Regular structural organization of intrahemisphere interzonal connections in the visual cortex of the cat.

The aim of the present work was to conduct a morphometric analysis of the cluster organization of neurons forming interzonal corticocortical connections in the visual cortex. The investigations used a method based on retrograde transport of horseradish peroxidase and mathematical analysis of the spatial distribution of labeled cells. Measurements yielded the following quantitative characteristics of the cell distribution--the volume and linear sizes of clusters, the distance between the centers of gravity of clusters, and the periodicity in the distribution of clusters along the cortical surface. Age-related features of the distribution of cells giving rise to cortical interzonal connections were identified. The experiments showed that the pattern of the cluster organization typical of adult cats was formed by the end of the second month of life. Quantitative differences in the spatial organization of neuron groups in the cortex of visual fields 17 and 18 were demonstrated.