Author/Editor     Schleicher, Axel; Amunts, Katrin; Geyer, Stephan; Kowalski, Tilo; Zilles, Karl
Title     An observer-independent cytoarchitectonic mapping of the human cortex using a stereological approach
Type     članek
Source     Acta Stereol
Vol. and No.     Letnik 17, št. 1
Publication year     1998
Volume     str. 75-82
Language     eng
Abstract     Cytoarchitectonic areas of the cerebral cortex cannot be identified in PET or fMRI images. Architectonic identification, however, is necessary if imaging data are to be interpreted as function of anatomical entities. Functional/structural correlation requires the superimposition of cytoarchitecturally defined cortical areas with functional data in a common reference system. Upto now, most delineations of areas were based on the observer's ability to detect subtle differences in cytoarchitecture. In order to exclude observer-dependent effects on mapping, we developed a fully automated stereological approach with which to localise the borders of cortical areas. A cortical area is characterised by a distinct laminar pattern. This pattern is represented by profile curves extending from the beginning of layer II to the white matter boundary. Histological sections were digitised using the grey level index procedure, and the profiles are constructed from these images. The shapes of neizghbouring profiles are compared by calculating their distances according to feature vectors extracted from the profiles. Profiles derived from a homogeneous area can be expected to be similar in shape and hence show low distance values between each other. Maximum distances can be found between profiles which lie on opposite sides of a structural boundary. The Mahalanobis distance was found to be more sensitive than other distance measures such as the Euclidean distance and toyield a defined spatial resolution. As an example, cell-stained sections of the human occipital cortex were analysed. The method not only verified boundaries which had been defined by visual inspection, it also revealed new ones which had not been detected visually.
Descriptors     CEREBRAL CORTEX
BRAIN MAPPING