Phase disparity in area 19 of the cat.

Binocular cells in area 19 are tuned to positional disparities. In effect, up to one-third of the cells respond preferentially to small incongruities between the optimal bar stimuli presented within the receptive fields of each eye. The aim of the present study was to determine whether cells in area 19 are also sensitive to phase disparities. Both types of disparities have been proposed as mechanisms through which stereoperception is achieved. Results indicate that phase disparities produced coherent interactions in 38% of the binocular cells, resulting in facilitation or summation. The remaining cells were phase insensitive. The overall results suggest that cells in area 19 code phase disparities in a proportion comparable to stimulus disparities, confirming that this area is implicated in binocular integration, albeit in a relatively smaller proportion than some of the other visual areas.