Nat. Neurosci. 19, 1123–1130 (2016); published online 26 August 2016; corrected after print 29 August 2016

In the version of this article initially published online, the first author's name appears as “Charles Jennings” without middle initial; it has been changed to “Charles G Jennings”. Another author's name appears in the author list as “Angela Roberts,” also without middle initial; it has been changed to “Angela C Roberts.” The error has been corrected in the PDF and HTML versions of this article.