How the brain integrates costs and benefits during decision making

TLDR

Decision making requires weighing benefits against costs, yet the neural systems mediating this cost–benefit computation remain poorly understood. The study aims to demonstrate that cost–benefit decision making can be modeled as a stochastic accumulation of the cost–benefit difference. Using fMRI and choice modeling, the authors show that ventromedial and left dorsolateral prefrontal cortex compute a cost–benefit difference by integrating benefit signals from the ventral striatum and cost signals from the amygdala. They found that this difference is accumulated in the middle intraparietal sulcus, and that the difference‑based accumulation mechanism, known from perceptual decisions, also underlies value‑based choices.

Abstract

When we make decisions, the benefits of an option often need to be weighed against accompanying costs. Little is known, however, about the neural systems underlying such cost–benefit computations. Using functional magnetic resonance imaging and choice modeling, we show that decision making based on cost–benefit comparison can be explained as a stochastic accumulation of cost–benefit difference. Model-driven functional MRI shows that ventromedial and left dorsolateral prefrontal cortex compare costs and benefits by computing the difference between neural signatures of anticipated benefits and costs from the ventral striatum and amygdala, respectively. Moreover, changes in blood oxygen level dependent (BOLD) signal in the bilateral middle intraparietal sulcus reflect the accumulation of the difference signal from ventromedial prefrontal cortex. In sum, we show that a neurophysiological mechanism previously established for perceptual decision making, that is, the difference-based accumulation of evidence, is fundamental also in value-based decisions. The brain, thus, weighs costs against benefits by combining neural benefit and cost signals into a single, difference-based neural representation of net value, which is accumulated over time until the individual decides to accept or reject an option.