Neural Computation, Vol 8, 705-730, Copyright © 1996 by The MIT Press
A theory of the visual motion coding in the primary visual cortex
Z Li
Computer Science Department, Hong Kong University of Science and Technology, Kowloon, Hong Kong.
This paper demonstrates that much of visual motion coding in the primary
visual cortex can be understood from a theory of efficient motion coding in
a multiscale representation. The theory predicts that cortical cells can
have a spectrum of directional indices, be tuned to different directions of
motion, and have spatiotemporally separable or inseparable receptive fields
(RF). The predictions also include the following correlations between
motion coding and spatial, chromatic, and stereo codings: the preferred
speed is greater when the cell receptive field size is larger, the color
channel prefers lower speed than the luminance channel, and both the
optimal speeds and the preferred directions of motion can be different for
inputs from different eyes to the same neuron. These predictions agree with
experimental observations. In addition, this theory makes predictions that
have not been experimentally investigated systematically and provides a
testing ground for an efficient multiscale coding framework. These
predictions are as follows: (1) if nearby cortical cells of a given
preferred orientation and scale prefer opposite directions of motion and
have a quadrature RF phase relationship with each other, then they will
have the same directional index, (2) a single neuron can have different
optimal motion speeds for opposite motion directions of monocular stimuli,
and (3) a neuron's ocular dominance may change with motion direction if the
neuron prefers opposite directions for inputs from different eyes.
