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.