I remember going to see the rats of N.I.M.H. way too young and being terrified (perhaps second only to my fear of the Wicked Witch of the West). Anyway, the secret is out…

Wong FK, Fei J-F, Mora-Bermúdez F, Taverna E, Haffner C, Fu J, et al. (2015) Sustained Pax6 Expression Generates Primate-like Basal Radial Glia in Developing Mouse Neocortex. PLoS Biol 13(8): e1002217. doi:10.1371/journal.pbio.1002217

The evolutionary expansion of the neocortex in mammals has been linked to enlargement of the subventricular zone (SVZ) and increased proliferative capacity of basal progenitors (BPs), notably basal radial glia (bRG). The transcription factor Pax6 is known to be highly expressed in primate, but not mouse, BPs. Here, we demonstrate that sustaining Pax6 expression selectively in BP-genic apical radial glia (aRG) and their BP progeny of embryonic mouse neocortex suffices to induce primate-like progenitor behaviour.

NIMH stood for “National Institute of Mental Health”. Which was, of course, secretly creating super-intelligent rats.