Morpho-functional properties of interneurons born at different developmental stages in the adult olfactory bulb

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The olfactory system is one of the oldest sensory modalities and is essential for the survival of many animal species. Olfaction provides vital information about food location and influences social and sexual behaviors. In mammals, the odors are perceived by the olfactory sensory neurons contained within olfactory epithelium. The sensory information is then transferred into the olfactory bulb where it is processed by the bulbar principal cells and interneurons. In the olfactory bulb the population of interneurons largely outnumbers the principal cells by the ratio 100:1 and remarkably, olfactory bulb retains a capacity to renew its neuronal population throughout the life span of animal. The morpho-functional properties of new neurons as well as cells born during early postnatal life remain still elusive. In addition, it is not clear how these cells respond to sensory stimulation and what are their functional and structural modifications in response to odor stimulation. Finally, the role of principall cells in the maturation and integration of cells born at different developmental stages remains completely unclear. We propose the series of experiments aiming at investigation of functional role of neurons born at different developmental periods in the olfactory bulb. By using morphological and electrophysiological recordings, combined with optogenetic stimulation we will test the hypothesis that neurons born in the adulthood bring to the neuronal circuitry properties that cannot be fulfilled by pre-existing population of interneurons. In addition, we will use powerful combination of in vivo intrinsic optical signal (IOS) imaging following odor stimulation, two-photon time-lapse imaging of structural and functional properties of adult-born and early-born interneurons to understand the implications of these cells in the bulbar circuitry. Overall these experiments will allow us to understand why and how the adult brain produces and incorporates new neurons into already existing, functioning circuits of the olfactory bulb.