Mollusks "Thinking" Differently

While animals may act similarly, the brain patterns they use to accomplish these identical behaviors may vastly differ, even when the animals have closely related brains, researchers from Georgia State University have discovered. This finding challenges basic ideas about the relationship between neurology and behavior. The scientists have not yet unraveled the cause for this, but this research shows that key animal behaviors can survive evolution processes that affect the brain.

The studies focused on two different species of nudibranch, gastropod mollusks similar to sea slugs that exist in many shapes and colors around the world. The team studied two species: the lion's mane nudibranch and the giant nudibranch. Both species swim in the same way — by flattening their bodies and then flexing them from side to side.

Image Credit: Tentaculata/WikiCommons[/caption]This shared form of propulsion isn't all they have in common. The species also both have simple nervous systems populated with similar neurons, which appear to be located in similar positions. Before this research was conducted, biologists assumed that the neural circuits governing movement in these species were the same — but the team from Georgia State has proven that they're not.After the researchers observed different brain patterns in the two nudibranch, they blocked the giant nudibranch's normal neural pathway for swimming and instead stimulated its brain to simulate the neural connections in the hooded nudibranch. The giant nudibranch was able to swim again, but now used its neurons the way the hooded nudibranch did. This confirmed that the two different brain patterns did indeed produce identical behaviors.

New Ideas About Neurology

These results suggest that the brain can find new ways to preserve important behaviors even as the nervous system evolves. The scientists are not sure how this process occurs, or what led to the peculiar case of the two nudibranch species, but they plan to keep exploring this phenomenon.

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“Perhaps some of the neurons in one or the other species have taken on additional functions that provide selective pressure to alter the ancestral connectivity,” the researchers suggested in their paper.

While this may simply be an example of random genetic diversity, it could also provide insight into our studies of the human brain. At the very least this research demonstrates the mystery that is the nervous system, and that even cases that appear simple at first glance can have complexities we would have never imagined just beneath the surface.

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