Sharpening of orientation selective receptive fields in the mammalian visual cortex by long-range interactions

Lateral intracortical interactions are believed to be responsible for the sharpening of the receptive field profiles of visual cortical cells. This study demonstrates a structurally imposed limitation of long range interactions on the frequently invoked cross orientation inhibition scheme: it leads to inhomogeneous input for different cell populations which is experimentally not observed. We propose a novel connection scheme called “circular inhibition“ which circumvents this problem. The scheme is analyzed by computer simulation of the early visual system of the cat, and by studying a simple analytically solvable model. Our model yields results consistent with the experimentally determined structure of the orientational hypercolumns in area 18 of the cat