Discrimination learning of grating orientation in visually deprived cats and the role of the superior colliculi.

Four cats deprived binocularly of pattern vision (BD cats), 4 control cats reared also in the laboratory (C cats), and 4 normal wild cats (N cats) were trained to discriminate gratings of progressively smaller difference in orientation. Differences in learning were found only in fine orientation discriminations. The stage of 15 degrees orientation difference was learned by 4 N cats, 2 C cats, and 1 BD cat. After the discrimination training, the superior colliculi were ablated in 2 C cats and 2 BD cats. In contrast to C cats, the BD cats were very deficient and failed to relearn even a horizontal versus vertical orientation discrimination. Thus, an abnormal neural strategy used by BD cats diminished their deficit in grating discrimination learning.