Nat. Med. 19, 107–112 (2013); published online 16 December 2012; corrected after print 12 August 2015

In the published article, in the Online Methods section, it is stated that the dose of DHE used is 20 mg/kg, when in fact DHE was administered at 2 mg/kg. The error has been corrected in the HTML and PDF versions of the article.