Stressed-Out Snails Become Forgetful
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ScienceShot: Stressed-Out Snails Become Forgetful

Snails get stressed out, too—and it's not good for them either. Scientists have found that multiple sources of stress can impair the memories of the slimy gastropods. A team placed pond snails (Lymnaea stagnalis, like the one above) in water-filled beakers that varied in stressfulness: Some were overcrowded, some contained water low in calcium (stressful, for a snail), and some were both overcrowded and low in calcium; the beakers varied inconsequentially in oxygen levels. Then, the team placed the snails in an uncrowded beaker containing water with a normal level of calcium and trained the snails to not come up for air—no big deal for pond snails, who can also get oxygen by absorbing it underwater through their skin. Each time a snail popped its breathing hole out from under its shell and above water, it received a gentle poke. After the lesson, the snails were put to a test: Could they remember to take in oxygen just underwater? The team reports today in PLOS ONE that whereas snails trained after spending time in an environment with just one stressor were able to remember the training for minutes or even hours, snails that were exposed to the multistressor environment were not able to form a memory of it at all; they came up for air despite their training. Because snail brains experience stress in a similar way to mammal brains, the findings are potentially analogous to higher-stakes, human-scale scenarios—like trying to absorb important information after hanging out in a crowded conference room, while hungry and tired.

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