Recurrent inhibition and clustered connectivity as a basis for Gabor-like receptive fields in the visual cortex.

A continuous-space model of visual cortex interactions which, starting from elongate Gaussian functions, leads to high-selective Gabor-like receptive fields, is proposed. The model is based on intracortical inhibition mechanisms occurring through medium-range clustered connections. The analysis, carried out under the assumption of a linear superposition of geniculate and intracortical contributions, shows how inhibition enhances both spatial and spatial-frequency selectivity. The effects of inhibition strength and of its spatial organization on the properties of the resulting receptive field are investigated. Specifically, the relationships between receptive fields and inhibition schemes are investigated by deriving analytical expressions for their dependence and through a systematic numerical parametric study. The emergence of periodic receptive fields, like the ones observed in neurophysiological measurements, is also pointed out in relation to the clustered nature of the inhibitory scheme.