Nat. Neurosci. 17, 1040–1042 (2014); published online 13 July 2014; corrected after print 4 August 2014

In the version of this article initially published, the e-mail address for author O.T. was given as and a protein in the last paragraph of the main text was given as SVA2. These should be, respectively, and SV2A. The errors have been corrected in the HTML and PDF versions of the article.