animals activate qualitatively different defensive modes,
including freezing and active fight-or-flight reactions. Whereas freezing is a form of …

The current review and synthesis was designed to provocatively develop and evaluate the
proposition that “fear of the unknown may be a, or possibly the, fundamental fear”(Carleton …

Objective: In addition to N-methyl-d-aspartate receptor antagonism, ketamine produces
opioid system activation. The objective of this study was to determine whether opioid …

Evolution has endowed all humans with a continuum of innate, hard-wired, automatically
activated defense behaviors, termed the defense cascade. Arousal is the first step in …

Anxiety disorders constitute a sizeable worldwide health burden with profound social and
economic consequences. The symptoms are wide-ranging; from hyperarousal to difficulties …

The roles of opioid receptors in pain and addiction have been extensively studied, but their
function in mood disorders has received less attention. Accumulating evidence from animal …

Abstract Methyl-CpG binding protein 2 (MeCP2) has crucial roles in transcriptional
regulation and microRNA processing,,,. Mutations in the MECP2 gene are found in 90% of …

We postulate that the cascade “Freeze-Flight-Fight-Fright-Flag-Faint” is a coherent
sequence of six fear responses that escalate as a function of defense possibilities and …

The authors present an overview of the neural bases of emotion. They underscore the role of
the prefrontal cortex (PFC) and amygdala in 2 broad approach-and withdrawal-related …

The central extended amygdala is an evolutionarily conserved set of interconnected brain
regions that play an important role in threat processing to promote survival. Two core …