Single neuron recording techniques will be used to compare the visual pathways of the cat and monkey with that of the owl. Comparison will be made at the level of the retina, visual thalamus and visual forebrain in both normal adult birds and in developing birds subjected to visual deprivation such as eye occlusion. The unique features of the organization of the avian visual system may provide new experimental approaches to the problem of the binocular visual disorders such as stereoblindness and amblyopia.