Nat. Neurosci. 18, 199–209 (2015); published online 19 January 2015; corrected after print 19 January 2015

In the version of this article initially published, the affiliation numbers given for several authors were incorrect. Astrid M. Vicente was listed as associated with affiliations 234–236 instead of 233–235, Veronica J. Vieland as 237 instead of 236, Kenneth S. Kendler as 110, 253 and 254 instead of 110, 252 and 253, and Zhaoming Zhao as 255 instead of 254 and 255. The errors have been corrected in the HTML and PDF versions of the article.