Dr. Cynthia Moss (left), principle investigator at the University of Maryland Auditory Neuroethology Laboratory, and her collaborator Dr. Susanne Sterbing-D’Angelo discover that sensors on bat wings affect flight maneuverability.
To help them navigate in the dark, bats have hairs on their wings that allow them to detect small changes in airflow in a way similar to feeling a light touch, university researchers found.
A study published in Cell Reports last month addressed the function of these hairs, which are widely distributed on the wings of bats. While scientists have known these hairs exist, their function was long unknown, said Cynthia Moss, a study co-author who completed the research while at this university.
“It had been hypothesized that they play a role in airflow sensing, and we did some experiments that demonstrate that indeed they do,” said Moss, currently a professor at Johns Hopkins University.
The study demonstrates that the hairs, while not receptors themselves, act as levers that activate sensory receptors in bats’ wings that are associated with light touch, Moss said.
The bat’s brain is wired to detect changes in airflow and touch information. Depending on the position of a bat’s wings as it is flying, the airflow stimulates the wings in different ways, Moss said.
This research is part of a larger project funded by the U.S. Air Force to learn about flight control in winged animals and apply the information to aerial vehicles, Johns Hopkins assistant research scientist Susanne Sterbing-D’Angelo, a co-author of the paper, wrote in an email.
“Bats are good models for these kinds of questions because bats are extremely maneuverable flyers, and they are the only mammals that are capable of true powered flight,” recent doctoral alumnus Mohit Chadha said.
In a 2011 study, the researchers focused on the neurophysiology of how these sensors might affect signals sent to a bat’s brain.
“When this earlier paper was published, we provided evidence that bats can actually sense airflow through their wings, and if we manipulate this, then it results in changes in flight behavior,” said Chadha, a co-author of the paper.
The behavioral study was conducted with brown bats placed in a flight room with obstacles for them to fly around. They recorded the flight paths before and after hair removal on their wings and measured the responses to the bats’ brains using electrodes.
“The first thing we showed was that if you depilate the bat wings, if you remove the hair from their wings, the brain responses are abolished,” Chadha said. “You see that in an obstacle course where the bats maneuver around the trees, the flight behavior of bats with their wings depilated made wider turns, and they didn’t fly as close to the obstacle.”
These studies suggest hairs catch airflow signals and the brain then processes the hair movements, Moss said.
“Touch is really important in guiding movement. This research helps us build general knowledge about how sensory systems are integrated with motor systems to enable complex behaviors,” Moss said.