Conditions for dominance of one eye during competitive development of central connections in visually deprived cats

Three groups of visually deprived cats were studied for evidence that one eye gained a competitive advantage over the other during development of central connections. We attempted to detect such an advantage by measuring lateral geniculate cell sizes, by recording the proportion of lateral geniculate Y-cells and the ocular dominance of cortical neurons, and/or by testing visual orienting behavior. Three cats were raised with one eye covered by the lids, and the other, by the nictitating membrane. Lids reduce illumination by 3--4 log units, nictitating membranes, by about one log unit, and both eliminate spatial patterns. Neither eye in these cats appeared to develop with a competitive advantage over the other. Four cats raised with monocular nictitating membrane closure developed with a clear advantage to the open eye, and in all ways data from these cats were indistinguishable from those previously reported for monocularly lid sutured cats. Finally, 4 cats reared with binocular lid closure, but with additional, temporally modulated stimulation through the right lids, showed no evidence of a competitive advantate to either eye. We conclude that interocular differences in light intensity or temporal patterns do not confer a significant competitive advantage to either eye during development of central connections.