In one corner of the basement of Ames Hall at the Johns Hopkins University, Cynthia Moss opened the door of a room where about a dozen Egyptian fruit bats dozed inside a milk crate attached to the wall.
"Come on, sweeties," she said, stirring them up, and they raced in circles around her head.
Adjacent to the climate-controlled bat rooms live 14 barn owls, whose spaces are quieter and where the floors are littered with the remains of bloodied mice — a recent meal — and droppings. Shreesh Mysore often places the owls, tummies down, inside a box-like apparatus and places little headphones over their ears as part of his research into how the birds focus their attention.
The two professors, who work in Hopkins' department of psychological and brain sciences, share an interest in the study of attention and hope to find ways to collaborate. They believe their work may lead to a better understanding of how blind people navigate the world, or the cause of disorders such as attention-deficit hyperactivity disorder, schizophrenia and autism.
Mysore explains how humans use attention to move through the world like this: As children learn to walk, the task requires great concentration. Once they master walking, it becomes almost automatic, requiring less of their immediate attention unless they trip or run into something. They store the knowledge of how to walk as a memory.
Mysore and Moss believe bats and owls also use memory to navigate.
"There's been an observation over the years that bats make mistakes," Moss said. "They make sounds but aren't listening to the echoes. So if they make mistakes, we infer that they're relying on memory."
She added: "Bats only work as hard as they have to. Relying on memory is less demanding."
Moss's bat lab is covered in black soundproofing material and features a battery of high-speed cameras lined up on the wall and 32 microphones. On a recent day, Wu-Jung Lee, a postdoctoral researcher, was hunched over a laptop on the floor, testing audio of moths' wings flapping. Lee brought in a luna moth in on a string harness to demonstrate how they would record the sound of the insect, then replay it later with bats in the room.
Such experiments, in which the bats' movements would be captured on the high-speed cameras and their squeaks recorded on the audio equipment, are an attempt to learn more about how bats process information. Moss has about 70 bats representing four different species for her work.
Moss said some blind people use a sort of echo-location — tongue clicks — to navigate, and once had a group of them visit the lab.
"We invited them to the lab thinking we could ask them questions we couldn't ask the bats," she said. "They use a combination of echo-location and memory and experience. I thought, of course this is true for the bats as well."
In Mysore's experiments, once the owl is still, he sticks electrodes as thin as a human hair into its brain while the room is darkened. The owl watches a giant TV screen where white dots flash occasionally against a black background, and various noises are played through headphones. The researchers simultaneously monitor the owl's brain activity to determine how the owl's neural circuits are processing the competing demands for attention.
Mysore said it's not well understood how disorders like ADHD, where there's an inability to focus attention, and autism, where attention is hyper-focused, occur. Much is known about how the brain processes one thing at a time, he said, but not the competing demands for attention that are common in the real world.
By doing the research with the owls, Mysore said, he's learning more about how their brains determine which thing requires more immediate attention — the sound or the white dot — and what that means.
Such experiments can't be performed on humans, Mysore said. "We are very far from figuring out what is going on in the neural circuits," he said.
Hopkins is building new cages for the owls and bats for the building's roof, which are expected to be ready by the spring. They'll have heaters in the winter and the professors hope they will offer a more natural home for the animals than the cages in the basement.
The roof cages, will, of course, be separated and the animals wouldn't be able to see each other.
"Owls are carnivorous," Moss said, "so they would eat the bats if they could."