Olfaction in Canines - fMRI Study in Fully Unrestrained Awake Dogs
Type of DegreeMaster's Thesis
Electrical and Computer Engineering
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For decades various attempts in vivo and in vitro have been made to explore the anatomical and physiological aspects of the olfactory system in canines and the ways to enhance it. Multiple studies have also attempted to understand the effects of odor detection training in canines. The current Thesis is aimed at further understanding the ways to improve the existing detection capability of the canines. In an attempt to achieve this, we first have shown that Zinc nanoparticles up-regulated directional brain connectivity in parts of the canine olfactory network. This provides a mechanistic explanation for previously reported enhancement in the olfaction capability of the dogs in the presence of zinc nanoparticles. In this study, we obtained fMRI data from awake and unrestrained dogs while they were being exposed to odorants with and without zinc nanoparticles, zinc nanoparticles suspended in water vapor and just the water vapor. We have then obtained the directional connectivity of the paths between the brain regions of olfactory network that were significantly stronger for the condition of Odorant + zinc nanoparticles compared to just odorant, water vapor + zinc nanoparticles, water vapor. From the results, we observe significant strengthening of the paths which indicates that zinc nanoparticles can indeed be a solution to improve the efficiency of canine detection capability in the realtime environments where the odorant concentrations are very low and would have otherwise been undetected. Then we attempt to explore the effectiveness of the odor detection training on the canines and also the possibilities to improvise the training regime if needed, all the while being able to distinguish a good detector dog from the rest. For this we study the longitudinal changes in the neuronal activity and behavior of canines resulted due to the detection training instead of the cross-sectional results. The behavioral traits and the fMRI data were obtained at three different timepoints of before the detections training(TP1), immediately after(TP2) and few months after the training(TP3) has been completed in the presence of discriminative and non discriminative odors from the dogs. We hypothesized that the neuronal activity and the behavioral scores significantly varied in correlation from TP1 to TP2 and be maintained same from TP2 to TP3. Further we have explored if the neuronal activity in the olfactory network at TP1 could be used to predict if a dog could be a successful detection dog.