Title

Early divergence of magnocellular and parvocellular functional subsystems in the embryonic primate visual system

Document Type

Journal Article

Publication Date

5-27-1997

Journal

Proceedings of the National Academy of Sciences of the United States of America

Volume

94

Issue

11

DOI

10.1073/pnas.94.11.5900

Keywords

Axon guidance; Lateral geniculate nucleus; Macaque monkey; Neuronal specificity; Retina

Abstract

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.

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