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

Silvio P. Sabatini
DIBE - University of Genoa, Via Opera Pia 11a, 16145 Genova, ITALY

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 the 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.