A thermal stressor, propranolol and LTM formation in freshly collected Lymnaea [RESEARCH ARTICLE]
Cayley Swinton, Erin Swinton, Iain Phillips, and Ken Lukowiak A heat stressor (1h at 30o C) in Lymnaea stagnalis before operant conditioning training of aerial respiration is sufficient to enhance long-term memory (LTM) formation in average cognitive-ability, laboratory-reared, inbred snails. However, in freshly collected outbred snails the same heat stressor blocks LTM formation in smart cognitive phenotype but not in average cognitive phenotype strains. Here we hypothesize that: 1) preventing the stress associated with the heat stressor before training allows LTM to form in the smart phenotype strains ; and 2) alleviating the stress before a memory recall session allows a formed LTM to be recalled in the smart phenotype strains. We found that an injection of propranolol, which mitigates the stressor, before snails experience the heat stressor enabled two strains of the smart phenotype snails to form LTM formation, consistent with our first hypothesis. However, the injection of propranolol before a memory test session, did not alleviate a memory recall block in the smart phenotype snails. Thus, our second hypothesis was not supported. Thus, smart cognitive phenotype snails encountering a heat stressor have an inability to form LTM, but this inability can be overcome by the pre-injection of propranolol.