Semi-automatic analysis of microscopic images of the human cerebral cortex using the grey level index

A new semi-automatic method is introduced which makes possible the quantitative examination of cresyl-fast-violet stained sections of the cerebral cortex. These sections are divided into measuring fields of 20 X 20 microns in a well-defined area. A scanning procedure then automatically determines the grey level index of every single field. The image of the histological section can be compared with the grey level index data matrix by means of a plotted image, the density of the plotted points of which is proportional to the measured grey level index. By overlaying this plotted image with the original section, the boundaries of the laminae can be fixed in the data matrix. The grey level index profiles--the grey level data plot as a function of the cortical depth--after smoothing and standardization are typical of special cortical areas. The mean thickness and the mean portion of the grey level index profile of the different laminae of the striate area are compared with data from other publications.