Hung-Hsiang Yu｜ Institute of Cellular and Organismic Biology, Academia Sinica

Insect and mammalian olfactory systems share similar glomerular organizations and remarkable information processing ability to discriminate thousands of odors in the environment, which is crucial for animals to look for food, avoid predators and seek for mates. We utilize Drosophila as a model to investigate how the olfactory system is assembled during development. Olfactory sensory neurons (OSNs) expressing the same olfactory receptor project axons into one of 50 morphologically-identifiable glomeruli in the primary olfactory center of the brain, the antennal lobe (AL), where dendrites of distinct types of projection neurons (PN) synapse with corresponding OSN axons to relay odorant information to high-order olfactory centers, including the mushroom body (MB) and lateral horn (LH), for further odorant decoding (Figure 1). An accurate olfactory connectivity map endows the olfactory system with the sensitive, robust and accurate odor-processing ability, and generating such a map relies on precise interconnections between appropriate OSN axons and PN dendrites within AL glomeruli. Our first research goal is to determine cellular and molecular mechanisms underlying how Semaphorin-1a (Sema-1a), a transmembrane protein crucial for neurite guidance, regulates the generation of proper PN dendritic patterns (Figure 2). Besides the robust and reliable response to external stimuli, the olfactory system also needs to adjust its wiring capacity to adapt into a changing environment. MB neurons are ideal model neurons to study the dynamic process of olfactory system formation, particularly on (i) how MB neurons are specified into same and different types of neurons in the system; (ii) how MB neurons undergo remodeling to trim existing connections and re-establish new connections. Our second research goal is to determine how MB neuron development impacts the olfactory system formation (Figure 3).