From the Reward Circuit to the Valuation System: How the Brain Motivates Behavior

Abstract

In this chapter, we expose how behavioral economists, experimental psychologists, and cognitive neuroscientists joined their efforts and merged two fields of investigation: reward learning and choice behavior. This collaboration was made possible by technical progress—the availability of brain-imaging scanners and conceptual links—the use of motivational value as a key variable. We then present evidence that motivational values are encoded in a so-called brain valuation system (BVS), which essentially comprises the ventral parts of the prefrontal cortex and basal ganglia. Some fundamental properties of the BVS have been uncovered: it encodes values that are personal (subject- and not object-specific), generic (expressed in a common neuronal currency), and automatic (generated even during distractive tasks). Next, we show example situations where the BVS interacts with other brain systems (such as the perceptual, motor, executive, episodic, and mirror systems) that can impact on, or be impacted by, motivational values. These neural interactions might explain a number of psychological phenomena, for instance, incentive motivation (why we put so much effort in a task), delay discounting (why we can resist the temptation of immediate pleasures), or mimetic desires (why we often pursue the same goals as others). Last, we point to unsolved issues, such as how values are encoded at the single-cell level, how the value code incorporates uncertainty, how the values of different features are integrated, how the values are different options are compared, how negative values are represented relative to positive values, etc.