Early divergence of magnocellular and parvocellular functional subsystems in the embryonic primate visual system
Proceedings of the National Academy of Sciences of the United States of America
Axon guidance; Lateral geniculate nucleus; Macaque monkey; Neuronal specificity; Retina
In both human and Old World primates visual information is conveyed by two parallel pathways: the magnocellular (M) and parvocellular (P) streams that project to separate layers of the lateral geniculate nucleus and are involved primarily in motion and color/form discrimination. The present study provides evidence that retinal ganglion cells in the macaque monkey embryo diverge into M and P subtypes soon after their last mitotic division and that optic axons project directly and selectively to either the M or P moieties of the developing lateral geniculate nucleus. Thus, initial M projections from the eyes overlap only in prospective layers 1 and 2, whereas initial P projections overlap within prospective layers 3-6. We suggest that the divergence of the M and P pathways requires developmental mechanisms different from those underlying competition-driven segregation of initially intermixed eye-specific domains in the primate visual system.
Meissirel, C., Wikler, K., Chalupa, L., & Rakic, P. (1997). Early divergence of magnocellular and parvocellular functional subsystems in the embryonic primate visual system. Proceedings of the National Academy of Sciences of the United States of America, 94 (11). http://dx.doi.org/10.1073/pnas.94.11.5900