Gyrification: Difference between revisions

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In [[brain anatomy]], '''gyrification''' (also known as '''foliation''') refers to the folding of the [[cerebral cortex]] during [[brain development]] in [[reptile]]s and [[mammal]]s, e.g. in [[turtles]], [[cetacean]]s and [[primate]]s<ref name=Hofman1989>{{cite journal
In [[brain anatomy]], '''gyrification''' refers to the folding of the [[cerebral cortex]] during [[brain development]] in [[reptile]]s and [[mammal]]s, e.g. in [[turtles]], [[cetacean]]s and [[primate]]s<ref name=Hofman1989>{{cite journal
  | author = Hofman, M.A.
  | author = Hofman, M.A.
  | year = 1989
  | year = 1989
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  | url = http://cercor.oxfordjournals.org/cgi/content/full/11/12/1101
  | url = http://cercor.oxfordjournals.org/cgi/content/full/11/12/1101
  | pmid = 11709481
  | pmid = 11709481
}}</ref>. The term is also often used to describe the folding patterns of the [[cerebellum]], which is highly convoluted in other [[taxa]], too, e.g. in [[bird]]s<ref name=Iwaniuk2006>{{citation
}}</ref>. In this process, [[gyrus|gyri]] (ridges) and [[sulcus|sulci]] (fissures) form on the outermost surface of the brain. The term ''gyrification'' is also sometimes used instead of the more common term ''[[foliation]]'' to describe the folding patterns of the [[cerebellum]], which is highly convoluted in other [[taxa]], too, e.g. in [[bird]]s<ref name=Iwaniuk2006>{{citation
  | author = Iwaniuk, A.N.; Hurd, P.L.; Wylie, D.R.
  | author = Iwaniuk, A.N.; Hurd, P.L.; Wylie, D.R.
  | year = 2006
  | year = 2006
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  | url = http://www.springerlink.com/index/V446J5073H3417L0.pdf  
  | url = http://www.springerlink.com/index/V446J5073H3417L0.pdf  
}}</ref>.  
}}</ref>.  
Possible causes of the non-isotropy include [[thermal]] [[noise]], variations in the number and timing of [[cell division]]s, [[cell migration]], [[cortical connectivity]], [[pruning]], [[brain size]] and [[metabolism]] ([[phospholipid]]s in particular), all of which may interact<ref name=Price2004>{{cite journal
Possible causes of the non-isotropy include [[thermal]] [[noise]], variations in the number and timing of [[cell division]]s, [[cell migration]], [[cortical connectivity]], [[synaptic pruning]], [[brain size]] and [[metabolism]] ([[phospholipid]]s in particular), all of which may interact<ref name=Price2004>{{cite journal
  | author = Price, D.J.
  | author = Price, D.J.
  | year = 2004
  | year = 2004

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In brain anatomy, gyrification refers to the folding of the cerebral cortex during brain development in reptiles and mammals, e.g. in turtles, cetaceans and primates[1][2][3][4]. In this process, gyri (ridges) and sulci (fissures) form on the outermost surface of the brain. The term gyrification is also sometimes used instead of the more common term foliation to describe the folding patterns of the cerebellum, which is highly convoluted in other taxa, too, e.g. in birds[5].

While the extent of cortical folding has been found to be partly determined by genetic factors[6][7], the underlying biomechanical mechanisms are not yet well understood. The overall folding pattern, however, can be mechanistically explained in terms of the cerebral cortex resembling a gel that buckles under the influence of non-isotropic forces[8][9]. Possible causes of the non-isotropy include thermal noise, variations in the number and timing of cell divisions, cell migration, cortical connectivity, synaptic pruning, brain size and metabolism (phospholipids in particular), all of which may interact[10][11].

This multitude of underlying processes has rendered the concept of gyrification increasingly important for clinical diagnostics in recent years, since gyrification in some areas of the human brain appears to correlate with measures of intelligence [12], and disturbances in the folding pattern — as determined by non-invasive neuroimaging — can be taken as indicators of neuropsychiatric diseases. Patients with schizophrenia or Williams syndrome, for example, can be readily distinguished from healthy control populations on the basis of gyrification measures[13][14].

References

  1. ↑ Hofman, M.A. (1989). "On the evolution and geometry of the brain in mammals.". Prog Neurobiol 32 (2): 137-58. DOI:10.1016/0301-0082(89)90013-0. Research Blogging. [e]
  2. ↑ Armstrong, E.; Schleicher, A.; Omran, H.; Curtis, M.; Zilles, K. (1995). "The Ontogeny of Human Gyrification". Cerebral Cortex 5 (1): 56-63.
  3. ↑ Mayhew, T.M.; Mwamengele, G.L.; Dantzer, V.; Williams, S. (1996). "The gyrification of mammalian cerebral cortex: quantitative evidence of anisomorphic surface expansion during phylogenetic and ontogenetic development.". Journal of Anatomy 188 (Pt 1): 53.
  4. ↑ Supèr, H.; Uylings, H.B.M. (2001), "The Early Differentiation of the Neocortex: a Hypothesis on Neocortical Evolution", Cerebral Cortex 11 (12): 1101–1109, DOI:10.1093/cercor/11.12.1101
  5. ↑ Iwaniuk, A.N.; Hurd, P.L.; Wylie, D.R. (2006), "Comparative Morphology of the Avian Cerebellum: I. Degree of Foliation", Brain Behav Evol 68 (1): 45–62, DOI:10.1159/000093530
  6. ↑ Bartley, A.J.; Jones, D.W.; Weinberger, D.R.. "Genetic variability of human brain size and cortical gyral patterns". Brain 120 (2): 257-269.
  7. ↑ Chenn, Anjen; Walsh, Christopher A. (2002), "Regulation of Cerebral Cortical Size by Control of Cell Cycle Exit in Neural Precursors", Science 297 (5580): 365–9, DOI:10.1126/science.1074192 [e]
  8. ↑ Van Essen, D.C. (1997). "A tension-based theory of morphogenesis and compact wiring in the central nervous system". Nature 385 (6614): 313-8.
  9. ↑ Mora, T.; Boudaoud, A. (2006). "Buckling of swelling gels". The European Physical Journal E - Soft Matter 20 (2): 119-124.
  10. ↑ Price, D.J. (2004). "Lipids make smooth brains gyrate". Trends in Neurosciences 27 (7): 362-364.
  11. ↑ Toro, R.; Perron, M.; Pike, B.; Richer, L.; Veillette, S.; Pausova, Z.; Paus, T. (2008). "Brain Size and Folding of the Human Cerebral Cortex". Cerebral Cortex.
  12. ↑ Lüders, Eileen; Narr, Katherine L.; Bilder, Robert M.; Szeszko, Philip R.; Gurbani, Mala N.; Hamilton, Liberty; Toga, Arthur W.; Gaser, Christian (2007), "Mapping the Relationship between Cortical Convolution and Intelligence: Effects of Gender", Cerebral Cortex 18 (9): 2019, DOI:10.1093/cercor/bhm227
  13. ↑ White, T.; Andreasen, N.C.; Nopoulos, P.; Magnotta, V. (2003), "Gyrification abnormalities in childhood- and adolescent-onset schizophrenia", Biological Psychiatry 54 (4): 418–426, DOI:10.1016/S0006-3223(03)00065-9
  14. ↑ Schmitt, J.E.; Watts, K.; Eliez, S.; Bellugi, U.; Galaburda, A.M.; Reiss, A.L. (2002). "Increased gyrification in Williams syndrome: evidence using 3D MRI methods". Developmental Medicine & Child Neurology 44 (5): 292-295. DOI:10.1111/j.1469-8749.2002.tb00813.x. Research Blogging.
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