The Boston Globe has a short but interesting article on cerebral folding – the science of why the brain is wrinkled up like a damp walnut.
The wrinkled surface of the brain folds into ‘ridges’ known as gyri and the ‘trenches’ known as sulci. This rippled landscape forms perhaps the most recognisable aspect of the human brain but we still don’t really know why we need this rather odd arrangement.
The standard answer “to fit more brain surface in the skull” really tells us nothing on its own as it’s not clear why the same material in the outer brain layers couldn’t be distributed differently.
Some answers are starting to emerge, however, not least from studies which look at differences in brain folding during the pre-birth growth phase and between people with different neurological conditions.
The article is full of fascinating findings from this research, not least of which is that the brain is smooth until quite late in pregnancy and only starts to fold in the last few months of development.
Premature babies seem to have this process partially disturbed for reasons that aren’t yet clear:
For example, 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‚Äôt match those of their counterparts who spend their full nine months in the womb. New research from Van Essen‚Äôs 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.
‚ÄúThat means there‚Äôs something different in how those brains are organized and in the connections that have formed,‚Äô‚Äô 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‚Äôt yet narrowed down what these influences may be.
The article is brief but is packed full of eye-opening discoveries on brain folding. It’s one of those areas were we know so little but what we do know is quite compelling.
Link to Globe article ‘Unfolding the mysteries of the brain’.