What's hot: the enhancing effects of thermal stress on long-term memory formation in Lymnaea stagnalis

The cellular basis of long-term memory (LTM) storage is not completely known. We have developed a preparation where we are able to specify that a single identified neuron, Right Pedal Dorsal 1 (RPeD1), is a site of LTM formation of associative learning in the pond snail, Lymnaea stagnalis. We demonstrated this by ablating the soma of the neuron but leaving behind its functional primary neurite, as evidenced by electrophysiological and behavioral analyses. The soma-less RPeD1 neurite continues to be a necessary participant in the mediation of aerial respiratory behavior, associative learning, and intermediate-term memory (ITM); however, LTM cannot be formed. However, if RPeD1's soma is ablated after LTM consolidation has occurred, LTM can still be accessed. Thus the soma of RPeD1 is a site of LTM formation.

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In Lymnaea two stressors that individually enhance memory in combination block memory formation

Canadian Journal of Zoology ◽

10.1139/cjz-2020-0207 ◽

2021 ◽

Author(s):

Romina Soudavari ◽

Anuradha Batabyal ◽

K. Lukowiak

Keyword(s):

Natural Environment ◽

Room Temperature ◽

Lymnaea Stagnalis ◽

Memory Formation ◽

Adaptive Behaviour ◽

Long Term Memory ◽

Term Memory

Stress plays an important role in memory formation in Lymnaea stagnalis (Linnaeus 1758). Individual stressors have been shown to enhance or perturb long-term memory (LTM) formation. However, when snails perceive a combination of two stressors it is unclear the outcome as regards LTM formation. Here we first show that when snails are exposed individually to either a predator stressor, crayfish effluent, (CE) a kairomone; or a thermal stressor (30°C) LTM formation is enhanced. In their natural environment Lymnaea may experience temperatures approaching 30°C and they may encounter crayfish at the same time. How such a combination of stressors alters adaptive behaviour is unknown. Here we show that when these two stressors are combined, LTM formation is blocked. Since boiling CE inactivates the kairomone, we used previously boiled CE and combined it with the thermal stressor, and found that LTM formation is again enhanced. These data show that; 1) It cannot accurately be predicted how a combination of stressors when combined interact to alter LTM formation; and 2) There is something different with hot-CE compared to room temperature CE.

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De Novo Protein Synthesis of Syntaxin-1 and Dynamin-1 in Long-Term Memory Formation Requires CREB1 Gene Transcription in Lymnaea stagnalis

Behavior Genetics ◽

10.1007/s10519-010-9374-9 ◽

2010 ◽

Vol 40 (5) ◽

pp. 680-693 ◽

Cited By ~ 20

Author(s):

Cong-Hui Guo ◽

Anthony Senzel ◽

Kathy Li ◽

Zhong-Ping Feng

Keyword(s):

Protein Synthesis ◽

Gene Transcription ◽

Lymnaea Stagnalis ◽

De Novo ◽

Memory Formation ◽

Long Term Memory ◽

Term Memory ◽

De Novo Protein Synthesis

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Long term memory of configural learning is enhanced via CREB upregulation by the flavonoid Quercetin in Lymnaea stagnalis

Journal of Experimental Biology ◽

10.1242/jeb.242761 ◽

2021 ◽

Author(s):

Anuradha Batabyal ◽

Veronica Rivi ◽

Cristina Benatti ◽

Johanna MC Blom ◽

Ken Lukowiak

Keyword(s):

Heat Stress ◽

Lymnaea Stagnalis ◽

Memory Formation ◽

Long Term Memory ◽

Pond Snail ◽

Mrna Levels ◽

Term Memory ◽

Configural Learning ◽

Flavonoid Quercetin

Animals respond to acute stressors by modifying their behaviour and physiology. The pond snail Lymnaea stagnalis exhibits configural learning (CL), a form of higher order associative learning. In CL snails develop a landscape of fear when they experience a predatory cue along with a taste of food. This experience results in a suppression of the food response; but the memory only persists for 3h. Lymnaea has been also found to upregulate heat shock proteins (HSPs) as a result of acute heat stress that leads to the enhancement of memory formation. A plant flavonoid quercetin blocks the upregulation of HSPs when experienced prior to heat stress. Here we used this blocking mechanism to test the hypothesis that HSP upregulation played a critical role in CL. Snails experienced quercetin prior to CL training and surprisingly instead of blocking memory formation it enhanced the memory such that it now persisted for at least 24h. Quercetin exposure both prior to or post CL enhanced long-term memory (LTM) up to 48h. We quantified CREB1 mRNA levels in the Lymnaea central nervous system following quercetin and found LymCREB1 to be upregulated following quercetin exposure. The enhanced LTM phenotype in L. stagnalis was most pronounced when quercetin was experienced during the consolidation phase. Additionally, quercetin exposure during the memory reconsolidation phase also led to memory enhancement. Thus, we found no support of our original hypothesis but found that quercetin exposure upregulated LymCREB1 leading to LTM formation for CL.

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