Worms' Mental 'GPS' Helps Them Find Dinner

Animals use a bit of a "foraging' strategy to look for things. Yet did you know that scientists have developed a mathematical theory-based on roundworm foraging-that helps predict how animals decide to switch from localized to very broad searching. The new theory could even help explain certain animal behaviors in a more unified way.

"How do you decide which route to take home or which problem to work on? This theory is exploring what ultimately makes us human-how we make decisions based on partial information affects all aspects of our lives," said Tatyana Sharpee, associate professor of Salk's Computational Neurobiology Laboratoryand senior author of the paper, which was published in eLife on December 9, 2014, in a news release. "What is surprising is that these simple organisms with a very small nervous system perform-or approximate-fairly complex, multistep, long-term planning strategies."

"Seeking information about a target is often better than seeking the target itself," researchers added. "And what this paper confirms in a theoretical model is that you don't need lots of neurons to perform these searches that include switching from a local to a global search-you can approximate it by using just three neurons, as in the roundworm C. elegans."

Looking for food sources is critical to an animal's survival. As such, researchers discussed how C elegans worms have been known to conduct an intense search of an area where they believe food may be.

Yet, after about 15 minutes, they turn less and explore a more extended area. Since the worms didn't have a chemical gradient to follow, the team work to explore the underlying strategy of the worms' behavior with data from Chalansani's experimental studies, Sharpee's lab developed virtual simulations of the worms to model their behavior.

Though this information-maximizing theory has been tested in a few types of behavior, Sharpee and others believe it could provide a basis for a larger, unified framework to examine different types of behavior across species, cells, neurons and larger scale phenomenon.

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