FUNCTIONAL CORRELATES OF THE ONTOGENY OF CEREBRAL LATERALITY IN THE RAT.
Item
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Title
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FUNCTIONAL CORRELATES OF THE ONTOGENY OF CEREBRAL LATERALITY IN THE RAT.
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Identifier
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AAI8203320
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identifier
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8203320
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Creator
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ROSS, DAVID ALAN.
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Contributor
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Dr. Stanley D. Glick
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Date
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1981
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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, Psychobiology
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Abstract
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Cerebral lateral asymmetry was once believed to be a unique attribute of humans but can no longer be considered as such. An ever increasing body of knowledge clearly indicates that the brains of normal animals are lateralized and that this lateralization is oftentimes manifest behaviorally. Thus, it has been shown that spontaneous side preferences and nocturnal and amphetamine-induced rotation are related to an intrinsic asymmetry in dopamine content, metabolism, and dopamine-stimulated adenylate cyclase activity in the corpus striatum of rats. In addition it has been demonstrated that rats have asymmetries in self-stimulation thresholds that are also related to rotation. Moreover, it has recently been shown that there exist asymmetries in 2-deoxy-D-glucose (dGlc) incorporation in several regions of the adult rat brain. This thesis documents asymmetries in dGlc incorporation in the neonatal rat, demonstrating that such asymmetries are present at birth, change during development and are sexually dimorphic.;Studies were initially performed to evaluate the suitability of a modification of the dGlc technique: it was shown that using this modification data are obtainable which are qualitatively and quantitatively similar to those obtained using less convenient methodology; dGlc uptake data were shown to be highly correlated with glucose utilization values. The developmental time course of dGlc phosphorylation was shown to reach a plateau by postnatal day thirty. Percent uptake data were obtained in seven brain regions for animals between zero and one hundred days old and demonstrated to have different characteristics in male and female rats. Relative brain dGlc activity was also calculated for seven brain regions and was related to changes in left-right asymmetry of each region, respectively: a significant inverse correlation between left-right asymmetry and relative activity was obtained indicating that as a region of the brain becomes more active, its asymmetry tends to be right-biased and vice versa.;Significant relationships between asymmetry and the age of the animals were also demonstrated: in females left-right asymmetry was positively correlated with age in hippocampus and diencephalon and negatively correlated with age in brainstem and midbrain indicative of right-to-left and left-to-right gradients, respectively. The only such significant relationship in males was a right-to-left gradient in midbrain. Absolute asymmetry of the caudate was also shown to decrease significantly with age.;An asymmetry in neonatal tail posture was identified and was shown to predict adult side preference in a rotometer. Neonatal females had right biased tails; this effect was significant. There was a nonsignificant trend for the tails of the males to be directed toward the left. The asymmetry in female neonatal tail posture was also shown to be inversely correlated with the number of males in each litter--suggesting a possible relationship between hormonal status prenatally and asymmetries observed at a later time.;The results of this study clearly establish that normal rats have asymmetries in tail posture and dGlc incorporation that are observable at birth and which change during development. These side-to-side differences in dGlc incorporation were observed within individual animals and are, therefore, most likely attributable to intrinsic lateralization in cerebral glucose uptake and not reflective of other factors, such as plasma glucose, that would affect dGlc incorporation equally on the two sides of the brain. The data were discussed in relation to the origins of cerebral lateralization and the differences in such lateralization between the sexes. Additionally, theories on the etiology of developmental disorders of cognition and of psychiatric disease were related to possible mechanisms involving altered cerebral dominance.
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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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Biomedical Sciences
