Fool me once, shame on me—fool me twice, blame the ACC
-- Benjamin Y Hayden, Michael L Platt, Nature Neuroscience 9, 857 - 859 (2006)

Abstract: The anterior cingulate cortex (ACC) is thought to detect unfavorable outcomes and thus influence behavior. A new paper reports that ACC-lesioned monkeys respond normally to reduced rewards, but do not maintain their improved behavioral strategy. The ACC thus is not a simple error detector, but an integrator of past reward experience.