Erratum: In the article “Population Coding of Reward Magnitude in the Orbitofrontal Cortex of the Rat” by Esther van Duuren, Jan Lankelma, and Cyriel M. A. Pennartz, which appeared on pages 8590–8603 of the August 20, 2008, issue, the authors would like to extend the original Acknowledgements to acknowledge Francisco A. Nieto Escámez, Ruud N. J. M. A. Joosten, Rein Visser, and Antonius B. Mulder for helping to collect the single-unit firing rate data that were originally described in the study by van Duuren et al. (2007) [van Duuren E, Escámez FA, Joosten RN, Visser R, Mulder AB, Pennartz CM (2007) Neural coding of reward magnitude in the orbitofrontal cortex of the rat during a fiveodor olfactory discrimination task. Learn Mem 14:446-456], and which provided a primary database for the novel analyses and results presented in the study by van Duuren et al. (2008).