Postnatal development of ocular dominance columns in layer IV of the cat's visual cortex of monocular deprivation

The segregation of geniculocortical fibers representing the two eyes and the effects of monocular dperivation on this segregation were studied by transneuronal transport of radioactive proline injected into one eye, and by physiological recordings. In the normal adult animal, this auto radiographic technique (7) has demonstrated that geniculocortical terminals from the two eyes are partially segregated (6). We examined the physiological correlate of this anatomical segregation by recording from single cells in identified laminae of area 17 in cats in which one eye had previously been injected with radioactive label. In layer IV, most cells had simple receptive fields and about 20% of the cells were monocularly driven from each eye. Cells were clustered according to eye preference , and transitions between groups of cells dominated by one eye or the other were marked with electrolytic lesions. Figure lA shows one such experiment in a normal cat. In this and similar experiments, a good correspondence was found between the distribution of cells in layer IV dominated by the injected eye and that of radioactively labelled terminals. Previous work in the monkey has disclosed that the geniculo-cortical projection is initially overlapping (5). The afferents representing the two eyes begin to segregate apart from each other * The experiments described here are presented fully in the two dominance columns and their development in layer IV of the cat's visual cortex: a quantitative study, in press, J. Ocular dominance in layer IV of the cat's visual cortex and the effects of monocular deprivation, in press, J. Physiol., 1978. ** These experiments were conducted in collaboration with C.