According to Crossley, these tiny collectors are also “great learners,” able to recall something with just one touch. In a new study, researchers took a deep look into the snail’s brain to understand what happens at the neurological level when the snail acquires a memory.
soothe memories
In the experiment, the researchers gave the snails two forms of training: strong and weak. During intense training, they first sprayed the snails with banana-flavored water. The snail treated it as neutral in its charm. The snail swallowed some, but then spit some out. The research team then fed the snails sugar, which they greedily ate.
Testing the snails a day later showed that the snails had learned to associate the banana flavor with sugar from that one experience. The snails seemed to perceive the flavor as more desirable and were much more willing to swallow the water.
In contrast, snails did not learn this positive association from weaker training sessions of a coconut-flavored bath followed by a more dilute sugar treat. The snail kept swallowing and spitting up water.
So far, this experiment has been essentially a snail version of Pavlov’s famous conditioning experiment, in which dogs learn to drool when they hear a bell. But the scientists looked at what happened when the snails were given a strong banana flavor training and then a few hours later a weak coconut flavor training. Suddenly the snail also learned from weak training.
When the researchers reversed the order and gave them weaker training first, they still failed to confer a memory. Although snails still form strong training memories, it had no retroactive reinforcing effect on previous experiences. Swapping the flavors used in high and low training had no effect.
Scientists believe that intense training pushes snails into a “learning-rich” period when the threshold for memory formation is low, something they otherwise wouldn’t learn (such as the weak training link between tastes). I concluded that I could learn. light sugar). Such mechanisms could help the brain direct resources toward learning at the right time. Food can make snails more wary of potential nearby food sources. Being in danger can sharpen your sensitivity to threats.
a Limnaea The snail, which combines flavored water and sugar, opens and closes its mouth quickly to swallow (right). A snail that has not learned associations keeps its mouth closed (left).Video: Michael Crossley, Kevin Stalas/Quanta Magazine
However, the effect on snails was temporary. A period rich in learning lasted only 4 hours after intensive training, from just 30 minutes. Subsequently, the snails no longer formed long-term memories during weak training sessions. It wasn’t because I forgot the intense workout, but the memory lasted for months.
It makes sense to have a significant window to enhance learning. Because if this process isn’t turned off, “it can be harmful to animals,” says Crossley. When that happens, animals not only invest significant resources in learning, but may learn associations that are detrimental to their survival.
change in perception
Using electrodes, researchers have uncovered what happens in the snail’s brain as it forms a trained long-term memory. In brain activity he two fine adjustments occur in parallel. The first encodes the memory itself. The second “is purely about changing the animal’s perception of other events,” says Crossley. “Change the way you see the world based on your past experiences.”
They also found that blocking the effects of dopamine, a brain chemical produced by neurons that activate spitting behavior, could induce the same changes in snail perception. In fact, it turned on the neurons for exhaling and left the neurons for swallowing on all the time. This experience had the same carry-over effect as strong training in the previous experiment. After several hours, the snails formed a long-term memory of the weak training.
