Tuesday’s Boston Globe has a nifty article about what we know (and don’t know!) about cortical folding - how all those wrinkles on the surface of the brain develop. Turns out that fetuses in the first and second trimesters have basically smooth brains; all the folding happens late in neonatal development.

…because so much of the folding takes place during the latter weeks of fetal development, premature infants arrive with much of their cortical development yet to be completed. And the folding patterns of preemies relegated to the neonatal intensive care unit don’t match those of their counterparts who spend their full nine months in the womb. New research from Van Essen’s lab shows that even when preemies reach their originally forecasted due dates, their brains are not as large or as folded as those of full-term newborns.

“That means there’s something different in how those brains are organized and in the connections that have formed,’’ Grant said. Perhaps some extra environmental influence in the hospital is disrupting folding or preemies are missing out on some vital influence that their counterparts get in the uterus, though researchers haven’t yet narrowed down what these influences may be.