What we can infer by comparing the shape of anatomical structures? Comparative anatomy of the parietal cortex in human and chimpanzee

Transcription

1 Interdisciplinary Workshop on 3D Paleo-Anthropology, Anatomy, Computer Science & Engineering - Synergies for the Future - June, Musée de Toulouse, France What we can infer by comparing the shape of anatomical structures? Comparative anatomy of the parietal cortex in human and chimpanzee E.P. Gilissen 1, M. Suliga 2, R. Deklerck 2, E. Nyssen 2, R. Achten 3, J.M. Erwin 4, P.R. Hof 5, C.C. Sherwood 6 1 Musée Royal de l Afrique Centrale et Université Libre de Bruxelles, 2 Vrije Universiteit Brussel, 3 Gent Universiteit, Belgique 4 McDaniel College, Maryland, Foundation for Comparative and Conservation Biology, Pennsylvania 5 Mount Sinai School of Medicine, New York Consortium in Evolutionary Primatology, New York 6 The George Washington University, Washington DC, USA

2 Why cortical folding? Simple mechanistic hypothesis: The functional necessity for cortical folding = packing the extended cortical surface into the restricted volume of the cranial vault (Welker, 1990) (Gorilla gorilla beringei, F)

3 Cortical folding and connectivity optimization (Innocenti, 1990) Frontal sections showing callosal connections (injection sites) (A) rat (Heimer et al. 1967) (B) rhesus macaque (Goldman-Rakic, 1982) This illustrates how gyration can shorten the trajectory of cortico-cortical axons

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5 Tension-mediated folding of cerebral cortex (Van Essen, 1997)

6 The simple mechanistic hypothesis is only a very partial explanation of cortical folding In the early enucleate monkey, the large changes in the dimensions of striate and extrastriate cortex disrupt the appropriate topographical relationship between cortical surfaces, which, in turn, may generate the unusual gyral pattern in these animals Gyri formation serves largely to accommodate cortical connectivity

7 Cortical folding and cortical areas cortical folds are much better predictors of the cortical areas than had been previously thought results suggest a common mechanism for the development of the cortical folds and the cytoarchitectonic fields

8 connectivity optimization and cortical areas Organization of cortical areas has evolved to optimize Interareal connections

9 Cortical folding Positioning of cortical areas Onset of connectivity Connectivity optimization

10 patterns of asymmetry in gyrification resemble the right frontal, left occipital asymmetries in cerebral torque asymmetries in both cerebral torque and gyrification may reflect a common neural developmental pattern of the cortex

11 Brain surface shape Cortical folding Positioning of cortical areas Onset of connectivity Connectivity optimization

12 Cortical surface viewing Native 3D Slices 6mm slabs Smoothed Flat map Ellipsoid

13 Flat maps are the most compact representation because the entire hemisphere can be seen in a single view, and they have no foreshortening because the surface is planar. However, flat maps do entail the introduction of selected cuts to prevent severe distortions in surface area.

14 A METHOD TO CONSTRUCT FLAT MAPS OF THE BRAIN'S SURFACE AND ITS APPLICATION Rudi Deklerck Dept. ETRO-IRIS, IBBT, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium Junfeng Guo, Alexandru Salomie, Marek Suliga, Edgard Nyssen, Liu Tao, Danielle Baleriaux, Jan Cornelis

15 A coarse mesh is defined on a grid corresponding to two hemi-ellipsoid Distance homogenization Examples of meshes during the deformation Obtention of a smooth high-resolution surface

16 Sulci identification «flat» cortical surface

17 Viewing the cortical surface with TeDiMedIA software

18 Central sulcus Central sulcus «flat» cortical surface and oblique section Postcentral sulcus Postcentral sulcus «flat» cortical surface and 3D reconstruction

19 RB 11 (Pan)-7659 Pan troglodytes

20 This research was supported by the Paul Broca II The evolution of cerebral asymmetry in Homo sapiens project 6th Framework of the European Community