title: Genetic dissection of memory for associative and non-associative learning in Caenorhabditis elegans.
abstract: The distinction between non-associative and associative forms of learning has historically been based on the behavioral training paradigm. Through discovering the molecular mechanisms that mediate learning, we can develop a deeper understanding of the relationships between different forms of learning. Here, we genetically dissect short- and long-term memory for a non-associative form of learning, habituation and an associative form of learning, context conditioning for habituation, in the nematode Caenorhabditis elegans. In short-term chemosensory context conditioning for habituation, worms trained and tested in the presence of either a taste (sodium acetate) or smell (diacetyl) context cue show greater retention of habituation to tap stimuli when compared with animals trained and tested without a salient cue. Long-term memory for olfactory context conditioning was observed 24 h after a training procedure that does not normally induce 24 h memory. Like long-term habituation, this long-term memory was dependent on the transcription factor cyclic AMP-response element-binding protein. Worms with mutations in glr-1 [a non-N-methyl-d-aspartate (NMDA)-type glutamate receptor subunit] showed short-term but not long-term habituation or short- or long-term context conditioning. Worms with mutations in nmr-1 (an NMDA-receptor subunit) showed normal short- and long-term memory for habituation but did not show either short- or long-term context conditioning. Rescue of nmr-1 in the RIM interneurons rescued short- and long-term olfactory context conditioning leading to the hypothesis that these interneurons function to integrate information from chemosensory and mechanosensory systems for associative learning.
authors.affiliation: Department of Psychology; Brain Research Centre, University of British Columbia, Vancouver, BC, V6T 2B5, Canada.
authors.forename: H L
authors.initials: HL
authors.lastname: Lau
authors.forename: T A
authors.initials: TA
authors.lastname: Timbers
authors.forename: R
authors.initials: R
authors.lastname: Mahmoud
authors.forename: C H
authors.initials: CH
authors.lastname: Rankin
mesh_terms: D000818:Animals; D001245:Association Learning; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D003213:Conditioning, Psychological; D003463:Cues; D006185:Habituation, Psychophysiologic / Q000235:genetics; D007395:Interneurons / Q000378:metabolism; D057567:Memory, Long-Term; D008570:Memory, Short-Term; D009154:Mutation; D018091:Receptors, AMPA / Q000235:genetics; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics; D012903:Smell; D013649:Taste; D014157:Transcription Factors / Q000235:genetics
chemical_list: C556191:CRH-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; C436186:NMR-1 protein, C elegans; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; D014157:Transcription Factors; C096470:glr-1 protein, C elegans