Extending the amygdala in theories of threat processing

Abstract

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 components of the central extended amygdala, the central nucleus of the amygdala (Ce) and the lateral bed nucleus of the stria terminalis (BST) are highly similar regions that serve complimentary roles by integrating fear- and anxiety-relevant information. Survival depends on the central extended amygdala's ability to rapidly integrate and respond to threats that vary in their immediacy, proximity, and characteristics. Future studies will benefit from understanding alterations in central extended amygdala function in relation to stress-related psychopathology.

Central amygdala lesions inhibit pontine nuclei acoustic reactivity and retard delay eyeblink conditioning acquisition in adult rats

“…Broadly speaking, in response to the aversive US the amygdala is proposed to rapidly initiate a state of Bconditioned arousal^early in EBC (Kapp, Wilson, Pascoe, Supple, & Whalen, 1990;Thompson et al, 1987), enhancing the salience of relevant stimuli and the rate at which eyeblink CRs emerge. Many studies have documented rapid changes in both autonomic and defensive behavior early in EBC (e.g., Lee & Kim, 2004;Prokasy, 1972), mediated by the CEA and its efferent projections to a variety of hypothalamic and brainstem targets (Applegate, Frysinger, Kapp, & Gallagher, 1982;Fox, Oler, Tromp, Fudge, & Kalin, 2015). What exactly drives the rapid increase in fear responding is not entirely clear, however-it likely reflects a combination of unconditioned (or generalized) fear and conditioned fear specific to the tone CS and/or training context.…”

Genotype-dependent responsivity to inflammatory pain: A role for TRPV1 in the periaqueductal grey

“…The VLPAG is the only subdivision which sends direct projections to the dorsal raphe nucleus (Kalén et al, 1985). Projections from the CeA to the VLPAG are known to play a role in modulation of pain (Rizvi et al, 1991) and are involved in anxiety/fearrelated behaviour (Fox et al, 2015;Rizvi et al, 1991). For example, stimulation of the CeA increased latency to respond in the tail-flick test of thermal nociception, an effect abolished after administration of lidocaine intra-VLPAG (De Oliveira et al, 2001).…”

Joy and Calm: How an Evolutionary Functional Model of Affect Regulation Informs Positive Emotions in Nature

“…Emerging from such literature great emphasis has been given to the limbic system and regions such as the amygdala in emotion and threat processing. Largely based upon the research of LeDoux (2014;, the amygdala is well-established as playing a key role in the processing of emotional information, regulating emotional responses and controlling fear reactions in a range of species (see for example Fox et al, 2015& Phelps & LeDoux, 2005. Indeed, much recent research still supports the notion that a phylogenetically old subcortical pathway provides rapid, but coarse, threat-related signals in humans via the amygdala (Mendez-Berolo et al, 2016;Maratos et al 2009).…”