Another Example of Conditioned Taste Aversion: Case of Snails

• Published in: Biology (Basel, Switzerland) Vol. 9; no. 12; p. 422
• Main Authors: Nakai, Junko, Totani, Yuki, Hatakeyama, Dai, Dyakonova, Varvara E., Ito, Etsuro
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 26.11.2020; MDPI
• Subjects: Animal behavior; Animal models; Conditioned stimulus; conditioned taste aversion; extinction; Extinction behavior; Food; Gastropoda; humans; insulin; Interstimulus interval; Invertebrates; Learning; Long term memory; long-delay learning; Lymnaea stagnalis; Mammals; memory; Nausea; Potassium chloride; probability; Protein synthesis; Review; selective associability; single-trial learning; snails; Sucrose; Sweet taste; taste; Taste aversion; Trace conditioning; Unconditioned stimulus; Lymnaea stagnalis; conditioned taste aversion; insulin; long-delay learning; single-trial learning; selective associability
• DOI: 10.3390/biology9120422
• ISSN: 2079-7737

Conditioned taste aversion (CTA) in mammals has several specific characteristics: (1) emergence of a negative symptom in subjects due to selective association with a taste-related stimulus, (2) robust long-term memory that is resistant to extinction induced by repeated presentation of the conditioned stimulus (CS), (3) a very-long-delay presentation of the unconditioned stimulus (US), and (4) single-trial learning. The pond snail, Lymnaea stagnalis, can also form a CTA. Although the negative symptoms, like nausea, in humans cannot be easily observed in invertebrate animal models of CTA, all the other characteristics of CTA seem to be present in snails. Selective associability was confirmed using a sweet sucrose solution and a bitter KCl solution. Once snails form a CTA, repeated presentation of the CS does not extinguish the CTA. A long interstimulus interval between the CS and US, like in trace conditioning, still results in the formation of a CTA in snails. Lastly, even single-trial learning has been demonstrated with a certain probability. In the present review, we compare, in detail, CTA in mammals and snails, and discuss the possible molecular events in CTA.