Ordinarily, if you want to see what's going on in a bat's brain, you have to hold the animal immobile and wire it up – not the best setup for studying how it reacts while moving through the real world. Now, however, scientists have devised a method of recording the brain activity of free-flying bats.

Cynthia Moss, a professor of Psychological and Brain Sciences at Johns Hopkins University, first conceived of recording the neural activity of bats-in-flight 25 years ago. At the time, however, the technology just wasn't there. More recently, working with an outside engineering firm, her team spent a year developing a wireless device that made it possible. Another year was spent in the trial-and-error process, perfecting it.

Now in use in a special "flight room," the device is very small and lightweight, in order to allow a big brown bat (Eptesicus fuscus) to fly while wearing it. It's mounted on the animal's head and incorporates a probe that extends into the brain.

While the bat flies through an obstacle course in the flight room, the device monitors the electrical activity of its brain, wirelessly transmitting that data to a ceiling-mounted receiver. At the same time, high-speed cameras track the bat's position in three-dimensional space, and an array of microphones record the high-frequency vocalizations it uses for echolocation.

By combining and syncing up these three types of data, the researchers have been able to establish what the bat's brain is doing as the animal focuses and then shifts its attention between various objects in its path. More specifically, they noted "bursts of activity in certain midbrain cells" which likely also occur in other animals – including humans – as they shift their attention.

It's even possible that findings made by studying the bats could be applied to the treatment of problems such as attention deficit disorder in people.

"If you want to understand how the brain operates in the real world, you have to have the animal moving through the world in a natural way," says postdoctoral fellow Melville Wohlgemuth, co-author of a paper on the research. "This idea of recording the brain without wires is brand new. And no one has used it to understand how an animal senses the world and reacts to that information."

The paper was recently published in the journal eLife.

Source: Johns Hopkins University

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