Dept of Genetics, University of Cambridge, Downing St, Cambridge, CB2 3EH, UK. (E-mail cjch@mole.cam.ac.uk).,
We have been studying a non-associative learning paradigm in Drosophila melanogaster, the habituation of the proboscis extension reflex. In the proboscis extension assay, when a starved, water-satiated fly has sucrose applied to one foot it responds by extending its proboscis. In wild type flies this reflex shows habituation. The application of a strong sucrose solution to one foot will depress the response through the contralateral foot for at least ten minutes. We have modified the protocol of Duerr and Quinn to include a vortexing step as a dishabituation stimulus. We have also studied how the habituation decays with time. We have also identified GAL4 lines that express in specific regions of the central brain eg. mushroom bodies, fan-shaped body and ellipsoid body. We are currently expressing tetanus toxin light chain (TeTxLC) in these regions of the fly brain, using the GAL4 system. TeTxLC has been shown to block synaptic transmission. By testing the behaviour of the resulting flies, we hope to determine the role each brain region plays in habituation. Once important regions have been identified, we plan to investigate the role of G-protein modulated signalling pathways in non-associative learning.