The Brain Making Choices: The Lesser of Two Evils or the Better of Two Goods....

The relevance of this topic to yesterday's election was mentioned in the post just below. Blair et al. have now used functional magnetic resonance imaging to delineate the functional roles of the ventromedial prefrontal cortex (vmPFC) and dorsal anterior cingulate cortices (ACd), which are considered important for reward-based decision making. Response choice often occurs in situations where both options are desirable (e.g., choosing between mousse au chocolat or crème caramel cheesecake from a menu) or, alternatively, in situations where both options are undesirable. Moreover, response choice is easier when the reinforcements associated with the objects are far apart, rather than close together, in value. The authors used functional magnetic resonance imaging to delineate the functional roles of the vmPFC and ACd by investigating these two aspects of decision making: (1) decision form (i.e., choosing between two objects to gain the greater reward or the lesser punishment), and (2) between-object reinforcement distance (i.e., the difference in reinforcements associated with the two objects). Responses within the ACd and vmPFC were both related to decision form but differentially. ACd showed greater responses when deciding between objects to gain the lesser punishment, while vmPFC showed greater responses when deciding between objects to gain the greater reward. Moreover, vmPFC was sensitive to reinforcement expectations associated with both the chosen and the forgone choice. In contrast, responses within ACd, but not vmPFC, related to between-object reinforcement distance, increasing as the distance between the reinforcements of the two objects decreased.


Figure: anterior cingulate and ventromedial prefrontal areas examined in study.