Correction to: Nature Neuroscience https://doi.org/10.1038/nn.4650, published online 02 October 2017.

In the version of this article initially published, equation (7) read

$$\begin{array}{r}M=\sum _{t=0}^{\infty }{\gamma }^{t}{T}^{t}={(I-\gamma {T}^{t})}^{-1}\end{array}$$

It should have read

$$\begin{array}{r}M=\sum _{t=0}^{\infty }{\gamma }^{t}{T}^{t}={(I-\gamma T)}^{-1}\end{array}$$

The error has been corrected in the HTML and PDF versions of the article.