The mammalian olfactory bulb: A comparative analysis.
Item
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Title
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The mammalian olfactory bulb: A comparative analysis.
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Identifier
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AAI9417504
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identifier
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9417504
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Creator
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Sawitzke, Sharon L.
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Contributor
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Advisers: Warren J. Kinzey | Ilya I. Glezer
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Date
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1994
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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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Anthropology, Physical | Biology, Anatomy | Biology, Neuroscience
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Abstract
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Traditionally, the size of the olfactory bulb has been directly related to the functional ability of the olfactory system. The catarrhine primates, because of their small olfactory bulbs (microsmatic), have been assumed to have a regressive olfactory system with reduced olfactory function. Behavioral studies within the last two decades have refuted the belief that olfactory function in these primates is minimal. The goal of this study was to evaluate the olfactory bulb of several mammalian species to determine if additional features corroborate the belief that olfactory system function is correlated with bulb size.;Two species of Macaca (M. mulatta and M. fascicularis) and four macrosmatic mammals (cat, rabbit, squirrel, and rat) were analyzed for bulb morphology, density of cells, and volume of those layers comprising the bulb.;Data showed that the only feature that could be construed as indicating decreased functional ability of catarrhine primates was reduced bulb size relative to brain size. In all other features the olfactory bulb in Macaca was comparable to the bulbs of the four macrosmatic mammals. One result, suggestive of the change that has occurred within the evolution of the neocortex, may indicate an improvement in the processing of information: the ratio of interneurons to identified second order neurons was increased in Macaca. One factor invalidates olfactory bulb size as an indicator of functional ability. Small olfactory bulbs (rat and Macaca) lack an olfactory ventricle and have a small subventricular layer, a layer of nonsynaptic, immature neurons. In larger bulbs, part of the volume which contributes to large size is the enlargement of the subventricular layer and the presence of an olfactory ventricle. This indicates that a larger portion of the bulb of Macaca and the rat is concerned with processing information than is found in larger olfactory bulbs.;In conclusion, the morphology of the olfactory bulb of the supposedly microsmatic catarrhine primate (Macaca) does not provide any evidence for reduced function in the olfactory system. At least one feature is strongly suggestive of a more highly developed mechanism for processing information within the bulb.
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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.
