| Description |
My thesis aims at determining whether or not neural activity affects connectivity in the Drosophila melanogaster olfactory circuit. Specifically, I am testing whether sensory activity is required for Projection neurons and Kenyon cell morphology. Therefore, my primary and central question is: does sensory activity reduction increase or decrease the number of synapses between neurons, and does this affect cellular morphology in Drosophila? There are more than 60 types of olfactory receptors within the sensory circuit18. Each sensory neuron that expresses the same type of olfactory receptor sends their axons to a specific type of projection neuron. These projection neurons send their axons to the secondary olfactory center, the calyx of the mushroom body. In the calyx, these projection neurons form presynaptic boutons, which are wrapped by postsynaptic claws of multiple Kenyon cells. Kenyon cells project to the mushroom body lobe, where they synapse with efferent neurons that produce a learned response to specific odors. In order to ablate olfactory receptors, we use knockout flies of Orco -/-, which is a gene required to form 80% of the olfactory receptor complexes4,15. My work focused on the presynaptic and postsynaptic connections between projection neurons and Kenyon cells. I examined if there are changes in the presynaptic sites of projection neurons and changes in postsynaptic sites in Kenyon cells in Orco -/- mutants, who are insensitive to many types of odors. To visualize presynaptic sites, I studied projection neurons in control flies and Orco -/- mutants using photoactivatable GFP, and the number of presynaptic sites were quantified. To analyze postsynaptic sites, I looked at data for both the control and Orco -/- knockout flies, comparing the number of Kenyon cells in each to determine if there is a change in the odor-insensitive flies. The results of this study show that through comparing control and Orco -/- fly Kenyon cell types, there is no significant difference between genotypes, implying that it is not the Orco that accounts for synaptic plasticity. We can now focus on other genes to knockout in order to continue to study how it affects olfactory synaptic plasticity referring to Kenyon cell claw numbers. |
