The roles of the amygdala in the affective regulation of body, brain and behaviour

Despite the great amount of knowledge produced by the neuroscientific literature affective phenomena, current models tackling non-cognitive aspects of behavior are often bio-inspired but rarely bio-constrained. This paper presents a theoretical account of affective systems centered on the amygdala. This account aims to furnish a general framework and specific pathways to implement models that are more closely related to biological evidence. The amygdala, which receives input from brain areas encoding internal states, innately relevant stimuli, and innately neutral stimuli, plays a fundamental role in motivational and emotional processes of organisms. This role is based on the fact that amygdala implements the two associative processes at the core of Pavlovian learning (CS-US and CS-UR associations), and that it has the capacity of modulating these associations on the basis of internal states. These functionalities allow the amygdala to play an important role in the regulation of the three fundamental classes of affective responses (namely, the regulation of body states, the regulation of brain states via neuromodulators, and the triggering of a number of basic behaviours fundamental for adaptation) and in the regulation of three high-level cognitive processes (namely, the affective labeling of memories, the production of goal-directed behaviours, and the performance of planning and complex decision making). Our analysis is conducted within a methodological approach that stresses the importance of understanding the brain within an evolutionary/adaptive framework and with the aim of isolating general principles that can potentially account for the wider possible empirical evidence in a coherent fashion.