Using Echolocation to determine how mammals view 3D space
Scientists from a National Science Foundation (NSF) research team have recently gained a deeper insight into how mammals understand 3D space. Bats were trained to fly around rooms, navigating obstacles and landing on specific perches in a study that aimed to interpret how these animals utilise echolocation to sense their environment.
Bats direct their calls to specific targets in their surroundings in order to inspect or avoid them in a similar way to humans and other mammals which use their eyes to scan a room/area whilst navigating through it. In particular the mid-brain superior colliculus which is responsible for “orientating behaviour” was studied as it plays an important role in how animals move through space. all mammal brains contain a mid-brain superior colliculus but for most species, that means using visual cues. For bats, it means acoustic ones, aka echolocation.
“We deal with a lot of complex information,” said Melville Wohlgemuth, a postdoctoral student in Moss’s lab who worked on the research. “When you put all this complex information together you have to parse out what’s important. The bat system is really good for that. When they make a vocalization, they get echoes back from all around their world. They need to pick out the one echo that is important to them. So this also gives us a good idea of how sensorimotor integration for attending to a specific stimulus in your world is conducted in the brain.”
Cynthia Moss of Johns Hopkins University researches spatial perception, memory, motor behaviors and more. Her Batlab created an echolocation model which calculates how bats receive and process signals from their calls, microphones were used to capture each echolocation emitted from the bats as they flew with high speed infrared cameras providing additional information on the bats angle in the air during the calls.
They offer a tremendous advantage over other mammals, because they use an active sensing system that gives us direct access to the information they’re using to guide their behavior,” said Cynthia Moss. “We can use the signals to really get inside the bat’s head.
These recordings sampled individual neurons from the bats mid-brain colliculus and researchers were tasked with discovering what roles each individual neuron had e.g. to determine if an object is near, to determine if the object is alive/moving and is therefore a prey item. This allowed scientists to understand how bats represent 3D space in their brains and marks the first time scientists have understood how echolocation works on a neural level in a free-flying bat and it could help us understand how mammals in general comprehend their environment.
“We really wanted to bring these experiments to the point where we could look at the neural activity in the context of natural behaviors,” Moss said. “So this has been a really big breakthrough, to make these recordings.”
A better understanding of echolocation could help improve unmanned aerial vehicles and other technology that uses sonar, said Ninad Kothari, a graduate student in Moss’s lab who built the echo model. It could also help blind people better navigate their world, “if they can use the rules that bats use,” Kothari said.
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