[
International Worm Meeting,
2015]
Sensory neurons perceive information from the environment, which affects animal's behavior. C. elegans is an excellent model organism for the study of neuronal circuits that regulate the behavior, because of its relatively simple nervous system. The animal can also learn and store memory of non-associative memory like habituation and associative memory of two environmental stimuli. We are interested in molecular mechanisms and cellular networks underlying the associative memory, and have developed protocols for induction of short-term and long-term olfactory appetitive memories, STM and LTM, respectively, in C. elegans. We used 1-nonanol, a weak, volatile aversive chemical to C. elegans, as a conditioned stimulus (CS) and potassium chloride (KCl), a strong attractive substance, as an unconditioned stimulus (US). We conditioned animals with massed and spaced trainings to induce STM and LTM, respectively. Young adult animals in a small plastic tube sealed the bottom with a 30 um-nylon mesh sheet were stimulated with 1-nonanol vapor in a beaker, and then with KCl solution. For the massed training, animals were repeatedly conditioned as described above eight times without an inter-trial interval (ITI) between the conditionings. For the spaced training, on the other hand, animals were conditioned in the similar way to the massed training with ITI, during which animals were rested on an NGM plate. Immediately or hours later after the conditioning, animals were analyzed by chemotaxis assay on an agar plate spotted with 1-nonanol. As results, the trained animals successfully learned and retained the memory for 6 hours by the massed training and for 48 hours after the spaced training. We have also examined whether the training induces CS-specific memory by using 2-nonanone as a CS, instead of 1-nonanol. After training with 2-nonanone and KCl, animals formed 2-nonanone-specific, but not 1-nonanol-specific, associative memory. These results demonstrate that the protocols can successfully induce associative STM and LTM in C. elegans. We are currently trying to elucidate neuronal circuits responsible for the learning and memory.