THE SPATIAL-DISTRIBUTION OF NEURONS AND GLIA IN HUMAN CORTEX BASED ON THE POISSON-DISTRIBUTION

  • 1 December 1987
    • journal article
    • research article
    • Vol. 9  (6) , 531-534
Abstract
A method was devised that employs deviations from the Poisson distribution to analyze the spatial arrangement of neurons and glia in human cerebral cortex. A field of randomly distributed points equal in number of a sample field of neuronal or glial cells is generated by computer, and the proportion of cells in the sample field that are closer to the nearest neighboring cells than to the nearest randomly distributed point is determined. We call this proportion the "Poisson ratio." When the cells are randomly distributed, the Poisson ratio is equal to 0.5. If the Poisson ratio is < 0.5, the cells are farther away from one another than a random distribution would predict (exclusionary pattern); if the Poisson ratio is < 0.5, the cells are closer to one another than a random distribution would predict (clustering). A simple nonparametric statistical test is used to determine the significance of differences in the ratios. This method was applied to samples of human cerebral cortex in order to test the hypothesis that patients with schizophrenic psychosis may have an altered pattern of neuronal clustering. The analysis revealed that there is no difference in the nearest-neighbor distribution of either neurons or glia between psychotic patients and controls. It was found, however, that there is a highly significant difference in the spatial distribution of neurons versus glia in human cerebral cortex. Neurons of layers II to VI in the human cortex show greater-than-expected distances among them and are distributed according to an exclusionary pattern, while neurons in layer I show a clustering pattern. Glia, on the other hand, show a random distribution throughout all layers. The data suggest that the glia of the human cortex form a nonspecific structural framework that, by itself, lacks laminar specialization. The exclusionary pattern noted for neurons in layers II to VI of the human cortex can probably be attributed to the large volume of neuronal processes relative to neuronal cell bodies.

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