Visual Response Properties of Neurons in the LGN of Normally Reared and Visually Deprived Macaque Monkeys

1 Howard Hughes Medical Institute, 2 Center for Neural Science, and 3 Department of Psychology, New York University, New York 10003; 4 Department of Neurobiology, State University of New York, Stony Brook, New York 11794-5230; and 5 Department of Psychology, University of Wisconsin, Madison, Wisconsin 53706 Levitt, Jonathan B., Robert A. Schumer, S. Murray Sherman, Peter D. Spear, and J. Anthony Movshon. Visual Response Properties of Neurons in the LGN of Normally Reared and Visually Deprived Macaque Monkeys. J. Neurophysiol. 85: 2111-2129, 2001. It is now well appreciated that parallel retino-geniculo-cortical pathways exist in the monkey as in the cat, the species in which parallel visual pathways were first and most thoroughly documented. What remains unclear is precisely how many separate pathways pass through the parvo- and magnocellular divisions of the macaque lateral geniculate nucleus (LGN), what relationships homologous or otherwise these pathways have to the cat's X, Y, and W pathways, and whether these are affected by visual deprivation. To address these issues of classification and trans -species comparison, we used achromatic stimuli to obtain an extensive set of quantitative measurements of receptive field properties in the parvo- and magnocellular laminae of the LGN of nine macaque monkeys: four normally reared and five monocularly deprived of vision by lid suture near the time of birth. In agreement with previous studies, we find that on average magnocellular neurons differ from parvocellular neurons by having shorter response latencies to optic chiasm stimulation, greater sensitivity to luminance contrast, and better temporal resolution. Magnocellular laminae are also distinguished by containing neurons that summate luminance over their receptive fields nonlinearly (Y cells) and whose temporal response phases decrease with increasing stimulus contrast (indicative of a contrast gain control mechanism). We found little evidence for major differences between magno- and parvocellular neurons on the basis of most spatial parameters except that at any eccentricity, the neurons with the smallest receptive field centers tended to be parvocellular. All parameters were distributed unimodally and continuously through the parvo- and magnocellular populations, giving no indications of subpopulations within each division. Monocular deprivation led to clear anatomical effects: cells in deprived-eye laminae were pale and shrunken compared with