UC San Diego

Recent studies suggest an intriguing role for the olfactory bulb as more than just a relay station from the nose to the brain. Rather, it is a place where the early processing of odor information can be modulated by experience, behavioral state and odor context, which in turn, affect olfactory perception. However, a comprehensive understanding of the plasticity which occurs within early stages of olfactory processing, such as in the olfactory bulb, is still lacking. The aim of my research is to better understand the role of experience in shaping the dynamics of odor representations by mitral cell ensembles in the awake olfactory bulb. Previously, the constraints of the conventional electrophysiological techniques made it difficult to reliably follow the activity of a neuronal population with single-cell resolution over more than a single day. However, using longitudinal two-photon calcium imaging of mitral cell activity, we are well poised to approach this question by studying mitral cell activity over the course of weeks to months.

In the research presented in my dissertation, we ask the following questions using two-photon calcium imaging: In the first chapter, we ask how plastic mitral cell odor representations are during passive odor experience, and further investigate how the behavioral state of the mouse affects this plasticity. In the second chapter, we ask what kind of changes occur in mitral cell odor representations during different types of learning. Results from these experiments aim to improve our understanding of how experiences shapes this early stage of olfactory processing and its relevance to the behavioral output in awake animals.