View Program - 63rd Annual Drosophila Research Conference

Fruit flies, and other animals, can navigate in a complex chemosensory environment. Certain odors can act as signals for food, danger, or as pheromones released by conspecifics to elicit innate behavioral responses. Since not all odor stimuli are informative, the brain must make sense of the complexity of the odor signals and interrupt their actual relevance. Fruit flies perceive odors through olfactory sensory neurons that are located in the sensilla on the third antennal segments and the maxillary palps, which exhibit diverse morphological types. The olfactory system of Drosophila resembles systems found in vertebrates in its overall anatomical organization but is significantly reduced in terms of cell number, which makes it an ideal model system to investigate odor processing in the brain. Associative learning represents one process by which new or altered relevance is assigned to a stimulus through experience. For example, an odor that is repetitively paired with a food reward becomes attractive while an odor that often occurs simultaneously with a punishment becomes a predictor for a negative situation and will be avoided in the future. Drosophila melanogaster can easily perform such learning and memory tasks and represents an excellent organism to investigate the neuronal mechanisms that control olfactory learning processes. In this work, we identify phenotypic variations based on learning and memory abilities among different recombinant inbred lines (RILS) in a mapping population. Operant conditioning is induced by presenting an odor with or without the availability of a sucrose reward to condition odors as positive (sugar associated) or negative stimulus. During the testing phase, the Drosophila are simultaneously presented with the previously conditioned CS+ and CS- odors. After sufficient time has passed, fly distribution is recorded to allow for associative appetitive conditioning to be reliably measured without bias due to innate preferences. Various control experiments are also done to test whether all genotypes respond normally to odor and light alone. Learning and memory tasks are tested using a custom-built Y-maze apparatus. After repeating Y-maze testing three times, we identified high and low learning phenotype groups and high and low memory phenotype groups.

Utilizing Y-mazes to Investigate Olfactory Learning Phenotypic Variations in Drosophila