the part of the visual system that projects to or originates from small neurons in the four dorsal layers (the parvocellular layers) of the lateral geniculate nucleus. It allows the perception of fine details, colors, and large changes in brightness. The parvocellular system is expanded in primates compared to that in other animals; it conducts information relatively slowly because of its small cells and slender axons. See also P-cell. Compare magnocellular system.