The organization of retinal maps within the dorsal and ventral lateral geniculate nuclei of the rabbit

Abstract

The cytoarchitectonic subdivisions in the rabbit's dorsal and ventral lateral geniculate nuclei have been related to the several retinal maps that can be defined in terms of the distribution of retinal axons within these nuclei. Destruction of different retinal sectors was combined with intravitreal injections of ³H-proline, so that the distribution of fiber degeneration and autoradiographic label in the geniculate nuclei could be used to define the retinal maps in each nucleus, and to compare the two nuclei with each other. The two nuclei show surprisingly similar patterns of organization. Each is made up of a laminated alpha sector that curves around a relatively cell-sparse beta sector. Two morphologically distinct layers of each alpha sector receive contralateral retinal afferents and between these there is a small region in receipt of ipsilateral afferents. In each nucleus, the lines of projection that represent single points in visual space pass perpendicular to the layers of the alpha sector and continue an almost straight course into the beta sector. Quantitative comparisons of the retinal maps show that the relative volumes devoted to the representation of segments of the visual field are approximately the same in the two nuclei.