Does Conditioned Taste Aversion Learning in the Pond Snail Lymnaea stagnalis Produce Conditioned Fear?
Does Conditioned Taste Aversion Learning in the Pond Snail Lymnaea stagnalis Produce Conditioned Fear?
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DOI：
10.1086/bblv220n1p71
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发表时间：
2011-02-01
影响因子：
1.6
通讯作者：
Ito, Etsuro
中科院分区：
文献类型：
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作者：
Kita, Serina;Hashiba, Ryuji;Ito, Etsuro
在对池塘蜗牛进行的条件性味觉厌恶(CTA)训练中，引起摄食反应的条件刺激(条件刺激CS；例如蔗糖)与引起全身撤退反应并抑制摄食的厌恶刺激(无条件刺激US)配对。在CTA训练和记忆形成后，CS不再引起摄食。我们假设这一结果的原因之一是，在CTA训练之后，CS现在引起了恐惧反应。与这一假设一致，我们预测CS将导致(1)心脏跳过一次跳动，(2)心率显著改变。这种变化在暴露在可怕刺激下的哺乳动物的准备中可以看到。我们发现，在表现出一次尝试CTA的长期记忆的蜗牛(即，优秀的学习者)中，CS显著增加了心跳跳过的可能性，但没有显著改变心率。在给予后向条件反射(US和CS)的对照组蜗牛或在一次尝试CTA训练后没有获得联想学习的蜗牛(即，糟糕的学习者)中，心跳跳过的概率没有改变。这些结果表明，作为获得CTA的结果，CS在条件化的蜗牛中唤起了条件性恐惧，这一点从神经系统对心脏活动的控制发生了变化来证明。
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.