UBC Theses and Dissertations
Modulation of habituation kinetics and behavioural shifts by members of the heterotrimeric G-protein signaling pathways McEwan, Andrea
Despite its apparent simplicity, the soil-dwelling nematode Caenorhabditis elegans has a surprisingly large capacity to learn and remember. Previous characterization of C. elegans genome and neuronal circuit makes this worm an ideal choice for studying behavior and the mechanisms that underlie it. Through careful behavioral and genetic studies, nematodes have been shown to form many different types of memory, including short-term non-associative memory called habituation. Habituation is the defined as the decrement in response after repeated, irrelevant stimuli. In the first part of this thesis, detailed analyses showed that as one response type, reversals, decreased other responses, accelerations, decelerations and pauses became more prevalent. An earlier large-scale screen of mutant strains of C.elegans showed that several genes related to heterotrimeric G-protein family of signaling pathways exhibited striking defects in habituation. To follow-up on those findings, in the second part of my thesis I investigated the role of heterotrimeric G-protein signaling pathway and showed that Gαi and Gαq signaling pathways share a broad role regulating habituation whereas the Gαs pathway modulates the rate of habituation. The analyses of all the behaviours nematodes preform in response to habituation training showed that heterotrimeric G-protein signaling pathways play a role in regulating the shift in behaviour during habituation training. Together these data add to our understanding of the mechanisms underlying habituation of the tap response in C. elegans.
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