Choose your path: Divergent basolateral amygdala efferents differentially mediate incentive motivation, flexibility and decision-making

Abstract

To survive in a complex environment, individuals form associations between environmental stimuli and rewards to organize and optimize reward seeking behaviors. The basolateral amygdala (BLA) uses these learned associations to inform decision-making processes. In this review, we describe functional projections between BLA and its cortical and striatal targets that promote learning and motivational processes central to decision-making. Specifically, we compare and contrast divergent projections from the BLA to the orbitofrontal (OFC) and to the nucleus accumbens (NAc) and examine the roles of these pathways in associative learning, value-guided decision-making, choice behaviors, as well as cue and context-driven drug seeking. Finally, we consider how these projections are involved in disorders of motivation, with a focus on Substance Use Disorder.

Keywords: Basolateral amygdala; Behavioral flexibility; Decision-making; Incentive motivation; Nucleus accumbens; Orbitofrontal cortex.

Figure 1:

Venn Schematic depicting circuitry contributions to learning and motivational processes categorized within our conceptual framework. See Table 1 for references. Areas of overlap indicate behavioral processes in which both the areas alone and the projections between areas are implicated. We operationally define 1) an incentive process as one in which reinforcing properties of rewarding outcomes transfer to reward-predictive cues, such that the motivational properties of the conditioned cues facilitate new learning or support ongoing appetitive behaviors, 2) a flexibility process as one in which changes to, or differences between, outcome value(s) facilitate changes in conditioned responding to associated cues and 3) a hybrid process as one in which both incentive and flexibility processes contribute to behavior at test. Notably, BLA alone plays a role in each of the behavioral paradigms listed (see Table 1), but for simplicity are not listed under BLA unless only BLA has been implicated. Abbreviations: BLA = Basolateral Amygdala; OFC = Orbitofrontal Cortex; NAc = Nucleus Accumbens; PIT = Pavlovian to Instrumental Transfer.