Nature Communications 4: Article number: 2258 (2013); Published: 27 August 2013; Updated: 27 November 2013.

An error was accidentally introduced into the sixth sentence of the Abstract in the original version of this Article. The sentence should have referred to ‘mice lacking NMDA receptors in the primary motor cortex’ and not ‘mice lacking primary motor cortex’. This has now been corrected in both the PDF and HTML versions of the Article.