title: Two forms of learning following training to a single odorant in Caenorhabditis elegans AWC neurons.
abstract: The nematode Caenorhabditis elegans can adapt to both the AWC-sensed odorants benzaldehyde (Bnz) and isoamyl alcohol (IsoA) and can reciprocally cross-adapt. Yet we reveal that these four adaptation scenarios actually represent two distinct forms of learning: nonassociative habituation and associative learning by pairing with a starvation unconditioned stimulus. Training to the single odorant IsoA leads to both associative and nonassociative memory traces, which can be preferentially accessed by either a Bnz or IsoA retrieval stimulus, respectively. This represents the first demonstration in which the form of learning displayed after training to a single stimulus is a function of the retrieval stimulus used. Furthermore, these two forms of learning can be genetically double dissociated despite both forms occurring within the AWC primary sensory neuron. We find that associative learning requires the cGMP-dependent kinase egl-4 and insulin signaling, which acts downstream of egl-4. In contrast, nonassociative learning requires neither of these genes, but does require the TRPV channel osm-9, which is dispensable for associative learning. In addition, we find that the arrestin arr-1 is promiscuous between associative and nonassociative learning in mediating the adaptive response to the IsoA retrieval stimulus, suggesting that distinct forms of memory may nonetheless use common downstream effectors.
authors: Department of Molecular Genetics, Faculty of Medicine, and The Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada.
authors: Schreiber
authors: S
authors: Pereira
authors: Derek
authors: D
authors: van der Kooy
mesh_terms: D000222:Adaptation, Physiological; D000704:Analysis of Variance; D000818:Animals; D030801:Animals, Genetically Modified; D019393:Arrestin / Q000235:genetics / Q000378:metabolism; D001245:Association Learning / Q000187:drug effects / Q000502:physiology*; D001547:Benzaldehydes / Q000008:administration & dosage; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D003214:Conditioning, Classical / Q000502:physiology*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D005508:Food Deprivation; D007328:Insulin / Q000008:administration & dosage; D018613:Microscopy, Confocal; D009474:Neurons / Q000502:physiology*; D009812:Odorants; D009833:Olfactory Pathways / Q000166:cytology*; D000439:Pentanols / Q000008:administration & dosage; D011930:Reaction Time / Q000235:genetics; D012701:Serotonin / Q000494:pharmacology; D015398:Signal Transduction / Q000235:genetics; D012903:Smell / Q000235:genetics / Q000502:physiology*; D013395:Sucrose / Q000494:pharmacology
chemical_list: D019393:Arrestin; D001547:Benzaldehydes; D029742:Caenorhabditis elegans Proteins; D007328:Insulin; D000439:Pentanols; D012701:Serotonin; D013395:Sucrose; C029683:isopentyl alcohol; D017869:Cyclic GMP-Dependent Protein Kinases; C470349:EGL-4 protein, C elegans; C032175:benzaldehyde