DEVELOPMENTAL NEUROSCIENCE

To Fold or Not to Fold

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Science  31 May 2013:
Vol. 340, Issue 6136, pp. 1016
DOI: 10.1126/science.340.6136.1016-b
CREDIT: M. NONAKA-KINOSHITA ET AL., THE EMBO JOURNAL (26 APRIL 2013) © 2013 NATURE PUBLISHING GROUP/EUROPEAN MOLECULAR BIOLOGY ORGANIZATION

The surface of the normal human brain is characterized by deep and complex folds. Ferret brains are similarly gyrencephalic, whereas mouse brains are smooth-surfaced, or lissencephalic. During development, proliferation of different subtypes of stem and progenitor cells shapes the brain surface. In order to understand the relative contributions of these different progenitor cell types, Nonaka-Kinoshita et al. manipulated the proliferation of these cells at different times during the brain development of mice and ferrets. Mice with an excess of basal progenitors had thicker brain layers but, despite an increase in brain surface area, the surface remained smooth. In contrast, ferrets with excess progenitor activity developed more brain folds than control mice. In both species, neuronal specification and the structure of brain layers remained normal. Thus, the brain's surface area and the amount of folding may be regulated by progenitor activity, but the distinction between lissencephalic or gyrencephalic brains is not simply due to the number of progenitors.

EMBO J. 10.1038/emboj.2013.96 (2013).

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