Olfactory associative learning in Caenorhabditis elegans is impaired in lrn-1 and lrn-2 mutants

The C. elegans mutants, lrn-1 and lrn-2, are impaired in associative learni ng using conditioned taste cues. Both mutants are defective in associative learning about appetitive and aversive events, indicating that lrn-1 and lr n-2 exert effects across motivational boundaries. In a new olfactory associ ative learning paradigm, in which wild type worms learn to avoid a previous ly attractive diacetyl odor after it has been paired with an aversive aceti c acid solution, lrn-1 and lrn-2 are impaired. Although defective in associ ative learning using a conditioned olfactory cue, nonassociative learning ( habituation and dishabituation) using this same olfactory cue is unaffected . The discovery that lrn-1 and lrn-2 are defective in associative learning with both taste and olfactory cues may suggest that associative learning in different sensory modalities converges on a common genetic pathway in C. e legans that is subserved by lrn-1 and lrn-2.