Modeling V1 Disparity Tuning to Time-varying Stimuli
Yuzhi Chen, Yunjiu Wang, and Ning Qian, J. Neurophysiol.
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Most models of disparity selectivity consider only
the spatial properties of binocular cells. However, the temporal
response is an integral component of real neurons' activities, and
time-varying stimuli are often used in the experiments of
disparity tuning. To understand the temporal dimension of V1
disparity representation, we incorporate a specific temporal
response function into the disparity energy model, and demonstrate
that the binocular interaction of complex cells is separable into
a Gabor disparity function and a positive time function.
We then investigate how the model simple and complex cells respond to
widely used time-varying stimuli, including motion-in-depth patterns,
drifting gratings, moving bars, moving random dot stereograms, and
dynamic random dot stereograms. It is found that both model simple
and complex cells show more reliable disparity tuning to time-varying
stimuli than to static stimuli, but similarities in the disparity
tuning between simple and complex cells depend on the stimulus.
Specifically, the disparity tuning curves of the two cell types are
similar to each other for either drifting sinusoidal gratings or
moving bars. In contrast, when the stimuli are dynamic random dot
stereograms, the disparity tuning of simple cells is highly
variable, whereas the tuning of complex cells remains reliable.
Moreover, cells with similar motion preferences in the two eyes cannot
be truly tuned to motion in depth, regardless of the stimulus types.
These simulation results are consistent with a large body of extant
physiological data, and provide some specific, testable predictions.
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