Effect of photoperiod and light intensity on learning ability and memory formation of the pond snail Lymnaea stagnalis

Ahmed A.A. Hussein*, El Sayed Baz, Janine Mariën, Menerva M. Tadros, Nahla S. El-Shenawy, Joris M. Koene

*Corresponding author for this work

    Research output: Contribution to JournalArticleAcademicpeer-review


    Natural light is regarded as a key regulator of biological systems and typically serves as a Zeitgeber for biological rhythms. As a natural abiotic factor, it is recognized to regulate multiple behavioral and physiological processes in animals. Disruption of the natural light regime due to light pollution may result in significant effects on animal learning and memory development. Here, we investigated whether sensitivity to various photoperiods or light intensities had an impact on intermediate-term memory (ITM) and long-term memory (LTM) formation in the pond snail Lymnaea stagnalis. We also investigated the change in the gene expression level of molluscan insulin-related peptide II (MIP II) is response to the given light treatments. The results show that the best light condition for proper LTM formation is exposure to a short day (8 h light) and low light intensity (1 and 10 lx). Moreover, the more extreme light conditions (16 h and 24 h light) prevent the formation of both ITM and LTM. We found no change in MIP II expression in any of the light treatments, which may indicate that MIP II is not directly involved in the operant conditioning used here, even though it is known to be involved in learning. The finding that snails did not learn in complete darkness indicates that light is a necessary factor for proper learning and memory formation. Furthermore, dim light enhances both ITM and LTM formation, which suggests that there is an optimum since both no light and too bright light prevented learning and memory. Our findings suggest that the upsurge of artificial day length and/or night light intensity may also negatively impact memory consolidation in the wild.

    Original languageEnglish
    Article number18
    Pages (from-to)1-9
    Number of pages9
    JournalInvertebrate Neuroscience
    Issue number4
    Early online date19 Oct 2020
    Publication statusPublished - Dec 2020


    We thank Maha F. Soliman for valuable comments as well as C.M. Popelier and O. Bellaoui for technical assistance and the organisers and participants of the 1st Symposium on Invertebrate Neuroscience for valuable comments and suggestions. This research was partly supported and funded by the Egyptian Mission Sector, Ministry of High Education and Scientific Research. This work was supported by Cultural Affairs and Missions Sector, Egyptian Ministry of Higher Education (Grant No. 2015/2016). Acknowledgements

    FundersFunder number
    Cultural Affairs and Missions Sector
    Egyptian Mission Sector
    Ministry of Higher Education and Scientific Research
    Ministry of Higher Education2015/2016


      • Conditioning
      • Gastropod
      • Light intensity
      • Memory
      • MIP II
      • Mollusk
      • Photoperiod


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