[Spatial organizations of projections from area 18 to area 17 in the cat visual cortex]

Spatial distribution of efferent neuronal connections from area 18 to area 17 in the cat was investigated using the microiontophoretic horseradish peroxidase injections in a single cortical columns of area 17. The localization of rertogradely labelled cells in area 18 was determined and plots of labelled cells distribution in the plane of cortical surface, in the sagittal and in the frontal planes were done. It was shown that neuronal connections from area 18 to the single column in area 17 are elongated (in the cortical surface plane) in the same rostrocaudal direction, along the representation of visual field vertical meridian, just as the intrinsic horizontal connections in area 18. This findings demonstrate the spatial correspondence between efferent and intrinsic connections distributions in area 18. Such area 18 connections provide more detailed analysis of the vertical components of visual objects.