Biological Cybernetics. Vol.80(3):171-183, 1999

An architectural hypothesis for direction selectivity in
the visual cortex: The role of spatially asymmetric
intracortical inhibition.

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

Within a linear field approach an architectural model for simple cell direction selectivity in
the visual cortex is proposed. The origin of direction selectivity is related to recurrent
intracortical interactions with a spatially asymmetric character along the axis of stimulus
motion. No explicit asymmetric temporal mechanisms are introduced or adopted.
The analytical investigation of network behavior, carried out under the assumption of
a linear superposition of geniculate and intracortical contributions, shows that motion
sensitivity of the resulting receptive fields emerges as a dynamic property of  the cortical
network without any feed-forward direction selectivity bias.
A detailed analysis of the effects of the architectural characteristics of the cortical
network on directionality and velocity response curves is conducted by a
systematic variation of model's parameters.