To identify neuronal mechanisms underlying stereopsis, we characterized
interactions between inputs from the two eyes in disparity-selective neurons
in macaque V1. All disparity-selective cells showed suppressive interactions
between the right and left eyes, and some showed facilitatory interactions.
Disparity selectivity was narrower than the receptive-field width and was
constant across the receptive field. Such position-invariant disparity selectivity
is also found in anesthetized cat V1. Complex cells have been suggested to
inherit their disparity selectivity from simple cells with receptive fields
mismatched between the two eyes. However, we found no such antecedent disparity-tuned
simple cells. We did find disparity-selective cells with some simple-cell
characteristics, but surprisingly, they also showed position-invariant disparity
selectivity rather than simple linear binocular interactions.
