EARLY POSTNATAL DEVELOPMENT OF RETINOGENICULATE TERMINATION PATTERNS IN MONKEYS.
Item
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Title
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EARLY POSTNATAL DEVELOPMENT OF RETINOGENICULATE TERMINATION PATTERNS IN MONKEYS.
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Identifier
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AAI8319771
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identifier
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8319771
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Creator
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HOLSTEIN, GAY ROBBINS.
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Contributor
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Pedro Pasik
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Date
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1983
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Language
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English
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Publisher
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City University of New York.
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Subject
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Psychology, Physiological
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Abstract
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The purpose of this investigation was to provide normative morphologic data on primate visual system development. A quantitative stereologic analysis was used to characterize the ontogenetic sequence in the retinogeniculate pathway.;Profiles of retinal boutons and their synapses in magnocellular lamina 1 (L1) and parvocellular lamina 6 (L6) of the dorsal lateral geniculate nucleus were measured in randomized electron micrographs of newborn, 1-, 2-, 4-, 8-, and 17-week-old rhesus monkeys. Using a stereologic procedure, distributions of spherical boutons and flat circular contact disk diameters were reconstructed from areal measurements of retinal profiles and length measurements of contacts identified in 1600-3700 um('2) of tissue from each age-lamina condition. These distributions were used to calculate mean bouton diameter, bouton density, mean synaptic and nonsynaptic contact areas, and synaptic and nonsynaptic densities. The density values were then adjusted for laminar growth to yield estimates of total numbers of boutons and synapses.;Retinal bouton size tends to increase during maturation and mean bouton diameter is significantly larger in L1 than in L6 of younger animals. Bouton density and number decrease during development in both regions, but are consistently higher in L6 than L1.;In magnocellular laminae, retinal (R) to principal cell dendrite (P) synapse number decreases during ontogeny, particularly in the older animals studied. Immature R to P elements decline almost monotonically, while the mature population shows no consistent trend. The number of R to interneuron dendrite (I) synapses, as well as nonsynaptic R to P contacts, changes little during development.;In parvocellular layers, R to P synapse number decreases during maturation; the greatest loss occurs in the mature population, although immature elements also decline. In these laminae, synapse elimination is predominant in younger animals. Although the number of R to I synapses remains stable, the number of nonsynaptic contacts increases dramatically.;Substantial bouton recession and synapse elimination occur at different rates in magnocellular and parvocellular pathways during early maturation. These alterations may be the consequence of early visual experience during which unutilized connections are eliminated.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Psychology
