Correction to: Nature Neuroscience https://doi.org/10.1038/s41593-017-0045-5 (2017), published online 13 November 2017.

In the version of this article initially published, paragraph 8 mentioned intra-accumbens administration of SB334867. This should have read systemic (intraperitoneal) administration. The error has been corrected in the HTML and PDF versions of the article.