Role of the Brain in Making Economic Decisions

Objective. The purpose of the protocol is to identify the brain regions mediating the social cooperation involved in economic decision-making, including whether negative mood and perceived interpersonal similarity affect behavior or brain regions utilized. Study Population. Healthy, normal adult volunteers will play and observe two-person reciprocal trust games during functional neuroimaging against either real people or computers masquerading as real people. Design. A between/within-subject, rapid event-related fMRI design will be employed for two series of experiments. In the first experiment, two persons-each in a separate MRI scanner-will interact with one another playing two-person reciprocal trust games while their brains are simultaneously scanned. In the second experiment, a third person will later observe the played games while in a scanner, trying to predict the decisions of the two other players in the first experiment. In the third experiment, a sad mood will be induced in half of the participants to examine if it affects levels of cooperative behavior and patterns of brain activation in the two types of trust games described above. Four additional series of experiments will employ between/within subject designs in which subjects are scanned alone, but under the deception that they are playing simultaneously with another subject. Outcome Measures. The data collected will consist of behavioral measures of cognitive performance, self- and other-mental representation, trusting and trustworthy behavior, corresponding fMRI images, personality scales, ratings of relationship and status, and types of strategy used. The results gained from this protocol will be of value in identifying a set of neural regions mediating dynamic social interaction between people engaged in economic decision-making.