Nat. Neurosci. 19, 135–142 (2016); published online 14 December 2015; corrected after print 23 December 2015

In the version of this article initially published, the neurometric slope values in the bottom panel of Figure 4a were given as 1.6, 1.0., 1.0; the correct values are 0.8, 0.5, 0.5. The x axes in Figure 4b, right panel, were numbered 0 to 3; the correct range is 0 to 1.5. The segments of the traces in Figure 6b–d with significant regression coefficients were gray; they should have been red. And the top segment of the bar for 0–10% in the bottom panel of Figure 7c was blue; it should have been pink. The errors have been corrected in the HTML and PDF versions of the article.