Development of connectional specificity in the lateral geniculate nucleus. In the first postnatal week (left), both relay cells (in gray) and interneurons (in black) receive a large number of retinal inputs originating in both eyes. By the end of the third postnatal week (right), and consistent with the refinement and eye segregation of RGC axons, the convergence onto relay cells is dramatically reduced and restricted to inputs coming from the same eye. At the same time, retinal synapses form in more proximal locations of the dendritic tree, increasing the efficiency of the afferent input. Inhibitory cells, on the other hand, maintain a large number of retinal inputs. If we consider that the cells depicted in the figure all sample from the same region of the retina, the difference in retinothalamic convergence between the relay cells and the interneurons would guaranty an equivalent coverage of visual space in the excitatory and inhibitory branches of the network.