Does conditioned taste aversion learning in the pond snail Lymnaea stagnalis produce conditioned fear?

Serina Kita, Ryuji Hashiba, Saya Ueki, Yukari Kimoto, Yoshito Abe, Yuta Gotoda, Ryoko Suzuki, Eriko Uraki, Naohisa Nara, Akira Kanazawa, Dai Hatakeyama, Ryo Kawai, Yutaka Fujito, Ken Lukowiak, Etsuro Ito*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


In conditioned taste aversion (CTA) training performed on the pond snail Lymnaea stagnalis, a stimulus (the conditional stimulus, CS; e.g., sucrose) that elicits a feeding response is paired with an aversive stimulus (the unconditional stimulus, US) that elicits the whole-body withdrawal response and inhibits feeding. After CTA training and memory formation, the CS no longer elicits feeding. We hypothesize that one reason for this result is that after CTA training the CS now elicits a fear response. Consistent with this hypothesis, we predict the CS will cause (1) the heart to skip a beat and (2) a significant change in the heart rate. Such changes are seen in mammalian preparations exposed to fearful stimuli. We found that in snails exhibiting long-term memory for one-trial CTA (i.e., good learners) the CS significantly increased the probability of a skipped heartbeat, but did not significantly change the heart rate. The probability of a skipped heartbeat was unaltered in control snails given backward conditioning (US followed by CS) or in snails that did not acquire associative learning (i.e., poor learners) after the one-trial CTA training. These results suggest that as a consequence of acquiring CTA, the CS evokes conditioned fear in the conditioned snails, as evidenced by a change in the nervous system control of cardiac activity.

Original languageEnglish
Pages (from-to)71-81
Number of pages11
JournalBiological Bulletin
Issue number1
Publication statusPublished - 2011 Feb
Externally publishedYes

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)


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