BACKGROUND: Previous functional imaging studies investigating the neural correlates of financial decision-making have suggested that subjects may adopt different response strategies depending on the degree of reward/punishment they received. We wanted to investigate whether there is a strategic difference, and whether a shift in response strategy relates to differential BOLD fMRI activation.
METHOD: A within-subject, block design using a modified continuous performance task divided into a reward and punishment session was used to examine fMRI BOLD responses in 18 healthy volunteers. Six black and white line drawings were simultaneously presented to the participants for 300 ms. They were to determine if one of the six drawings depicted an animal or insect. The background colour of the screen indicated whether they could win NOK 3 and lose NOK 1 for correct and incorrect responses, or whether there were no monetary consequences. In the punishment session, the amounts that could be won or lost were reversed. Strategic flexibility was measured as a difference in response bias (lnβ) between monetary contingencies.
RESULTS: Both the reward and the punishment block yielded significant activations in the bilateral: ventral striatum, anterior insula, anterior cingulate and the orbitofrontal cortex compared to blocks without monetary consequences. Participants adopted a more liberal response bias in the punishment block than in the no-punishment block. Those who showed greater response-strategy flexibility in the punishment session had increased dorsolateral prefrontal cortex, sensory motor area and ventral lateral orbitofrontal cortex activation compared to those who were less strategically flexible. There was no difference in activations between the reward and punishment blocks.
CONCLUSIONS: These findings suggest that there are differences in response strategies in studies using financial decision-making models and that these differences manifest as differential activation patterns that may need to be modelled or controlled for in future studies.