Brain complexity: bat brains have a GPS memory (Introduction)

by David Turell , Monday, August 20, 2018, 20:02 (2076 days ago) @ David Turell

New research in mammals for 3-D natural studies of behavior using bats:

https://www.scientificamerican.com/article/the-bat-man-neuroscience-on-the-fly/?utm_sou...

"The vast majority of experiments probing navigation in the brain have been done in the confines of labs, using earthbound rats and mice. He constructed the flight tunnel on a disused plot on the grounds of the Weizmann Institute of Science—the first of several planned arenas—because he wanted to find out how a mammalian brain navigates a more natural environment. In particular, he wanted to know how brains deal with a third dimension.

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"The tunnel, which Ulanovsky built in 2016, has already proved its scientific value. So have the bats. They have helped Ulanovsky to discover new aspects of the complex encoding of navigation—a fundamental brain function essential for survival. He has found a new cell type responsible for the bats’ 3D compass, and other cells that keep track of where other bats are in the environment.

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"And for brain scientists hitting the limits of what they can learn from highly simplified behaviour in the lab, Ulanovsky is a pioneer of "natural neuroscience." Over the years, his arenas and tunnels have been getting larger, more sophisticated and less like an artificial lab environment. Up next is a giant maze that will allow his team to ask even more advanced questions about how the brain copes with making decisions—such as which way to turn—on the wing.

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"In this set-up, he has been able to reveal the 3D territory of a typical bat-nav neuron. For example, place-cell fields—measured in rats as flat circles of a particular size—turned out in flying bats to be almost spherical, showing none of the vertical elongation that some rat experiments had predicted. He worked out how head-direction cells operate as a 3D compass, and discovered another type of navigation cell—the long-sought vector cell—which tracks angle and distance to a particular goal. One series of experiments helped put to rest a once-popular theory from rat studies that proposed that a certain type of brain oscillation creates grid-like neural maps; the oscillation turned out to be absent in bats, and therefore not necessary for such map-building.

"He also explored the influence of a bat’s social world. When he put a companion bat into the flight room, he discovered that the monitored bat had ‘social place cells’ that track the companion’s position. He’d imagined that such cells must exist somewhere in the brain—bats obviously need to know where their fellow bats are, as well as their predators—but was not expecting they would necessarily show up inside the hippocampus. He is now monitoring how the brains of two or three bats register the social interaction of up to ten companion bats living together in the large flight room for several months.

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"Since the inaugural flight in March 2016, Ulanovsky and his students have collected data from more than 200 neurons across different bats. These early data hint at interesting insights. For example, Ulanovsky found that a single cell would fire at one location in a small area but also at a quite different location in a large area, indicating that place cells might represent multiple spatial scales, not just one particular scale. Researchers hadn’t been able to spot this pattern in experiments in small enclosures. Ulanovsky needs more data to confirm this, but it would be in line with the predictions of some theoreticians. “If place cells all had small, laboratory-sized place fields, there would not be enough neurons in the hippocampal area to individually cover the great distances that bats travel,” says Ulanovsky, “so it makes sense that some place cells respond to multiple scales.”

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“'Behavioural neuroscientists like myself are increasingly realizing how important it is to move away from overtrained lab-animal brains,” she says. In typical lab experiments, animals are trained in a very specific, usually unnatural, task. “That may not have anything to do with how that animal has evolved brain connectivity to optimize foraging in the wild,” she says.

"Like others around the world, Angelaki’s lab is starting to use neural loggers to monitor more natural rodent behaviour, such as foraging for food scattered in their enclosures. She predicts that more researchers will start setting up their experiments with an eye on the natural world. “Over the next five years or so, results will start to emerge and there will be a big change in neuroscience practice,” she says.

"However, as Moser notes, Ulanovsky’s bats aren’t yet doing anything as clever as finding a fruit tree in the wild. “It doesn’t take much thought to fly up and down a tunnel,” he says. So Ulanovsky is nursing an even bigger mind-reading ambition. He is seeking funding for a maze 40 metres wide and 60 long—a little under half the size of a football pitch—to test how bat brains represent more complex environments, then plan and make decisions about how to navigate them."

Comment: Humans must have a GPS also. Our artificial insemination expert, when we had cattle, had a stroke and lost his geographic sense except for our local town, but had to be driven into Houston when he needed to go there.