Modulation of prefrontal cortex activity by information toward a decision rule

We used fMRI to investigate how the information content of a sti-mulus in£uences activity in brain systems that support decision making. Subjects learned decision rules that were based upon the color, shape, or ¢ll pattern of a series of stimuli. Each stimulus was classi¢ed by its information content, de¢ned formally by the deci-sion rules it excluded. While activity in dorsolateral prefrontal cortex (dlPFC) increased with increasing stimulus information, activity in the striatum did not. In contrast, within both the stria-tum and dlPFC, stimuli consistent with the rule evokedgreater ac-tivity than stimuli inconsistent with the rule. This dissociation indicates that dlPFC supports modi¢cation of sets of stimulus-re-sponse contingencieswhile the striatum supports stimulus-speci¢