How the brain calculates a quick escape


An impala runs away from a cheetah. IMAGE/Valerio Ferraro / REDA&CO/Universal Images Group via Getty Images

Survival of the fittest often means survival of the fastest. But fastest doesn’t necessarily mean the fastest moving. It might mean the fastest thinking. When faced with the approach of a powerful predator, for instance, a quick brain can be just as important as quick feet.

After all, it is the brain that tells the feet what to do — when to move, in what direction, how fast and for how long. And various additional mental acrobatics are needed to evade an attacker and avoid being eaten. A would-be meal’s brain must decide whether to run or freeze, outrun or outwit, whether to keep going or find a place to hide. It also helps if the brain remembers where the best hiding spots are and recalls past encounters with similar predators.

All in all, a complex network of brain circuitry must be engaged, and neural commands executed efficiently, to avert a predatory threat. And scientists have spent a lot of mental effort themselves trying to figure out how the brains of prey enact their successful escape strategies. Studies in animals as diverse as mice and crabs, fruit flies and cockroaches are discovering the complex neural activity — in both the primitive parts of the brain and in more cognitively advanced regions — that underlies the physical behavior guiding escape from danger and the search for safety. Lessons learned from such studies might not only illuminate the neurobiology of escape, but also provide insights into how evolution has shaped other brain-controlled behaviors.

This research “highlights an aspect of neuroscience that is really gaining traction these days,” says Gina G. Turrigiano of Brandeis University, past president of the Society for Neuroscience. “And that is the idea of using ethological behaviors — behaviors that really matter for the biology of the animal that’s being studied — to unravel brain function.”

Think fast

Escape behavior offers useful insight into the brain’s inner workings because it engages nervous system networks that originated in the early days of evolution. “From the moment there was life, there were species predating on each other and therefore strong evolutionary pressure for evolving behaviors to avoid predators,” says neuroscientist Tiago Branco of University College London.

Not all such behaviors involve running away, Branco notes. Rather than running you might jump or swim. Or you might freeze or play dead. “Because of the great diversity of species and their habitats and their predators, there are many different ways of escaping them,” Branco said in November in San Diego at the 2022 meeting of the Society for Neuroscience.

Of course, sometimes an animal might choose fight over flight. But unless you’re the king of the jungle (or perhaps a roadrunner much smarter than any wily predatory coyote), fighting might be foolish. When an animal is the prey, escape is typically its best choice. And it needs to choose fast.

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