Economic choice behavior entails the computation and comparison of subjective values. A central contribution of neuroeconomics has been to show that subjective values are represented explicitly at the neuronal level. This result at hand, the field has increasingly focused on the difficult question of where in the brain and how exactly values are compared to make a decision. I will describe a series of results suggesting that good-based decisions emerge from a neural circuit within the orbitofrontal cortex (OFC). The main lines of evidence are (1) the fact OFC lesions specifically disrupt value-guided behavior, (2) the fact that during economic choice different groups of neurons in OFC encode the input and the output of the decision process, (3) the fact that these groups of cells are computationally sufficient to generate decisions and (4) the fact that activity fluctuations in each group of neurons correlate with choice variability. I will also discuss a newly developed theory of optimal coding for economic decisions. Its central concept is that neuronal tuning functions are optimal if they insure maximal expected payoff. In this framework, I will show that value coding in OFC is functionally rigid (linear tuning) but parametrically plastic (range adaptation with optimal gain).