Translational studies of goal-directed action as a framework for classifying deficits across psychiatric disorders

Abstract

The ability to learn contingencies between actions and outcomes in a dynamic environment is critical for flexible, adaptive behavior. Goal-directed actions adapt to changes in action-outcome contingencies as well as to changes in the reward-value of the outcome. When networks involved in reward processing and contingency learning are maladaptive, this fundamental ability can be lost, with detrimental consequences for decision-making. Impaired decision-making is a core feature in a number of psychiatric disorders, ranging from depression to schizophrenia. The argument can be developed, therefore, that seemingly disparate symptoms across psychiatric disorders can be explained by dysfunction within common decision-making circuitry. From this perspective, gaining a better understanding of the neural processes involved in goal-directed action, will allow a comparison of deficits observed across traditional diagnostic boundaries within a unified theoretical framework. This review describes the key processes and neural circuits involved in goal-directed decision-making using evidence from animal studies and human neuroimaging. Select studies are discussed to outline what we currently know about causal judgments regarding actions and their consequences, action-related reward evaluation, and, most importantly, how these processes are integrated in goal-directed learning and performance. Finally, we look at how adaptive decision-making is impaired across a range of psychiatric disorders and how deepening our understanding of this circuitry may offer insights into phenotypes and more targeted interventions.

Keywords: ADHD; amygdala; basal ganglia; depression; goal-directed action; schizophrenia.

Figure 1

Cortico-striatal circuits involved in instrumental conditioning. (A) Evaluative learning processes, shown in red, are mediated by bilateral connections between the medial orbitofrontal cortex (mOFC) and basolateral amygdala (BLA), which are relayed to the anterior caudate nucleus (aCN). Contingency learning processes, shown in green, are thought to occur in the medial prefrontal cortex (mPFC) and are relayed to the aCN to mediate control of action selection. Reward information is also relayed to the nucleus accumbens (NAc) to provide motivational drive for the performance of instrumental behaviors. The dlPFC and dorsal anterior cingulate cortex (dACC) play a role in comparing action values and can exert a modulatory influence over circuits involving prefrontal and aCN activity. Together, the contingency and evaluative circuits allow for the acquisition of goal-directed behaviors. (B) Stimulus-response associations, or habits, are mediated by projections from premotor (PM) and sensorimotor cortices (SM) to the posterior putamen (Pu). (C) The lateral orbitofrontal cortex (lOFC) and the BLA encode the value assigned to reward predictive stimuli, which the NAc uses to mediate instrumental performance. Mid-brain dopamine modulates plasticity in the dorsal striatum, and is associated with motivational processes in the ventral striatum. The balance between striatal output to the direct (D1) and indirect (D2) pathways serves to promote or inhibit behavior, respectively.