Scientists records brain activity of free-flying bats

April 10, 2018, Johns Hopkins University
A bat fitted with wireless brain activity recording equipment flies in a room equipped with high-speed cameras and an array of microphones to pick up echolocation calls. Credit: Dave Schmelick and Len Turner/Johns Hopkins University

Johns Hopkins University researchers have developed a way to study the brain of a bat as it flies, recording for the first time what happens as a roving animal focuses and refocuses its attention.

This groundbreaking advance allows us to see what happens in the brains of naturally behaving animals, uninhibited by laboratory constraints. Because bats share the same basic brain structure as all mammals, including humans, the achievement, published today in the journal eLife, deepens our understanding of what happens in the brain as we move through the world.

"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," said co-author Melville Wohlgemuth, a postdoctoral fellow. "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."

To study a bat as it flew, the team first needed a wireless recording device that wouldn't weigh down an animal that itself weighs less than an ounce.

Such a device took about a year to develop with the help of an outside engineering firm, and then another year of trial and error to perfect. The team also equipped a "flight room" with high-speed cameras and an array of microphones to pick up the bat's echolocation calls.

None of this existed 25 years ago when senior author Cynthia Moss, a professor of psychological and brain sciences at Johns Hopkins, first dreamed of studying a bat as it flew. Until now, researchers have been limited to observing the brains of stationary animals engaged in simple and often contrived behaviors—like watching a pixel on a computer screen. They could learn from the brain of an immobile bat, but an artificial circumstance can only reveal so much about how the brain behaves in a real-world situation.

And in the real world, what bats and other animals typically do is move.

Johns Hopkins University researchers have developed a way to study the brain activity of a bat as it flies. Credit: Dave Schmelick and Len Turner/Johns Hopkins University

"Twenty-five years ago, I was talking with a colleague about recording neural activity from a free-flying bat, and he looked at me like I had two heads," Moss said. "It has taken a lot of effort and advancement in technology to make this possible."

The Johns Hopkins team is among the first in the world to wirelessly record brain activity, and the first to do it as an animal moved through space, shifting its attention from object to object. Bats produce high frequency sounds that bounce off objects, and they listen to echoes to "see" where the objects are in the environment.

The team was ultimately able to combine data about the bat's location, the time of the bat's vocalizations, and the bat's brain activity, to determine which objects caused neurons to fire and, therefore, what the bat was paying attention to.

As a bat focused on objects, the researchers observed bursts of activity in certain midbrain cells—something that would likely happen when any animal, including humans, shifts attention.

"We can see how the moving animal interacts with objects, just like a person would walking in the woods," Wohlgemuth said.

Finally observing in a free-moving animal was monumental for the authors, who see much potential in using the technique for future studies.

"To see signals in the when an animal is really looking at something and then to see a neuron fire, was the holy grail for me," said co-author Ninad Kothari, a graduate student. "As this research goes forward, we can take the information we get from like bats, mice and owls and put it into human terms to potentially help people with attention deficits."

Explore further: What bats reveal about how humans focus attention

More information: Ninad B Kothari et al, Dynamic representation of 3D auditory space in the midbrain of the free-flying echolocating bat, eLife (2018). DOI: 10.7554/eLife.29053

Related Stories

What bats reveal about how humans focus attention

February 23, 2016

You're at a crowded party, noisy with multiple conversations, music and clinking glasses. But when someone behind you says your name, you hear it and quickly turn in that direction.

How a flying bat sees space

October 21, 2015

Recordings from echolocating bat brains have for the first time given researchers a view into how mammals understand 3-D space.

Recommended for you

Scientists see human immune response in the fruit fly

June 19, 2018

Washington State University researchers have seen how both humans and fruit flies deploy a protein that a plays a critical role in their immune responses to invading bacteria. The discovery gives scientists evolutionary insight ...

World's first known manta ray nursery discovered

June 19, 2018

A graduate student at Scripps Institution of Oceanography at the University of California San Diego and colleagues from NOAA's Office of National Marine Sanctuaries have discovered the world's first known manta ray nursery.

Road rules for gene transfer are written in DNA

June 19, 2018

A new discovery suggests that bacteria's ability to transfer genes, like those associated with antibiotic resistance, are governed by a previously unknown set of rules that are written in the DNA of the recipient.

Blue gene regulation helps plants respond properly to light

June 19, 2018

Researchers at the RIKEN Center for Sustainable Resource Science (CSRS) have discovered a process through which gene expression in plants is regulated by light. Published in Proceedings of the National Academy of Sciences ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.