The temperature sensitivity of memory formation and persistence is altered by cold acclimation in a pond snail

There are reports on the inability of inbred, laboratory-reared Lymnaea stagnalis to perform feeding and aerial respiration in the cold. It has also been suggested that laboratory-bred snails have an inability to perform aerial respiration in winter months in the laboratory. Here, we used an inbred, laboratory-reared strain of Lymnaea (the S-strain) to demonstrate that the snails are capable of performing those behaviours in a cold (4°C) environment after a 2 day acclimation period. In addition, the inbred snails were able to perform aerial respiration during winter months at room temperature (20°C) in the laboratory. The persistence of long-term memory (LTM) was extended for at least 4 weeks by placing S-strain snails into a 4°C environment following training. Typically, the cold block (CB) procedure (1 h at 4°C) immediately after a training session blocks LTM formation in the S-strain but not in a freshly collected strain. Four weeks at 4°C transformed the S-strain phenotype into one resisting the CB procedure. Thus, with a 4 week cold spell snails gain a resistance to the CB procedure, and that would explain why freshly collected snails are resistant to the procedure. However, we found that F1 progeny of a freshly collected strain reared in the laboratory were resistant to the CB procedure. This suggests that an unknown selection resulted in the S-strain being susceptible to the CB procedure.