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S. A. Castellano. The Folding of the Human Brain: From Shape to Function. PhD Thesis University of London, Division of Radiological Sciences and Medical Engineering, King's College London, September 1999.


This thesis explores the relationship between the shape of the surface of the human brain and the function of the underlying tissue. In this work, structural information is provided by magnetic resonance imaging. Functional information is gathered using functional magnetic resonance imaging and by electrophysiological monitoring with sub-durally implanted metal electrodes lying directly on the brain surface, which are localised using X-ray computed tomography images. The thesis examines techniques for comparing the information provided by the functional modalities with the shape of the underlying brain surface structures. The feasibility of comparing localisation of functional regions provided by functional magnetic resonance imaging with that provided by direct electrophysiological mapping is explored. The possibility of relating the shape of the cortical surface to the function of the brain is examined. Suitable geometrical measures for quantifying the shape of the brain surface are proposed. The measures discussed include measures of convexity in both two and three dimensions, measures based on surface area and volume measurements, and a set of measures based on integrals of intrinsic and extrinsic curvatures. Published work comparing surface shape and function is reviewed. Practical methods for applying the set of measures considered to discrete surfaces extracted from MR volumes are proposed. A discrete triangulated surface model has been devised to allow the calculation of these shape measures, and is described in detail. The smoothing of this surface model, and of measures extracted from it, is discussed in relation to noise in the surface fitted to the discrete dataset obtained from the anatomical images. The techniques are then applied to three-dimensional magnetic resonance images of a number of human brains. Initially the set of measures is applied to a series of normal ex-vivo foetal brains with gestational ages ranging from 19 weeks to 40 weeks. The shape measures are shown to reliably characterise the development of folding during normal development, with differences between gestational ages being significantly greater than the variability in the measures when applied to several brains of the same gestational age. The measures are then applied to a series of abnormally developed foetal brains, to a set of normal adult brains, and to a set of schizophrenic adult brains, in order to characterise the ability of the measures to distinguish between normal and abnormal brain surface shapes


S. A. Castellano

BibTex Reference

   Author = {Castellano, S. A.},
   Title = {The Folding of the Human Brain: From Shape to Function},
   School = {University of London},
   Address = {Division of Radiological Sciences and Medical Engineering, King's College London},
   Month = {September},
   Year = {1999}

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