An automated learning apparatus for classical conditioning of Lymnaea stagnalis

The European Zoological Journal

Oike

2017

In the present review, we outline the relationship between starvation and taste-aversive learning (conditioned taste aversion: CTA) in the pond snail Lymnaea stagnalis and introduce the "necessity knows no law" concept. When snails were fooddeprived for a short period, the snails learned and formed memory of CTA well, whereas when snails were food-deprived for a prolonged period, the snails appeared not to learn CTA or form long-term memory (LTM) of it. However, in severely food-deprived snails (i.e. snails that were food-deprived for a prolonged period), memory was found to indeed form but was overpowered by the effect of severe food deprivation. That is, snails are partially restricted in the "necessity knows no law" concept. Moreover, this CTA-LTM was context dependent and was observed only when the snails were in a context similar to that in which the training occurred. In addition, when insulin was injected into the severely food-deprived snails, they started to exhibit learning and memory. That is, insulin rescued the snails' "hidden" ability of memory retrieval. In addition to these topics in snails, we survey the literature on starvation and learning obtained in other animals for general discussion. We hope that this review will stimulate further detailed studies of motivation in invertebrates.

Section: Introductionmentioning

confidence: 99%

Necessity knows no law in a snail

Ito

The European Zoological Journal

Oike

2017

“…We used a de novo , automatic training apparatus that was developed at the Sakakibara laboratory of Tokai University (Takigami et al, 2016 ), with slight modifications. In this conditioning apparatus, the pond water, which was propelled by a water pump, constantly flowed on snails at a speed of 200 ml per min.…”

Section: Methodsmentioning

confidence: 99%

“…Recent studies at the Ito laboratory have used an automated learning apparatus for CTA (see “Materials and Methods” Section for its details; Takigami et al, 2016 ). We have obtained good results in Dutch snails using a 5-s presentation of a 100 mM sucrose (the concentration in the reservoir) as the CS and a 0.2-s presentation of a 9 V electric shock as the US.…”

Section: Introductionmentioning

confidence: 99%

Two Strains of Lymnaea stagnalis and the Progeny from Their Mating Display Differential Memory-Forming Ability on Associative Learning Tasks

Sunada

Front. Behav. Neurosci.

Nakamura

et al. 2017

Self Cite

The pond snail Lymnaea stagnalis learns and forms long-term memory (LTM) following both operant conditioning of aerial respiratory behavior and classical conditioning of taste aversive behavior. In the present study, we examined whether there are interstrain differences in the ability to form LTM following these two types of conditioning. A strain of Lymnaea (TC1) collected in Alberta, Canada exhibits superior memory-forming ability following aerial respiratory operant conditioning compared to a laboratory-reared strain of Lymnaea from Netherlands known as the Dutch strain. We asked whether the offspring of the Canadian TC1 and Dutch snails (i.e., filial 1 (F1) cross snails) would have the superior memory ability and found, rather, that their memory ability was average like the Dutch snails. That is, the Canadian TC1 snails have superior ability for LTM formation following aerial respiratory operant conditioning, but the Dutch and the generated F1 cross have average ability for memory forming. We next examined the Canadian TC1, Dutch and F1 cross snails for their ability to learn and form memory following conditioned taste aversion (CTA). All three populations showed similar associative CTA responses. However, both LTM formation and the ratio of good-to-poor performers in the memory retention test were much better in the Dutch snails than the Canadian TC1 and F1 cross snails. The memory abilities of the Canadian TC1 and F1 cross snails were average. Our present findings, therefore, suggest that snails of different strains have different memory abilities, and the F1 cross snails do not inherit the memory ability from the smart strain. To our knowledge, there have been a limited number of studies examining differences in memory ability among invertebrate strains, with the exception of studies using mutant flies.

“…We used an automatic training apparatus (Takigami et al, 2016;Sunada et al, 2017), with slight modifications (Totani et al, 2020). The main difference from the previous studies was the US used.…”

Section: Protocol Of Cta Trainingmentioning

confidence: 99%

Induction of LTM following an Insulin Injection

Nakai

Dyakonova

et al. 2020

eNeuro

Self Cite

The pond snail Lymnaea stagnalis learns conditioned taste aversion (CTA) and consolidates it into long-term memory (LTM). One-day food-deprived snails (Day 1 snails) show the best CTA learning and memory, whereas more severely food-deprived snails (5 days) do not express good memory. However, previous studies showed that CTA-LTM was indeed formed in 5-day food-deprived snails (Day 5 snails), but its recall was prevented by the effects of food deprivation. CTA-LTM recall in Day 5 snails was expressed following 7 days of feeding and then 1 day of food deprivation (Day 13 snails). In the present study, we thus hypothesized that memory recall occurs because Day13 snails are in an optimal internal state. One day of food deprivation before the memory test in Day 13 snails increased the mRNA level of molluscan insulin-related peptide (MIP) in the CNS. Thus, we further hypothesized that an injection of insulin into Day 5 snails following 7 additional days with access to food (Day 12 snails) activates CTA neurons and mimics the food deprivation state before the memory test in Day 13 snails. Day 12 snails injected with insulin could recall the memory. In addition, the simultaneous injection of an anti-insulin receptor antibody and insulin into Day 12 snails did not allow memory recall. Insulin injection also decreased the hemolymph glucose concentration. Together, the results suggest that an optimal internal state (i.e., a 6 spike in insulin release and specific glucose levels) are necessary for LTM recall following CTA training in snails.