To date, Drosophila has been the primary genetic model for the behavioural analysis of learning and memory. Several "learning" mutants have been described in Drosophila, yet all of the learning mutations isolated so far have only partial effects, and most have other pleiotropic effects that can make the discrimination of deficits in learning as opposed to in sensorimotor function difficult. We have chosen to assay for associative learning mutants in C. elegans based on the animal's excellent genetics, anatomy and hermaphroditic lifestyle. We have devised an associative learning paradigm based on the chemotactic properties of Na+ and Cl- ions. What we have been able to demonstrate is that, following conditioning, in which one ion is paired with E. coli for an hour, followed by a one hour presentation of the other ion alone, worms will significantly prefer the paired ion over the unpaired ion (80:20) when compared to naive animals that equally prefer both ions (50:50). The development of an associative learning assay in C. elegans offers the potential to isolate novel genes involved in learning and memory pathways and to describe any isolated mutations at a resolution previously unattainable. Through a screen of EMS generated mutants, we have isolated two mutant lines (lrn-1 and lrn-2) that are without associative learning but normal in tests of non-associative learning and sensorimotor performance.
Olfactory Associative Learning Paradigm
Copper Aversion Paradigm
PCR MappingPCR Mapping Strategy for learning mutants
Benzotaxis
Olfactory Habituation
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