Cortical Folding


Many subjects dealing with brain anatomy and physiology discuss the regions of the brain which are responsible for hearing, vision , motion, decision making etc.  However today’s discussion will talk about why the brain has a wrinkled high surface area type structure and what can be learned regarding the nature of these folds and various types of neurological diseases.

Lets start with discussing the high surface area of the brain itself.  The brain is wrinkled not to be gross looking or because it just is.  The brain is wrinkled due to the need for increased surface area.  By having an increased surface area you can increase the number of neurons that can be compacted into a space.  More neurons means more potential for processing power! Now the Cortex itself (the upper brain) is folded into what are called gyri (hills) and sulci (valleys)  These gyri and sulci make up that classic brain feature that we all are familiar with.  But is the brain always like this?

Turns out its not!  During the first 25 weeks of development your brain is actually smooth.  As you progress in the womb your nerve fibers are developing and reaching out and creating a massive complex of potential neural circuits.  The process of reaching out to make connections with different neurons causes  the brain to literally tug on itself thus creating these folds.

Because of the importance of having high surface area, babies who are not left for a full 9 month term (premature babies) will have to catch up developmentally in terms of mental processes.  But like many things in biology its not just as simple as the more folds the better.  For example having too many sucli actually makes for an increased number of weak neural connections.

Pictures are refrenced in the below works.

What  neurologists are interested in are the differences between a patients brain who lacks a mental disorder and those of patients who in fact suffer from these disorders in terms of their folds.  In order to do this they used inflated sulci and gyri maps from controls, and then overlayed experimental images onto the templates to determine differences in metric distortion/levels and areas of folding.  What they found was patients who suffer from  diseases such as Autism,Schizophrenia, and even Bipolar disorder, have a marked difference in their cortical folding when compared to a patient who does not suffer.  Even more so the areas of the brain associated with particular symptoms of those diseases are folded differently.  So for example in a patient with schizophrenia, hearing voices is not uncommon.  When they image and measure the folding pattern of the brain in a Schizophrenic patients hearing area they find that the folds are different.  This implies incorrect neuronal circuitry.

Images taken from below refrenced works

This imaging technic is highly important in helping us to understand on a functional and anatomical level debilitating mental disorders.  Through this knowledge better treatment plans can be assigned and even potentially better drugs.

•Dubois J., Benders M., Borradori-Tolsa C., Cachia A., Lazeyras F., Ha-Vinh Leuchter R., Sizonenko S.V., Warfield S. K., Mangin J. F., Hu P. S. (2008). Primary cortical folding in the human newborn: an early marker of later functional development. Brain. 131, 2028-2041.
•Hilgetag, C.  Barbas, H. 2009. Sculpting the brain.  Scientific American. February Pp 66-68.
•McIntosh A.M., Moorhead T.W.J., McKirdy J, Hall J., Sussmann J.E.D., Stanfield A.C., Harris J.M., Johnstone E.C., Lawrie S.M. (2009) Prefrontal gyral folding and its cognitive correlates in bipolar disorder and schizophrenia. Acta Psychiatrica Scandinavica. 119: 192–198.
•Stanfield A. C., William T., Moorhead J., Harris J. M., Owens D. G.C., Lawrie S. M., Johnstone E. C. (2008). Increased Right Prefrontal Cortical Folding in Adolescents at Risk of Schizophrenia for Cognitive Reasons. Biological Psychology. 63:80–85.
•Wisco , Kuperberg G., Manoach D., Quinn B. T. ,Busa E., Fischl B., Heckers S., Sorensen A. G. (2007). Abnormal cortical folding patterns within Broca’s area in schizophrenia: Evidence from structural MRI. Schizophrenia Research. 317–327.
•Wu Nordahl C., Dierker D., Mostafavi I., Schumann C.,. Rivera S. M, Amaral D. G., Van Essen D. C. (2007). Cortical Folding Abnormalities in Autism Revealed by Surface-Based Morphometry. The Journal of Neuroscience. 27(43):11725–11735.
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Posted on January 24, 2011, in Medicine and tagged , , , , , , , . Bookmark the permalink. Leave a comment.

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