Comparison of the effects of unilateral and bilateral eye closure on cortical unit responses in kittens.

IN THE NORMAL CAT OR KITTEN about four-fifths of cells in the striate cortex can be driven by both eyes (3, 4). If, however, one eye of a newborn kitten is sewn shut and the visual cortex recorded from 3 months later, only a small fraction of cells can be driven from the deprived eye (8) . In contrast, many cells in the latera .I geniculate are driven normally from the d ,eprived eye (7 ), suggesting that the abnormality occurs somewhere between geniculate cells and cortex. Since clear receptive-field orientations and directional preferences to movement are seen in cortical cells of newborn visually inexperienced kittens, the deprivation effects presumably represent some sort of disruption of innately determined connections, rather than a failure of postnatal development related to lack of experience. In these experiments the use of monocular deprivation made it possible to compare adjacent geniculate layers, and also to compare the two eyes in their ability to influence cortical cells, so that each animal acted, in a sense, as its own control. The results led us to expect that depriving both eyes for similar periods would lead to an almost total unresponsiveness of cortical cells to stimulation of either eye. That should be so, provided the effects of depriving one eye were independent of whether or not the other eye was simultaneously deprived. It seemed worthwhile to test such an assumption, since any interdependence of the two pathways would be of considerable interest. We accordingly raised kittens with both eyes covered by lid suture, and recorded from the striate cortex when the animals had reached an age of 23-43 months.