Correction to: Neuropsychopharmacology advance online publication 22 August 2007; doi:10.1038/sj.npp.1301531

Following the online publication of this article, the authors have provided the following affiliation corrections: Dr Louise Levine retired from Eli Lilly and Co.; she is not affiliated with Merck and Co. When this study was conducted, she and all other authors were employees of Eli Lilly and Co.’