PROVIDENCE, R.I. [Brown University] — In a paper published this week in Science, researchers at Brown University and from the Republic of Georgia have learned how bats can home in on a target, while nearly instantaneously taking account of and dismissing other objects in their midst. The trick lies in their neurons: Bats can separate the cavalcade of echoes returning from their sonar pulses by distinguishing changes in amplitude — the intensity of the sound — between different parts of each echo within 1.5 decibels, to decide whether the object is a target or just background clutter.
The minute change in amplitude is enough to cause a delay in the bats' neural response to an echo, letting the bat know what is clutter and what is the target. It is as if the bat is using two screens — a main screen that keeps it locked in on its target by virtue of its neural response to the echo and another, secondary screen that keeps note of surrounding objects but doesn't fixate on them.
"Everything the bat sees using sonar is based on the timing of the neural responses and nothing else," said James Simmons, professor of neuroscience at Brown and an author on the paper.
The research is important because it could help refine the maneuverability of sonar-led vehicles and improve their ability to remain fixed on a target even in dense, distracting surroundings.
"What the bat does is it takes clutter and defocuses it, like a camera would, so the target remains highly defined and in focus," Simmons said.
Tengiz Zorikov from the Institute of Cybernetics in the Republic of Georgia contributed to the research. The U.S. Office of Naval Research, National Institutes of Health, and the National Science Foundation funded the work.
Contact: Richard Lewis Richard_Lewis@brown.edu 401-863-3766 Brown University