Monetary reward magnitude effects on behavior and brain function during goal-directed behavior

Reward may modulate the cognitive processes required for goal achievement, while individual differences in personality may affect reward modulation. Our aim was to test how different monetary reward magnitudes modulate brain activation and performance during goal-directed behavior, and whether individual differences in reward sensitivity affect this modulation. For this purpose, we scanned 37 subjects with a parametric design in which we varied the magnitude of monetary rewards (a,notsign0, a,notsign0.01, a,notsign0.5, a,notsign1 or a,notsign1.5) in a blocked fashion while participants performed an interference counting-Stroop condition. The results showed that the brain activity of left dorsolateral prefrontal cortex (DLPFC) and the striatum were modulated by increasing and decreasing reward magnitudes, respectively. Behavioral performance improved as the magnitude of monetary reward increased while comparing the non reward (a,notsign0) condition to any other reward condition, or the lower a,notsign0.01 to any other reward condition, and this improvement was related with individual differences in reward sensitivity. In conclusion, the locus of influence of monetary incentives overlaps the activity of the regions commonly involved in cognitive control.