Sensory perception is the fundamental process by which all organisms gain knowledge of their world. Perceptions arise from stimulations of sensory receptors that are translated into neuronal signals. These signals become processed and refined greatly before reaching conscious awareness in higher brain areas. Understanding the mechanisms and functions of this processing is a significant and major challenge for science. The use of model systems, such as the mammalian olfactory system, is helpful in this task due to simplified circuit organizations relative to other sensory systems. This dissertation aims to address three critical questions in olfactory processing.
• First, odor sampling is fundamentally linked with respiration in mammals. Yet very little is known about the network activities and synaptic and circuit processing that result from respiration. Does respiration drive network activity and actively refine sensory representations in the olfactory system?
• Second, olfactory circuits are organized, as in many sensory systems, within columns. However, it is not known if olfactory columns interact or are individual processing elements. Do olfactory columns interact combinatorially or in an organized manner?
• Finally, when olfactory processing is impaired, either by age or disease, great risks to humans can result. Can we use animal model systems to recapitulate olfactory processing impairments found in humans from aging and Alzheimer's disease?
In this dissertation physiological, anatomical and behavioral measurements of sensory processing within olfactory circuits at the synaptic, neuronal, circuit, network and behavioral levels will be presented. The results demonstrate that respiration is an active process which generates network activity and refines sensory representations through functionally distinct circuits; that olfactory columns are not separate parallel processing structures, but interact non-stochastically; and finally, that the evolutionary time course of sensory and cognitive processing abilities must be carefully measured in animal models of Alzheimer's disease to distinguish between ageing and disease-related impairments.
|Advisor:||Shepherd, Gordon M.|
|Commitee:||Barrett, Sean, Greer, Charles, Mazer, James, Mochrie, Simon|
|School Location:||United States -- Connecticut|
|Source:||DAI-B 74/05(E), Dissertation Abstracts International|
|Keywords:||Circuits networks, Lateral inhibition, Olfaction, Olfactory bulb, Sensory processing, Synaptic inputs|
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