The amygdala: securing pleasure and avoiding pain

Abstract

The amygdala has traditionally been associated with fear, mediating the impact of negative emotions on memory. However, this view does not fully encapsulate the function of the amygdala, nor the impact that processing in this structure has on the motivational limbic corticostriatal circuitry of which it is an important structure. Here we discuss the interactions between different amygdala nuclei with cortical and striatal regions involved in motivation; interconnections and parallel circuitries that have become increasingly understood in recent years. We review the evidence that the amygdala stores memories that allow initially motivationally neutral stimuli to become associated through pavlovian conditioning with motivationally relevant outcomes which, importantly, can be either appetitive (e.g. food) or aversive (e.g. electric shock). We also consider how different psychological processes supported by the amygdala such as conditioned reinforcement and punishment, conditioned motivation and suppression, and conditioned approach and avoidance behavior, are not only psychologically but also neurobiologically dissociable, being mediated by distinct yet overlapping neural circuits within the limbic corticostriatal circuitry. Clearly the role of the amygdala goes beyond encoding aversive stimuli to also encode the appetitive, requiring an appreciation of the amygdala's mediation of both appetitive and fearful behavior through diverse psychological processes.

Triangulating the sexually dimorphic brain through high-resolution neuroimaging of murine sex chromosome aneuploidies

“…Our finding of altered amygdalar structure in XXY mice relative to XY littermates is notable in light of the known importance of amygdalar circuitry in appetitive conditioning and social behavior (Fernando et al 2013; Felix-Ortiz and Tye 2014), and documented abnormalities in both these domains amongst XXY mice (Lue et al 2005; Liu et al 2010). However, the most pronounced anatomical alterations detected by our study impact non-amygdala structures such as the lateral septum, BNST and hypothalamus—indicating the need for broader behavioral characterization of XXY mice, especially through tests of fear conditioning, stress reactivity, aggression and defensive behavior (Koolhaas et al 1998; Risold and Swanson 1997; Calandreau et al 2007).…”

Functional organization of human subgenual cortical areas: Relationship between architectonical segregation and connectional heterogeneity

“…reward-related information, whereas cortical activity in the anterior insula is associated with the processing of physical properties such as intensity of odor or taste (McCabe and Rolls, 2007; Rolls, 2009; Small, 2012). The amygdala also plays a pivotal role in the encoding of aversive and appetitive stimuli, as well as in the amygdala–cingulate interactions occurring during potential threat assessment (Fernando et al, 2013; Fiddick, 2011; Fossati, 2012; Shin and Liberzon, 2010; Toyoda et al, 2011). Although we found both s24 and s32 to be co-activated with the laterobasal nucleus of the amygdala, only area s24 was associated with the perception of gustation, i.e., it was the only cyto- and receptorarchitectonical distinct cortical area within sACC(Palomero-Gallagher et al, 2008), which is activated during the emotional evaluation of taste.…”

The Nucleus Accumbens: An Interface Between Cognition, Emotion, and Action

“…Each of these regions processes dissociable types of information that, in turn, may bias distinct patterns of behavior via interactions with the NAc. For example, the hippocampus is essential for spatial navigation, processing the relationships between different stimuli, and recognition of novelty (Floresco et al 1997, Ito et al 2008, Mannella et al 2013.By contrast, the BLA plays a key role in forming associations between neutral stimuli that predict appetitive or aversive consequences as well as in monitoring changes in the affective salience or perceived value of these stimuli (Everitt et al 1991, Fernando et al 2013, Shiflett & Balleine 2010. By further comparison, different regions of the rodent medial PFC (anatomically homologous to different regions of the human anterior cingulate cortex) have been implicated in a variety of cognitive, affective, and reward-related functions not easily summarized in a single phrase.…”